resistance remains largely under-explored. The risk of horizontal gene transfer between soil microorganisms, commensal bacteria and/or human pathogens needs to be further elucidated, and the environmental triggers for gene transfer need to be better understood. Findings of antibiotic resistance from animal manures are emerging, but even fewer bioremediation studies using sewage sludge have made any reference to antibiotic resistance. Resistance mechanisms, including those to antibiotics, have been considered by some authors to be a positive trait associated with resilience in strains intended for bioremediation. Nevertheless, recognition of the potential risks associated with antibiotic resistant bacteria and genes in contaminated soils appears to be increasing and requires further investigation. Careful selection of bacterial candidates for bioremediation possessing minimal antibiotic resistance as well as pre-treatment of organic wastes to reduce selective pressures (e.g., antibiotic residues) are suggested to prevent environmental contamination with antibiotic-resistant bacteria and genes.

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Shifts in microbial community, pathogenicity-related genes and antibiotic resistance genes during dairy manure piled up

Authors: Zhang X, Ma CJ, Zhang W, and more...

Source: MICROBIAL BIOTECHNOLOGY 13(4):1039-1053, 2020, DOI: 10.1111/1751-7915.13551

**Abstract:** The uncomposted faeces of dairy cow are usually stacked on cow breeding farms, dried under natural conditions and then used as cow bedding material or they may be continuously piled up. However, no information is available to evaluate variations in the human and animal pathogen genes and antibiotic resistance during the accumulation of fresh faeces of dairy cow to manure. Here, we present the metagenomic analysis of fresh faeces and manure from a dairy farm in Ning Xia, showing a unique enrichment of human and animal pathogen genes and antibiotic resistance genes (ARGs) in manure. We found that manure accumulation could significantly increase the diversity and abundance of the

pathogenic constituents. Furthermore, pathogens from manure could spread to the plant environment and enphytotic pathogens could affect the yield and quality of crops during the use of manure as a fertilizer. Levels of virulence genes and ARGs increased with the enrichment of microbes and pathogens when faeces accumulated to manure. Accumulated manure was also the transfer station of ARGs to enrich the ARGs in the environment, indicating the ubiquitous presence of environmental antibiotic resistance genes. Our results demonstrate that manure accumulation and usage without effective manure management is an unreasonable approach that could enrich pathogenic microorganisms and ARGs in the environment. The manure metagenome structure allows us to appreciate the overall influence and interaction of animal waste on water, soil and other areas impacted by faecal accumulation and the factors that influence pathogen occurrence in products from dairy cows.

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Indole-3-acetic acid synthesizing chromium-resistant bacteria can mitigate chromium toxicity in *Helianthus annuus* L.

Authors: Hadia-e-Fatima, Ahmed A

Source: PLANT SOIL AND ENVIRONMENT 66(5):216-221, 2020, DOI: 10.17221/581/2019-PSE

**Abstract:** Use of microorganisms as heavy metal remediators is an effective approach for chromium reduction in plants. Chromium carcinogenicity (Cr6+) beyond the permissible levels elicits environmental and health problems. To reduce chromium toxicity along with the plant growth improvement, a cost-effective and eco-friendly remediation approach is necessary. In the current study, chromium-resistant bacterial species were evaluated for growth improvement of sunflower. Three auxin-producing bacteria able to tolerate hexavalent chromium, i.e., Sporosarcina saromensis (El) and two species of Bacillus cereus (AR and 3a) were selected for the proposed study. Growth studies along with auxin synthesis potential of bacterial isolates with and without chromium were
conducted. Results revealed a 188% enhancement in plant height under laboratory-grown plants with *B. cereus* (AR) under 500 mg/L chromium stress (Cr6+). *B. cereus* (3a) also showed an 81% increase in leaf number with 400 mg/L chromium stress in laboratory-grown plants. Similarly, 73% increment in the amount of auxin was reported in the case of inoculation with *S. saromensis* isolate (El) over respective control treatment. These improvements provide an excellent means of reducing chromium (Cr6+) in the contaminated soils naturally by stimulating plant growth along with bioremediation potential.

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## Growth enhancement and cadmium uptake efficiency in *Medicago sativa* by endophytic bacteria isolated from *Dathura innoxiad*

**Authors:** Aurangzeb N, Khan A, Nisa S, Nazish M, and more...

**Source:** FRESENIUS ENVIRONMENTAL BULLETIN 29(4):2134-2143

**Abstract:** Application of endophytic bacteria can enhance heavy metal removal efficiency of hyperaccumulator plants. These endophytic bacteria can alter metal solubility and facilitate metal accumulation and plant growth. The present study was aimed to isolate endophytic bacteria from roots of Dathura innoxia, growing in heavy metal (HM) contaminated soils and to evaluate their potential to solubilize cadmium (Cd) and promote phytoextraction. Among the eleven isolates, two strains *Bacillus cereus* and *Pseudomonas azotoformans* were able to significantly affect Cd bioleaching. Furthermore, resistance capability of these endophytic bacteria was determined by exposing them to 100 mg/l- 400 mg/l Cd solution for various time intervals. Results of study showed that both *Bacillus cereus* and *Pseudomonas azotoformans* were able to tolerate 100 mg/l and 200 mg/l of Cd concentration in liquid media. Medicago sativa seedlings grown in artificially contaminated soils with 100 mg/kg and 200 mg/kg of Cd concentration were bioaugmented with similar to 10(8) colony-forming units (CFU) per milliliter of bacterial strains to determine

their role in growth and uptake of exposed metal. Inoculation of bacterial strains significantly stimulated plant biomass (51 g - 59 g). The study concluded that isolated endophytic bacteria can be utilized effectively for phytoextraction of Cd in non-host plants as well.

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## Screening of Heavy Metal-Immobilizing Bacteria and Its Effect on Reducing Cd2+ and Pb2+ Concentrations in Water Spinach (*Ipomoea aquatic* Forsk.)

**Authors:** Wang T, Wang XY, Tian W, and more...

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 17(9), 2020, DOI: 10.3390/ijerph17093122

**Abstract:** Microbial immobilization is considered as a novel and environmentally friendly technology that uses microbes to reduce heavy metals accumulation in plants. To explore microbial resources which are useful in these applications, three water spinach rhizosphere soils polluted by different levels of heavy metals (heavy pollution (CQ), medium pollution (JZ), and relative clean (NF)) were collected. The community composition of heavy metal-immobilizing bacteria in rhizosphere soils and its effects on reducing the Cd2+ and Pb2+ concentrations in water spinach were evaluated. Four hundred strains were isolated from the CQ (belonging to 3 phyla and 14 genera), JZ (belonging to 4 phyla and 25 genera) and NF (belonged to 6 phyla and 34 genera) samples, respectively. In the CQ sample, 137 strains showed a strong ability to immobilize Cd2+ and Pb2+, giving Cd2+ and Pb2+ removal rates of greater than 80% in solution; Brevundimonas, Serratia, and Pseudoarthrobacter were the main genera. In total, 62 strains showed a strong ability to immobilize Cd2+ and Pb2+ in the JZ sample and Bacillus and Serratia were the main genera. A total of 22 strains showed a strong ability to immobilize Cd2+ and Pb2+ in the NF sample, and Bacillus was the main genus. Compared to the control, *Enterobacter bugandensis* CQ-7, *Bacillus thuringensis* CQ-33,
and *Klebsiella michiganensis* CQ-169 significantly increased the dry weight (17.16-148%) of water spinach and reduced the contents of Cd2+ (59.78-72.41%) and Pb2+ (43.36-74.21%) in water spinach. Moreover, the soluble protein and Vc contents in the shoots of water spinach were also significantly increased (72.1-193%) in the presence of strains CQ-7, CQ-33 and CQ-169 compared to the control. In addition, the contents of Cd and Pb in the shoots of water spinach meet the standard for limit of Cd2+ and Pb2+ in vegetables in the presence of strains CQ-7, CQ-33 and CQ-169. Thus, the results provide strains as resources and a theoretical basis for the remediation of Cd- and Pb-contaminated farmlands for the safe production of vegetables.

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## Responses of soil bacterial community and Cd phytoextraction to a *Sedum alfredii*-oilseed rape (*Brassica napus* L. and *Brassica juncea* L.) intercropping system

**Authors:** Cao X, Luo JP, Wang XZ, and more...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 723, 2020, DOI: 10.1016/j.scitotenv.2020.138152

**Abstract:** Soil pollution with heavy metals has become a common problem in agricultural ecosystems and poses a threat to food safety and human health, Intercropping is now considered a promising alternative to address this issue. However, our understandings about the influences of intercropping systems on rhizosphere microbiota composition and their association with plant performance are still limited. In this study, rhizobox microcosm experiments were conducted to investigate the influence of cropping regimes (i.e. monoculture and intercropping) on the rhizosphere bacterial microbiota and their linkages with the phytoextraction of cadmium (Cd) by Zhongyouza 19 (*Brassica napus* L.), Xikou Huazi (*Brassica juncea* L.) and *Sedum alfredii* using 16S rRNA gene sequencing. Cadmium accumulation in shoots of *B. napus* and *B. juncea* grown under intercropping were enhanced by 370% and 27.8% respectively, as compared to monoculture. Soil compartmentation as a major determinant explained 57.6% of the rhizosphere bacterial

microbiota variation, whereas plant species and cropping regime accounted for 26.4% of the variation. The overall abundance of the taxa was Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Verrucomicrobia, and Actinobacteria, Intercropping significantly enriched amplicon sequence variants (ASVs) abundance belonging to Actinobacteria, Bacilli, Deltaproteobacteria while depleting that of Acidobacteria in rhizosphere. Intercropping with *S. alfredii* influenced more on microbial composition of *B. napus* rhizosphere. The change in rhizosphere bacterial communities was related to metal availability, soil properties, and plant parameters. The enriched families of Pedosphaeraceae, Ruminococcaceae, Chitinophagaceae, Gemmatimonadaceae, Nitrosomonadaceae, and Parachlamydiaceae were positively correlated with metal concentration in plants. These results indicate that *S. alfredii* and oilseed rape intercropping could be a promising approach for enhancing the remediation of Cd contaminated soil. Understanding the complex plant-microbe metal interactions of intercropping system could facilitate the development of remediation strategy for phytoremediation of contaminated soils and sustainable agricultural production.

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## Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

**Authors:** Torabi E, Wiegert C, Guyot B, Vuilleumier S, Imfeld G.

**Source:** JOURNAL OF ENVIRONMENTAL SCIENCES 92:163-175, 2020, DOI: 10.1016/j.jes.2020.02.009

**Abstract:** The soil dissipation of the widely used herbicides S-metolachlor (SM) and butachlor (BUT) was evaluated in laboratory microcosms at two environmentally relevant doses (15 and 150 mu g/g) and for two agricultural soils (crop and paddy). Over 80% of SM and BUT were dissipated within 60 and 30 days, respectively, except in
experiments with crop soil at 150 mu g/g. Based on compound-specific isotope analysis (CSIA) and observed dissipation, biodegradation was the main process responsible for the observed decrease of SM and BUT in the paddy soil. For SM, biodegradation dominated over other dissipation processes, with changes of carbon isotope ratios (Delta delta C-13) of up to 6.5% after 60 days, and concomitant production of ethane sulfonic acid (ESA) and oxanilic acid (OXA) transformation products. In crop soil experiments, biodegradation of SM occurred to a lesser extent than in paddy soil, and sorption was the main driver of apparent BUT dissipation. Sequencing of the 16S rRNA gene showed that soil type and duration of herbicide exposure were the main determinants of bacterial community variation. In contrast, herbicide identity and spiking dose had no significant effect. In paddy soil experiments, a high (4:1, V/V) ESA to OXA ratio for SM was observed, and phylotypes assigned to anaerobic Clostridiales and sulfur reducers such as Desulfuromonadales and Syntrophobacterales were dominant for both herbicides. Crop soil microcosms, in contrast, were associated with a reverse, low (1:3, V/V) ratio of ESA to OXA for SM, and Alphaproteobacteria, Actinobacteria, and Bacillales dominated regardless of the herbicide. Our results emphasize the variability in the extent and modes of SM and BUT dissipation in agricultural soils, and in associated changes in bacterial communities.

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## Effect of Indigenous Microbial Consortium on Bioleaching of Arsenic from Contaminated Soil by *Shewanella putrefaciens*

**Authors:** Tran TM, Han HJ, Ko JI, Lee JU

**Source:** SUSTAINABILITY 12(8), 2020, DOI: 10.3390/su12083286

**Abstract:** The effects of indigenous microbial consortium on removal of As from As-contaminated soil using an Fe(III)-reducing bacterium Shewanella putrefaciens were investigated under circumneutral pH condition. Sequential extraction of As revealed that more than 30% of As was associated with Fe(III)-

(oxy)hydroxides in the soil. Bioleaching experiments were conducted anaerobically with a supply of lactate as a carbon source. The highest As removal efficiency (57.5%) was obtained when *S. putrefaciens* and indigenous bacterial consortium coexisted in the soil. *S. putrefaciens* and indigenous bacteria solely removed 30.1% and 16.4% of As from the soil, respectively. The combination of *S. putrefaciens* and indigenous bacteria led to a higher amount of labile As after microbial dissolution of Fe(III)- (oxy)hydroxides. After microbial treatment, soil quality represented by pH and organic content appeared to be preserved. The results indicated that the ecological and physiological understanding of the indigenous microbiome might be important for the efficient application of bioleaching technology to remove As from contaminated soils.

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## Enantioselective effects of imazethapyr residues on Arabidopsis thaliana metabolic profile and phyllosphere microbial communities

**Authors:** Zhao QQ, Liu WY, Li Y, and more...

**Source:** JOURNAL OF ENVIRONMENTAL SCIENCES 93:57-65, 2020, DOI: 10.1016/j.jes.2020.03.009

**Abstract:** Imazethapyr (IM) is a widely used acetolactate synthase-inhibiting chiral herbicide. It has long-term residuals that may be absorbed by the human body through the edible parts of plants, such as vegetable leaves or fruits. Here, we selected a model plant, *Arabidopsis thaliana*, to determine the effects of R-IM and S-IM on its leaf structure, photosynthetic efficiency, and metabolites, as well as the structures of microorganisms in the phyllosphere, after 7 days of exposure. Our results indicated enantiomeric differences in plant growth between R-IM and S-IM; 133 mu g/kg R-IM showed heavier inhibition of photosynthetic efficiency and greater changes to subcellular structure than S-IM. R-IM and S-IM also had different effects on metabolism and leaf microorganisms. S-IM mainly increased lipid compounds and decreased amino acids, while R-IM increased sugar accumulation. The relative abundance of Moraxellaceae human pathogenic
bacteria was increased by R-IM treatment, indicating that R-IM treatment may increase leaf surface pathogenic bacteria. Our research provides a new perspective for evaluating the harmfulness of pesticide residues in soil, phyllosphere microbiome changes via the regulation of plant metabolism, and induced pathogenic bacterial accumulation risks

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Structural and functional
responses of bacterial and
fungal communities to
multiple heavy metal
exposure in arid loess

Authors: Zeng XY, Li SW, Leng Y, Kang XH.

Source: SCIENCE OF THE TOTAL ENVIRONMENT
723:138081, 2020, DOI: 10.1016/j.scitotenv.2020.138081

**Abstract** Concentration gradients of multiple heavy metals (HMs) in the arid loess region near a smelter were determined. In order to understand the response of soil microbes to multiple HM gradients, bacterial and fungal community structures and functions were analyzed using high-throughput RNA gene sequencing and the PICRUSt method. RDA/PCA analyses revealed that soil pH, HMs, and electrical conductivity (EC) jointly affected the bacterial communities in the soils. The soil microbial community structures responded differently to HMs, EC, and pH. High HMs increased the abundances of the bacterial phyla Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Chloroflexi, and the genera Blastococcus, Rubrobacter, Quadrisphaera, and Tunicatimonas, whereas they decreased the abundances of the phyla Proteobacteria and Acidobacteria and the genera Streptomyces and Nocardioides. High EC and low pH decreased the abundance of most of the dominant bacterial phyla but increased the abundances of Firmicutes, Deinococcus-Thermus, and Nitrospirae. Furthermore, high HMs and EC reduced the numbers of soil-specific bacterial and fungal groups and drove the succession of certain groups that were highly resistant to increased HMs and EC. In addition, many bacterial and fungal groups exhibited different response patterns to each HM, implying that, in multiple HM-contaminated soils, HMs jointly shaped the microbial communities. PICRUSt

analysis suggested that high HMs significantly decreased the total gene abundance and most KEGG modules in the soils. High EC and low pH significantly enhanced the abundances of several two-component system-, electron transfer-, and methanogenesis-related modules. We conclude that excessive multiple HMs and EC principally repressed the microbial activity and severely drove the gradient succession of bacterial and fungal communities in the arid loess region.

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A comparative study on the
antibiotic resistance pattern
of soil bacterial communities
in flood affected and
unaffected areas of
kothamangalam municipality

Authors: Gopal G, John N

Source: MATERIALS TODAY-PROCEEDINGS 25:252-256, 2020, DOI: 10.1016/j.matpr.2020.01.272

**Abstract:** Floods have remarkable effects on both above- and below-ground ecosystem processes. Soil microorganisms are very sensitive to environmental disturbances, and drastic changes in soil microbial community are expected from water logging conditions. Kothamangalam is one of the seriously flood affected region of Ernakulam district. Different bacterial species were isolated from rhizosphere and non-rhizosphere soils of flood affected and non-affected areas of Kothamangalam Municipality. The isolated bacterial strains were subjected to check their cultural and morphological characteristics, antibiotic sensitivity and pathogenicity pattern. The present study revealed the significant difference among strains, in their morphology, antibiotic sensitivity and pathogenicity pattern.

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The Cultivable Bacterial
Microbiota Associated to the
Medicinal Plant *Origanum vulgare* L.: From Antibiotic
# Resistance to Growth-Inhibitory Properties

**Authors:** Castronovo LM, Calonico C, Ascrizzi R, and More...

**Source:** FRONTIERS IN MICROBIOLOGY 11:862, 2020, DOI: 10.3389/fmicb.2020.00862

**Abstract:** The insurgence of antibiotic resistance and emergence of multidrug-resistant (MDR) pathogens prioritize research to discover new antimicrobials. In this context, medicinal plants produce bioactive compounds of pharmacological interest: some extracts have antimicrobial properties that can contrast different pathogens. For such a purpose, *Origanum vulgare* L. (Lamiaceae family) is a medicinal aromatic plant, whose essential oil (EO) is recognized for its antiseptic, antimicrobial and antiviral activities. The cultivable bacteria from different compartments (i.e., flower, leaf, stem and soil) were isolated in order to: (i) characterize the bacterial microbiota associated to the plant, determining the forces responsible for the structuring of its composition (by evaluation of cross inhibition); (ii) investigate if bacterial endophytes demonstrate antimicrobial activities against human pathogens. A pool of plants belonging to *O. vulgare* species was collected and the specimen chemotype was defined by hydrodistillation of its essential oil. The isolation of plant associated bacteria was performed from the four compartments. Microbiota was further characterized through a culture-independent approach and next-generation sequencing analysis, as well. Isolates were molecularly typed by Random Amplified Polymorphic DNA (RAPD) profiling and taxonomically assigned by 16S rRNA gene sequencing. Antibiotic resistance profiles of isolates and pairwise cross-inhibition of isolates on agar plates (i.e., antagonistic interactions) were also assessed. High level of diversity of bacterial isolates was detected at both genus and strain level in all different compartments. Most strains were tolerant against common antibiotics; moreover, they produced antagonistic patterns of interactions mainly with strains from different compartments with respect to that of original isolation. Strains that exhibited high inhibitory properties were further tested against human pathogens, revealing a strong capacity to inhibit the growth of strains resistant to several antibiotics. In conclusion, this study regarded the characterization of *O. vulgare* L. chemotype and of the bacterial communities associated to this medicinal plant,

also allowing the evaluation of antibiotic resistance and antagonistic interactions. This study provided the bases for further analyses on the possible involvement of endophytic bacteria in the production of antimicrobial molecules that could have an important role in clinical and therapeutic applications.

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# The Impact of Pesticides on the Microbial Community of Agrosoddy-Podzolic Soil

**Authors:** Astaykina AA, Streletskii RA, Maslov MN, and more...

**Source:** EURASIAN SOIL SCIENCE, 53(5):696-706, 2020, DOI: 10.1134/S1064229320050038

**Abstract:** The impact of three types of pesticides (herbicide metribuzin, insecticide imidacloprid, and fungicide benomyl) on the structure of microbial complexes and indicators of biological activity of agrosoddy-podzolic soil (Moscow oblast) has been assessed using the method of next-generation sequencing (NGS). The pesticides have been applied both separately and together at one- and tenfold rates. It has been found that pesticides have a greater impact on the fungal community in comparison with the prokaryotic community; in the latter, only changes in the abundances of the phyla of Actinobacteria and Proteobacteria have been observed. The study of fungal communities with the use of molecular-genetic analysis has revealed two dominant divisions of fungi in all soil samples: Ascomycota (72.6 +/- 8.0%) and Basidiomycota (26.0 +/- 7.7%). Moreover, in the samples treated with tenfold rate of pesticides (both in mixture and separately), the abundances of representatives of the Basidiomycota division have increased. Pesticide application has a short-term stimulating effect on the carbon content of microbial biomass. It has been shown that insecticide imidacloprid stimulates nitrogen fixation, whereas other types of pesticides do not affect this factor.

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Monitoring resistomes and antibiotic bacterial
microbiomes in the aerosols
from fine, hazy, and dusty
weather in Tianjin, China
using a developed high-
volume tandem liquid
impinging sampler

Authors: Zhao Y, Chen Z, Hou J, and more...

Source: SCIENCE OF THE TOTAL ENVIRONMENT
731, 2020, DOI: 10.1016/j.scitotenv.2020.139242

**Abstract** Accurate quantification of the airborne antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) is critically important to assess their health risks. However, the currently widely used high-volume filter sampler (HVFS) often causes the desiccation of the sample, interfering with subsequent bacterial culture. To overcome this limitation, a high-volume tandem liquid impinging sampler (HVTLIS) was developed and optimized to investigate the airborne bacterial microbiomes and antibiotic resistomes under different weathers in Tianjin, China. Results revealed that HVTLIS can capture significantly more diverse culturable bacteria, ARB, and ARGs than HVFS. Compared with fine and hazy weathers, dusty weather had significantly more diverse and abundant airborne bacteria, ARGs, and human opportunistic pathogens with the resistance to last-resort antibiotics of carbapenems and polymyxin B, implicating a potential human health threat of dusty bioaerosols. Intriguingly, we represented the first report of Saccharibacteria predominance in the bioaerosol, demonstrating that the potential advantage of HVTLIS in collecting airborne microbes.

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Effects of cadmium perturbation on the microbial community structure and heavy metal resistome of a tropical agricultural soil

Authors: Salam LT, Obayori OS, Ilori MO, Amund, Olukayode O

Source: BIORESOURCES AND BIOPROCESSING
7(1), 2020, DOI: 10.1186/s40643-020-00314-w

**Abstract:** The effects of cadmium (Cd) contamination on the microbial community structure, soil physicochemistry and heavy metal resistome of a tropical agricultural soil were evaluated in field-moist soil microcosms. A Cd-contaminated agricultural soil (SL5) and an untreated control (SL4) were compared over a period of 5 weeks. Analysis of the physicochemical properties and heavy metals content of the two microcosms revealed a statistically significant decrease in value of the soil physicochemical parameters (P &#60; 0.05) and concentration of heavy metals (Cd, Pb, Cr, Zn, Fe, Cu, Se) content of the agricultural soil in SL5 microcosm. Illumina shotgun sequencing of the DNA extracted from the two microcosms showed the predominance of the phyla, classes, genera and species of Proteobacteria (37.38%), Actinobacteria (35.02%), Prevotella (6.93%), and *Conexibacter woesei* (8.93%) in SL4, and Proteobacteria (50.50%), Alphaproteobacteria (22.28%), Methylobacterium (9.14%), and *Methylobacterium radiotolerans* (12,80%) in SL5, respectively. Statistically significant (P &#60; 0.05) difference between the metagenomes was observed at genus and species delineations. Functional annotation of the two metagenomes revealed diverse heavy metal resistome for the uptake, transport, efflux and detoxification of various heavy metals. It also revealed the exclusive detection in SL5 metagenome of members of RND (resistance nodulation division) protein czcCBA efflux system (czcA, czrA, czrB), CDF (cation diffusion facilitator) transporters (czcD), and genes for enzymes that protect the microbial cells against cadmium stress (sodA, sodB, ahpC). The results obtained in this study showed that Cd contamination significantly affects the soil microbial community structure and function, modifies the heavy metal resistome, alters the soil physicochemistry and results in massive loss of some autochthonous members of the community not adapted to the Cd stress.

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New Insights into the
Microbial Degradation of D-
Cyphenothrin in
## Contaminated Water/Soil
Environments

**Authors:** Huang YH, Lin ZQ, Zhang WP, and more...

**Source:** MICROORGANISMS 8(4), 2020, DOI: 10.3390/microorganisms8040473

**Abstract:** Persistent use of the insecticide D-cyphenothrin has resulted in heavy environmental contamination and public concern. However, microbial degradation of D-cyphenothrin has never been investigated and the mechanism remains unknown. During this study, for the first time, an efficient D-cyphenothrin-degrading bacterial strain Staphylococcus succinus HLJ-10 was identified. Response surface methodology was successfully employed by using Box-Behnken design to optimize the culture conditions. At optimized conditions, over 90% degradation of D-cyphenothrin (50 mg center dot L-1) was achieved in a mineral salt medium within 7 d. Kinetics analysis revealed that its half-life was reduced by 61.2 d, in comparison with the uninoculated control. Eight intermediate metabolites were detected in the biodegradation pathway of D-cyphenothrin including cis-D-cyphenothrin, trans-D-cyphenothrin, 3-phenoxybenzaldehyde, alpha-hydroxy-3-phenoxy-benzeneacetonitrile, trans-2,2-dimethyl-3-propenyl-cyclopropanol, 2,2-dimethyl-3-propenyl-cyclopropionic acid, trans-2,2-dimethyl-3-propenyl-cyclopropionaldehyde, and 1,2-benzenedicarboxylic acid, dipropyl ester. This is the first report about the degradation of D-cyphenothrin through cleavage of carboxylester linkage and diaryl bond. In addition to degradation of D-cyphenothrin, strain HLJ-10 effectively degraded a wide range of synthetic pyrethroids including permethrin, tetramethrin, bifenthrin, allethrin, and chlorempenthrin, which are also widely used insecticides with environmental contamination problems. Bioaugmentation of D-cyphenothrin-contaminated soils with strain HLJ-10 substantially enhanced its degradation and over 72% of D-cyphenothrin was removed from soils within 40 d. These findings unveil the biochemical basis of a highly efficient D-cyphenothrin-degrading bacterial isolate and provide potent agents for eliminating environmental residues of pyrethroids.

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## Responses of soil microbial biomass and enzyme activity to herbicides imazethapyr and flumioxazin

**Authors:** Pertile M, Antunes JEL, Araujo FF, and more...

**Source:** SCIENTIFIC REPORTS 10(1), 2020, DOI: 10.1038/s41598-020-64648-3

**Abstract:** The use of herbicides is important for controlling weeds in crops. However, they can present impacts on soil properties, such as biological properties. In this study, we evaluated the responses of soil microbial biomass and enzymes activity to the application of the herbicides imazethapyr and flumioxazin and their mixture in an experiment under laboratory conditions, using soils with a different history of use. Soil microbial biomass C (MBC) decreased, while microbial biomass N (MBN) was not affected after the application of the herbicides as compared to the control. Soil respiration, respiratory quotient, and dehydrogenase (DHA) activity increased significantly after the application of the herbicides compared to the control. The hydrolysis of fluorescein diacetate (FDA) was not significantly different between the control and the herbicide treatments. The principal response curve showed the largest initial effects for the flumioxazin, followed by imazethapyr and their mixture. Flumioxazin had a different influence on soil respiration and respiratory quotient than imazethapyr and their mixture. Finally, the effects of herbicides on soil microbial biomass and enzymes are short-term as we observed recovery in the biological parameters over time.

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## Effects of Cd on soil microbial biomass depend upon its soil fraction distribution

**Authors:** Zalaghi R, Masir MN, Moezzi A
**Source:** TOXICOLOGICAL AND ENVIRONMENTAL CHEMISTRY 101(9-10):486-496, 2019, DOI: 10.1080/02772248.2020.1742715

**Abstract:** Partitioning between soil fractions of Cd added to agricultural soil at 50 and 100mg kg(-1) and its effects on soil respiration and microbial biomass were studied for up to 60 days. Initially, Cd was distributed mostly into the exchangeable and carbonate fractions but decreased in the former fraction within 60 days. Cd pollution resulted in decreased basal and substrate-induced respiration by about 25%, and of microbial biomass carbon by about 35%. Soil biological properties were improved during the incubation and they were shown the highest correlations with Cd in bounded to Fe-Mn oxid fraction. It could be because of the lower concentration of this fraction and the sharper changes in it during the incubation as compared to the rest of Cd fractions (especially as compared with exchangeable fraction; more toxic fraction of Cd).

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## Biodegradation of Allethrin by a Novel Fungus *Fusarium proliferatum* Strain CF2, Isolated from Contaminated Soils

**Authors:** Bhatt P, Zhang WP, Lin ZQ, and more...

**Source:** MICROORGANISMS 8(4), 2020, DOI: 10.3390/microorganisms8040593

**Abstract:** Continuous use of allethrin has resulted in heavy environmental contamination and has raised public concern about its impact on human health, yet little is known about the kinetics and microbial degradation of this pesticide. This study reported the degradation kinetics in a novel fungal strain, Fusarium proliferatum CF2, isolated from contaminated agricultural fields. Strain CF2 utilized 50 mg center dot L-1 of allethrin as the sole carbon source for growth in minimal salt medium and tolerated high concentrations of allethrin of up to 1000 mg center dot L-1. The optimum degradation conditions for strain CF2 were determined to be a temperature of 26 degrees C and pH 6.0 using response surface methodology. Under optimum conditions, strain CF2 completely degraded allethrin within 144 hours. The

degradation kinetics of allethrin followed first order reaction kinetics. Kinetics analysis showed that its half-life was substantially reduced by 507.1 hours, as compared to the uninoculated control. This study provides new insights into the microbial degradation of allethrin with fungal *F. proliferatum* CF2.

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## Microbial remediation of a pentachloronitrobenzene-contaminated soil under Panax notoginseng: A field experiment

**Authors:** Zhang N, Guo D, Zhu Y, and more...

**Source:** PEDOSPHERE 30(4):563-569, 2020, DOI: 10.1016/S1002-0160(17)60476-4

**Abstract:** Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used: i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m(-2) of solid bacterial inoculum (A), and iii) soil with 0.30 kg m(-2) of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant
biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P &#60; 0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.

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## Screening strains for microbial biosorption technology of cadmium

Authors: Huang HJ, Jia QJ, Jing WX, and more...

Source: CHEMOSPHERE 251, 2020, DOI: 10.1016/j.chemosphere.2020.126428

**Abstract:** Heavy metals contaminate the environment and provide a threat to public health through drinking water and food chain. Microbial biosorption technology provides a more economical and competitive solution for bioremediation of toxicants such as heavy metals, and microbial genetic modification may modify microbes towards optimal sorption. It is very important to screen suitable strains for this purpose. In this study, three different types of microorganisms Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae were isolated and identified, from uncontaminated soils, and compared their sorption differences with respect to cadmium (Cd2+). We evaluated the effects of contact time and initial concentration on Cd2+ uptake, and found pseudo-second-order kinetic models were more suitable to describe biosorption processes. Adsorption isotherms were used to reflect their biosorption capacity. The maximum biosorption capacities of three strains calculated by the Langmuir model were 37.764, 56.497, and 22.437 mg Cd/g biomass, respectively. In bacteria, Cd2+ biosorption mainly occurred on cell wall, while the difference in biosorption between yeast inside and outside the cell was not significant. We found that due to the structural differences, the removal rate of E. coli surface decreased at a high concentration, while S. cerevisiae still had a lower biosorption capacity. FTIR spectroscopy reflected the difference in functional groups involved in biosorption by three strains. SEM-EDS analysis showed the binding of Cd2+ to microorganisms mainly relied on ion exchange mechanism. Based on the above results, we

suggested that B. subtilis is more suitable to get genetically modified for heavy metal biosorption.

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## Sulfamethoxazole affects the microbial composition and antibiotic resistance gene abundance in soil and accumulates in lettuce

Authors: Cheng S, Shi MM, Xing LJ, Wang X, and more...

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI: 10.1007/s11356-020-08902-1

**Abstract:** Pot experiments were set up to simulate the soil contamination by three initial concentrations of sulfamethoxazole (SMX) (S1, 100 mg/kg; S2, 200 mg/kg; S3, 300 mg/kg). The content of SMX in soil and its accumulation in lettuce were analysed. Additionally, the effects of SMX on soil microorganisms and antibiotic resistance genes were studied by Illumina high-throughput sequencing and droplet digital polymerase chain reaction (ddPCR). The results demonstrated that the SMX content in soil reduced by 97%, 86% and 75% in the S1, S2 and S3 treatment groups after 120 days, respectively. The accumulated SMX in lettuce was positively correlated with the initial concentration of SMX in soil. SMX contamination significantly reduced the bacterial diversity and altered the composition of bacterial and fungal communities in soil. The dominant bacterial and fungal genera in the SMX-contaminated soil were obviously different from those in the control soil. The relative abundance of sul1 (sulfonamide resistance gene) remarkably increased in the SMX-contaminated soil, while that of other ARGs, such as sul2 and tetracycline and quinolone resistance genes, showed no significant change.

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## Effect of multiple heavy metals pollution to bacterial diversity and community structure in farmland soils
**Authors:** Li CZ, Wang XF, Huang H, and more...

**Source:** HUMAN AND ECOLOGICAL RISK ASSESSMENT, 2020, DOI: 10.1080/10807039.2020.1752143

**Abstract:** Heavy metal pollution poses a serious hazard to the soil bacterial community. In this study, the 16 s rRNA high-throughput sequencing technology was used to analyze bacterial diversity and structure of dry field soil at different levels of heavy metal pollution. Further, the relationships between soil parameters and bacterial community were analyzed. Based on the study findings, we classified the levels of heavy metal pollution in soil samples from the study area could be divided into four grades: high risk (HR), considerable risk (CR), moderate risk (MR) and low risk (LR). In this study, heavy metal concentrations and pH showed significant effect on bacterial community structure. The distribution of bacterial community richness and diversity was MR &#62; LR &#62; CR &#62; HR. Bacterial communities such as Acidobacteria, Chloroflexi and Gemmatimonadetes were highly resistant to the lower pH (pH &#60; 6.5) and the high levels of heavy metal pollution compared with other bacterial community, which were abundant in HR samples. However, Proteobacteria, Actinobacteria, Bacteroidetes and Latescibacteria were more abundant in alkaline soils (pH &#62; 7.5). Further, available Cd, Pb and Zn concentrations were lower in alkaline soils than acidic soils, which reduced the impact of heavy metals on bacterial community diversity and structure.

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Designing of dual biosensor system for detection of zinc and chromium from contaminated soil using saponin biosurfactant and bioluminescence bacteriaind

**Authors:** Hajimohammadi R, Ahar MJ, Ahmadpour S

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY, 2020, DOI: 10.1080/03067319.2020.1760858

**Abstract:** In this study, a dual biosensor system for detecting chromium (VI) and zinc (II) in contaminated soil including toxic metals has been successfully designed using two strains of immobilised bioluminescent (BL) Escherichia coli Gap and Gfp. Saponinbiosurfactant was used to extract the chromium (Cr6+) and zinc (Zn2+) from soil to the aqueous phase. From obtained results when extracted metals ions were injected into the dual biosensor system, the luminescence level of biosensor decreased dramatically for both zinc and chromium. The concentrations of extracted chromium and zinc are well correlated with metals ions toxicity data achieved by biosensor system. The optimum aeration rate of biosensor system was obtained 30 ml/min. Dual biosensor system may be applied as an in-situ biosensor to detect the toxicity of chromium and zinc in contaminated soil including toxic metals. Therefore, this system can be proposed as a potential alternative to detection of toxic metals in soils.

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The influence on biosorption potentials of metal-resistant bacteria Enterobacter sp. EG16 and Bacillus subtilis DBM by typical red soil minerals

**Authors:** Feng WL, Li YY, Lin ZY, and more...

**Source:** JOURNAL OF SOILS AND SEDIMENTS, 2020, DOI: 10.1007/s11368-020-02650-y

**Abstract:** Purpose Due to the inevitable interaction between bacteria and soil minerals, whether bacteria could exert the excepted functions in the soil is yet to be confirmed and how minerals affect biosorption potential is needed to be investigated. The purposes of this study were to explore the adsorption behavior and mechanism of metal-resistant bacteria attaching to typical red soil minerals under different conditions and to discuss whether biosorption potential would be altered after the addition of functional bacteria to soil. Materials and methods Here, we tested equilibrium adsorption along with zeta potential analysis, scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and desorption to investigate the adsorption of two metal-
resistant bacteria (Gram-negative *Enterobacter* sp. EG16 and Gram-positive *Bacillus subtilis* DBM) onto typical red soil minerals including goethite, kaolinite, and gibbsite under different environmental factors. Results and discussion We found that the minerals adsorbed more EG16 cells than DBM, and the adsorption capacities followed the sequence of goethite > kaolinite > gibbsite. Both the surfaces of bacteria and mineral were pH-dependent in our tested pH range (4.0-7.0), and the maximum adsorption was at pH 4.0. Increasing ionic strength resulted in less adsorption of bacteria onto goethite, whereas bacterial adsorption onto kaolinite was the opposite. These observations elucidated that electrostatic interaction was the dominant contributor. The adsorption conformed to the Langmuir and pseudo-second-order kinetic model implying chemical adsorption, and the result of FTIR also supported that. Desorption experiment has suggested the significant contribution of electrostatic force and the minor dominator of functional groups for bacteria-mineral combination. Conclusions The results of this study indicated that electrostatic interaction was the dominant contributor to bacteria-mineral combination and functional groups coordination contributed less than 10%. This finding suggested most adhered bacteria could still provide active sites for heavy metal biosorption. Thus, although 50-90% of added functional bacteria has adhered to minerals, the bacteria-mineral combination had a limited impact on biosorption.

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## Heavy metals-resistant bacteria (HM-RB): Potential bioremediators of heavy metals-stressed *Spinacia oleracea* plantd

**Authors:** Desoky EM, Merwad ARM, Semida WM, and more...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 198, 2020, DOI: 10.1016/j.ecoenv.2020.110685

**Abstract:** Microorganism technologies can provide a potential alternative to traditional methods of removing heavy metals to conserve agricultural soils. This study aimed to identify and characterize heavy metals-resistant bacteria

(HMRB) isolated from industry-affected soil and their desired impact as bioremediators of heavy metals-stressed spinach plants. Three of 135 isolates were selected based on a high level of resistance to heavy metals. Based on morphological and biochemical characteristics, the selected isolates were identified as *Bacillus subtilis* subsp. spizizenii DSM 15029 T DSM (MA3), *Paenibacillus jamilae* DSM 13815 T DSM (LA22), or *Pseudomonas aeruginosa* DSM 1117 DSM (SN36). Experiments were implemented to investigate the three isolated HM-RB ability on improving attributes of growth, physio-biochemistry, and components of the antioxidant defense system of spinach plant exposed to the stress of cadmium (Cd2+; 2 mM), lead (Pb2+; 2 mM) or 2 mM Cd2++2 mM Pb2+. Compared to control, Cd2+ or Pb2+ stress markedly lowered plant fresh and dry weights, leaf contents of chlorophylls and carotenoids, rates of transpiration (Tr), net photosynthesis (Pn) and stomatal conductance (gs), relative water content (RWC), and membrane stability index (MSI). In contrast, contents of a.tochopherol (alpha.TOC), ascorbic acid (AsA), glutathione (GSH), proline, soluble sugars, Cd2+, and Pb2+, as well as activities of enzymatic and non-enzymatic antioxidants were markedly elevated. The application of HM-RB promoted the tolerance to heavy metal stress in spinach plants by improving Tr, Pn, gs, RWC, and MSI, while activities of enzymatic and non-enzymatic antioxidants were suppressed. These results reflected positively in promoting plant growth under heavy metal stress. Therefore, the application of HM-RB as potential bioremediators may be a promising strategy for promoting plant growth and productivity under heavy metal stress.

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## Suppression treatment differentially influences the microbial community and the occurrence of broad host range plasmids in the rhizosphere of the model cover crop *Avena sativa* L.

**Authors:** Allegrini M, Gomez ED, Smalla K, Zabaloy MC
**Source:** PLOS ONE 14(10), 2019, DOI: 10.1371/journal.pone.0223600

**Abstract:** Cover crop suppression with glyphosate-based herbicides (GBHs) represents a common agricultural practice. The objective of this study was to compare rhizospheric microbial communities of A. sativa plants treated with a GBH relative to the mechanical suppression (mowing) in order to assess their differences and the potential implications for soil processes. Samples were obtained at 4, 10, 17 and 26 days post-suppression. Soil catabolic profiling and DNA-based methods were applied. At 26 days, higher respiration responses and functional diversity indices (Shannon index and catabolic evenness) were observed under glyphosate suppression and a neat separation of catabolic profiles was detected in multivariate analysis. Sarcosine and Tween 20 showed the highest contribution to this separation. Metabarcoding revealed a non-significant effect of suppression method on either alpha-diversity metrics or beta-diversity. Conversely, differences were detected in the relative abundance of specific bacterial taxa. Mesorhizobium sequences were detected in higher relative abundance in glyphosate-treated plants at the end of the experiment while the opposite trend was observed for Gaiella. Quantitative PCR of amoA gene from ammonia-oxidizing archaea showed a lower abundance under GBH suppression again at 26 days, while ammonia-oxidizing bacteria remained lower at all sampling times. Broad host range plasmids IncP-1 beta and IncP-1 epsilon were exclusively detected in the rhizosphere of glyphosate-treated plants at 10 days and at 26 days, respectively. Overall, our study demonstrates differential effects of suppression methods on the abundance of specific bacterial taxa, on the physiology and mobile genetic elements of microbial communities while no differences were detected in taxonomic diversity.

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# Development and performance evaluation of native microbial consortium for multi metal removal in lab scale aerobic and anaerobic bioreactor

**Authors:** Gola D, Chawla P, Malik A, Ahammad SZ

**Source:** ENVIRONMENTAL TECHNOLOGY & INNOVATION 18, 2020, DOI: 10.1016/j.eti.2020.100714

**Abstract:** Shortage of freshwater force farmers to use untreated wastewater for irrigation which leads to the accumulation of contaminants like heavy metals in the food chain and deteriorate the quality of produce and soil. Present study focused on bioremediation of multiple heavy metals (Cd, Cu, Cr, Zn. Pb and Ni) from wastewater used for irrigation of food crops using four continuous Stirred Tank Reactor (CSTR), two aerobic and two anaerobic. One set of bioreactor (aerobic and anaerobic) was fed with actual wastewater, showed heavy metal removal up to 30%-100%. Whereas other set fed with spiked with metal ion concentration showed removal up to 70%-100%, indicating the improvement in removal efficiency due to acclimatization of microbial consortia at higher metal concentration. Present study clearly shows the ability of native microbial consortia in removing even higher concentrations of heavy metals from actual wastewater under ambient conditions. The present bioreactors configuration can be scale up for the onsite wastewater treatment with further optimization of the removal process. It was recommended that after using the present treatment process, treated water is safe for irrational purposes.

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# Taxonomic and functional analysis of soil microbial communities in a mining site across a metal(loid) contamination gradient

**Authors:** Navas M, Perez-Esteban J, Torres Mi-A, and more...
**Source:** EUROPEAN JOURNAL OF SOIL SCIENCE, 2020, DOI: 10.1111/ejss.12979

**Abstract:** Soil microorganisms surviving in mining sites have developed metal-resistance mechanisms to biotransform metals. Their use as biofertilizers can improve phytoremediation efficiency in contaminated soils by reducing metal toxicity while promoting plant growth. We analysed through whole-metagenome shotgun sequencing the composition, diversity and function of microbial communities present in a contaminated mine soil along a gradient of metals (As, Cu, Fe, Mn, Pb, Zn) to identify tolerant species carrying metal-resistance functional genes that can be used in association with plants for phytoremediation. Soil samples were collected from an abandoned copper mine, across three areas with different levels of metal contamination (unaffected, moderately contaminated and highly contaminated). The relative abundance of Proteobacteria, especially genus Bradyrhizobium, increased in the highly contaminated area, whereas Actinobacteria dominated in the unaffected area. Archaea (Euryarchaeota) predominated in the moderately contaminated area, Haloarcula, Halobacterium and Halorubrum being the most abundant genera. The fungi Basidiomycota did not exhibit differences among the areas, whereas Ascomycota, especially the genus Aspergillus, increased in areas with low metal concentrations. Metal-resistance genes associated with Fe (acn, furA, dpsA), Cu (cop-unnamed, copF, actP, copA, mmco, cutO) and As (arsT, arsC, aioA/aoxB) metabolism were the most abundant and were affected by the gradient of soil contamination. Those associated with Cu predominated in the most contaminated area, whereas As and Fe genes were more abundant in the least contaminated. Among the carriers of these metal-resistance genes, Bradyrhizobium diazoefficiens, *Pseudomonas aeruginosa*, *Halorubrum trapanicum*, *Aspergillus fumigatus* and *A. fischeri* were dominant in the most contaminated area. These species could give rise to promising biofertilizers to be used in association with suitable plants for the phytoremediation of contaminated mining sites.

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# Effects of Cd and Pb on diversity of microbial community and enzyme activity in soil

**Authors:** Xiao L, Yu Z, Liu H, and more...

**Source:** ECOTOXICOLOGY, 2020, DOI: 10.1007/s10646-020-02205-4

**Abstract:** Pollution due to heavy metals is a serious global environmental problem, particularly in China. It is thus important to study the effects of heavy metal pollution, especially in mining areas. Cadmium (Cd) and lead(Pb) severely damage the microbial life in soil. The concentration of heavy metals and their toxic effects on microbes and enzymes in soil were examined in this study using contaminated soil samples. The Biolog method was used to analyze the characteristics of the microbial community. The results showed that the addition of Cd2+ and Pb2+ in different concentrations has a significant impact on microbial and enzyme activity in soil. With an increase in their concentrations, activities of the microbial community and enzymes decreased gradually. Each index related to the structure of the microbial community in soil decreased, indicating that pollution due to Cd and Pb reduced its size and functional activity. This study provides a reference for future research on the functional diversity of the microbial community in soil and plays its role in their environmental management.

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# Adaptation of soil fungi to heavy metal contamination in paddy fields-a case study in eastern China

**Authors:** Lin Y, Xiao W, Ye Y, and more...

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI: 10.1007/s11356-020-09049-9

**Abstract:** Soil fungi have been widely studied, but the effects of heavy metal contamination at various levels as well as the abundance and diversity of heavy metal tolerant fungi in the contaminated paddy soils are still unknown. The
purpose of this study is to analyze the adaptability of fungi at different levels of heavy metal contamination to identify species that have strong adaptability to heavy metals. In this research, the technology of high-throughput sequencing was applied to study fungal communities in severe level (SL), moderate level (ML), light level (LL), and clean level (CL) for soil samples polluted by heavy metal, as well as to analyze the relations between environmental variables and fungal communities. The spearman analysis showed that 6 dominant fungal phyla and 18 dominant fungal genera were significantly correlated with these environmental variables. The alpha-diversity indexes of the soil fungal community from SL, ML, and CL were, mostly, drastically higher than the LL samples (p &#60; 0.05). Meanwhile, Ascomycota, the main fungal phylum, was spotted to yield a strong tolerance towards heavy metals, especially in ML. The most dominant genera of tolerant fungi in this area, which are Aspergillus, Penicillium, and Fusarium, could absorb and transport the heavy metals with the help of nutrients under certain heavy metal contamination levels. Therefore, this study indicated that some fungi, which have strong biodegradability on heavy metals, can reduce toxicity of heavy metals and create a proper soil environment to grow food crops.

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## Response of microbial community composition in soils affected by coal mine exploitation

**Authors:** Hamidovic S, Cvijović GG, Waisi H, Zivotic L, and more...

**Source:** ENVIRONMENTAL MONITORING AND ASSESSMENT 192(6), 2020, DOI: 10.1007/s10661-020-08305-2

**Abstract:** Surface mining activities, despite their benefits, lead to the deterioration of local and regional environmental quality and play a role in global ecosystem pollution. This research aimed to estimate the culturable microbial population structure at five locations near the opencast coal mine "Kakanj" (Bosnia and Herzegovina) via agar plate and phospholipid fatty acids (PLFA) method and to establish its relationship to the physical and chemical properties of soil. Using the ICP-OES method, the heavy metal pollution of all

examined locations (overburden, former grass yard, forest, arable soil, and greenhouse) was observed. Substantial variations among the sites regarding the most expressed indicators of heavy metal pollution were noted; Cr, Pb, Ni, and Cu content ranged from 63.17 to 524.47, 20.57 to 349.47, 139.13 to 2785.67, and 25.97 to 458.73 mg/kg, respectively. In the overburden sample, considerable low microbial activity was detected; the bacterial count was approximately 6- to 18-fold lower in comparison with the other samples. PLFA analysis showed the reduction of microbial diversity, reflected through the prevalence of normal and branched saturated fatty acids, their ratio (ranged from 0.92 to 7.13), and the absence of fungal marker 18:2 omega 6 fatty acid. The principal component analysis showed a strong negative impact of heavy metals Na and B on main microbial and PLFA profiles. In contrast, stock of main chemical parameters, including Ca, K, Fe, and pH, was positively correlated with the microbial community structure.

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## Biodegradation of diazinon by fungal strain *Apergillus niger* MK640786 using response surface methodology

**Author:** Hamad MTMH

**Source:** ENVIRONMENTAL TECHNOLOGY & INNOVATION, 18, 2020, DOI: 10.1016/j.eti.2020.100691

**Abstract:** The Lake Burullus is one of most important lakes in north Delta of Egypt. It is exposed to huge amounts of contaminated drainage water contain serious pollutants especially Organophosphours. Diazinon is an organophosphorus pesticide widely used in agriculture. Evidence of diazinon residues in water has generated an urgent need to develop treatment systems for protected human health and the environment from damage. The aim of this work was the optimization of diazinon biodegradation from aqueous solutions by Aspergillus niger MK640786 using the response surface methodology. Aspergillus niger MK640786 was succeeded to reduce the diazinon at optimal conditions were as follows: temperature 30
degrees C, initial concentration 25 mg/l, pH 5 and within 7 days of incubation. Under these conditions, the degradation rate of diazinon was 82%. The half-life values of diazinon with strain Aspergillus niger were, 3.8, 3.9,7.2,10.9 and 15.8 d(-1) respectively. In contrast, the t1/2 values of diazinon in the non-inoculated were 14.36549, 17.71808, 34.83199, 40.65586 and 47.8675 d(-1) respectively. We can conclude that Aspergillus niger has able to remove diazinon with the lowest cost and a high efficiency.

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Effects of di-n-butyl
phthalate and di-2-ethylhexyl
phthalate on pollutant
removal and microbial
community during
wastewater treatment

Authors: Wang Q, Liang L, Fang C, Chen L

Source: ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, 198, 2020, DOI: 10.1016/j.ecoenv.2020.110665

**Abstract:** Due to the wide use of plastic products and the releasability of plasticizer into surrounding environment, the hazards, residues and effects of phthalic acid esters (PAEs) in ecosystems have been paid more and more attention. Little information is available about the effects of PAEs on the normal wastewater treatment, although the distribution of PAEs in soil and other ecosystems is closely related to the discharge of sewage. In this study, the effects of high concentrations of di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) on pollutant removal and the microbial community during landfill leachate treatment was investigated. After domestication, the activated sludge was used in the co-treatment of landfill leachate and simulated domestic wastewater. We verified that this process reduced the toxicity of landfill leachate. However, high concentrations of added DBP and DEHP were removed first, while the removal of these pollutants from raw landfill leachate was limited. The results of high-throughput sequencing revealed that the bacterial diversity was diminished and the microbial community structure was significantly affected by the addition of DBP and DEHP. The DBP and DEHP

samples had 79.05% and 82.25% operational taxonomic units (OTU), respectively, in common with the raw activated sludge. Many genera of PAE-degrading bacteria that had no significant evolutionary relationship were found in the raw activated sludge. And the widespread presence of PAE-degrading bacteria could effectively keep the concentrations of PAEs low during the wastewater treatment.

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Removal and
biomineralization of Pb2+ in
water by fungus
*Phanerochaete chrysoporium*

Authors: Zhao WW, Zhu G, Daugulis AJ, and more...

Source: JOURNAL OF CLEANER PRODUCTION, 260, 2020, DOI:10.1016/j.jclepro.2020.120980

**Abstract:** The removal and biomineralization of Pb2+ (200 mg/L) in water were investigated utilizing mature mycelia of *Phanerochaete chrysoporium*. Mycelial dosage, initial Pb2+ concentration, solution pH and treatment time all were shown to have an influence on Pb2+ removal. Granular, lead-containing precipitation was formed on the fungal hyphae upon exposure to lead nitrate, which was confirmed from scanning electron micrograph/Energy Dispersive Spectrometer (SEM/EDS). Energy dispersive X-ray spectroscopic analysis revealed the presence of lead (48.5% by weight) along with phosphorus in the precipitate. This extracellular precipitate was further identified as pyromorphite lead hydroxyphosphate [Pb-5(PO4)(3)OH] by X-ray powder diffraction (XRD) analysis. During Pb2+ removal, size-enlarged mineral precipitation, and clustered nanospherical particles formed on the hyphae were revealed by SEM/XRD. A remarkable increase of mycelial phosphatase activity of 1.5 times that of the control and decreased phosphate concentration in solution (16.76 mg/L to 1.39 mg/L) initially upon exposure to Pb2+ suggested that phosphatase may hydrolyze organic phosphorus into inorganic phosphate and release it into solution, participating in the biomineralization of Pb2+. Toxicity tests showed that the toxicity of Pb2+ polluted water decreased after treatment. The results clearly demonstrate previously unknown
lead biomineralization as pyromorphite through
fungal phosphatase.

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Remedial potential of
bacterial and fungal strains
(Bacillus subtilis, Aspergillus
niger, Aspergillus flavus and
Penicillium chrysogenum)
against organochlorine
insecticide Endosulfan

Author: Ahmad KS

Source: FOLIA MICROBIOLOGICA, 2020, DOI: 10.1007/s12223-020-00792-7

**Abstract:** Endosulfan, an organochlorine insecticide, is known to cause detrimental effects to the environment and human health due to its excessive usage. Its highly toxic nature calls for an environmental-friendly approach for its detoxification. Environmental transformation of Endosulfan was assessed through biodegradation by isolated and cultured soil microbes (Bacillus subtilis (BS), Aspergillus niger (AN), Aspergillus flavus (AF) and Penicillium chrysogenum (PC)). Degradation of 10 mg/L Endosulfan was determined in aqueous solution at regular time intervals and analysed by gas chromatography-mass spectrometry for 35 days. BS and AN displayed substantial potential to degrade Endosulfan and subsequently transform it into its daughter products (95 and 77%, respectively). Endosulfan transformation followed first-order reaction kinetics. Chromatogram peaks revealed less toxic metabolites by Endosulfan transformation (Endosulfan diol, Endosulfan ether, Endosulfan hydroxyether and Endosulfan lactone). Half-life of Endosulfan obtained by various strains utilised in the experiments was in the order, PC (69) &#62; AF (34.6) &#62; AN (17.3) &#62; BS (11.5) days. Statistical analysis was performed in MINITAB to evaluate the significance of results. Bioaugmentation of contaminated sites with such efficient microbes can facilitate rapid pesticide transformation and decontamination of the environment.

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Microbial degradation of two
highly persistent fluorinated
fungicides - epoxiconazole
and fludioxonil

Authors: Alexandrino DAM, Mucha AP, Almeida CMR, Carvalho MF

Source: JOURNAL OF HAZARDOUS MATERIALS 394, 2020, DOI: 0.1016/j.jhazmat.2020.122545

**Abstract:** Biodegradation of two highly persistent fluorinated fungicides, epoxiconazole (EPO) and fludioxonil (FLU), by microbial consortia enriched from estuarine sediment and agricultural soil is reported. After an enrichment period of 6 months, four microbial consortia were able to completely remove and defluorinate the fungicides in co-metabolic conditions. Defluorination was biologically mediated and results suggest it is not a primary catabolic step, as fungicide removal was always faster than its defluorination. Three of the four enriched consortia had similar biodegradation performances in the absence of a co-substrate. Biodegradation kinetics revealed that microbial degradation followed a first-order kinetics, with cultures being capable of biodegrading concentrations up to 10 mg L-1 of EPO or FLU, in a maximum of 21 days. Estimated half-life values for these compounds were significantly lower than those reported in literature, highlighting the unique metabolic performance of the obtained consortia. Analysis of their microbial composition revealed that they integrate several bacterial species belonging to the Proteobacteria phylum, with the most common genera being Pseudomonas, Ochrobactrum and Comamonas. This is the first study providing clear evidence on the biodegradation of EPO and FLU, opening doors for the design of bioremediation technologies for the recovery of ecosystems polluted with such recalcitrant compounds.

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The bacterial microbiota in
florfenicol contaminated
soils: The antibiotic
## resistome and the nitrogen cycle

**Authors:** Wang M, Xie X, Wang M and more...

**Source:** ENVIRONMENTAL POLLUTION 259, 2020, DOI: 10.1016/j.envpol.2019.113901

**Abstract:** Soil antibiotic resistome and the nitrogen cycle are affected by florfenicol addition to manured soils but their interactions have not been fully described. In the present study, antibiotic resistance genes (ARGs) and nitrogen cycle genes possessed by soil bacteria were characterized using real-time fluorescence quantification PCR (qPCR) and metagenomic sequencing in a short-term (30 d) soil model experiment. Florfenicol significantly changed in the abundance of genes conferring resistance to aminoglycosides, beta-lactams, tetracyclines and macrolides. And the abundance of Sphingomonadaceae, the protein metabolic and nitrogen metabolic functions, as well as NO reductase, nitrate reductase, nitrite reductase and N2O reductase can also be affected by florfenicol. In this way, ARG types of genes conferring resistance to aminoglycosides, beta-lactamases, tetracyclines, colistin, fosfomycin, phenicols and trimethoprim were closely associated with multiple nitrogen cycle genes. Actinobacteria, Chlorobi, Firmicutes, Gemmatimo-nadetes, Nitrospirae, Proteobacteria and Verrucomicrobia played an important role in spreading of ARGs. Moreover, soil physicochemical properties were important factors affecting the distribution of soil flora. This study provides a theoretical basis for further exploration of the transmission regularity and interference mechanism of ARGs in soil bacteria responsible for nitrogen cycle.

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## Effect of Long-Term Pesticides and Chemical Fertilizers Application on the

## Microbial Community Specifically Anammox and Denitrifying Bacteria in Rice Field Soil of Jhenaidah and Kushtia District, Bangladesh

**Authors:** Rahman MM, Nahar K, Ali MM, and more...

**Source:** BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 104(6):828-833, 2020, DOI: 10.1007/s00128-020-02870-5

**Abstract:** In this study, we investigated the effect of long-term pesticides and chemical fertilizers application on the microbial communities specifically anammox and denitrification bacteria in rice field soils. The abundances of microbial communities (16S rDNA), anammox (hszB), and denitrification (narG, nirK, nirS, and nosZ) genes were quantified by q-PCR. 10 pesticides (5 insecticides, 3 fungicides and 2 herbicides) and chemical fertilizers urea, potassium, phosphate, DAP (di-ammonium phosphate), gypsum, and boric acid were used by local farmers. Nitrate, SOC (ammonia, soil organic carbon), N and C content significantly (p < 0.05) decreased in the rice field soils as compared to the upland soils. Abundance of 16S rDNA, hszB, narG, nirK, nirS, and nosZ genes significantly (p &#60; 0.05) decreased in the rice field soils and positively correlated with chemical properties of soils. Our results provide useful information and further maintenance should be instilled to the potential of chemical and biological factors decreased in rice field soils.

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## Characterization and Identification of Naphthalene Degrading Bacteria Isolated from Petroleum Contaminated Sites and Their Possible Use in Bioremediation

**Authors:** Rabani MS, Sharma R, Singh R, Gupta M
**Source:** POLYCYCLIC AROMATIC COMPOUNDS, 2020, DOI: 10.1080/10406638.2020.1759663

**Abstract:** Naphthalene is a simple polycyclic aromatic hydrocarbon (PAH) regarded as a common environmental pollutant. A total number of 16 bacterial isolates obtained from various petroleum contaminated sites of Gwalior (MP), India were screened for their naphthalene degradation potential. Enrichment method was used for the isolation of bacteria by amending the medium with 100 mg l(-1) naphthalene dissolved in acetone. Out of 16 bacterial isolates, only two isolates designated as RS2(3) and GS2 have shown a good naphthalene degradation potential based on maximum tolerance level at 1000 mg l(-1) and growth of the isolates as 0.536 and 0.133, respectively measured in terms of optical density (OD) at 600 nm. The degradation was determined by GC analysis, GS2 showed 73% and 48% degradation, while RS2(3) showed 52% and 29% at 100 and 200 mg l(-1) naphthalene concentration, respectively. The isolates were also characterized for their heavy metal tolerance against four selected heavy metals (Cadmium, Chromium, Copper and Zinc) at different concentrations (0.1%, 0.5% and 1.0%). Out of total 16 bacterial isolates only twelve were found resistant to one percent concentration of any one of the four heavy metals. Moreover, the antibiotic sensitivity of the isolates was also determined against four different antibiotics. These isolates were characterized morphologically, biochemically and identified as strain Bacillus licheniformis JUG GS2 (MK106145) and Bacillus sonorensis JUG (RS2(3)) (MK156710) by 16S rRNA gene sequencing. The study infers that Bacillus licheniformis and Bacillus sonorensis strains can be helpful to remediate contaminations attributed to naphthalene and heavy metals as well.

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World within world:
Intestinal bacteria combining
physiological parameters to
investigate the response of

## Metaphire guillelmi to tetracycline stress

**Authors:** Chao H, Sun M, Ye M, and more...

**Source:** ENVIRONMENTAL POLLUTION, 261, 2020, DOI: 10.1016/j.envpol.2020.114174

**Abstract:** Due to the abusive usage of antibiotics in animal husbandry, a large amount of residual antibiotics has been released into the environment, therein posing great threat against both environment security and public health. Therefore, it is of great significance to investigate the toxicity of antibiotics on the widely-applied bioindicator-earthworm. In this work, the physiological parameters and the intestinal bacteria community of Metaphire guillelmi were monitored simultaneously to evaluate their sensitivity to the tetracycline (TC) exposure. As expected, the antioxidant enzyme activity and coelomocyte apoptosis acted fairly well as biomarkers for the TC toxicity. In contrast, the intestinal bacteria of Metaphire guillelmi responded varyingly to different TC doses. When TC concentration increased from 0 to 35.7 μg cm(-2), the percentage of the Proteobacteria phylum declined significantly from 85.5% to 34.4%, while the proportions of the Firmicutes, Planctomycetes and Atinomycete phyla clearly increased (p \#60; 0.05). Meanwhile, the levels of TC resistance genes tetA, tetC, and tetW increased with the increasing TC concentration, in contrast to the declined abundance in denitrifying genes nirS and nosZ (p \#60; 0.05). By analyzing the correlation between the antioxidant enzyme activity and the dominant intestinal bacteria in the worm gut, it is interesting to found that the four dominant bacteria genera Mesorhizobium, Aliihoeflea, Romboutsia, and Nitrospira are the promising bioindicator of TC stress due to their sensitive response. This work shed novel light on evaluating the ecotoxicological risks posed by residual TC in environment by using a combination of physiological parameters and intestinal bacterial activity in earthworms.

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Longitudinal screening of
antibiotic residues, antibiotic
resistance genes and
zoonotic bacteria in soils
fertilized with pig manure

**Authors:** Van den Meersche T, Rasschaert G, Vanden Nest T, and more...

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI: 10.1007/s11356-020-09119-y
**Abstract:**

Fertilization with animal manure is one of the main routes responsible for the introduction of antibiotic residues, antibiotic resistance genes, and zoonotic bacteria into the environment. The aim of this study was to assess the effect of the use of pig (swine) manure as a fertilizer on the presence and fate of six antibiotic residues, nine antibiotic resistance genes, and bacteria (zoonotic bacteria *Salmonella* spp. and *Campylobacter* spp. and *E. coli* as indicator for Gram-negative bacterial species of the microbiota of livestock) on five fields. To the best of our knowledge, the present study is the first to assess a multitude of antibiotic residues and resistance to several classes of antibiotics in pig manure and in fertilized soil over time in a region with an intensive pig industry (Flanders, Belgium). The fields were sampled at five consecutive time points, starting before fertilization up to harvest. Low concentrations of antibiotic residues could be observed in the soils until harvest. The antibiotic resistance genes studied were already present at background levels in the soil environment prior to fertilization, but after fertilization with pig manure, an increase in relative abundance was observed for most of them, followed by a decline back to background levels by harvest-time on all of the fields studied. No apparent differences regarding the presence of antibiotic resistance genes in soils were observed between those fertilized with manure that either contained antibiotic residues or not. With regard to dissemination of resistance, the results presented in this study confirm that fertilization with animal manure directly adds resistance genes to the soil. In addition, it shows that this direct mechanism may be more important than possible selective pressure in soil-dwelling bacteria exerted by antibiotic residues present in the manure. These results also indicate that zoonotic bacteria detected in the manure could be detected in the soil environment directly after fertilization, but not after 1 month. In conclusion, although some antibiotic residues may be present in both manure and soil at concentrations to exert selective pressure, it

seems that antibiotic resistance is mostly introduced directly to soil through fertilization with animal manure.

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Dissolved organic matter
does not promote glyphosate
degradation in auto-
heterotrophic aquatic
microbial communities

**Authors:** Artigas J, Batisson I, Carles L

**Source:** ENVIRONMENTAL POLLUTION 259, 2020, DOI:10.1016/j.envpol.2020.113951

**Abstract:** Environmental dissolved organic matter (DOM) has been proved to increase microbial population sizes and stimulate the degradation of some pesticide molecules. Among these molecules, the present study investigated the biodegradation of the herbicide glyphosate depending on photoautotrophs DOM supply in a microbial consortium isolated from river biofilms. Degradation experiments in the laboratory were performed in dark and light conditions, as well as after antibiotic supply, in order to characterize the eventual interactions between photoautotrophs and heterotrophs activity during glyphosate degradation. Fifty percent of the initial concentration of glyphosate (0.6 mM) was transformed into aminomethyl phosphonic acid (AMPA) after 9 days in presence or absence of light. Accordingly, the photoautotrophic DOM supply was not stimulating glyphosate degradation by microbial heterotrophs. This lack of response was probably explained by the low net primary production values and weak dissolved organic carbon production recorded in light treatments. The supply of the antibiotic drastically stopped glyphosate transformation demonstrating the central role of bacteria in the biodegradation of the herbicide. Glyphosate also modified the structure of prokaryotes assemblages in the consortium by increasing the relative abundances of Alphaproteobacteria and slightly decreasing those of Gammaproteobacteria. The chemoorganotrophic bacteria *Phenylobacterium* sp. (Alphaproteobacteria) was related to the transformation of glyphosate in our microbial consortium. The present study highlights the complexity of microbial interactions between
photoautotrophs and heterotrophs in microbial assemblages that can contribute to the degradation of pesticides present in aquatic environments.

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# Destruction of Cell Topography, Morphology, Membrane, Inhibition of Respiration, Biofilm Formation, and Bioactive Molecule Production by Nanoparticles of Ag, ZnO, CuO, TiO2, and Al2O3 toward Beneficial Soil Bacteria

Authors: Ahmed B, Ameen F, Rizvi A, and more...

Source: ACS OMEGA, 5(14):7861-7876, 2020, DOI: 10.1021/acsomega.9b04084

**Abstract:** The unregulated discharge of nanoparticles (NPs) from various nanotechnology industries into the environment is expected to alter the composition and physiological functions of soil microbiota. Considering this knowledge gap, the impact of five NPs (Ag, ZnO, CuO, Al2O3, and TiO2) differing in size and morphology on growth behavior and physiological activity of Azotobacter chroococcum, Bacillus thuringiensis, Pseudomonas mosselii, and Sinorhizobium meliloti were investigated. Various biochemical and microscopic approaches were adopted. Interestingly, all bacterial strains were found sensitive to Ag-NPs and ZnO-NPs but showed tolerance toward CuO, Al2O3, and TiO2-NPs. The loss of cellular respiration due to NPs was coupled with a reduction in population size. ZnO-NPs at 387.5 erg mL (-1) had a maximum inhibitory impact on A. chroococcum and reduced its population by 72%. Under Ag-NP stress, the reduction in IAA secretion by bacterial strains followed the order S. meliloti (74%) > P. mosselii (63%) > A. chroococcum (49%). The surface of bacterial cells had small- or large-sized aggregates of NPs. Also, numerous gaps, pits, fragmented, and disorganized cell envelopes were visible. Additionally, a treated cell surface appeared corrugated with depressions and alteration in cell length and a strong heterogeneity was noticed under atomic

force microscopy (AFM). For instance, NPs induced cell roughness for *P. mosselii* followed the order 12.6 nm (control) > 58 nm (Ag-NPs) > 41 nm (ZnO-NPs). TEM analysis showed aberrant morphology, cracking, and disruption of the cell envelope with extracellular electrodense materials. Increased permeability of the inner cell membrane caused cell death and lowered EPS production. Ag-NPs and ZnO-NPs also disrupted the surface adhering ability of bacteria, which varied with time and concentration of NPs. Conclusively, a plausible mechanism of NP toxicity to bacteria has been proposed to understand the mechanistic basis of ecological interaction between NPs and resourceful bacteria. These results also emphasize to develop strategies for the safe disposal of NPs.

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# Study of Arsenic-Contaminated Soil Bacterial Community Using Biochip Technology

Authors: Bunin E, Khatisashvili G, Varazi T, and more...

Source: WATER AIR AND SOIL POLLUTION, 231(5), 2020, DOI: 10.1007/s11270-020-04575-1

**Abstract:** The ecosystems near arsenic mining industrial areas are characterized with an elevated level of pollutants. In Caucasus region, such a hotspot is presented in Western Georgia: Uravi and Tsana abandoned arsenic production facilities and nearby mining tailings stored in deteriorating conditions that pose a threat to the population. The research presents a study of the local bacteria community of highly arsenic-contaminated soils (from 400 mg/kg at Uravi arsenic sulfide mineral processing facility to 11.3 g/kg at arsenic oxide storage area in Tsana) using an innovative, multitasking microscale bioanalytical method for environmental enquiries - DNA biochip (microarray). The detected *Shewanella* spp., *Bacillus* spp., and sulfate-reducing bacteria were considered as promising objects for future projects on in situ recovery of vast arsenic-contaminated areas applying remediation methods.

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## Probing the single and combined toxicity of PFOS and Cr(VI) to soil bacteria and the interaction mechanisms

Authors: Li Ji, Zheng T, Yuan D, and more...

Source: CHEMOSPHERE, 249, 2020, DOI: 10.1016/j.chemosphere.2020.126039

**Abstract:** Many research focused on the removal of perfluorooctane sulfonic acid (PFOS) and hexavalent chromium (Cr(VI)) in some industrial wastewater (e.g. electroplating wastewater), but few research reported the combined toxicity of PFOS and Cr(VI) to soil bacteria. Therefore, the toxicity and mechanisms of the combined PFOS and Cr(VI) to bacteria (with *Bacillus subtilis* as a model) are explored. The results show that the combined PFOS and Cr(VI) exhibits much higher toxicity to the bacteria than that of Cr(VI) alone. The growth profile of *Bacillus subtilis* exposed by the combined pollution decreased by 18% and 56%, respectively, compared with that of single Cr(VI) and the control, indicating the combined toxicity to *Bacillus subtilis* is synergistic. Moreover, the changes of EPSs in *Bacillus subtilis*, such as decreased potential, increased extracellular polysaccharides, decreased extracellular proteins and irregular morphology, also confirmed that the combined PFOS and Cr(VI) caused greater toxicity. The increase of intracellular ROS and permeability of dye 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) suggest that oxidative damage and increased membrane permeability are the main mechanisms of toxicity induced by the combined PFOS and Cr(VI). This work could provide useful information for the risk assessment of co-exposure to PFOS and heavy metals in the natural environment.

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## Ecological responses of soil microbial abundance and diversity to cadmium and soil properties in farmland

## around an enterprise-intensive region

Authors: Liu H, Wang C, Xie Y, Luo Y, and more...

Source: JOURNAL OF HAZARDOUS MATERIALS, 392, 2020, DOI: 10.1016/j.jhazmat.2020.122476

**Abstract:** Microorganisms play a vital role in soil biochemical process in contaminated managed ecosystems. In the present study, a field investigation was conducted in farmland around an industrial intensive region contaminated with cadmium, and the changes of microbial assemblages in contaminated soils were assessed by 16S rRNA sequencing and the further statistical analysis. The results revealed obvious variations in microbial richness between referenced and contaminated soils, with Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria and Nitrospirae dominating the studied communities around the industrial intensive region. Redundancy analysis and Spearman correlation heatmap revealed that about 68.95 % of overall variation in microbial community composition was explained by soil physiochemical properties and Cd existence, among which pH, soil total phosphorus, total nitrogen, organic carbon (OC) and available Cd were identified as dominant factors. No significant difference was found in the similarities and Beta-diversity analysis among different groups. In conclusion, this study revealed the ecological effects of physiochemical parameters and Cd stress on the diversity and abundance of microbial communities, and these findings provided the detailed and integrated correlation between the main factors and microbial indexes in Cd contaminated farmland around the industrial intensive region.

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## Microbial strategies in non-target invasive *Spartina densiflora* for heavy metal clean up in polluted saltmarshes
Authors: Mesa-Marin J, Redondo-Gomez S, Rodriguez-Llorente I, Pajuelo E, Mateos-Naranjo E

Source: ESTUARINE COASTAL AND SHELF SCIENCE, 238, 2020, DOI: 10.1016/j.ecss.2020.106730

**Abstract:** Rhizoremediation is the use of microorganisms from the rhizosphere to assist plant phytoremediation. Optimistic results have been obtained these years for this biotool, but its effects in non-target cohabiting species has never been studied. This concern, in principle pointless, gains importance when the non-target species is an invasive plant. It is the case of highly polluted saltmarshes in SW Spain, where the native cordgrass *Spartina maritima*, proposed for heavy metal rhizoremediation, cohabitates with the invasive *Spartina densiflora*. In this work, we designed a greenhouse experiment where *S. densiflora* was placed in pots with natural metal polluted soil from Tinto marsh and inoculated with a bacterial consortium designed for rhizoremediation purposes with *S. maritima*. After 30 days of treatment, our data revealed that inoculated *S. densiflora* showed better fitness and metal accumulation capacity than non-inoculated control plants. This enhancement was demonstrated by increased *S. densiflora* biomass (58% for belowground tissues), amelioration of photosynthetic parameters (i.e., 48% for net photosynthetic rate (A(N)) and stomatal conductance (g(s)) and 17% for intrinsic water-use efficiency (iWUE)), and finally by an increase of inoculated *S. densiflora* root metal uptake, reaching around 40% in case of cadmium and lead. Within this scenario, the rhizoremediation strategy proposed using *S. maritima* should be managed cautiously, and if would be entitled to determine to which extent its practical implementation may boost invasive capability of *S. densiflora*.

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## Co-presence of the anionic surfactant sodium lauryl ether sulphate and the pesticide chlorpyrifos and effects on a natural soil microbial community

Authors: Pescatore T, Patrolecco L, Rolando L and more...

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI: 10.1007/s11356-020-08840-y

**Abstract:** There is a growing concern about the simultaneous presence in the environment of different kinds of pollutants, because of the possible synergic or additive effects of chemical mixtures on ecosystems. Chlorpyrifos (CPF) is an organophosphate insecticide extensively used in agricultural practices. The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component of several commercial products, including foaming agents used in underground mechanised excavation. Both compounds are produced and sold in high amounts worldwide and can be found in the environment as soil contaminants. The persistence of SLES and CPF in agricultural soils and their possible effects on the natural microbial community was evaluated in microcosms. The experimental set consisted of soil samples containing the autochthonous microbial community and treated with only SLES (70 mg/kg), only CPF (2 mg/kg) or with a mix of both compounds. Control microcosms (without the contaminants) were also performed. Soil samples were collected over the experimental period (0, 7, 14, 21 and 28 days) and analysed for CPF, SLES and the main metabolite of CPF (3, 5, 6-trichloropyridinol, TCP). The half-life time (DT50) of each parent compound was estimated in all experimental conditions. At the same time, the abundance, activity and structure of the microbial community were also evaluated. The results showed that the co-presence of SLES and CPF did not substantially affect their persistence in soil (DT50 of 11 and 9 days with co-presence and 13 and 10 days, respectively, when alone); however, in the presence of SLES, a higher amount of the metabolite TCP was found. Interestingly, some differences were found in the bacterial community structure, abundance and activity among the various conditions.

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## Bioaugmentation assisted mycoremediation of heavy metal and/metalloid landfill contaminated soil using
## consortia of filamentous fungi

Authors: Hassan A, Pariatamby A, Ossai IC, Hamid F

Source: BIOCHEMICAL ENGINEERING JOURNAL, 157, 2020, DOI: 10.1016/j.bej.2020.107550

**Abstract:** This research aimed to demonstrate the significance of bioaugmentation in the mycoremediation of metals and metalloid (Cr, Cu, As, Fe, Mn) polluted landfill soil using consortia of autochthonous filamentous fungi. The fungal consortia used were Ascomycota, all isolated fungi, and Basidiomycota. Bioremediation was monitored for pH, redox potential, electrical conductivity, residual heavy metal/metalloid content, fungal population and enzyme activity at day 0 (initial day), day 20, day 60 and day 100. Results have shown a decreasing trend for all the monitored physicochemical parameters. Fungal organisms have a maximum tolerance index of 1.0 on Fe, Cu and Cr supplemented Agar medium. Highest colony count of 1.17 x 10(10) CFU/g soil was recorded in Basidiomycota treated soil. On the other hand, a consortium of all isolated fungi proved efficient in the removal of As (77 %), Mn(71 %), Cr(60 %), and Cu(52 %). Meanwhile, Fe removal of 56 % was prioritized by the Ascomycota consortium. Acid phosphatase had the weakest activity (0.03 - 0.72 mu mol PNPg (-1) dry soil h(-1)) for all the treatments. FTIR results have shown the appearance of absorption peaks at 1485 - 1445 cm (-1) only in soil amended with fungal consortia. Fungi bioaugmented soil had the maximum metal bio removal efficiency than the untreated control soil (P &\#60; 0.05).

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## Sequential microbial-photocatalytic degradation of imidacloprid

Authors: Sharma T, Kaur M, Sobti A, and more...

Source: ENVIRONMENTAL ENGINEERING RESEARCH, 25(4):597-604, 2020, DOI: 10.4491/eer.2019.150

**Abstract:** In the present study, the application of sequential biological and photocatalytic process was evaluated as a feasible process for the degradation of imidacloprid (IMI) in soil. Photocatalysis was carried out as a post and pre-treatment to the biological process as Microbial Photocatalytic (MP) and Photocatalytic Microbial (PM), respectively, to enhance the degradation and mineralization of IMI in soil. By both the processes, there was an enhancement in the percentage degradation of IMI i.e 86.2% for PM and 94.6% for MP process. The obtained results indicate that MP process is apparently more efficient in degradation of IMI which was observed with 15 days of biological treatment followed by 18 h of photocatalytic degradation (15 d + 18 h). The present work also reveals that though the difference in terms of the degradation of IMI after 5 d + 18 h, 10 d + 18 h & 15 d + 18 h of MP process is not drastic, yet significant variation has been observed in terms of mineralization that truly signifies the removal of IMI from the soil. The LC analysis has shown that the intermediates formed during MP process are more and smaller in comparison to PM process, which further provides evidence that MP process is better than PM process for effective degradation of IMI in soil.

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## Metagenomic applications in microbial diversity, bioremediation, pollution monitoring, enzyme and drug discovery. A review

Authors: Datta S, Rajnish KN, Samuel M, and more...

Source: ENVIRONMENTAL CHEMISTRY LETTERS, DOI: 0.1007/s10311-020-01010-z

**Abstract:** Metagenomics is a technology employed to study genetic material directly isolated from environmental samples. Metagenomics thus reveals knowledge on microbial communities of uncultivable organisms in environmental niches, using screening technologies based on sequence and function. Applications include the identification of novel bacteria or gene clusters encoding for enzymes that degrade pollutants. Metagenomics also help to diagnose and monitor pathogens. Here, we
review application of metagenomics for
bioremediation, pollution monitoring, enzyme,
and drug discovery.

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Effects of biodegradable
plastic film mulching on soil
microbial communities in two
agroecosystems

Authors: Bandopadhyay S, Sintim H Y, DeBruyn JM

Source: PEERJ, 8, 2020, DOI: 10.7717/peerj.9015

Abstract: Plastic mulch films are used globally in
crop production but incur considerable disposal
and environmental pollution issues.
Biodegradable plastic mulch films (BDMs), an
alternative to polyethylene (PE)-based films, are
designed to be tilled into the soil where they are
expected to be mineralized to carbon dioxide,
water and microbial biomass. However,
insufficient research regarding the impacts of
repeated soil incorporation of BDMs on soil
microbial communities has partly contributed to
limited adoption of BDMs. In this study, we
evaluated the effects of BDM incorporation on
soil microbial community structure and function
over two years in two geographical locations:
Knoxville, TN, and in Mount Vernon, WA, USA.
Treatments included four plastic BDMs (three
commercially available and one experimental
film), a biodegradable cellulose paper mulch, a
non-biodegradable PE mulch and a no mulch
plot. Bacterial community structure determined
using 16S rRNA gene amplicon sequencing
revealed significant differences by location and
season. Differences in bacterial communities by
mulch treatment were not significant for any
season in either location, except for Fall 2015 in
WA where differences were observed between
BDMs and no-mulch plots. Extracellular enzyme
assays were used to characterize communities
functionally, revealing significant differences by
location and sampling season in both TN and WA
but minimal differences between BDMs and PE
treatments. Overall, BDMs had comparable
influences on soil microbial communities to PE
mulch films.

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Bacterial community
diversity in the rhizosphere
of nickel hyperaccumulator
plant species from Borneo
Island (Malaysia)

Authors: Lopez S, van der Ent A, Sumail S, and
more...

Source: ENVIRONMENTAL MICROBIOLOGY, 22(4):1649-1665, 2020, DOI: 10.1111/1462-2920.14970

Abstract: The Island of Borneo is a major
biodiversity hotspot, and in the Malaysian state
of Sabah, ultramafic soils are extensive and
home to more than 31 endemic nickel
hyperaccumulator plants. The aim of this study
was to characterize the structure and the
diversity of the rhizosphere bacterial
communities of several of these nickel
hyperaccumulator plants and factors that affect
these bacterial communities in Sabah. The most
abundant phyla were Proteobacteria,
Acidobacteria and Actinobacteria. At family
level, Burkholderiaceae and Xanthobacteraceae
(Proteobacteria phylum) were the most abundant
families in the hyperaccumulator rhizospheres.
Redundancy analysis based on soil chemical
analyses and relative abundances of the major
bacterial phyla showed that abiotic factors of
the studied sites drove the bacterial diversity.
For all R. aff. bengalensis rhizosphere soil
samples, irrespective of studied site, the
bacterial diversity was similar. Moreover, the
Saprospiraceae family showed a high
representativeness in the R. aff. bengalensis
rhizosphere soils and was linked with the nickel
availability in soils. The ability of R. aff.
bengalensis to concentrate nickel in its
rhizosphere appears to be the major factor
driving the rhizobacterial community diversity
unlike for other hyperaccumulator species.

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Cadmium influences the
litter decomposition of
*Solidago canadensis* L. and
soil N-fixing bacterial
communities
Authors: Wang C, Wei M, Wang S, and more...

Source: CHEMOSPHERE, 246, 2020, DOI:
10.1016/j.chemosphere.2019.125717

**Abstract:** It is important to illuminate the effects of litter decomposition of invasive alien species on soil N-fixing bacterial communities (SoNiBa), especially under heavy metal pollution to better outline the mechanisms for invasion success of invasive alien species. This study attempts to identify the effects of litter decomposition of *Solidago canadensis* L. on SoNiBa under cadmium (Cd) pollution with different concentrations (i.e., low concentration, 7.5 mg/kg soil; high concentration, 15 mg/kg soil) via a polyethylene litterbags-experiment. Electrical conductivity and total N of soil were the most important environmental factors for determining the variations of SoNiBa composition. *S. canadensis* did not significantly affect the alpha diversity of SoNiBa but significantly affect the beta diversity of SoNiBa and SoNiBa composition. Thus, SoNiBa composition, rather than alpha diversity of SoNiBa, was the most important determinant of the invasion success of *S. canadensis*. Cd with 15 mg/kg soil did not address distinct effects on alpha diversity of SoNiBa, but Cd with 7.5 mg/kg soil noticeably raised the number of species and species richness of SoNiBa mainly due to the hormonal effects. The combined *S. canadensis* and Cd with 15 mg/kg soil obviously decreased cumulative mass losses and the rate of litter decomposition (k) of *S. canadensis*, but the combined *S. canadensis* and Cd with 7.5 mg/kg soil evidently accelerated cumulative mass losses and k of *S. canadensis*. Thus, Cd with 7.5 mg/kg soil can accelerate litter decomposition of *S. canadensis*, but Cd with 15 mg/kg soil can decline litter decomposition of *S. canadensis*.

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Characterization of a high
cadmium accumulating soil
bacterium, *Cupriavidus* sp.
WS2

Authors: Shi Z, Zhang Z, Yuan M., and more...

Source: CHEMOSPHERE, 247, 2020, DOI:
10.1016/j.chemosphere.2020.125834

**Abstract:** Cadmium (Cd) is one of the most harmful heavy-metals, its accumulation in crops can lead to severe ecological and healthy problems. Bioremediation using microbes to remove Cd or reduce the bioavailability of Cd is considered as a promising approach for Cd pollution control. Here, we described the isolation and characterization of a high Cd-accumulating bacterial strain, Cupriavidus sp. WS2, from the heavy-metals contained soil at the Wuhan Iron and Steel Company area. WS2 can survive under the high Cd conditions and immobilize Cd by biosynthesizing intracellular Cd-containing nanoparticle inclusions. In the co-inoculation test WS2 also significantly decreased the accumulation of Cd in rice seedlings. All our results suggested that Cupriavidus sp. WS2 may harbor a great potential for the bioremediation applications of Cd pollution.

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Lead toxicity induced
phytotoxic impacts on
rapeseed and clover can be
lowered by biofilm forming
lead tolerant bacteria

Authors: Shah T, Munsif F, D'amato R, Nie L

Source: CHEMOSPHERE, 246, 2020, DOI:
10.1016/j.chemosphere.2019.125766

**Abstract:** Lead (Pb+2) is a heavy metal and one of the main environmental pollutant, toxic to plants, animals and humans. Present study was conducted to evaluate ten plant growth promoting bacteria strains (B1-10) for biofilm production and their effect on growth indices, physiology, yield, antioxidant profile and lead uptake in rapeseed (Brassica napus) and clover (*Trifolium repens*) in lead polluted soil under nutrient broth medium and pot condition. Three pre-characterized biofilm forming lead tolerant growth promoting strains (B3: *Pseudomonas fluorescens*), B6: *Pseudomonas putida* and (B8: *Bacillus safensis*) were used to inoculate rapeseed and clover growing in the soil polluted with different levels (400, 800 and 1200 mg kg(-1)) of Pb arranged in completely randomized design with factorial arrangement. Results from screening experiment exhibited that more biofilm was produced by B3, B6 and B8 under highest level of lead contamination (1200 mg
kg(-1)). Further, lead contamination decreased rapeseed and clover growth, physiology and yield at all levels of lead stress. But biofilm forming lead tolerant growth promoting bacteria application in lead contaminated soil enhanced rapeseed and clover growth, physiology, yield, antioxidant profile, proline and decreased malanodialdehyde content (which was decreased by different strains application under lead stress) of rapeseed and clover over no inoculation. Inoculation with all strains also increased the lead uptake in roots, shoots and decreased lead uptake in seeds of rapeseed and clover than plants in lead stress without inoculation.

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## The metolachlor degradation kinetics and bacterial community evolution in the soil bioelectrochemical remediation

Authors: Li X, Li Y, Zhang X, and more...

Source: CHEMOSPHERE, 248, 2020, DOI: 10.1016/j.chemosphere.2020.125915

**Abstract:** Herbicide-polluted soils have posed a threat to the crop growth and agro-product quality and safety. Even worse, the low-content of residue is still appreciable for a long time in subsurface soils. The soil bioelectrochemical remediation system (BERS) provides an inexhaustible electron acceptor to cause in situ indigenous microorganisms to generate biocurrent and accelerate the removal of metolachlor (ML). As a result of carbon fiber amendment, the highest current density (637 +/- 19 mA/m(2)) to date has been generated in a soil BERS. The ML half-life and complete removal time decreased from 21 to 3 d and from 245 to 109 d, respectively. Importantly, the soil BERS was verified to be an effective treatment method for low-polluted sediments/soils, whether by ML or by its degradates. The quantitative degradates of ML showed that the first step was dechlorination based on the bioelectrochemical degradation pathway. The biocurrent selectively enriched special species, e.g., Geobacter and Thermincola for bioelectricity generation and Ralstonia, Phyllobacterium and Stenotrophomonas for degradation in soils. Meanwhile, Flavi-solibacter

and Gemmatimonas occupied the core niche in strengthening interspecific relationships by the biocurrent. This study firstly revealed the explicit abundance of Geobacter in agricultural soils and laid a foundation for the function design of mixed bacteria in the sediment/soil BERS.

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## Carbon and nitrogen cycling in a lead polluted grassland evaluated using stable isotopes (delta C-13 and delta N-15) and microbial, plant and soil parameters

Authors: Rijk IJC, Ekblad A

PLANT AND SOIL, 449(1-2):249-266, 2020, DOI: 10.1007/s11104-020-04467-7

**Abstract:** Aims Carbon (C) and nitrogen (N) cycling are key ecosystem functions potentially altered by heavy metal pollution. We used an ecosystem approach to study the long-term effect of lead (Pb) on C and N cycles in a natural grassland in a former shooting range. Methods Microbial activity was evaluated by substrate-induced respiration (SIR) in situ, adding isotopically labelled C-4-sugar to the soil. C and N contents and natural abundance of isotopes were measured in grass leaves, soil and microbial biomass together with root biomass. Results A reduced microbial activity and microbial biomass per area, together with a higher soil C stock and C:N ratio suggested a lower microbial decomposition in high Pb compared to low Pb areas. A more closed N cycle in the high Pb area was indicated by 2-3 parts per thousand lower delta N-15 in leaves and soil compared to low Pb areas. Higher delta C-13 in leaves and higher root biomass but similar leaf nutrient contents indicated plant responses and adaptions to the high Pb. Conclusions The applied ecosystem approach revealed that Pb slowed down the C and N cycles, possibly by indirect effects rather than by direct toxicity. The ecosystem seems to have adapted to altered conditions.

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# Inoculation of Cd-contaminated paddy soil with biochar-supported microbial cell composite: A novel approach to reducing cadmium accumulation in rice grains

Authors: Liu Y, Tie B, Peng O, and More...

Source: CHEMOSPHERE, 247, 2020, DOI: 10.1016/j.chemosphere.2020.125850

**Abstract:** Bioremediation of heavy metal-contaminated soil using metal-resistant microbes is a promising remediation technology. However, as exogenous bacteria sometimes struggle to survive and grow when introduced to new soils, it is important to develop appropriate carriers for microbial populations. In this study, we report a novel approach to remediating Cd-contaminated rice paddy soil using biochar-supported microbial cell composites (BMCs) produced from agricultural waste (cornstalks). Pot experiments showed that amendment with BMC was more efficient at reducing root and grain Cd content than pure bacteria, while improving soil Cd fractionation toward more stabilized and less labile forms. Bacteria in the BMC medium grew more readily with more abundant metabolites than those raised in free cells, probably because biochar provides shelter via porous structures (as confirmed by scanning electron microscopy) as well as additional nutrients. Overall, the improved long-term production of microbial biomass caused by BMC inoculation results in a higher remediation efficiency. Our results demonstrate the feasibility of using biochar as an appropriate carrier for metal-tolerant bacteria to remediate Cd-contaminated paddy fields.

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Zeolite-supported nanoscale zero-valent iron for immobilization of cadmium, lead, and arsenic in farmland soils: Encapsulation mechanisms and indigenous microbial responses

Authors: Li Z, Wang L, Wu J, and More...

Source: ENVIRONMENTAL POLLUTION, 260, 2020, DOI: 10.1016/j.envpol.2020.114098

**Abstract:** Zeolite-supported nanoscale zero-valent iron (Z-NZVI) has great potential for metal(loid) removal, but its encapsulation mechanisms and ecological risks in real soil systems are not completely clear. We conducted long-term incubation experiments to gain new insights into the interactions between metal(loid) s (Cd, Pb, As) and Z-NZVI in naturally contaminated farmland soils, as well as the alteration of indigenous bacterial communities during soil remediation. With the pH-adjusting and adsorption capacities, 30 g kg(-1) Z-NZVI amendment significantly decreased the available metal(loid) concentrations by 10.2-96.8% and transformed them into strongly-bound fractions in acidic and alkaline soils after 180 d. An innovative magnetic separation of Z-NZVI from soils followed by XRD and XPS characterizations revealed that B-type ternary complexation, heterogeneous coprecipitation, and/or concurrent redox reactions of metal(loid)s, especially the formation of Cd-3(AsO4)(2), PbFe2(AsO4)2(OH)(2), and As-0, occurred only under specific soil conditions. Sequencing of 16S rDNA using Illumina MiSeq platform indicated that temporary shifts in iron-resistant/sensitive, pH-sensitive, denitrifying, and metal-resistant bacteria after Z-NZVI addition were ultimately eliminated because soil characteristics drove the re-establishment of indigenous bacterial community. Meanwhile, Z-NZVI recovered the basic activities of bacterial DNA replication and denitrification functions in soils. These results confirm that Z-NZVI is promising for the long-term remediation of metal(loid)s contaminated farmland soil without significant ecotoxicity.

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Assessing microbial degradation degree and bioavailability of BDE-153 in natural wetland soils: Implication by compound-specific stable isotope analysis
Authors: Wang G, Liu Y, Tao W, and more...

Source: ENVIRONMENTAL POLLUTION, 260, DOI: 10.1016/j.envpol.2020.114014

**Abstract:** Microbial degradation is an important pathway for the attenuation of polybrominated diphenyl ethers (PBDEs) in natural soils. In this study, the compound-specific stable isotope analysis (CSIA) was applied to characterize microbial degradation of BDE-153, one of the prevailing and toxic PBDE congeners, in natural wetland soils. During the 45-day incubation, the residual percentages of BDE-153 decreased to 67.9% and 73.6% in non-sterilized soils spiked with 1.0 and 5.0 µg/g, respectively, which were both much lower than those in sterilized soils (96.0% and 97.2%). This result indicated that microbial degradation could accelerate BDE-153 elimination in wetland soils. Meanwhile, the significant carbon isotope fractionation was observed in non-sterilized soils, with delta C-13 of BDE-153 shifting from -29.4 parts per thousand to -26.7 parts per thousand for 1.0 µg/g and to -27.2 parts per thousand for 5.0 µg/g, respectively, whilst not in sterilized soils. This phenomenon indicated microbial degradation could induce stable carbon isotope fractionation of BDE-153. The carbon isotope enrichment factor (epsilon(c)) for BDE-153 microbial degradation was first determined as -7.58 parts per thousand, which could be used to assess the microbial degradation and bioavailability of BDE-153 in wetland soils. Based on delta C-13 and epsilon(c), the new methods were developed to dynamically and quantitatively estimate degradation degree and bioavailability of BDE-153 during degradation process, respectively, which could exclude interference of physical processes. This work revealed that CSIA was a promising method to investigate in situ microbial degradation of PBDEs in field studies.

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Comparative characterization
of microbial communities
that inhabit arsenic-rich and
antimony-rich contaminated
sites: Responses to two
different contamination
conditions

Authors: Sun X, Kong T, Xu R, Li B, Sun W

Source: ENVIRONMENTAL POLLUTION, 260, 2020, DOI: 10.1016/j.envpol.2020.114052

**Abstract:** Due to extensive mining and industrial activities, arsenic (As) and antimony (Sb) contaminations are becoming a global environmental concern. Both As and Sb are toxic and carcinogenic metalloids from the group 15 in the periodic table. Since As and Sb share many similar geochemical properties, it is often assumed that they exert similar environmental pressure on the native microbial communities. This hypothesis, however, still requires further confirmation. In the current study, a systematic comparison of microbial responses to As and Sb contamination were conducted. The results suggested that regular geochemical parameters, such as pH, nitrate, and TOC, were the driving forces for shaping the microbial community. In correspondence, two heavily contaminated groups showed similar microbial community compositions and the same microbial populations were enriched. The interactions between the contaminant fractions (As and Sb related fractions) and the individual OTUs, however, suggested the different and more diverse impacts of As comparing to Sb fractions, with more taxa significantly impacted by As species comparing to Sb species. The identification of the keystone taxa in the heavily contaminated samples revealed a group of microbial populations that could survive in both As and Sb heavily contaminated conditions and may providing critical environmental services to the community. Further investigation of these key microbial populations may provide valuable insights on employing these microorganisms for remediation applications.

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Transcriptome profiling of
the fungus *Aspergillus
nidulans* exposed to a
commercial glyphosate-based
herbicide under conditions of
apparent herbicide tolerance

Authors: Mesnage R, Oestreicher N, Poirier F, Nicolas V, Boursier C, Velot C
Source: ENVIRONMENTAL RESEARCH, 182, 2020, DOI: 10.1016/j.envres.2020.109116

**Abstract:** Glyphosate-based herbicides, such as Roundup (R), are the most widely used non-selective, broad-spectrum herbicides. The release of these compounds in large amounts into the environment is susceptible to affect soil quality and health, especially because of the non-target effects on a large range of organisms including soil microorganisms. The soil filamentous fungus Aspergillus nidulans, a well-characterized experimental model organism that can be used as a bio-indicator for agricultural soil health, has been previously shown to be highly affected by Roundup GT Plus (R450: 450 g/L of glyphosate) at concentrations far below recommended agricultural application rate, including at a dose that does not cause any macroscopic effect. In this study, we determined alterations in the transcriptome of A. nidulans when exposed to R450 at a dose corresponding to the no-observed-adverse-effect level (NOAEL) for macroscopic parameters. A total of 1816 distinct genes had their expression altered. The most affected biological functions were protein synthesis, amino acids and secondary metabolisms, stress response, as well as detoxification pathways through cytochromes P450, glutathione-S-transferases, and ABC transporters. These results partly explain the molecular mechanisms underlying alterations in growth parameters detected at higher concentrations for this ascomycete fungus. In conclusion, our results highlight molecular disturbances in a soil fungus under conditions of apparent tolerance to the herbicide, and thus confirm the need to question the principle of "substantial equivalence" when applied to plants made tolerant to herbicides.

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## Resistant fungi isolated from contaminated uranium mine in Brazil shows a high capacity to uptake uranium from water

Authors: Coelho E, Reis TA, Cotrim M, Mullan TK, Correa B

Source: CHEMOSPHERE, 248, 2020, DOI: 10.1016/j.chemosphere.2020.126068

**Abstract:** The Osamu Utsumi uranium mine occupies a 20 km(2) area in the city of Caldas, which is located in the state of Minas Gerais, Brazil. Since mining activities ended at Osamu Utsumi 24 years ago, the surrounding area has become contaminated by acid effluents containing high concentrations of uranium. Thus, the aim of this study was to assess the uranium bioremediation capacity of 57 fungi isolated from the mine area. In tolerance tests, 38% (22) of the fungal isolates were considered tolerant to uranium, including 10 Penicillium species. At a uranium concentration of 2000 mg L-1 48 fungi did not exhibit mycelial growth index inhibition. Minimal inhibitory concentration (MIC) analysis showed growth of 25 fungi above a uranium concentration of 8000 mg L-1. At high uranium concentrations, some fungi (i.e., Talaromyces amestolkiae and Penicillium citrinum) showed morphological changes and pigment (melanin) production. Among the fungal isolates, those considered to be more tolerant to uranium were isolated from soil and sediment samples containing higher concentrations of heavy metal. When comparing the results of resistance/tolerance tests with those for uranium biosorption capacity, we concluded that the fungi isolated from the Osamu Utsumi mine with the best potential for uranium bioremediation were Gongronella butleri, Penicillium piscarium, Penicillium citrinum, Penicillium ludwigii, and Talaromyces amestolkiae. Biosorption tests with live fungal biomass showed that 11 species had a high potential for uranium uptake from contaminated water.

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## New insights into the microbial degradation and catalytic mechanism of synthetic pyrethroids

Authors: Zhan H, Huang Y, Lin Zi, Bhatt P, Chen S

Source: ENVIRONMENTAL RESEARCH, 182, 2020, DOI: 10.1016/j.envres.2020.109138

**Abstract:** The significant applications of pyrethroid insecticides in agro-ecosystem and household environments have raised serious
environmental concerns. Environmental bioremediation has emerged as an effective and eco-friendly approach to remove or neutralize hazardous compounds. Bioaugmentation accelerates pyrethroid degradation in liquid cultures and soil. Pyrethroid-degrading microorganisms have been extensively studied to cope with pyrethroid residues. Microorganisms primarily hydrolyze the ester bonds of pyrethroids, and their degradation pathways have been elaborated. The functional genes and enzymes involved in microbial degradation have also been screened and studied. Carboxylesterase plays a key role in pyrethroid degradation by cleaving its carboxylester linkage. The catalytic mechanism is dependent on a specific catalytic triad, consisting of three amino acid residues (glutamine, histidine, and serine) within the active site of the carboxylesterase enzyme. Pyrethroid-degrading strains and enzymes have proven to be effective for the bioremediation of pyrethroid-contaminated environments. In this review, we have summarized newly isolated pyrethroid-degrading strains and proposed the degradation pathways along with key functional genes/enzymes. To develop an efficient bioremediation strategy, pyrethroid-degrading microorganisms should be comprehensively explored.

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## Algae-based heavy metal remediation in acid mine drainage: a review

Author: Mang KC, Ntushelo K

Source: APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH, 18(2):2499-2512, 2020, DOI: 10.15666/aeer/1802_24992512

Abstract: The production of acid mine drainage (AMD) is among the factors responsible for much of the degradation of water and soil resources and the disruption of biodiversity in the environment. Several studies have shown that

organisms (either macro or micro) present at sites contaminated with AMD have the potential to bioaccumulate heavy metals and hence stimulate their application in bioremediation processes. Algal strains are not an exception to those organisms found in AMD. This review was aimed at examining the heavy metal remediation of AMD using algae, remediation properties of algae and different algal-based methods used in heavy metal remediation of AMD. Algal strains such as Spirulina sp., Chlorella spp., Scenedesmus spp., Cladophora spp., Oscillatoria spp., Anabaena spp. and Phaeodactylum tricornutum act as "hyper-accumulators" and "hyper-adsorbents" with a high selectivity for different elements from AMD. However, algae-based methods of abating AMD are not the ultimate solution to the problem and there is room for more studies. The current study suggests further attention to phycoremediation individually and synergistically with sulphate-reducing bacteria.

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## Bacterial abundance along a gradient of heavy metal contaminated soils in the region of Zlatitsa-Pirdop valley, western Bulgaria

Source: Aleksova M, Palov D, Dinev N, and more...

Source: COMPTES RENDUS DE L ACADEMIE BULGARE DES SCIENCES, 73(3):433-440, 2020, DOI: 10.7546/CRABS.2020.03.18

Abstract: This study presents the distribution of bacterial abundance in the soil from three sites along the gradient of Cu (53-860 mg kg (-1)), Zn and Pb, located in the region of Zlatitsa-Pirdop valley, Western Bulgaria. The bacterial abundance was determined by the use of colony forming units and quantitative PCR techniques in five soil samples, collected at 0-20 cm depth. Our results showed that the number of cultivable heterotrophic bacteria and 16S rRNA gene copies decreased in long-term heavy metals contaminated soils. The distribution of 16S rRNA gene copies was mainly affected by the concentration of heavy metals, as well as by the land use. The principal component analysis was used to visualize the relationships between
bacterial abundance, soil physico-chemical properties and sampling sites. The results showed that the less polluted sites were grouped in a single cluster with the highest number of 16S r RNA gene copies, whereas the most polluted site was clustered separately. This study highlights that heavy metal contamination and the land use have significant impact on soil bacteria.

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## Complete genome sequencing and comparative genomic analyses of *Bacillus* sp. S3, a novel hyper Sb(III)-oxidizing bacterium

Authors: Li JK, Gu TY, Li LZ, and more...

Source: BMC MICROBIOLOGY, 20(1), 2020, DOI: 10.1186/s12866-020-01737-3

**Abstract:** Background Antimonite [Sb(III)]-oxidizing bacterium has great potential in the environmental bioremediation of Sb-polluted sites. *Bacillus* sp. S3 that was previously isolated from antimony-contaminated soil displayed high Sb(III) resistance and Sb(III) oxidation efficiency. However, the genomic information and evolutionary feature of *Bacillus* sp. S3 are very scarce. Results Here, we identified a 5,436,472 bp chromosome with 40.30% GC content and a 241,339 bp plasmid with 36.74% GC content in the complete genome of *Bacillus* sp. S3. Genomic annotation showed that *Bacillus* sp. S3 contained a key aioB gene potentially encoding As (III)/Sb(III) oxidase, which was not shared with other *Bacillus* strains. Furthermore, a wide variety of genes associated with Sb(III) and other heavy metal (loid) s were also ascertained in *Bacillus* sp. S3, reflecting its adaptive advantage for growth in the harsh eco-environment. Based on the analysis of phylogenetic relationship and the average nucleotide identities (ANI), *Bacillus* sp. S3 was proved to a novel species within the *Bacillus* genus. The majority of mobile genetic elements (MGEs) mainly distributed on chromosomes within the *Bacillus* genus. Pan-genome analysis showed that...

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## Kinetic Study of the Biodegradation of Acephate by Indigenous Soil Bacterial Isolates in the Presence of Humic Acid and Metal Ions

Authors: Singh S, Kumar V, Singla S and more...

Source: BIOMOLECULES, 10(3), 2020, DOI: 10.3390/biom10030433

**Abstract:** Many bacteria have the potential to use specific pesticides as a source of carbon, phosphorous, nitrogen and sulphur. Acephate degradation by microbes is considered to be a safe and effective method. The overall aim of the present study was to identify acephate biodegrading microorganisms and to investigate the degradation rates of acephate under the stress of humic acid and most common metal ions Fe(III) and copper Cu(II). *Pseudomonas azotoformans* strain ACP1, *Pseudomonas aeruginosa* strain ACP2, and *Pseudomonas putida* ACP3 were isolated from acephate contaminated soils. Acephate of concentration 100 ppm was incubated with separate strain inoculums and periodic samples were drawn for UV-visible, FTIR (Fourier-transform infrared spectroscopy) and MS (Mass Spectrometry) analysis. Methamidophos, S-methyl O-hydrogen phosphorothioamide, phosphenothioic S-acid, and phosphenamide were the major metabolites formed during the degradation of acephate. The rate of degradation was applied using pseudo-first-order kinetics to calculate the half-life (t(1/2)) values, which were 14.33-16.72 d(-1) (strain(s) + acephate), 18.81-21.50 d(-1) (strain(s) + acephate + Cu(II)), 20.06-23.15 d(-1) (strain(s) + acephate + Fe(II)), and 15.05-17.70 d(-1) (strains + acephate + HA). The biodegradation efficiency of the three bacterial strains can be ordered as *P. aeruginosa* > *P. putida* > *P. azotoformans*. The present study illustrated the decomposition mechanism of acephate under different conditions, and the same may be applied to the removal of other xenobiotic compounds.

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## Modulations in growth, structure, cell viability and antioxidant enzyme of a
nodule

bacterium

Mesorhizobium

ciceri

### induced by pesticides

Authors: Shahid M, Zaidi A, Saghir KM

Source: ENVIRONMENT DEVELOPMENT AND SUSTAINABILITY, DOI: 10.1007/s10668-020-00758-2

**Abstract:** A rapid increase in the application of synthetic pesticides in agricultural practices causes a severe hazard to agro-sustainability and soil microflora. Considering these threatening problems, the present study aimed to investigate the impact of different groups of pesticides on growth, cellular morphostructure, permeability and antioxidant enzyme of a symbiotic Gram-negative bacterium recovered from chickpea nodules. Pesticide-tolerant strain BRM5 was characterized and phylogenetically (accession no. KY013481) identified as *Mesorhizobium ciceri*. Strain BRM5 tolerated up to the level of 1200, 1600, 1600, 2400, 2400, 1800, 2400, 2400 and 3200 μg mL (-1) of glyphosate, quizalofop, atrazine, kitazin, metalaxyl, hexaconazole, fipronil, monocrotophos and imidacloprid, respectively. Among all concentrations, 3X concentrations of each pesticide had most fatal to bacterial cells. The growth pattern of strain BRM5 was decreased linearly with increasing incubation times. Scanning electron micrograph (SEM) images of pesticide-treated bacterial cells revealed the distorted, broken, irregular, misshaped and larger-sized cell as compared to untreated cells. Upon staining with acridine orange (AO)/propidium iodide (PI), active/living cells appeared as green colour, whereas dead cells appeared as red colour under confocal microscope (CLSM). This is the clear indication of ...

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### Effect of Fe-Mn-Ce modified biochar composite on microbial diversity and properties of arsenic-contaminated paddy soils

Authors: Zhang G, Liu X, Gao M, Song Z

Source: CHEMOSPHERE, 50, 2020, DOI: 10.1016/j.chemosphere.2020.126249

**Abstract:** In this study, we investigated the mechanism of decrease in arsenic (As) bioavailability after addition of biochar (BC) supplemented with iron (Fe)- manganese (Mn)-cerium (Ce) oxide (FMCBC) to As-contaminated paddy soil. We explored the effects of these composites on the oxidation, reduction, microbial community, and soil enzyme activity of As-contaminated paddy soil. Results showed that FMCBCs improve soil pH, significantly improve the redox capacity of soil, and reduce bioavailable forms of As. FMCBCs can convert As from a specifically or non-specifically bound form into amorphous hydrous oxide bound- and crystalline hydrous oxide bound form. The application of FMCBCs increased soil enzyme activity (urease, catalase, alkaline phosphatase, and peroxidase), and greatly influenced the relative abundance of certain microorganisms (Proteobacteria, Acidobacteria, and Gemmatimonadetes), which improved soil enzyme heavy metal tolerance and prevented their denaturation. Thus, FMCBCs can not only change the form and distribution of As in soil but also create an environment suitable for microbial growth, consequently affecting the geochemical cycling of As in soil. (C) 2020 Elsevier Ltd. All rights reserved.

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### Ecotoxicological effect of mesotrione on enzyme activity and microbial community in agricultural soils

Authors: Sun Y B, Wang L, Xu YM, Liang XF, Zheng SN

Source: APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH, 18(2):3525-3541, 2020, DOI: 10.15666/aeer/1802_35253541

**Abstract:** Multiple experiments were performed to evaluate the ecotoxicological effect of mesotrione on soil enzymatic activity, functional diversity, and genetic microbial biodiversity. The
results showed that catalase and invertase activity initially increased with higher mesotrione concentration and then declined slightly. However, urease activity experienced a 11.9-23.2% reduction in comparison to control soil. The average well-color development (AWCD) was positively affected by the mesotrione treatment, the amount of carbohydrate, amino acid, and phenolic acid increased by 1.7-2.1, 1.1-1.6, and 1.7-2.5 times, respectively, when compared with the blank treatment. However, the utilization of carboxylic and acid amine was prohibited after applying 50-100 mg kg (-1) and 20-100 mg kg(-1) mesotrione. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the shift in the bacterial community structure for different mesotrione treatments can be mainly attributed to an increment in band intensity, while the dissimilarity in the bacterial genetic structure decreased with increasing mesotrione content in the soil. Sequencing and phylogenetic analyses showed that the four bands in the denaturing gradient gel electrophoresis results were closely related to Bacillus subterraneus, Clostridium sp., and Bacillus sp. Obtained results show that abuse of mesotrione may pose a potential risk for soil microbial functioning.

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## Ecological remediation of petroleum-contaminated soil based on microbial degradation

Authors: Wang C, Li Z, Geng X, Zhang H

Source: APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH, 18(2):2727-2746, 2020, DOI: 10.15666/aeer/1802_27272746

Abstract: In the process of oil exploitation, refining, storage, transportation and use, due to the limitations of technological level and treatment technology, a large amount of petroleum-containing wastewater and waste residue are inevitably discharged into the soil, thus affecting the whole soil ecosystem. In this paper, an ecological remediation method for

petroleum contaminated soil based on microbial degradation is proposed. The natural biodegradation of petroleum contaminants in soil is discussed. The types of degrading microorganisms and their degradation mechanisms for saturated hydrocarbons and aromatic hydrocarbons are introduced, and the chemical composition of petroleum and the number of microorganisms in the soil are analyzed. The effects of nutrients, oxygen supply, temperature, humidity and pH on the degradation efficiency of petroleum are studied, and the in-situ soil ecological remediation is carried out after the degradation of pollutants. Experiments show that the ecological remediation of petroleum contaminated soil based on microbial degradation can be more thorough in essence. This method has the advantages of requiring only a low time investment, being, low cost, simple and effective, and having a good remediation effect and no secondary pollution.

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## Atrazine Bioremediation and Its Influence on Soil Microbial Diversity by Metagenomics Analysis

Authors: Bhardwaj P, Singh KR, Jadeja NB, Phale PS, Kapley A

Source: INDIAN JOURNAL OF MICROBIOLOGY, DOI: 10.1007/s12088-020-00877-4

Abstract: Pesticide accumulation in agricultural soils is an environmental concern, often addressed through distinct bioremediation strategies. This study has tried to analyze various soil bioremediation options viz., biostimulation, bioaugmentation, and natural attenuation in terms of efficiency and the response of autochthonous microbial flora by using atrazine as a model contaminant. Soil mesocosms were established with 100 kg of soil simulating the field conditions. The soil previously exposed to the herbicide was used for the bioaugmentation strategy undertaken in this study. We have tried to analyze how the microbial community responds to a foreign compound, both in terms of taxonomic and functional capacities? To answer this, we have analyzed metagenome of the mesocosms at a time point when 90% atrazine was degraded. Bioaugmentation for
bioremediation proved to be efficient with a DT90 value of 15.48 +/- 0.79 days, in comparison to the natural attenuation where the DT90 value was observed to be 41.20 +/- 1.95 days. Metagenomic analysis revealed the abundance of orders Erysipelotrichales, Selemonadales, Clostridiales, and Thermoanaerobacterales exclusively in SBS mesocosm. Besides Pseudomonas, bacterial genera such as Chromobacter, Xanthomonas, Stenotrophomonas, and Cupriavidus have emerged as the dominant members in various bioremediation strategies tested in this study. Inclusive results suggest that inherent microbial flora adjust their community and metabolic machinery upon exposure to the pollutant. The site under pollutant stress showed efficient microbial communities to bio-remediate the newly polluted terrestrial ecologies in relatively less time and by economic means.

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## Responses of Bacterial and Fungal Community Structure to Different Rates of 1,3-Dichloropropene Fumigation

Authors: Zeng Y, Abdo Z, Charkowski A, Stewart JE, Frost K

Source: PHYTOBIOMES JOURNAL 3(3):212-223, 2019, DOI: 10.1094/PBIOMES-11-18-0055-R

**Abstract:** 1,3-Dichloropropene (1,3-D) is a well-known nematicidal soil fumigant on many crop species. Currently, little is known about its impact on soil microbial communities using culture-free methods. In this study, we investigated changes in soil bacterial and fungal diversity and composition at two depths (30.5 and 61 cm) in response to management practices of applying 1,3-D at four different rates (103, 122, 140, and 187 liters/ha) relative to an untreated control in potato production fields using 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing. A total of 12,783 operational taxonomic units (OTUs) for 16S and 1,706 OTUs for ITS were obtained. Sequencing revealed that Proteobacteria, Firmicutes, Actinobactena, and Ascomycota were dominant phyla in soils. Comparing alpha diversity of microbial communities at the different chemical rates with untreated plots showed that bacterial communities in plots treated with 1,3-D

fumigation at 140 liters/ha were richer, which was supported by higher richness indices. Other diversity indices and overall soil microbial community structure were not significantly influenced by any rates of 1,3-D fumigation, although higher bacterial and fungal richness and diversity were observed in posttreatment soils and/or at 30.5 cm. Of the identified microbial families, the differential abundance of 45 bacterial and 24 fungal families was affected by sample depth, 1,3-D rate, or the interaction of sample depth and 1,3-D. The bacterial family Enterobacteriaceae, which includes species that specialize in decay of complex carbohydrates, increased in abundance post-1,3-D fumigation, and the fungal family Ophiocordycipitaceae, which includes nematode and insect pathogens, decreased, suggesting that the nematode and soil insect death caused by fumigation may selectively impact specific fungal and bacterial families.

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## Co-occurrence of antibiotic, biocide, and heavy metal resistance genes in bacteria from metal and radionuclide contaminated soils at the Savannah River Site

Authors: Thomas JC, Oladeinde A, Kieran TJ, and More...

Source: MICROBIAL BIOTECHNOLOGY, DOI: 10.1111/1751-7915.13578

**Abstract:** Contaminants such as heavy metals may contribute to the dissemination of antimicrobial resistance (AMR) by enriching resistance gene determinants via co-selection mechanisms. In the present study, a survey was performed on soils collected from four areas at the Savannah River Site (SRS), South Carolina, USA, with varying contaminant profiles: relatively pristine (Upper Three Runs), heavy metals (Ash Basins), radionuclides (Pond B) and heavy metal and radionuclides (Tim's Branch). Using 16S rRNA gene amplicon sequencing, we explored the structure and diversity of soil bacterial communities. Sites with legacies of metal and/or radionuclide contamination displayed significantly lower bacterial diversity compared to the reference site. Metagenomic
analysis indicated that multidrug and vancomycin antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) including those associated with copper, arsenic, iron, nickel and zinc were prominent in all soils including the reference site. However, significant differences were found in the relative abundance and diversity of certain ARGs and MRGs in soils with metal/radionuclide contaminated soils compared to the reference site. Co-occurrence patterns revealed significant ARG/MRG subtypes in predominant soil taxa including Acidobacteriaceae, Bradyrhizobium, Mycobacterium, Streptomyces, Verrumicrobium, Actinomadura and Solirubacterales. Overall, the study emphasizes the potential risk of human activities on the dissemination of AMR in the environment.

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# The Arsenic Methylation Cycle: How Microbial Communities Adapted to Use as Weapons in the Continuing War for Dominance

Authors: Chen J, Rosen BP

Source: FRONTIERS IN ENVIRONMENTAL SCIENCE, 8, DOI: 10.3389/fenvs.2020.00043

**Abstract:** Arsenic is toxic and widely distributed in the environment. Most microorganisms have evolved mechanisms to use methylarsenicals as weapons in microbial warfare. This has created cycles of arsenic methylation and demethylation, which constitutes an important part of arsenic biogeochemical cycles and environmental health. Arsenic methylation forms methylarsenite [MAs(III)], arsenobetaine, arsenosugars and the new identified methylarsenical antibiotic, arsinothricin (AST). Bacteria use MAs(III) and AST as antibiotic to obtain a competitive advantage over other bacteria. Microbes produce toxic MAs(III) by (1) methylation of arsenite [As(III)] or (2) reduction of methylarsenate [MAs(V)]. In air, MAs(III) is oxidized to MAs(V) by oxygen, which conferring methylation to be considered as a detoxification pathway in aerobes. MAs(V) also can be re-reduced to MAs(III) by other bacteria, which can enable its survival and dominance with more competitive advantage than other sensitive

bacteria. The different composition and diversity of microbial community could generate the sustained pool of MAs(III). These complex interactions have an emergent property., that is, overall scheme of arsenic-containing antibiotics emerges from interaction of multiple species. In response to production of the antibiotic MAs(III), other members of microbial communities have evolved at least four mechanisms for MAs(III) resistance: (1) ArsH detoxifies MAs(III) by oxidation to less toxic MAs(V); (2) Arsl degrades MAs(III) by cleavage of the C-As bond to form less toxic As(III); (3) the ArsP efflux permease confers selective resistance to MAs(III); and (4) the unrelated ArsK efflux permease confers resistance to both trivalent inorganic and organoarsenicals. Environmental application of anthropogenic aromatic arsenicals further fuels bacterial warfare and selection for novel resistance mechanisms. In another microbial adaptation to use environmental arsenic as a weapon, some soil bacteria synthesize a methylarsenate analog of the amino acid glutamic acid termed AST; AST shows a broad-spectrum antibiotic action against both Gram-negative and Gram-positive bacteria. In response to the environmental challenge presented by AST, arsN genes evolved to detoxify it by acetylation of the alpha-amino group. Thus, to battle for surviving and thriving in the microbial community, life has to adapted and use environmental arsenic as a weapon. Both MAs(III) and AST are natural products with antibiotic-like properties, both are toxic methylarsenicals produced by some microbe and further kill off its competitors, and resistances have arisen for both.

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ERA / PUBLICATIONS

SCIENTIFIQUES / MICROBIOLOGIE et BIOCONTROLE

Methyl t-butyl ether-degrading bacteria for bioremediation and biocontrol purposes
**Authors:** d'Errico G, Aloj V, Ventorino V, Bottiglieri A, and more...

**Source:** PLOS ONE 15(2), 2020, DOI: 10.1371/journal.pone.0228936

**Abstract:** A total of fifteen potential methyl t-butyl ether (MtBE)-degrading bacterial strains were isolated from contaminated soil. They have been identified as belonging to the genera Bacillus, Pseudomonas, Kocuria, Janibacter, Starkeya, Bosea, Mycolicibacterium, and Rhodovarius. *Bacillus aryabhattai* R1B, *S. novella* R8b, and *M. mucogenicum* R8i were able to grow using MtBE as carbon source, exhibiting different growth behavior and contaminant degradation ability. Their biocontrol ability was tested against various fungal pathogens. Both *S. novella* R8b and *B. aryabhattai* were effective in reducing the development of necrotic areas on leaves within 48 hours from *Botritys cinerea* and Alternaria alternata inoculation. Whereas, *M. mucogenicum* effectively controlled *B. cinerea* after 72 hours. Similar results were achieved using *Pythium ultimum*, in which the application of isolated bacteria increased seed germination. Only *M. mucogenicum* elicited tomato plants resistance against *B. cinerea*. This is the first report describing the occurrence of bioremediation and biocontrol activities in *M. mucogenicum*, *B. aryabhattai* and *S. novella* species. The production of maculosin and its antibiotic activity against *Rhizoctonia solani* has been reported for first time from *S. novella*. Our results highlight the importance of multidisciplinary approaches to achieve a consistent selection of bacterial strains useful for plant protection and bioremediation purposes.

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Determinations of in vitro
Antagonistic Effects of
Microbiomes Isolated from
Vermicompost Against Major
Plant Fungal Disease Agents
of Vegetables

Authors: Soylu EM, Soylu S, Kara M, Kurt S

Source: KSU TARIM VE DOGA DERGISI-KSU JOURNAL OF AGRICULTURE AND NATURE, 23(1):7-18, 2020, DOI: 10.18016/ksutarimdoga.vi.601936

**Abstract:** In this study, in vitro antagonistic potentials of bacterial microbiomes, obtained from earthworm fertiliser, vermicompost, were investigated on inhibitions of mycelial growth of major foliar and soilborne fungal disease agents *Sclerotinia sclerotiorum*, *Macrophomina phaseolina*, *Botrytis cinerea*, *Verticilium dahliae*. Total of 69 putative bacterial biocontrol agent (BCA) isolates were obtained from commercial vermicompost lots. Among them, 28 bacterial isolates (49.12% of total isolates) were inhibited mycelial growth of *S. sclerotiorum* by 1.72-75.43%, *M. phaseolina* by 1.67-65.83%, *B. cinerea* by 3.44-57.18%, *V dahliae* by 2.28-58.74%, respectively. Majorities of bacterial isolates were identified as *Bacillus* spp. Certain isolates of *Bacillus* spp. have caused noticeable morphological changes on mycelia of *S. sclerotiorum*. Antagonistic potentials of bacterial isolates were found to increase by pre-incubation time prior the fungal inoculation. Due to high antagonistic properties, efficient isolates of *Bacillus* spp. may be used as biocontrol agent against soilborne diseases as an alternative to pesticides to promote organic and sustainable agriculture.

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ERA / PUBLICATIONS
SCIENTIFIQUES / PESTICIDES ET FAUNE SAUVAGE

Nest-boxes for raptors as a
biological control system of
vole pests: High local success
with moderate negative
consequences for non-target
species - ScienceDirect

Authors: Paz Luna A, Bintanel H, Viñuela J, Villanúa D

Source: Biological Control 146, 2020, DOI: 10.1016/j.biocontrol.2020.104267.

**Abstract:** Biological control of rodents in agricultural areas, increasing avian predator abundance by nest-box provisioning, has been
proposed during the last decades in several regions around the world as an alternative to the widespread use of anticoagulant rodenticides (AR) to protect crops. (...) Here we test the effectiveness of providing nest-boxes to common kestrels (Falco tinnunculus) and barn owls (*Tyto alba*) in reducing the abundance of two different vole species using indirect index methods to estimate rodent abundance in late spring (May). We monitored the abundance of both vole species in a treatment (with nest boxes) and control (without nest boxes) areas during three years in alfalfa fields, using a BACI design.

Our results showed a clear-cut reduction in the abundance of the two vole species, the common vole (*Microtus arvalis*) and the mediterranean-pine vole (*Microtus duodecimcostatus*) in the experimental area after applying the treatment (nest box installation) in alfalfa crops. We also found a significant decrease in the presence of both species of voles on fruit-tree plantations and alfalfa crops but we did not find significant effects in the cereal fields, where voles were in general very scarce. These results suggest higher efficacy of biological control in this study area than in some areas of NW Spain, what could be explained by several non-exclusive hypotheses presented in the discussion.

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## Mediation of Oxidative Stress
Toxicity Induced by
Pyrethroid Pesticides in Fish

Authors: Yang C, Lim W, Song G

Source: Comp Biochem Physiol C Toxicol Pharmacol 234:108758, 2020, DOI: 10.1016/j.cbpc.2020.108758

Abstract: In this review, we examine the occurrence of pyrethroid pesticides in the aquatic environment and oxidative stress-induced toxicity in fish exposed to pyrethroids. Organophosphate and organochlorine pesticides are banned in most countries because they cause high toxicity and bioaccumulation in non-target organisms. However, pyrethroids are approximately 1000 times more toxic to fish than to mammals and birds. Fish-specific organs such as the gills and their late metabolic action against this type of pesticide make fish highly susceptible to the toxicity of pyrethroid pesticides. Oxidative stress plays an important

role in the neurological, reproductive, and developmental toxicity caused by pyrethroids. Deltamethrin, cypermethrin, and lambda-cyhalothrin are representative pyrethroid pesticides (...)

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## Toxic Elements in Blood of
Red-Necked Nightjars
(Caprimulgus Ruficollis)
Inhabiting Differently
Polluted Environments

Authors: Espín S, Sánchez-Virola P, Zamora-Marín JM, et al.

Source: Environ Pollut 262:114334,2020, DOI: 10.1016/j.envpol.2020.114334

Abstract: (...) rare earth elements (REE) and other minor elements (ME) are becoming a new threat due to their use in modern technology. (...) The order Caprimulgiformes is among the most understudied groups of birds (...) we sampled 48 red-necked nightjars (*Caprimulgus ruficollis*) inhabiting three different scenarios of contaminant exposure (agricultural-urban area, n = 15; mining area, n = 17; and control area, n = 16) in southeastern Spain, and report for the first time concentrations of 50 elements (i.e. trace elements, ATSDR's list toxic elements, REE and ME) (...). Concentrations of As, Cd, Pb and Mn were significantly higher in individuals captured at the mining area compared to the other sites. Lead levels in the mine site were of particular concern since it was in the range of blood concentrations related to subclinical/clinical effects in other species, (...) Moreover, additive effects related to metal cocktail exposure in the mining area could be expected. (...) most REE and ME concentrations were close to the LOQ, (...).

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## Longitudinally Monitored
Lifetime Changes in Blood
Heavy Metal Concentrations
and Their Health Effects in
Urban Birds
Authors: Bauerová P, Krajzingrová T, Těšický M, et al.

Source: Sci Total Environ 723:138002, 2020, DOI: 10.1016/j.scitotenv.2020.138002

**Abstract:** Urban heavy metal pollution can impair the health of humans and other organisms inhabiting cities. While birds are suggested as one of the appropriate bioindicators for essential and non-essential trace element monitoring, the process of particular elements' accumulation in blood and its possible adverse health effects during ageing of individuals remain unexplored. We have investigated lifetime changes in blood lead (Pb), cadmium (Cd), arsenic (As) and zinc (Zn) concentrations and searched for links to health-related traits in sub-urban free-living great tit (Parus major) population (...) This study demonstrates the suitability of avian blood for actual heavy metal spatial and temporal biomonitoring even in situations when the precise age of the individuals remains unknown.

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## From seeds to plasma: Confirmed exposure of multiple farmland bird species to clothianidin during sowing of winter cereals

Authors: Lennon Rosie J, Peach Will J, Dunn Jenny C, Shore Richard F... Brown Colin D

Source: Science of The Total Environment 723, 2020, DOI: 10.1016/j.scitotenv.2020.138056

**Abstract:** (...)little is known about the extent to which farmland birds are exposed to the neonicotinoid compounds during standard agricultural practices. This study uses winter cereal, treated with the neonicotinoid clothianidin, as a test system to examine patterns of exposure in farmland birds during a typical sowing period. The availability of neonicotinoid-treated seed was recorded post-sowing at 39 fields (25 farms) (...) avian blood samples were collected from 11 species of farmland bird from a further six capture sites to quantify the prevalence and level of clothianidin exposure associated with seed treatments. (...) Exposure was confirmed in 32% of bird species observed in treated fields and 50% of individual birds post-sowing; the median concentration

recorded in positive samples was 12 ng/mL. Results here provide clear evidence that a variety of farmland birds are subject to neonicotinoid exposure following normal agricultural sowing of neonicotinoid-treated cereal seed. Furthermore, the widespread availability of seeds at the soil surface was identified as a primary source of exposure.

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## Assessment of the effects of early life exposure to triphenyl phosphate on fear, boldness, aggression, and activity in Japanese quail (Coturnix japonica) chicks

Authors: Hanas AK, Guigueno MF, Fernie KJ, Letcher RJ, Chamberland FSM, Head JA

Source: Environmental Pollution, 258, 2020, DOI: 10.1016/j.envpol.2019.113695.

**Abstract:** Triphenyl phosphate (TPHP) is an organophosphate ester (OPE) used as a flame retardant (FR) and plasticizer. (...) this is the first study on the behavioural effects of TPHP in birds. Early life stage Japanese quail (Coturnix japonica) were exposed to nominal doses of 0 ng/g (vehicle-control), 5 ng/g (low dose), 50 ng/g (mid dose), and 100 ng/g (high dose) TPHP, both as embryos (via air cell injection prior to incubation) and as chicks (via daily gavage until 5 days post-hatch). The low dose reflects TPHP levels recorded in wild avian eggs, but actual environmental exposure levels may be higher given that TPHP is known to be rapidly metabolized in birds. (...) high-TPHP chicks exhibited less neophobia than vehicle-controls, and low-TPHP chicks exhibited more aggression towards conspecifics. No differences were observed in the responses of Japanese quail chicks to activity or tonic immobility (fear response) tests.

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## Organochlorine pesticides in feathers of three raptor species in southern Brazil
Authors: Aver GF, Espín S, Dal Corno RDB *et al.*

Source: Environ Sci Pollut Res 27:5971-5980,
2020, DOI:10.1007/s11356-019-07370-6

Abstract: In this study, we determined the presence of organochlorine pesticides (OCPs) in back feathers from three raptor species, Phalcoboenus chimango, Milvago chimachina and Caracara plancus. Samples were obtained from live animals and ten OCPs were detected: alpha-HCH, beta-HCH and gamma-HCH (lindane), heptachlor, heptachlor epoxide, aldrin, endosulfan I, endosulfan II, endosulfan sulfate and p,p'-DDE. The concentrations found were higher than those reported in other raptor species, and C. plancus showed greater values (...) This is the first study reporting OCPs in back feathers of these species in Brazil, (...).

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Trace element distribution in
tissues and risk of exposure
of ruddy shelduck wintering
in Nanhaizi Wetland, Baotou,
China

Authors: Liu L, Du C, Sun Y *et al.*

Source: Environ Sci Pollut Res 27:6429-6437, 2020, DOI: 10.1007/s11356-019-07132-4

Abstract: (...) The Yellow River receives a significant amount of industrial and agricultural wastewater. Therefore, the environmental quality of NHZW directly affects the survival of migratory birds in the Baotou region. We aimed to determine the trace element distribution in tissues and risk of exposure in ruddy shelduck (...) Trace element concentration was greatest in feathers, followed by the kidneys, liver, and muscle, in descending. There was no significant difference in trace element accumulation between sexes. Exposure doses of Hg in water; Cr, Pb, and Cu in soil; and Pb, Cu, and Hg in corn were higher than the tolerable daily intake and may adversely affect ruddy shelduck. The calculated hazard quotients (HQ) for trace elements were ranked as follows: Hg Cr Pb Zn Cu As, where Hg and Cr were at high risk levels (HQ 1).

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Uptake, Metabolism, and
Elimination of Fungicides
from Coated Wheat Seeds in
Japanese Quail (*Coturnix japonica*)

Authors: Michael S Gross, Thomas G Bean, Michelle L Hladik, Barnett A Rattner, and Kathryn M Kuivila

Source: Journal of Agricultural and Food Chemistry 68(6):1514-1524, 2020, DOI: 10.1021/acs.jafc.9b05668

Abstract: Pesticides coated to the seed surface potentially pose an ecological risk to granivorous birds (...). To assess the toxicokinetics of seeds treated, Japanese quail (*Coturnix japonica*) were orally dosed with commercially coated wheat seeds. (...) The high detection frequencies observed in fecal samples potentially offer a non-invasive matrix to monitor pesticide exposure. With the summation of total body burden across plasma, tissue, and fecal samples, less than 9% of the administered dose was identified as the parent fungicide, demonstrating the importance to monitor both active ingredients and their metabolites in biological samples.

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Oxidative state of the
frugivorous bat *Sturnira
lilium* (Chiroptera:
Phyllostomidae) in
agricultural and urban areas
of southern Brazil

Authors: Oliveira FW, Schindler MSZ, Corá DH *et al.*

Source: Environ Sci Pollut Res 2020, DOI: 10.1007/s11356-020-09552-z

Abstract: (...) bats have been used to indicate environmental contaminants in urban and agricultural environments, since they are extremely sensitive to changes in the ecosystem and easily accumulate waste in their body tissues. (...) In this study, we aimed to evaluate the oxidative state of *S. lilium* individuals in
agricultural and urban areas in southern Brazil. (...) Parameters of the superoxide dismutase (SOD) and catalase (CAT) enzyme activity, non-protein thiols (NPSH), and lipid peroxidation (TBARS) were determined based on liver tissue. (...) The present findings suggest that the species *S. lilium*, which are widely distributed and abundant in Brazil in urban and agricultural areas, can usefully be employed in biomonitoring programs. (...)

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## Crop protection and biodiversity in agro-ecosystems

Authors: Niggli U, Riedel J, Brühl C, Liess M, Schulz R, Altenburger R, Märländer B, Bokelmann W, Heß J, Reinek A, Gerowitt B

Source: Pflanzenschutz und Biodiversität in Agrarökosystemen 2020, DOI: 10.12767/buel.v98i1.

Abstract: The Scientific Advisory Board for the National Action Plan on the Sustainable Use of Plant Protection Products (NAP) advises the German Federal Ministry of Food and Agriculture (BMEL). The Board has provided its opinion on the impact of crop protection on biodiversity in agro-ecosystems. These losses are reduced through the use of direct chemical, biological or physical crop protection, and by means of indirect, systematic, preventative measures. Out of the many effects of crop pesticides, their impact on biodiversity is difficult to grasp. Current intensive farming is geared towards efficiency and global competitiveness. It is bringing about multicausal changes in landscapes and ecosystems, reducing the diversity of natural habitats and agroecosystems, and is thus adversely impacting on the biodiversity of numerous groups of species. ...

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## Mercury in fish from streams and rivers in New York State: Spatial patterns, temporal

## changes, and environmental drivers

Authors: Riva-Murray K, Richter W, Roxanna Razavi N. et al.

Source: Ecotoxicomic 2020, DOI: 10.1007/s10646-020-02225-0

Abstract: Mercury (Hg) concentrations in freshwater fish across the state of New York frequently exceed guidelines considered harmful to humans and wildlife,... We analyzed existing data to describe recent spatial patterns, identify key environmental drivers, and assess temporal changes. Size classes within sportfishes and prey fishes formed ‘functional taxa’ (FT), and standardized scores were generated from 2007-2016 data for 218 sites. Muscle Hg in ≥1 sportfish FT exceeded human-health guidelines of 50 ng/g (sensitive populations) and 300 ng/g (general population, GP) at 93 and 56% of sites, respectively, but exceeded 1000 ng/g (a state threshold) at only 10% of sites. Whole-body Hg in ≥1 prey fish FT exceeded wildlife thresholds of 40 ng/g and 100 ng/g at 91 and 51% of sites, respectively. ...Comparisons of 2010-2015 sportfish Hg concentrations with those of 1998 and 2000-2005 showed inconsistent temporal changes both among and within eight sites examined. ...

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## Anthropogenic factors affecting wildlife species status outcomes: why the fixation on pesticides?

Authors: Brain RA, Anderson JC

Source: Environ Sci Pollut Res 2020, DOI: 10.1007/s11356-020-08980-1

Abstract: ...the implication of conventional agriculture in the broader narrative of wildlife species status outcomes (SSOs) lacks context and relativity... Moreover, in addition to the land use challenge, there are multiple other factors affecting wildlife SSOs, including a figurative plague of invasive species, a literal plague of disease, a barrage of buildings, bumpers, grilles, and windshields to collide with, light pollution to confuse cues with, poachers to contend with, and even more complicated factors such as
climate change. ... Based on the available evidence, this manuscript attempts to address these questions from a holistic and relative perspective within the context of land use change, economic development, population growth, and associated implications of global connectivity and commerce.

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## Pesticides and conservation of large ungulates: Health risk to European bison from plant protection products as a result of crop depredation

Authors: Klich D, Łopucki R, Stachniuk A, Sporek M, Fornal E, Wojciechowska M, et al.

Source: PLoS ONE 15(1):e0228243, 2020, DOI: 10.1371/journal.pone.0228243

Abstract: The coexistence of large mammals and humans in the contemporary landscape is a big challenge for conservationists. Wild ungulates that forage on arable fields are exposed to the negative effects of pesticides, ... In this paper we assessed the threat posed by pesticides to the European bison ... LC-QTOF-MS/MS two-step analysis of pesticide residues in liver samples, which included MS and targeted MS/MS scans, was conducted. It was found that European bison are exposed to pesticides as a result of crop depredation: the presence of tetraconazole, fluopyram and diazinon residues...The concentration levels of the detected substances were quite low, but ... potential health risk to European bison may result from the synergistic interaction of these substances...

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## Evaluation of Mercury Contamination in Iranian Wild Cats Through Hair Analysis

Authors: Dahmardeh BR, Poma G

Source: Biol Trace Elem Res 2020, DOI: 10.1007/s12011-020-02148-1

Abstract: The present study aimed to investigate the total mercury (Hg) concentrations in hair samples of 40 wild cats belonging to eight different species collected from various provinces of Iran and to characterize their risk of Hg exposure. Total Hg levels in Iranian wild cats ranged from 62 to 3670 ng/g dw hair, with a median value of 488 ng/g dw hair. The lowest median Hg concentration was found in west Iran (251 ng/g dw hair), while the highest median level was measured in the north-east of the country (736 ng/g dw hair), likely related to potential contamination of industrial effluents. The overall contamination of Iranian wild cats with mercury can be considered generally low, but 20% of the samples reached levels above 1100 ng/g dw hair, set as indicative of an environmental Hg concern according to the U.S. Fish and Wildlife Service. (...)

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## Mercury bioaccumulation in tropical bats from a region of active artisanal and small-scale gold mining

Authors: Carrasco-Rueda F, Loiselle BA & Frederick PC

Source: Ecotoxicology 2020, DOI: 10.1007/s10646-020-02195-3

Abstract: (...) Animals associated with mercury-contaminated aquatic systems are at high risk of experiencing effects of this heavy metal, but it is not clear how far the effects may extend into nearby terrestrial systems. We report mercury contamination levels in bats in agricultural areas at increasing distances from gold mining (~3-89 km of distance). (...) We collected 112 fur samples from 30 bat species and eight guilds, and provide the first reports of concentrations in 12 species.

All mercury concentrations were below the level at which health is likely to be affected (10 ppm). We found guild-influenced differences among mercury concentration levels, with the highest concentrations in aerial insectivores and carnivores, and the lowest in canopy frugivores. (...)
ERA / PUBLICATIONS
SCIENTIFIQUES /
PESTICIDES / CLIMAT
et VdT/ENCHY

Acute toxicity, oxidative stress and DNA damage of chlorpyrifos to earthworms (*Eisenia fetida*): The difference between artificial and natural soils

Pesticides can damage the soil environment, including damage to sentinel organisms such as earthworms. When assessing the toxicity of pesticides towards earthworms, assays are usually performed using standardized artificial soil, however, soil physicochemical properties may affect pesticide toxicity. In the present study, the toxicity of a commonly used insecticide (chlorpyrifos) to earthworms (Eisenia fetida) was determined in artificial soil and three typical natural soils (fluvo-aquic soil, black soil and red clay) by measuring acute and subchronic toxicity. (...)

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Metal oxide nanoparticles facilitate the accumulation of bifenthrin in earthworms by causing damage to body cavity

In this study, we explored the influence of two metal oxide nanoparticles, nano CuO and nano ZnO (10, 50, 250 mg/kg), on accumulation of bifenthrin (100 mg/kg) in earthworms (Eisenia fetida) and its mechanism. (...)

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Acute and chronic toxicity of the fungicide carbendazim to the earthworm *Eisenia fetida* under tropical versus temperate laboratory conditions

Research efforts into the potential side-effects of pesticides on beneficial organisms have focused on temperate test species and conditions. There is thus a need for studies into the ecotoxicity of a vaster range of pesticides under tropical conditions. The present study therefore aimed to compare the acute and chronic toxicity of the fungicide carbendazim to the earthworm *Eisenia fetida* under tropical and temperate conditions. (...)

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Do Long-Term Continuous Cropping and Pesticides Affect Earthworm Communities?

Earthworm species composition, the density of individuals, and their biomass were investigated in spring barley and faba bean fields in a long-term (52-year) experiment conducted at the Production and Experimental Station in Balcyny, in north-eastern Poland (...)

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Effects of ciprofloxacin exposure on the earthworm *Eisenia fetida*
The widespread use of the antibiotic ciprofloxacin (CIP) poses a serious risk to soil organisms. Here, earthworms (*Eisenia fetida*) were used to explore the effect of CIP exposure on growth, reproduction, mortality, antioxidant enzyme activity, DNA damage, and mRNA levels. (...)

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## Towards a spatiotemporally explicit toxicokinetic-toxicodynamic model for earthworm toxicity

(...) While for the exposure assessment, advanced exposure models can take the spatial and temporal scale of substances into account, the effect assessment in the lower tiers considers only a limited temporal and spatial variability. However, for soil organisms, such as earthworms, those scales play a significant role as species move through the soil in response to environmental factors. To overcome this gap, we propose a conceptual integration of pesticide exposure, ecology, and toxicological effects on earthworms using a modular modeling approach.

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## Synthesis of earthworm trace metal uptake and bioaccumulation data: Role of soil concentration, earthworm ecophysiology, and experimental design

(...) The uptake of trace metals by earthworms can cause transfer from immobilized pools in the soil to predators within terrestrial food chains. We report a synthesis and evaluation of uptake and bioaccumulation empirical data across different metals, earthworm genera, ecophysiological groups, soil properties, and experimental conditions (metal source, uptake duration, soil extraction method).

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## Environmental risk for aquatic and terrestrial organisms associated with drift from pesticides used in soybean crops

Several countries included the assessment of environmental drift contamination risk for the registration of pesticides. This practice is not yet totality effective in Brazil; however, due to the large number of pesticides in use, it is important to identify the real contamination risk during pesticide spraying. Therefore, this study determined the indices of environmental risks for exposure to drift from terrestrial applications of fungicides, herbicides, and insecticides that are used in soybean crops under Brazilian climate conditions and established buffer zones for the application of these products.

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## Wormcasts produced by three earthworm species (*Alma millsoni*, *Eudrilus eugeniae* and *Libyodrilus violaceus*) exposed to a glyphosate-based herbicide reduce growth, fruit yield and quality of tomato (*Lycopersicon esculentum*)

It remains unknown if casts produced by earthworms exposed to a glyphosate-based herbicide (GBH) will retain their agricultural benefit. This study investigated the agricultural importance of surface casts produced by three earthworm species (*Alma millsoni*, *Eudrilus eugeniae* and *Libyodrilus violaceus*) exposed to a GBH on growth, fruit yield and quality of tomato (*Lycopersicon esculentum*). (...)

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## Is nano ZnO/chlorpyrifos mixture more harmful to
## earthworms than bulk ZnO? A multigeneration approach

As chlorpyrifos is one of the most widely used organophosphorus insecticides and ZnO-NPs are identified as NPs of the highest concern due to their negative effects on aquatic and soil organisms the objective of this study was to evaluate mixture toxicity of CHP and ZnO (bulk and nanoparticles (20 nm)) on two types of soil, artificial (AS) and natural (NS), and over two generations of earthworms. (...)

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## Residue and toxicity of cyantraniliprole and its main metabolite J9Z38 in soil-earthworm microcosms

As part of a new generation of diamide insecticides, cyantraniliprole has broad application prospects. In the present study, a QuEChERS-UPLC-MS/MS method was established to determine the residues of cyantraniliprole and its main metabolite J9Z38 in soil and earthworms. (...)

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## The Toxic Effects of Sulfoxaflor Induced in Earthworms (Eisenia fetida) under Effective Concentrations

Sulfoxaflor is a new kind of neonicotinoid insecticide that is used to control sap-feeding insect pests. In this study, a hazard assessment of sulfoxaflor on soil invertebrate earthworms was performed under effective concentrations. The ...

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# DROIT ET POLITIQUE DE

# L'ENVIRONNEMENT

## Aquatic Pollutants - Transfer Project

ANR 12/06/20

Aquatic Pollutants Transfer Project : Appel Additionnel pour financer des projets de recherche de transfert des résultats.

Les initiatives de programmation conjointe dédiées à l'eau (Water JPI), à l'Océan (JPI Ocean) et à la résistance antimicrobienne (JPI AMR) ont lancé un Appel additionnel afin de financer des projets de recherche qui valorisent le transfert des résultats. Seul la France (ANR), l'Allemagne (Jülich/BMBF) et la Suède (SRC) y participent.

Cet appel additionnel s'inscrit en complément du premier appel conjoint pour financer des projets de recherche et innovation transnationaux sur les risques pour la santé humaine et l'environnement posés par la présence de polluants et de pathogènes dans l'eau. Cet appel additionnel vise plus particulièrement à optimiser et valoriser le transfert de connaissances de la recherche vers la société. Les propositions doivent se concentrer sur la communication de la recherche, l'utilisation des résultats de la recherche par les utilisateurs finaux et responsables politiques. Il s'agit également d'améliorer l'impact des projets recherches. Les dossiers doivent être soumis en ligne sur le site de soumission (Ce lien est accessible sur le site des trois Initiatives de programmation conjointe.) Les participants français doivent également s'enregistrer sur la plateforme de l'ANR. [et si possible y déposer une copie de dossier scientifique]

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## Le réseau d'épidémiosurveillance financé par le plan Ecophyto - Réorientations à opérer

La mission conjointe CGEDD-CGAAER d'expertise relative aux réorientations à opérer du réseau d'épidémiosurveillance est intervenue dans un contexte où les moyens alloués à cette action du plan Ecophyto ont été réduits de 23 % pour l'année 2019. Mis en place en 2009 dans le cadre du plan Ecophyto, le réseau d'épidémiosurveillance est une des composantes
de la surveillance biologique du territoire et s'inscrit dans le cadre de la directive 2009/128/CE du Parlement européen et du Conseil du 21 octobre 2009 instaurant un cadre d'action communautaire pour parvenir à une utilisation des pesticides compatible avec le développement durable. Ce réseau fonctionne de manière relativement autonome au sein du plan Ecophyto et par rapport aux plans officiels de surveillance des organismes nuisibles réglementés. La gouvernance du réseau d'épidémiosurveillance distincte de celle de la surveillance des organismes réglementés et autonome par rapport à celle du plan Ecophyto, doit être repensée dans le cadre d'une stratégie sanitaire intégrée nationale, cohérente avec le nouveau règlement européen 2016/2031 en santé des végétaux, en veillant à la cohérence entre les échelons national et régional. Les moyens financiers du réseau d'épidémiosurveillance proviennent uniquement de subventions attribuées par l'Agence française pour la biodiversité à partir du produit des redevances pour pollution diffuse. Gérés par les chambres régionales d'agriculture, ils sont répartis en totalité entre les régions sans qu'il soit suffisamment tenu compte de la complexité des systèmes de culture, des plans de relance et des besoins de financement des actions qui pourraient être mutualisées. Il est proposé à court terme de réserver une part de l'enveloppe de crédits Ecophyto dédiée à l'épidémiosurveillance pour financer les actions d'ampleur nationale et de revoir les critères de répartition entre régions de la part régionale de l'enveloppe. A plus long terme, il serait justifié de diversifier les ressources pour financer la surveillance sanitaire du territoire en complétant les crédits du budget de l'État et ceux du plan Ecophyto notamment par des redevances sanitaires, des subventions des conseils régionaux et des contributions professionnelles. Le réseau de surveillance biologique du territoire trop cloisonné avec un partage supra régional insuffisant requiert une dynamique collective d'ensemble. Le contenu, la forme et les modes de diffusion des bulletins de santé du végétal, produit principal et visible du réseau d'épidémiosurveillance, doivent évoluer en fonction des attentes des différents publics cibles qu'il faut mieux définir. Si le réseau d'épidémiosurveillance ne contribue pas directement à la baisse d'usage des produits phytopharmaceutiques, il est indispensable pour surveiller les évolutions des bioagresseurs favorisées par le changement climatique, ainsi que pour l'agriculture biologique. Un schéma

national des données de la surveillance biologique du territoire doit être élaboré précisant les modalités de production des données, l'organisation du système d'information pour leur gestion, la politique de leur diffusion, ainsi que la gouvernance de l'ensemble. [...]

Les diverses améliorations suggérées et la rationalisation proposée de la mise en œuvre du réseau d'épidémiosurveillance devraient permettre de le conforter à court terme. Elles ne doivent pas dispenser d'une réflexion stratégique de plus long terme sur l'ensemble de la surveillance sanitaire du végétal et sur le rôle des différents acteurs.

Auteurs : LAVARDE Patrick, MALEZIEUX Sylvie, BELLEMAIN Véronique

Publié le 22 avril 2020

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## REGLEMENTATION / DROIT

### Acide perfluorooctanoïque (PFOA), ses sels et les composés apparentés au PFOA

RÈGLEMENT DÉLÉGUÉ (UE) 2020/784 DE LA COMMISSION du 8 avril 2020 modifiant l'annexe I du règlement (UE) 2019/1021 du Parlement européen et du Conseil aux fins d'y inscrire l'acide perfluorooctanoïque (PFOA), ses sels et les composés apparentés au PFOA

Numéro officiel : UE/2020/784

Date de signature : 08/04/2020

Liens juridiques : Modification le 04/07/2020

Règlement UE/2019/1021 20/06/2019

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Substances actives
beflubutamide, bénalaxyl,
benthiavalicarb, bifénazate,
boscalid, bromoxynil, captane,
cyazofamid, diméthomorphe,
## éthéphon, étoxazole, famoxadone, fenamiphos, flumioxazine, fluoxastrobine, folpet, formétanate, métribuzine, milbémectine, Paecilomyces lilacinus - souche 251, phenmedipham, phosmet, pirimiphos-méthyl, propamocarbe, prothioconazole et S-métolachlore : prolongation de la validité de l'approbation

RÈGLEMENT D'EXÉCUTION (UE) 2020/869 DE LA COMMISSION du 24 juin 2020 modifiant le règlement d'exécution (UE) n° 540/2011 en ce qui concerne la prolongation de la validité de l'approbation des substances actives beflubutamide, bénalaxyl, benthiavalicarb, bifénazate, boscalid, bromoxynil, captane, cyazofamid, diméthomorphe, éthéphon, étoxazole, famoxadone, fenamiphos, flumioxazine, fluoxastrobine, folpet, formétanate, métribuzine, milbémectine, Paecilomyces lilacinus - souche 251, phenmedipham, phosmet, pirimiphos-méthyl, propamocarbe, prothioconazole et S-métolachlore

Numéro officiel : UE/2020/869
Date de signature : 24/06/2020
Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

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## Enregistrement, l'évaluation et l'autorisation des substances chimiques, ainsi que les restrictions applicables à ces substances (REACH)

RÈGLEMENT (UE) 2020/878 DE LA COMMISSION du 18 juin 2020 modifiant l'annexe II du règlement (CE) n° 1907/2006 du Parlement européen et du Conseil concernant l'enregistrement, l'évaluation et l'autorisation des substances chimiques, ainsi

que les restrictions applicables à ces substances (REACH)

Numéro officiel : UE/2020/878
Date de signature : 18/06/2020
Liens juridiques : Modification le 01/01/2021
Règlement CE/1907/2006 18/12/2006

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## Mise sur le marché des produits phytopharmaceutiques : approbation renouvelée de la substance active «carvone»

RÈGLEMENT D'EXÉCUTION (UE) 2019/706 DE LA COMMISSION du 7 mai 2019 renouvelant l'approbation de la substance active «carvone» conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques, et modifiant l'annexe du règlement d'exécution (UE) n° 540/2011 de la Commission

Numéro officiel : UE/2019/706
Date de signature : 07/05/2019
Historique : Rectification par Règlement d'exécution UE/2020/653 14/05/2020

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## Mise sur le marché des produits phytopharmaceutiques : non-approbation de l'extrait de propolis en tant que substance de base

RÈGLEMENT D'EXÉCUTION (UE) 2020/640 DE LA COMMISSION du 12 mai 2020 portant non-approbation de l'extrait de propolis en tant que substance de base conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques

Numéro officiel : UE/2020/640
Date de signature : 12/05/2020

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## Mise sur le marché des produits phytopharmaceutiques : approbation de la substance de base «L-cystéine»

RÈGLEMENT D'EXÉCUTION (UE) 2020/642 DE LA COMMISSION du 12 mai 2020 portant approbation de la substance de base «L-cystéine» conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques, et modifiant l'annexe du règlement d'exécution (UE) n° 540/2011 de la Commission

Numéro officiel : UE/2020/642
Date de signature : 12/05/2020
Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

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## Mise sur le marché des produits phytopharmaceutiques : non-approbation des racines de Saponaria officinalis L. en tant que substance de base

RÈGLEMENT D'EXÉCUTION (UE) 2020/643 DE LA COMMISSION du 12 mai 2020 portant non-approbation des racines de Saponaria officinalis L. en tant que substance de base conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques

Numéro officiel : UE/2020/643
Date de signature : 12/05/2020

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## Mise sur le marché des produits phytopharmaceutiques : approbation de la substance

## active «sénécioate de lavandulyle» en tant que substance à faible risque

RÈGLEMENT D'EXÉCUTION (UE) 2020/646 DE LA COMMISSION du 13 mai 2020 portant approbation de la substance active «sénécioate de lavandulyle» en tant que substance à faible risque, conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques, et modifiant le règlement d'exécution (UE) n° 540/2011 de la Commission

Numéro officiel : UE/2020/646
Date de signature : 13/05/2020
Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

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## Dérogation temporaire d'épandage par voie aérienne de produits phytopharmaceutiques pour les vignes dans les départements de l'Aude et de l'Hérault

Arrêté du 22 mai 2020 établissant une dérogation temporaire d'épandage par voie aérienne de produits phytopharmaceutiques pour les vignes dans les départements de l'Aude et de l'Hérault

Numéro officiel : AGRG2012554A
Date de signature : 22/05/2020

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## Modalités d'épandage des boues issues du traitement des eaux usées urbaines pendant la période de covid-19

Arrêté du 30 avril 2020 précisant les modalités d'épandage des boues issues du traitement des
eaux usées urbaines pendant la période de covid-19

Numéro officiel : TREL2011136A

Date de signature : 30/04/2020

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## Mise sur le marché des produits phytopharmaceutiques : approbation de la substance active «foramsulfuron» renouvelée

RÈGLEMENT D'EXÉCUTION (UE) 2020/616 DE LA COMMISSION du 5 mai 2020 renouvelant l'approbation de la substance active «foramsulfuron» conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques, et modifiant l'annexe du règlement d'exécution (UE) n° 540/2011 de la Commission

Numéro officiel : UE/2020/616

Date de signature : 05/05/2020

Liens juridiques : Modification le 01/06/2020

Règlement d'exécution UE/540/2011 25/05/2011

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## Approbation de la substance active « métalaxyl-M » et restreignant l'utilisation de semences traitées avec des produits phytopharmaceutiques contenant cette substance

RÈGLEMENT D'EXÉCUTION (UE) 2020/617 DE LA COMMISSION du 5 mai 2020 renouvelant l'approbation de la substance active «métalaxyl-M» et restreignant l'utilisation de semences traitées avec des produits phytopharmaceutiques contenant cette substance, conformément au règlement (CE) n° 1107/2009 du Parlement européen et du Conseil concernant la mise sur le marché des produits phytopharmaceutiques, et modifiant l'annexe du règlement d'exécution (UE) n° 540/2011 de la Commission

Numéro officiel : UE/2020/617

Date de signature : 05/05/2020

Liens juridiques : Modification le 01/06/2020

Règlement d'exécution UE/540/2011 25/05/2011

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## Produits biocides «HYPRED's octanoic acid based products» : règlement d'autorisation de l'Union

REGLEMENT D'EXÉCUTION (UE) 2020/579 DE LA COMMISSION du 27 avril 2020 accordant une autorisation de l'Union pour la famille de produits biocides «HYPRED's octanoic acid based products»

Numéro officiel : UE/2020/579

Date de signature : 27/04/2020

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## Famille de produits biocides «SOPURCLEAN» : règlement d'autorisation de l'Union

REGLEMENT D'EXÉCUTION (UE) 2020/580 DE LA COMMISSION du 27 avril 2020 accordant une autorisation de l'Union pour la famille de produits biocides «SOPURCLEAN»

Numéro officiel : UE/2020/580

Date de signature : 27/04/2020

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PUBLICATIONS DU
RESEAU ECOTOX

New insights into
methylmercury induced
behavioral and energy-
related gene transcriptional
responses in European glass
eel (Anguilla anguilla)

Authors: Liu HT, Lamarins A, Labonne J, Monperrus M, Coste P, Huchet E, Rives J, Seiliez I, Bolliet V

Source: CHEMOSPHERE 255:127020, 2020, DOI: 10.1016/j.chemosphere.2020.127020

Abstract: The effect of methylmercury (MeHg) was investigated in glass eel migration behavior and metabolism. To migrate up estuary, glass eels synchronize their swimming activity to the flood tide and remain on or in the substratum during ebb tide. Following seven days of exposure to MeHg (100 ng L-1), glass eels migration behavior was expressed by their swimming synchronization to the water current reversal every 6.2 h (mimicking the alternation of flood and ebb tides) and their swimming activity level. In relation to their behavior, we then analyzed the energy-related gene expression levels in individual head, viscera and muscle. Results showed that MeHg decreased the number of glass eels synchronized to the change in water current direction and their swimming activity level. This last effect was more pronounced in non-synchronized fish than in synchronized ones, supporting the idea that non-synchronized glass eels could be more vulnerable to stress. As regard the expression of energy-related genes, no significant difference was observed between control and MeHg-exposed fish. In contrast, when the swimming activity levels were plotted against transcriptional responses, positive correlations were evidenced in viscera and especially in the head of exposed glass eels but not in control. Finally, it is noteworthy that non-synchronized glass eels displayed lower expression level of metabolism genes than their synchronized counterpart, but only in the head. Altogether, these results support the interest of focusing on the head to investigate the facultative migration behavior in

glass eels and the effect of environmental
stressors on this rhythmic behavior.

Field measurement and
modelling of chlorotoluron
and flufenacet persistence in
unamended and amended
soils

Authors: Marin-Benito JM, Carpio MJ, Mamy L, Andrades MS, Sanchez-Martin MJ, Rodriguez-Cruz MS

Source: SCIENCE OF THE TOTAL ENVIRONMENT
725:138374, 2020, DOI:
10.1016/j.scitotenv.2020.138374

Abstract: The dissipation and persistence of two cereals herbicides, chlorotoluron and flufenacet, were studied in a field experiment including three replicated plots of unamended soil (S), soil amended with spent mushroom substrate (S+ SMS), and soil amended with green compost (S+ GC), during the winter wheat cultivation campaign. The SMS and GC organic residues were applied to the soil at rates of 140 or 85 t residue ha(-1), and herbicides were sprayed as Erturon (R) and Herold (R) formulations for chlorotoluron and flufenacet, respectively. Concentrations of both herbicides and of their metabolites were regularly measured in the three soil treatments (0-10 cm) from 0 to 339 days. The dissipation kinetics fitted well the single first order (SFO) model, except that of chlorotoluron that fitted the first order multi-compartment (FOMC) model better in the unamended soil. The dissipation rates of herbicides were lower in amended than in unamended soils. The results also showed that the DT50 of chlorotoluron (66.2-88.0 days) and flufenacet (117-145 days) under field conditions were higher than those previously obtained at laboratory scale highlighting the importance of the changing environmental conditions on the dissipation process. Similarly, the formation of chlorotoluron and flufenacet metabolites under field conditions was different from that previously observed in the laboratory. The performance of the MACRO pesticide fate model, parameterized with laboratory data, was then tested against field data. There was a very good agreement between measured and simulated chlorotoluron residue levels in the three soil treatments, while the ability of the model to reproduce the dissipation of flufenacet was good
in the unamended soil and very good in S + SMS and S + GC soils. MACRO might be used to estimate the remaining amounts of herbicides in amended soils from degradation data previously obtained at laboratory scale. This would help to manage herbicide doses in different environmental conditions to preserve the sustainability of agricultural systems.

## Combined thermal and insecticidal stresses on the generalist predator *Macrolophus pygmaeus*

Authors: Ricupero M, Abbes K, Haddi K, Kurtulus A, Desneux N, Russo A, Siscaro G, Biondi A, Zappala L

Source: SCIENCE OF THE TOTAL ENVIRONMENT 729:138922, 2020, DOI: 10.1016/j.scitotenv.2020.138922

Abstract: Ecotoxicological risk assessments of pesticides on non-target arthropods are often carried out under constant and optimal temperature regimes. However, living organisms rarely experience these conditions in real field situations. Understanding the impact of pesticides on non-target beneficial arthropods under temperature stresses is especially important in terms of global warming. We assessed the lethal and sublethal effects of four modern insecticides (chlorantraniliprole, cyantraniliprole, spinetoram, spinosad), on the generalist predator *Macrolophus pygmaeus* (Hemiptera: Miridae) under a range of temperatures (from 10 to 40 degrees C) frequently experienced in a real field scenario. A reduction coefficient (E-x) was calculated by summarizing the mortality and predator reproductive capacity and, the chemicals were classified according to the International Organization for Biological Control (IOBC) toxicity classes. The insecticides showed a marked synergistic effect with temperature, as the predator mortality and reproductive outputs were significantly correlated with increasing temperatures. Spinosyns interacted significantly with temperature causing the highest mortality and lowest fertility rates. Anthranilic diamides showed a safer ecotoxicological profile compared to spinosyns, with cyantraniliprole being more harmful than chlorantraniliprole. These results suggest that temperature should be taken into account in pesticide ecotoxicology studies within

the framework of integrated pest management and the recent climate changes.

## Plants in the Light of Ionizing Radiation: What Have We Learned From Chernobyl, Fukushima, and Other "Hot" Places?

Authors: Mousseau TA, Moller AP

Source: FRONTIERS IN PLANT SCIENCE 11:552, 2020, DOI: 10.3389/fpls.2020.00552

Abstract: Perhaps the main factor determining success of space travel will be the ability to control effects of ionizing radiation for humans, but also for other living organisms. Manned space travel will require the cultivation of food plants under conditions of prolonged exposure to ionizing radiation. Although there is a significant literature concerning the effects of acute high dose rate exposures on plant genetics, growth, and development, much less is known concerning the effects of chronic low dose irradiation especially those related to the impacts of the high energy protons and heavy ions that are encountered in the space environment. Here, we make the argument that in situ studies of the effects of radionuclides at nuclear accident sites (e.g., Chernobyl and Fukushima), atomic bomb test sites, and areas of naturally high radiation levels, could provide insights concerning the mechanisms of radiation effects on living systems that cannot be assessed short of conducting research in space, which is not yet feasible for large scale, long term, multigenerational experiments. In this article we review the literature concerning the effects of chronic low-dose rate radiation exposure from studies conducted in Chernobyl, Fukushima, and other regions of the world with high ambient radiation levels (parts of India in particular). In general, mutation rates and other measures of genetic damage are considerably elevated, pollen and seed viability are reduced, growth rates are slower, and the frequency of developmental abnormalities is increased, although there is considerable variation among taxa for these effects. In addition, there are interactions between radiation and other environmental stressors (e.g., temperature, drought, heavy metals) that may play important roles in
determining susceptibility to radiation induced stress.

# Assessment of residential exposures to agricultural pesticides: A scoping review

Authors: Teysseire R, Manangama G, Baldi I, Carles C, Brochard P, Bedos C, Delva F

Source: PLOS ONE 15(4):e0232258, 2020, DOI: 10.1371/journal.pone.0232258

**Abstract:** The assessment of residential exposure to agricultural pesticides is a major issue for public health, regulatory and management purposes. In recent years, research into this field has developed considerably. The purpose of this scoping review is to provide an overview of scientific literature characterizing residential exposure to agricultural pesticides and to identify potential gaps in this research area. This work was conducted according to the JBI and PRISMA guidelines. Three databases were consulted. At least two experts selected the eligible studies. Our scoping review enabled us to identify 151 articles published between 1988 and 2019 dealing with the assessment of residential exposure to agricultural pesticides. Of these, 98 (64.9%) were epidemiological studies investigating possible links between pesticide exposure and the onset of adverse health effects, principally cancers and reproductive outcomes. They predominantly used Geographic Information Systems and sometimes surveys or interviews to calculate surrogate exposure metrics, the most common being the amounts of pesticides applied or the surface area of crops around the dwelling. Twenty-six (17.2%) were observational measurement studies conducted to quantify levels of pesticide exposure and identify their possible determinants. These studies assessed exposure by measuring pesticides in biological and environmental matrices, mostly in urines and house dust. Finally, we found only eight publications (5.3%) that quantified the risk to human health due to residential exposure for management purposes, in which exposure was mainly determined using probabilistic models. Pesticide exposure appears to be largely correlated with the spatial organization of agriculture activities in a territory. The determinants and routes of exposure remain to be explored to improve the conduct of epidemiological and risk assessment studies and

to help prevent future exposures. Improvement could be expected from small-scale studies combining different methods of exposure assessment.

# Spatio-temporal assessment of the polychlorinated biphenyl (PCB) sediment contamination in four major French river corridors (1945-2018)

Authors: Dendievel AM, Mourier B, Coynel A, Evrard O, Labadie P, Ayrault S, Debret M, Koltalo F, Copard Y, Faivre Q, Gardes T, Vauclin S, Budzinski H, Grosbois C, Winiarski T, Desmet M

Source: EARTH SYSTEM SCIENCE DATA 12(2):1153-1170, 2020, DOI: 10.5194/essd-12-1153-2020

**Abstract:** Environmental pollution by polychlorinated biphenyls (PCBs) is a key cause for concern about river quality because of their low degradation rates leading to their accumulation in sediments and living organisms. An original interdisciplinary work was conducted along the four main French rivers (Seine, Rhone, Loire and Garonne rivers), which flow into major European seas. We completed a dataset based on sediment analyses provided by monitoring agencies, port authorities and research teams on different solid matrices (sediment cores, bed and flood deposits, suspended particulate matter and dredged sediments). This dataset focused on the seven indicator PCBs and their sum (Sigma PCBi) from 1945 to 2018 (n Sigma PCBi = 1416). Special effort was put into the quality control to provide robust spatio-temporal information. Taking into account hydrological and human drivers, we outlined two main pollution trends: (1) from 1945 to 1975, a quick increase in Sigma PCBi (up to 4 mg kg(-1) dry weight, dw) and a sharp decrease in the 1980s on the Seine and Loire rivers and (2) increasing but moderate Sigma PCBi levels (50 to 150 μg kg(-1) dw) followed by a decline after the 1990s on the Rhone and Garonne rivers. In addition to these patterns, PCB emissions from urban and industrial areas or accidental events were significant in each river. Finally, when calculating specific flux, the Rhone exhibited the uppermost Sigma PCBi load (up to 12 μg m(-2) yr(-1) in 1977-1987), at least 25 %
higher than those of the Seine and Loire rivers, while the Garonne showed a very low flux. In western Europe, we confirmed that the Rhone, Seine and Loire rivers contribute significantly to the PCB contamination of the seas, while French specific Sigma PCB fluxes are 2 orders of magnitude lower than those found in American or Asian rivers. The dataset is available at https://doi.org/10.1594/PANGAEA.904277 (Dendievel et al., 2019).

## Seasonal monitoring of cellular energy metabolism in a sentinel species, *Dreissena polymorpha* (bivalve): Effect of global change?

Authors: Louis F, Rocher B, Barjhoux I, Bultelle F, Dedourge-Geffard O, Gaillet V, Bonnard I, Delahaut L, Pain-Devin S, Geffard A, Paris-Palacios S, David E

Source: SCIENCE OF THE TOTAL ENVIRONMENT 725:138450, 2020, DOI: 10.1016/j.scitotenv.2020.138450

Abstract: Aquatic organisms such as bivalves are particularly sensitive to seasonal fluctuations associated with climate changes. Energy metabolism management is also closely related to environmental fluctuations. Changes in both biotic and abiotic conditions, such as the reproduction status and temperature respectively, may affect the organismenergy status. A bivalve sentinel species, *Dreissena polymorpha* was sampled along its one-year reproduction cycle in situ (2018-2019) to study naturalmodulations on severalmarkers of energy metabolismregarding seasonal variations in situ. A panel of different processes involved in energymetabolism was monitored through different functions such as energy balance regulation, mitochondrial density, and aerobic/anaerobic metabolism. The typical schema expected was observed in amajor part of measured responses. However, themonitored population of *D. polymorpha* showed signs of metabolism disturbances caused by an external stressor from April 2019. Targeting a major part of energymetabolismfunctions, a global analysis of responses suggested a putative impact on the mitochondrial respiratory chain due to potential pollution. This study highlighted also the particular relevance of in situ monitoring to

investigate the impacts of environmental change on sentinel species.

## Dissipation of S-metolachlor and butachlor in agricultural soils and responses of bacterial communities: Insights from compound-specific isotope and biomolecular analyses

Authors: Torabi E, Wiegert C, Guyot B, Vuilleumier S, Imfeld G

Source: JOURNAL OF ENVIRONMENTAL SCIENCES 92:163-175, 2020, DOI: 10.1016/j.jes.2020.02.009

Abstract: The soil dissipation of the widely used herbicides S-metolachlor (SM) and butachlor (BUT) was evaluated in laboratory microcosms at two environmentally relevant doses (15 and 150 mu g/g) and for two agricultural soils (crop and paddy). Over 80% of SM and BUT were dissipated within 60 and 30 days, respectively, except in experiments with crop soil at 150 mu g/g. Based on compound-specific isotope analysis (CSIA) and observed dissipation, biodegradation was the main process responsible for the observed decrease of SM and BUT in the paddy soil. For SM, biodegradation dominated over other dissipation processes, with changes of carbon isotope ratios (Delta delta C-13) of up to 6.5% after 60 days, and concomitant production of ethane sulfonic acid (ESA) and oxanilic acid (OXA) transformation products. In crop soil experiments, biodegradation of SM occurred to a lesser extent than in paddy soil, and sorption was the main driver of apparent BUT dissipation. Sequencing of the 16S rRNA gene showed that soil type and duration of herbicide exposure were the main determinants of bacterial community variation. In contrast, herbicide identity and spiking dose had no significant effect. In paddy soil experiments, a high (4:1, V/V) ESA to OXA ratio for SM was observed, and phylotypes assigned to anaerobic Clostridiales and sulfur reducers such as Desulfuromonadales and Syntrophobacterales were dominant for both herbicides. Crop soil microcosms, in contrast, were associated with a reverse, low (1:3, V/V) ratio of ESA to OXA for SM, and Alphaproteobacteria, Actinobacteria, and