different biomes and the generation of pathogenic-resistant bacteria that pose a great threat to human health. The aim of this review is to give an overview of the potential role of bacteriophages in the dissemination and the transfer of ARGs to pathogens in food production and processing and the consequent contribution to antibiotic resistance transmission through faecal oral route carrying ARGs to our dishes.

Accès au document

# Isolation of antibiotic-resistant bacteria in biogas digestate and their susceptibility to antibiotics

**Authors:** Sun H, Bjerketorp J, Levenfors J, Schnurer A

**Source:** ENVIRONMENTAL POLLUTION 266, 1, 2020, DOI: 10.1016/j.envpol.2020.115265

**Abstract:** Antibiotics are widely used to prevent and treat diseases and promote animal growth in the livestock industry, and therefore antibiotic residues can end up in biogas digestate from processes treating animal manure (AM) and food waste (FW). These digestates represent a potential source of spread of antimicrobial resistance (AMR) when used as fertilisers. This study evaluated AMR risks associated with biogas digestates from two processes, using AM and FW as substrate, by isolation and identification of antibiotic-resistant bacteria (ARB) and testing their susceptibility to different antibiotics. ARB from the digestates were isolated by selective plating. The antibiotic susceptibility profile of isolates was determined using ampicillin, ceftazidime, meropenem, vancomycin, ciprofloxacin, rifampicin, chloramphenicol, clindamycin, erythromycin, tetracycline, gentamicin or sulfamethoxazole/trimethoprim, representing different antibiotic classes with differing mechanisms of action. In total, 30 different bacterial species belonging to seven genera were isolated and classified. Bacillus and closely related genera, including Paenibacillus, Lysinibacillus and Brevibacillus, were the

dominant ARB in both digestates. Most of the ARB strains isolated were non-pathogenic and some were even known to be beneficial to plant growth. However, some were potentially pathogenic, such as an isolate identified as Bacillus cereus. Many of the isolated species showed multi resistance and the AM digestate and FW digestate both contain bacterial species resistant to all antibiotics tested here, except gentamicin. A higher level of resistance was displayed by the FW isolates, which may indicate higher antibiotic pressure in FW compared with AM digestate. Overall, the results indicate a risk of AMR spread when these digestates are used as fertiliser. However, most of the ARB identified are species commonly found in soil, where AMR in many cases is abundant already, so the contribution of digestate-based fertiliser to the spread of AMR may still be very limited.

Accès au document

# Antimicrobial resistance: more than 70 years of war between humans and bacteria

**Authors:** Nadeem SF, Gohar UF, Tahir SF and more ...

**Source:** CRITICAL REVIEWS IN MICROBIOLOGY, 2020, DOI: 10.1080/1040841X.2020.1813687

**Abstract:** Development of antibiotic resistance in bacteria is one of the major issues in the present world and one of the greatest threats faced by mankind. Resistance is spread through both vertical gene transfer (parent to offspring) as well as by horizontal gene transfer like transformation, transduction and conjugation. The main mechanisms of resistance are limiting uptake of a drug, modification of a drug target, inactivation of a drug, and active efflux of a drug. The highest quantities of antibiotic concentrations are usually found in areas with strong anthropogenic pressures, for example medical source (e.g., hospitals) effluents, pharmaceutical industries, wastewater influents, soils treated with manure, animal husbandry and
aquaculture (where antibiotics are generally used as in-feed preparations). Hence, the strong selective pressure applied by antimicrobial use has forced microorganisms to evolve for survival. The guts of animals and humans, wastewater treatment plants, hospital and community effluents, animal husbandry and aquaculture runoffs have been designated as "hotspots for AMR genes" because the high density of bacteria, phages, and plasmids in these settings allows significant genetic exchange and recombination. Evidence from the literature suggests that the knowledge of antibiotic resistance in the population is still scarce. Tackling antimicrobial resistance requires a wide range of strategies, for example, more research in antibiotic production, the need of educating patients and the general public, as well as developing alternatives to antibiotics (briefly discussed in the conclusions of this article).

Accès au document

## Seasonal variations in export of antibiotic resistance genes and bacteria in runoff from an agricultural watershed in Iowa

**Authors:** Neher TP, Ma LY, Moorman TB and more ...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 738, 2020, DOI: 10.1016/j.scitotenv.2020.140224

**Abstract:** Seasonal variations of antimicrobial resistance (AMR) indicators in runoff water can help improve our understanding of AMR sources and transport within an agricultural watershed. This study aimed to monitor multiple areas throughout the Black Hawk Lake (BHL) watershed (5324 ha) in central Iowa during 2017 and 2018 that consists of both swine and cattle feeding operations as well as known areas with manure application. The measured indicators included plate counts for fecal indicator bacteria (FIB) *E. coli*, Enterococcus, antibiotic resistant fecal indicator bacteria (ARBs) tylosin resistant

Enterococcus, tetracycline resistant Enterococcus, and antibiotic resistance genes (ARGs): ermB, ermF (macrolide), tetA, tetM, tetO, tetW (tetracycline), sul1, sul2 (sulfonamide), aadA2 (aminoglycoside), vgaA, and vgaB (pleuromutilin). Both the plate count and the ARG analyses showed seasonal trends. Plate counts were significantly greater during the growing season, while the ARGs were greater in the pre-planting and post-harvest seasons (Wilcoxon Rank-SumTest p < 0.05). The ermB gene concentration was significantly correlated (p &#60; 0.05) with *E. coli* and Enterococcus concentrations in 2017, suggesting a potential use of this ARG as an indicator of environmental AMR and human health risk. Flow rate was not a significant contributor to annual variations in bacteria and AMR indicators. Based on observed seasonal patterns, we concluded that manure application was the likely contributor to elevated ARG indicators observed in the BHL watershed, while the driver of elevated ARB indicators in the growing season can only be speculated. Understanding AMR export patterns in agricultural watersheds provides public health officials knowledge of seasonal periods of higher AMR load to recreational waters.

Accès au document

## Linkage of antibiotic resistance genes, associated bacteria communities and metabolites in the wheat rhizosphere from chlorpyrifos-contaminated soil

**Authors:** Guo AY, Pan CR, Ma JY, Bao YY

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 741, 2020, DOI: 10.1016/j.scitotenv.2020.140457

**Abstract:** Rhizosphere is a crucial site for the proliferation of antibiotic resistance genes (ARGs) in agricultural soil. Pesticide contamination is ubiquitous in soil, such as
chlorpyrifos as one of the most commonly used pesticides. However, limited knowledge is reported about ARGs profiles changes and the driving mechanism of ARGs prevalence in rhizosphere soil after adding pesticide. In this study, irrespective of chlorpyrifos presence, the abundances of ARGs (tetM, tetO, tetQ, tetW, tetX, sul1 and sul2) and intI1 in rhizosphere soil of wheat were obviously higher than those in bulk soil. 20.0 mg center dot kg(-1) chlorpyrifos significantly increased the abundance of total ARGs and intI1 in bulk soil, respectively, at day 50 and 100, but not in rhizosphere soil. Rhizosphere influence on ARGs was far greater than chlorpyrifos. ARGs and intI1 abundances were higher at day 50 than ones at day 100. C/N ratio and NO3--N content, which were affected by rhizosphere and cultivation time, significantly explained the increased ARGs. Compared to bulk soil, rhizosphere shifted host bacteria of tetracycline resistance genes (TRGs), intI1 at genus level, and host bacteria of sul1, sul2 at phylum level. Rhizosphere simplified the linkage of ARGs, host bacteria and metabolites. Bacterial communities played important roles in the variation of ARGs and intI1, and the difference in the distribution of potential hosts between bulk and rhizosphere soil was related to metabolites abundance and composition. These results provide valuable information for understanding the linkage of ARGs, associated bacteria communities and metabolites in the wheat rhizosphere soil.

Accès au document

## The formation mechanism of antibiotic-resistance genes associated with bacterial communities during biological decomposition of household garbage

Authors: Liang ZS, Zhang YN, He T and more ...

Source: JOURNAL OF HAZARDOUS MATERIALS 398, 2020, DOI: 10.1016/j.jhazmat.2020.122973

**Abstract:** Food wastes are significant reservoir of antibiotic-resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) available for exchange with clinical pathogens. However, food wastes-related changes of antibiotic resistance in long-period decomposition have been overlooked. Here, we evaluated the comprehensive ARG profile and its association with microbial communities, explained how this might vary with household garbage decomposition. Average of 128, 150 and 91 ARGs were detected in meat, vegetable and fruit wastes, respectively, with multidrug and tetracycline as the predominant ARG types. ARG abundance significantly increased at initial stage of waste fermentation and then decreased. High abundance of Eubacterium-coprostanoligenes, *Sporanaerobacter*, *Peptoniphilus*, *Peptostreptococcus* might be explained for the high relative abundance of ARGs in meat, while high abundance of *Advenella*, *Prevotella*, *Solobacterium* was attributed to the high diversity of ARGs in vegetables. Significant correlations were observed among volatile organic compounds, mobile genetic elements and ARGs, implying that they might contribute to transfer and transport of ARGs. Network analysis revealed that aph(2')-Id-01, acrA-05, tetO-1 were potential ARG indicators, while *Hathewaya*, *Paraclostridium* and *Prevotellaceae* were possible hosts of ARGs. Our work might unveil underlining mechanism of the effects of food wastes decomposition on development and spread of ARGs in environment and also clues to ARG mitigation.

Accès au document

Untreated swine wastes changed antibiotic resistance and microbial community in the soils and impacted abundances of antibiotic resistance genes in the vegetables
**Authors:** Gao FZ, He LY, He LX, Zou HY and more
...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT
741, 2020, DOI: 10.1016/j.scitotenv.2020.140482

**Abstract:** Animal waste fertilization is a traditional agricultural practice, which may have adverse effects to soil ecosystem. However, the side-effects of animal waste fertilization on vegetables are less studied. Here we selected a swine farming village for investigation with a nearby village without swine farming as comparison. In the swine farming village, the farmers use untreated swine manure and wastewater as fertilizers for vegetable cultivation. In the reference village, the farmers mainly use commercial organic fertilizers. The objective of this study is to assess the impacts of untreated swine waste fertilization on both soils and vegetables in terms of antibiotics, antibiotic resistance genes (ARGs) and bacterial microbial communities. The results indicate that untreated swine waste fertilization caused both antibiotic and ARG contaminations and changed the microbial community compositions in the soils. Varieties of tetracyclines and related resistance genes were detected especially in swine wastewater treated soils. The soil quality was impacted with the relations to bacterial abundances and microbial geochemical functions. Proteobacteria and Bacteroidetes were prevalent and positively correlated to ARGs in soils, indicating they were potential antibiotic resistant bacteria. Antibiotics and ARGs were detected in vegetables of both villages. The abundances of ARGs were relatively higher in some vegetable samples of the swine farming village than the reference village. In addition, intracellular parasites Rickettsiales with positive correlation to ARGs were prevalent in some vegetables of swine farming village, indicating potential health risks through eating contaminated vegetables. The results of this study suggest that untreated swine wastes may cause adverse effects to not only agricultural soils but also associated vegetables.

Accès au document

Oxytetracycline, copper, and
zinc effects on nitrification
processes and microbial
activity in two soil types

**Authors:** Tang Q, Xia LL, Ti CP and more ...

**Source:** FOOD AND ENERGY SECURITY, 2020, DOI:
10.1002/fes3.248

**Abstract:** The distribution, fate, and effects of antibiotics and heavy metal residues in agricultural soil caused by long-term application of organic fertilizers are of increasing concern. However, the ecotoxic effects of the interaction between antibiotics and heavy metals vary with the physicochemical properties of the soil, and it is still unclear how these substances interact with soil microbial functions. A short-term microcosm experiment was conducted to investigate effects of the typical antibiotic oxytetracycline (OTC) with heavy metals (zinc [Zn] and copper [Cu]) alone or in combination on nitrification process and soil microbial activity in two different types of soil (FQ: sandy loam soil and NB: clay loamy soil). Results indicated that soil types influenced the toxic effects of antibiotics and heavy metals. Zn and Cu alone and when combined with OTC inhibited and retarded nitrification processes and reduced nitrous oxide emissions, which were mainly attributed to the inhibitory effects on ammonia-oxidizing microorganisms. Moreover, Zn and Cu alone or combined with OTC increased soil respiration, but decreased the abundances of bacteria and fungi. In contrast, OTC alone had no significant effect on soil respiration but increased the abundance of fungi in both soils. Together, our results suggest that the widespread occurrence of antibiotics and heavy metals in agriculture soils may pose significant eco-environmental risks by altering nitrification process and soil microbial activity.

Accès au document
# Effects of co-loading of polyethylene microplastics and ciprofloxacin on antibiotic degradation efficiency and microbial community structure soil

**Authors:** Wang J, Liu XH Dai YX and more ...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 741, 2020, DOI: 10.1016/j.scitotenv.2020.140463

**Abstract:** Microplastics (MPs) have become a global environmental concern while soil plastic pollution has been largely overlooked. In view of the severe antibiotic contamination in arable soils owing to land application of sewage sludge and animal manure, the invasion of MPs along with antibiotics may pose an unpredictable threat to soil microbial communities and ecological health. In this work, polyethylene MPs and ciprofloxacin (CIP) were applied to a soil microcosm to investigate the CIP degradation behavior and their combined effects on soil microbial communities. Compared with that of the individual amendment of CIP, the co-amendment of CIP and MPs reduced the CIP degradation efficiency during the 35 d cultivation period. In addition, the high-throughput sequencing results illustrated that the combined loading of MPs and CIP in soil significantly decreased the microbial diversity compared with that of individual contamination. As for the community structure, the microbial compositions at the phylum level were consistent among all treatments, and the most dominant phyla were Proteobacteria, Actinobacteria, and Chloroflexi. At the genus level, only one genus, namely Arthrobacter, was remarkably changed in the CIP-amended soil compared with that in the blank control, but four genera were significantly altered in the MPs-CIP co-amended soil. Serratia and Chromobacter were abundant in the combined polluted soil, which might have been involved in accelerated depletion of soil total nitrogen based on redundancy analysis. These findings may contribute to the understanding of

bacterial responses to the combined pollution MPs and antibiotics in soil ecosystems.

Accès au document

# Antibiotic resistance gene abundance and bacterial community structure in soils altered by Ammonium and Nitrate Concentrations

**Authors:** Sun SL, Lu C, Liu J and more ...

**Source:** SOIL BIOLOGY & BIOCHEMISTRY 149, 2020, DOI: 10.1016/j.soilbio.2020.107965

**Abstract:** Antibiotic resistance genes (ARGs) in soils pose a risk to ecological and human health, and are considered emerging pollutants. Application of nitrogen fertilizer affects the soil bacterial community structure and could be a trigger for the development of ARGs. This study explored the effects of two forms of nitrogen (NH4+-N and NO3--N) on the abundance of six ARGs (blaTEM-1, cmlA, str, stil1, tetO, and tnpA-4) and bacterial community structure in soils using quantitative polymerase chain reaction and high-throughput sequencing. Our results show that the addition of 100-200 mg kg(-1) NH4+-N or NO3--N increased the relative abundance of ARGs but decreased 16S rRNA gene abundance. Nitrogen addition at a rate of 100 mg kg(-1) NH4+-N significantly reduced the abundance and diversity of the bacterial community, and the community structure differed in soil receiving NH4+-N and NO3--N treatments. Pearson correlation and redundancy analysis supported a correlation between the soil bacterial community and ARGs with the addition of NH4+-N or NO3--N. The increase in ARGs abundance with inorganic N may be ascribed to the changes in host bacterial communities. These findings suggest that NH4+-N and NO3--N application may trigger the development of ARGs in soil bacterial communities, and could be another risk factor in addition to the well-known effects of antibiotic exposure from animal manure on ARGs abundance in soil. We recommend that future
work on this topic be attentive to experimental
designs that include appropriate controls and
references to improve understanding of the ARGs
profiles in the soil bacterial communities.

Accès au document

Effect of Drug-Resistant Bacteria on Agriculture, Livestock, and Environment

Authors: Sagar S, Kaistha S, Das AJ, Kumar R

Source: Book chapter: ANTIBIOTIC RESISTANT BACTERIA: A CHALLENGE TO MODERN MEDICINE. 57-67, 2020, DOI: 10.1007/978-981-13-9879-7_5

**Abstract:** Antibiotic-resistant bacteria are the most severe cause of concern for the public health globally. Misuse and intermittent use of antibiotic are mainly responsible for the emergence of drug resistance in bacteria in developing countries. Further, the poor agricultural practices, consistent feed of antibiotics to livestock without prescription of medical practitioners, and environmental factors are also responsible for the emergence and dissemination of drug-resistant bacteria around the world. A big portion of commercially available antibiotics has been consumed by livestock every year, and the waste product of such antibiotics consumed by animals is responsible for contamination of agricultural and nonagricultural land. In the current chapter, we have tried to figure out these three major factors which are also responsible for the emergence of antibiotic resistance in bacteria.

Accès au document

Characteristics of microbial
community of soil subjected
to industrial production of
antibiotics

Authors: Borcinova M, Pitkina A, Maresova H, and more ...

Source: FOLIA MICROBIOLOGICA, 2020, DOI: 10.1007/s12223-020-00819-z

**Abstract:** Ecosystems worldwide are exposed to pollutants connected to the industrial production of pharmaceuticals. The objective of this study was to study the composition and characteristics of the soil microbial communities that had been exposed to long-term selection pressure caused by the industrial production of penicillin G. Soil samples from four sites among the penicillin G production plant were analysed using 16S rRNA profiling via Illumina MiSeq platform and were compared with the control samples from four sites outside the plant. Total metagenomic DNA from the impacted soil was also used for the preparation ofE. coliT1R-based fosmid library which was consequently qualitatively tested for the presence of penicillin G acylase (PGA)-encoding genes using the method of sequence homology. Analyses of alpha diversity revealed that the long-term antibiotic presence in the soil significantly increased the microbial diversity and richness in terms of Shannon diversity index (p= 0.002) and Chao estimates (p= 0.004). Principal component analysis showed that the two types of communities (on-site and control) could be separated at the phylum, class and genus level. The on-site soil was enriched in Betaproteobacteria, Deltaproteobacteria, Gemmatimonadetes, Acidobacteria and Planctomycetia, while a significant decrease in Actinobacteria was observed. Metagenomic fosmid library revealed high hit rates in identifying PGAs (14 different genes identified) and confirmed the biotechnological potential of soils impacted by anthropogenic activity. This study offers new insights into the changes in microbial communities of soils exposed to anthropogenic activity as well as indicates that
those soils may represent a hotspot for
biotechnologically interesting targets.

Accès au document

Genetic Determinants for Metal Tolerance and Antimicrobial Resistance Detected in Bacteria Isolated from Soils of Olive Tree Farms

Authors: Glibota N, Grande MJ, Galvez A, Ortega E

Source: ANTIBIOTICS-BASEL 9, 8, 2020, DOI: 10.3390/antibiotics9080476

**Abstract:** Copper-derived compounds are often used in olive tree farms. In a previous study, a collection of bacterial strains isolated from olive tree farms were identified and tested for phenotypic antimicrobial resistance and heavy metal tolerance. The aim of this work was to study the genetic determinants of resistance and to evaluate the co-occurrence of metal tolerance and antibiotic resistance genes. Both metal tolerance and antibiotic resistance genes ... were detected in the bacterial strains from Cu-treated soils. A high percentage of the strains positive for metal tolerance genes also carried antibiotic resistance genes ... to beta-lactams and tetracycline. Significant associations were detected between genes involved in copper tolerance and genes coding for beta-lactamases or tetracycline resistance mechanisms. A significant association was also detected between zntA (coding for a Zn(II)-translocating P-type ATPase) and tetCgenes. In conclusion, bacteria from soils of Cu-treated olive farms may carry both metal tolerance and antibiotic resistance genes. The positive associations detected between metal tolerance genes and antibiotic resistance genes suggests co-selection of such genetic traits by exposure to metals.

Accès au document

Antibiotic resistance genes, bacterial communities, and functions in constructed wetland-microbial fuel cells: Responses to the co-stresses of antibiotics and zinc

Authors: Li H, Xu H, Song HL and more ...

Source: ENVIRONMENTAL POLLUTION 265, B, 2020, DOI: 10.1016/j.envpol.2020.11508

**Abstract:** The effects of the continuous accumulation of Zinc (Zn) on the fate of antibiotic resistance genes (ARGs) in constructed wetland-microbial fuel cells (CW-MFCs) remain unclear. In this study, the impacts of Zn addition and a circuit mode on antibiotic removal, occurrence of ARGs, the bacterial community, and bacterial functions were investigated in three groups of CW-MFCs. The results showed that continuous Zn exposure enriched the target ARGs during the initial stage, while excessive Zn accumulation decreased antibiotic removal and the abundance of ARGs. A principal component analysis demonstrated that ARGs and the bacterial community distribution characteristics were significantly impacted by the mass accumulation of antibiotics and Zn, as well as the circuit mode. A redundancy analysis, partial least squares path modeling, and Procrustes analysis revealed that the accumulation of antibiotics and Zn, the composition of the bacterial community, the circuit mode, and the abundance of Intl associated with horizontal gene transfer jointly contributed to the distributions of ARGs in the electrodes and effluent. Moreover, continuous exposure to Zn decreased the bacterial diversity and changed the composition and function of the bacterial community predicted using PICRUSt tool. The co-occurrence of ARGs, their potential hosts and bacterial functions were further revealed using a network analysis. A variation partition analysis also showed that the accumulation of target pollutants and the circuit mode had a significant impact on the bacterial community composition and functions. Therefore, the interaction among
ARGs, the bacterial community, bacterial
functions, and pollutant accumulations in the
CW-MFC was complex. This study provides useful
implications for the application of CW-MFCs for
the treatment of wastewater contaminated with
antibiotics and heavy metals.

Accès au document

Detection of sul1 and sul2
genes in sulfonamide-
resistant bacteria (SRB) from
sewage, aquaculture sources,
animal wastes and hospital
wastewater in South-West
Nigeria

Authors: Adekanmbi, AO., Adejoba, AT., Banjo, OA., Saki, M.

Source: GENE REPORTS 20, 2020, DOI: 10.1016/j.genrep.2020.100742

**Abstract:** Background: The indiscriminate use of antibiotics has placed a lot of selective pressure on bacteria from several environments. This study aimed at detecting the occurrence of sulfonamide resistance genes and antibiogram of sulfonamide-resistant bacteria (SRB) isolated from sewage, aquaculture sources, animal wastes and hospital wastewater. Methods: SRB were isolated on medium incorporated with sulfadiazine (SDZ). Antibiotic susceptibility was carried out using disc diffusion method, while detection of sul1, sul2 and sul3 genes was done by polymerase chain reaction (PCR) using specific primers. Results: A total of forty-eight SRB; aquaculture (8), animal wastes (16), hospital wastewater (10) and sewage (14) belonging to sixteen genera were obtained, with Pseudomonas spp. and Bacillus spp. predominating. In the Gram-negative SRB, there was 100% resistance to ertapenem, tetracycline (77.5%), ampicillin (75%), cefpodoxime (47.5%), streptomycin (27.5%), amoxicillin-clavulanate (22.5%), ciprofloxacin (22.5%), imipenem (15%), cefotaxime (12.5%) and ceftazidime (7.5%). In

the Gram-positive SRB, there was 100% resistance to ampicillin, tetracycline and ertapenem, while 50% and 12.5% respectively were resistant to cefpodoxime and imipenem. No resistance was observed to amoxicillin-clavulanate and ciprofloxacin. 85.4% of the SRB were multidrug resistant (MDR). sul1 was detected in *Pseudomonas aeruginosa* H19A (hospital wastewater), *Bacillus* sp. AQE3 (aquaculture pond) and *Leclercia* sp. S5C (sewage) while sul2 was detected in *Pseudomonas aeruginosa* PG4A (animal waste) and *Klebsiella* sp. S6C (sewage). None of the SRB harboured sul3 and no co-occurrence of the sul genes was observed. Conclusion: This study confirms the sources sampled in this study as important media for the proliferation of MDR bacteria and resistance genes.

Accès au document

The Effects of Tetracycline
Residues on the Microbial
Community Structure of
Tobacco Soil in Pot
Experiment

Authors: Zheng JY, Zhang JiX, Gao L and more ...

Source: SCIENTIFIC REPORTS 10, 1, 2020, DOI: 10.1038/s41598-020-65203-w

**Abstract:** To evaluate the micro-ecological effects of tetracycline residues on tobacco soil, high-throughput sequencing technology was used to study the effects of the addition of different concentrations (0, 5, 50, and 500 mg.kg(-1)) of tetracycline on the abundance, diversity, and structure of bacterial and fungal communities in the rhizosphere and non-rhizosphere soil of flue-cured tobacco in China. Results showed that the presence of tetracycline had an important but varying effect on soil bacterial and fungal community richness, diversity, and structure. Changes in the diversity indices (Chao index and Shannon index) of soil bacterial and fungal communities showed a similar pattern after the
addition of tetracycline; however, a few
differences were found in the effects of
tetracycline in the rhizosphere and non-
rhizosphere soil, suggesting an evident
rhizosphere-specific effect. The bacterial
community at the phylum level in the
rhizosphere closely clustered into one group,
which might be the result of tobacco root
secretions and rhizodeposition. Tetracycline
showed a concentration-dependent effect on the
soil bacterial community structure. The soil
bacterial community structures observed after
treatments with higher concentrations of
tetracycline (50 and 500 mg.kg(-1)) were found
to be closely related. Moreover, the effects of
the treatments with higher concentrations of
tetracycline, on the soil bacterial community at
the phylum level, were different from those with
lower concentrations of tetracycline (5 mg.kg(-
1)), and CK treatments. This might have resulted
from the induction of increasing selective
pressure with increasing antibiotic
concentration. Tetracycline continued to affect
the soil bacterial community throughout the
experiment. Tetracycline was found to have a
varying impact on the community structure of
soil fungi compared to that of soil bacteria, and
the addition of an intermediate concentration of
tetracycline (50mg.kg(-1)) significantly increased
the soil fungal diversity in the non-rhizosphere
soil. The biological effects of tetracycline on the
soil fungal community and the fungal-bacterial
interactions, therefore, require further
elucidation, warranting further research.

Accès au document

Bioremediation of Fluazifop-
p-butyl herbicide by some
soil bacteria isolated from
various regions of Turkey in
an artificial agricultural field

Authors: Erguven GO, Nuhoglu Y

Source: ENVIRONMENT PROTECTION ENGINEERING 46, 3: 5-15, 2020, DOI: 10.37190/epe200301

**Abstract:** The bioremediation rate of fluazifop-p-butyl (C19H20F3NO4) was monitored. Bacteria were isolated in agricultural soil samples. Fifteen sterilised glass jars were inoculated with 2, 5, 10, 20 cm(3) of a homogenised bacterial mixture (10(9) CFU/cm(3)), then sterile agricultural soil and 60 mg of fluazifop-p-butyl (in liquid form) were added to each jar. Each week, filtrated water drained from bottles was analysed for fluazifop-p-butyl concentration, chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and total organic carbon (TOC). Additionally, pH and dissolved oxygen concentration were monitored. The highest biodegradation rate was observed in the soil sample containing 20 cm(3) of the culture media. In this media, fluazifop-p-butyl, COD, BOD5 and TOC removals were measured as 91, 83, 96 and 86%, respectively, at the end of the 2 months. The DO level was measured between 3 and 6 mg O-2/dm(3) in the first month for all cultures. An increase of pH was recorded during the first month and after this time a pH decrease was noted.

Accès au document
Combined use of municipal
solid waste biochar and
bacterial biosorbent
synergistically decreases
Cd(II) and Pb(II)
concentration in edible
tissue of forage maize
irrigated with heavy metal-
spiked water

Authors: Abedinzadeh M, Etesami H, Alikhani
HA, Sha S

Source: HELIYON 6, 8, 2020, DOI: 10.1016/j.heliyon.2020.e04688

**Abstract:** A pot experiment was carried out to evaluate the effect of a municipal solid waste (MSW) biochar and a bacterial strain on the forage maize growth and the concentration of lead (Pb) and cadmium (Cd) in the edible tissue of maize irrigated with water contaminated with Cd (5 mg L-1) and Pb (100 mg L-1). Experimental treatments included (i) bacterial strain at two levels: no bacterial strain and Enterobacter cloacae R7; (ii) MSW biochar at three levels: 0, 1, and 3% (w/w); and (iii) irrigation water quality at five levels: plants irrigated with 100% freshwater (FW), plants irrigated with 75%FW + 25% contaminated water (CW), plants irrigated with 50%FW + 50% CW, plants irrigated with 25%FW + 75% CW, and plants irrigated with 100% CW. The effect of various treatments on maize growth indices and concentration of Pb(II) and Cd(II) in the plant was significant at 5% level. The concentration of these metals in the shoot of plants irrigated with 75 and 100% CW was higher than the permissible limits for Cd(II) and Pb(II) in livestock feed. However, the concentration of these metals in the shoot of the plants irrigated with 25 and 50% CW was lower than the permissible limit for this use. In this study, the combined application of 3% biochar and E. cloacae R7 had a significant effect on increased root dry weight (ranging from 29 to 33%), shoot dry weight (ranging from 32 to 43%) and bacterial

root colonization (ranging from 33 to 53%) and on
reduced concentration of Pb (ranging from 78 to
80%) and Cd (ranging from 72 to 76%) of the
shoot of maize plant (edible tissues used by
livestock), which was below the permissible
limits for livestock feed, compared to
corresponding controls. According to the results
of this study, to reduce the concentration of the
heavy metals in forage maize shoot (below the
permissible limits for livestock feed), it is
suggested using heavy metal -contaminated
water either in combination with freshwater (50
or 75% FW) or in combination with biochar and
bacterial biosorbent, averting human/animal
health risk.

Accès au document

Arsenic mobilization affected
by extracellular polymeric
substances (EPS) of the
dissimilatory iron reducing
bacteria isolated from high
arsenic groundwater

Authors: Liu H, Li P, Wang HL and more ...

Source: SCIENCE OF THE TOTAL ENVIRONMENT
735, 2020, DOI: 10.1016/j.scitotenv.2020.139501

**Abstract:** The factors that control arsenic (As) mobilization by dissimilatory iron reduction (DIR) are complicated. The association between As mobilization and extracellular polymeric substance (EPS) of dissimilatory iron reducing bacteria (DIRB) remained unclear. In this study, three DIRB were isolated from high arsenic groundwater to understand the effects of EPS on As mobilization. In the laboratory settings, strain Klebsiella oxytoca IR-ZA released As into aqueous phase from As-bearing ferrihydrite, while strain Shewanella putrefaciens IAR-S1 and S. xiamenensis IR-S2 resequestrated As by forming secondary minerals during ferrihydrite reduction. Characterization of EPS contents with Fourier Transform Infrared Spectroscopy and high-performance liquid chromatography suggested
that mannan and succinic acid were the main different EPS contents of the DIRB. The biomineralization processes were tightly regulated by EPS compositions. Mannan secreted by IAR-S1 and IR-S2 promoted while succinic acid secreted by IR-ZA suppressed the biomineralization and As immobilization. Energy-dispersive X-ray Spectroscopy mapping indicated that As in the secondary minerals was wrapped with EPS. X-ray diffraction and room temperature Mossbauer spectroscopy showed these secondary minerals were vivianite and magnetite, respectively. The amount of As mobilized into aqueous phase was strongly affected by available anions (H2PO4- and HCO3). Our results indicated that the EPS of DIRB significantly influenced As mobilization.

Accès au document

## Bioremediation potential of new cadmium, chromium, and nickel-resistant bacteria isolated from tropical agricultural soil

**Authors:** Minari GD, Saran LM, Constancio MTL and more ...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 204, 2020, DOI: 10.1016/j.ecoenv.2020.111038

**Abstract:** Soil management using fertilizers can modify soil chemical, biochemical and biological properties, including the concentration of trace-elements as cadmium (Cd), chromium (Cd) and nickel (Ni). Bacterial isolates from Cd, Cr, and Ni-contaminated soil were evaluated for some characteristics for their use in bioremediation. Isolates (592) were obtained from soil samples (19) of three areas used in three maize cultivation systems: no-tillage and conventional tillage with the application of mineral fertilizers; minimum tillage with the application of sewage sludge. Four isolates were resistant to Cr3+ (3.06 mmol dm(-3)) and Cd2+ (2.92 mmol dm(-3)). One isolate was resistant to the three metals at 0.95

mmol dm(-3). All isolates developed in a medium of Cd2+, Cr3+ and Ni2+ at 0.5 mmol dm(-3), and removed Cd2+ (17-33%) and Cr6+ (60-70%). They were identified by sequencing of the gene 16S rRNA, as bacteria of the genera Paenibacillus, Burkholderia, Ensifer, and two Cupriavidus. One of the Cupriavidus isolate was able to remove 60% of Cr6+ from the culture medium and showed high indole acetic acid production capacity. We evaluated it in a microbe-plant system that could potentially be deployed in bioremediation by removing toxic metals from contaminated soil.

Accès au document

## Biochar-bacteria-plant partnerships: Eco-solutions for tackling heavy metal pollution

**Authors:** Harindintwali JD, Zhou JL, Yang WH and more ...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 204, 2020, DOI: 10.1016/j.ecoenv.2020.111020

**Abstract:** Over the past 30 years, the ever-rising demands of the modern and growing population have led to the rapid development of agricultural and industrial sectors worldwide. However, this expansion has exposed the environment to various pollutants including heavy metal (HM)s. Almost all HMs are serious toxicants and can pose serious health risks to living organisms in addition to their bioaccumulative and non-biodegradable nature. Different techniques have been developed to restore the ecological functions of the HM-contaminated soil (HMCS). However, the major downfalls of the commonly used remediation technologies are the generation of secondary wastes, high operating costs, and high energy consumption. Phytoremediation is a prominent approach that is more innocuous than the existing remediation approaches. Some microbes-plant interactions enhance the bioremediation process, with heavy metal resistant-plant growth promoting bacteria
(HMRPGPB) being widely used to assist phytoremediation of HMs. However, the most common of all major microbial assisted-phytoremediation disturbances is that the HM-contaminated soil is generally deficient in nutrients and cannot sustain the rapid growth of the applied HMRPGPB. In this case, biochar has recently been approved as a potential carrier of microbial agents. The biochar-HMRPGPB-plant association could provide a promising green approach to remediate HM-polluted sites. Therefore, this review addresses the mechanisms through which biochar and HMRPGPB can enhance phytoremediation. This knowledge of biochar-HMRPGPB-plant interactions is significant with respect to sustainable management of the HM-polluted environment in terms of both ecology and economy, and it offers the possibility of further development of new green technologies.

Accès au document

## 4-Nitrophenol biodegradation by an isolated and characterized microbial consortium and statistical optimization of physicochemical parameters by Taguchi Methodology

**Authors:** Sarkar P, Dey A

**Source:** JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 8, 5, 2020, DOI: 10.1016/j.jece.2020.104347

**Abstract:** A metabolically versatile and highly efficient 4-Nitrophenol degrading bacterial consortium was isolated from a pesticide-contaminated agricultural soil by successive enrichment on a mineral salt medium. Based on the phylogenetic analysis, the members of the consortium were found to be *Brevibacterium* sp. PNP1 (MH169212), *Pseudomonas* sp. PNP2 (MH169213), *Agromyces mediolanus* PNP3 (MH169214) and *Microbacterium oxydans* PNP4

(MH169215). Taguchi Design of experiments approach (DOE) was applied using Qualitek-4 software for the optimization of parameters to enhance the biomass growth and 4-Nitrophenol biodegradation efficiency. Nine physicochemical parameters such as magnesium sulphate, phosphate ion, yeast extract, calcium chloride, temperature, pH, inoculum dose, incubation time, and agitation speed were chosen for optimization due to their crucial impact on biomass growth and 4-Nitrophenol degradation. 27 trials of biodegradation experiments were performed under the L-27 Orthogonal Array (OA) designed by the Taguchi approach. The experimental data were analyzed using the Signal-to-noise (S/N) ratio with the 'bigger is better' characteristics to identify the influential parameters and to establish the optimum conditions for maximizing 4-Nitrophenol biodegradation. Validation of the predicted data with the confirmatory experiments revealed that 1.19 g/L of biomass and 99.12% of 4-Nitrophenol degradation could be attained resulting in 121.48% and 249.88% enhancement in the biomass growth and 4-Nitrophenol degradation respectively, at the optimized condition of yeast extract 2.0 g/L, pH 9.5, temperature 32 degrees C, incubation time 78 h, agitation 160 rpm, and inoculum dose 0.5 absorbance units (AU) of OD600.

Accès au document

## The "Plastisphere" of Biodegradable Plastics Is Characterized by Specific Microbial Taxa of Alpine and Arctic Soils

**Authors:** Ruthi J, Bolsterli D, Pardi-Comensoli L and more ...

**Source:** FRONTIERS IN ENVIRONMENTAL SCIENCE 8, 2020, DOI: 10.3389/fenvs.2020.562263

**Abstract:** Plastic pollution poses a threat to terrestrial ecosystems, even impacting soils from remote alpine and arctic areas. Biodegradable
plastics are a promising solution to prevent long-
term accumulation of plastic litter. However,
little is known about the decomposition of
biodegradable plastics in soils from alpine and
polar ecosystems or the microorganisms involved
in the process. Plastics in aquatic environments
have previously been shown to form a microbial
community on the surface of the plastic distinct
from that in the surrounding water, constituting
the so-called "plastisphere." Comparable studies
in terrestrial environments are scarce. Here, we
aimed to characterize the plastisphere
microbiome of three types of plastics differing in
their biodegradability in soil using DNA
metabarcoding. Polylactic acid (PLA),
polybutylene adipate terephthalate (PBAT), and
polyethylene (PE) were buried in two different
soils, from the Swiss Alps and from Northern
Greenland, at 15 degrees C for 8 weeks. While
physico-chemical characteristics of the polymers
only showed minor (PLA, PBAT) or no (PE)
changes after incubation, a considerably lower
alpha-diversity was observed on the plastic
surfaces and prominent shifts occurred in the
bacterial and fungal community structures
between the plastisphere and the adjacent bulk
soil not affected by the plastic. Effects on the
plastisphere microbiome increased with greater
biodegradability of the plastics, from PE to PLA.
Copiotrophic taxa within the phyla
Proteobacteria and Actinobacteria benefitted the
most from plastic input. Especially taxa with a
known potential to degrade xenobiotics,
including Burkholderiales, Caulobacterales,
Pseudomonas, Rhodococcus, and Streptomyces,
thrived in the plastisphere of the Alpine and
Arctic soils. In addition, Saccharimonadales
(superphylum Patescibacteria) was identified as
a key taxon associated with PLA. The association
of Saccharibacteria with plastic has not been
reported before, and pursuing this finding
further may shed light on the lifestyle of this
obscure candidate phylum. Plastic addition
affected fungal taxa to a lesser extent since only
few fungal genera such as Phlebia and Alternaria
were increased on the plastisphere. Our findings
suggest that the soil microbiome can be strongly
influenced by plastic pollution in terrestrial
cryoenvironments. Further research is required
to fully understand microbial colonization on

plastic surfaces and the biodegradation of plastic
in soils.

Accès au document

Novel metabolites of
triazophos formed during
degradation by bacterial
strains Pseudomonas
kilonensis MB490,
Pseudomonas kilonensis
MB498 and Pseudomonas sp.
MB504 isolated from cotton
fields

Authors: Ambreen S, Yasmin A

**Source:** JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART B-PESTICIDES FOOD CONTAMINANTS AND AGRICULTURAL WASTES, 2020, DOI: 10.1080/03601234.2020.1823171

**Abstract:** In the current scenario of overuse of pesticides (resulting in soil and water pollution and ultimately leading to biomagnification), a research project was carried out to study biodegradation of Triazophos. For this purpose, three bacterial strains (*Pseudomonas kilonensis* MB490, *Pseudomonas kilonensis* MB498 and *Pseudomonas* sp. MB504), isolated from cotton fields of Mianwali, Pakistan were investigated for Triazophos degradation and metabolite formation in M-9 broth, soil slurry and soil microcosm after incubation for 9 days. There was 88.4-95.8% Triazophos degradation in M-9 broth, 99.90% degradation in soil slurry and 92.74 to 96% Triazophos degradation in soil microcosm by these bacteria after 9 days. While there was negligible Triazophos degradation (upto 7%) in the controls without bacteria. According to GCMS analysis, 7 unique and novel metabolites (1, 2, 4-Triazole-4-amine, N-(2-Thienylmethyl), Benzene sulfonic acid hydrazide, Benzene sulfonic acid methyl ester, 4H-1,2,4-Triazole-4-benzenesulfonamide, 4, 5 dihydro-N-(O-toyl)-3-furamide, Ethyl 4-phenyldiazenylbenzoate and
Dibutyl methanephosphonate) of Triazophos were revealed. Current results strongly suggest the potential of these bacterial strains for the remediation of Triazophos contaminated agricultural soils.

Accès au document

## Inoculation of *Brassica napus* L. genotypes with endophytic bacteria promote growth and alleviate cadmium toxicity

**Authors:** Shah AU, Rajab H, Jalal A, Ajmal M and more ...

**Source:** JOURNAL OF ANIMAL AND PLANT SCIENCES-JAPS 30(5):1187-1193, 2020, DOI: 10.36899/JAPS.2020.5.0136

**Abstract:** Cadmium is a non-essential heavy metal that is highly toxic for most of the plants, even at low concentrations. Cadmium tolerant endophytic bacteria isolated from different sources have been effectively used for mitigating cadmium toxicity and plant growth promotion. In the present study, the potential of an endophytic bacterial strain known as *Serratia* sp. IU01, previously isolated from *Solanum nigrum*, was evaluated in terms of alleviating cadmium toxicity and promoting host plant growth. A significant increase in the biomass of two genotypes of *Brassica napus* L. exposed to different concentrations of cadmium was observed after three weeks inoculation with *Serratia* sp. IU01 compared to sole cadmium treated plants. High performance liquid chromatography (HPLC) analysis revealed the steady-levels of one of the key antioxidants, i.e., glutathione, were significantly higher in the sole cadmium treated plants compared to control plants. However, inoculation of the cadmium treated plants with the bacterial endophyte resulted in a significant reduction in glutathione contents compared to sole cadmium treated plants, which suggest the antioxidants released by the endophyte in the host environment have assisted the host plant in minimizing the magnitude of the resultant oxidative damage.

The precursor of glutathione, i.e., cysteine, showed a similar pattern in the sole cadmium treated and inoculated plants. Our data suggested that inoculation of Brassica napus with the bacterial isolate Serratia sp. IU01, under cadmium stress provide a physiological advantage to the plants in terms of growth promotion and alleviating cadmium toxicity.

Accès au document

## Biodegradation of diesel oil by cold-adapted bacterial strains of *Arthrobacter* spp. from Antarctica

**Authors:** Abdulrasheed M, Zakaria NN, Ahmad Roslee AF and more ...

**Source:** ANTARCTIC SCIENCE 32(5):341-353, 2020, DOI: 10.1017/S0954102020000206

**Abstract:** Bioremediation has been proposed as a means of dealing with oil spills on the continent. However, the introduction of non-native organisms, including microbes, even for this purpose would appear to breach the terms of the Environmental Protocol to the Antarctic Treaty. This study therefore aimed to optimize the growth conditions and diesel degradation activity of the Antarctic native bacteria *Arthrobacter* spp. strains AQ5-05 and AQ5-06 through the application of a one-factor-at-a-time (OFAT) approach. Both strains were psychrotolerant, with the optimum temperature supporting diesel degradation being 10-15 degrees C. Both strains were also screened for biosurfactant production and biofilm formation. Their diesel degradation potential was assessed using Bushnell-Haas medium supplemented with 0.5% (v/v) diesel as the sole carbon source and determined using both gravimetric and gas chromatography and mass spectrophotometry analysis. Strain AQ5-06 achieved 37.5% diesel degradation, while strain AQ5-05 achieved 34.5% diesel degradation. Both strains produced biosurfactants and showed high biofilm adherence. Strains AQ5-05 and AQ5-06 showed high cellular hydrophobicity rates of 73.0% and 81.5%, respectively, in hexadecane,
with somewhat lower values of 60.5% and 70.5%, respectively, in tetrahexadecane. Optimized conditions identified via OFAT increased diesel degradation to 41.0% and 47.5% for strains AQ5-05 and AQ5-06, respectively. Both strains also demonstrated the ability to degrade diesel in the presence of heavy metal co-pollutants. This study therefore confirms the potential use of these cold-tolerant bacterial strains in the biodegradation of diesel-polluted Antarctic soils at low environmental temperatures.

Accès au document

## Xenobiotic thiencarbazone-methyl biotransformation investigation by bacteria *Streptococcus pneumoniae*, *Escherichia coli* and *Streptococcus pyogenes*

**Authors:** Ahmad KS, Hafeez N, Gul MM and more ...

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY, 2020, DOI: 10.1007/s13762-020-02948-x

**Abstract:** Xenobiotic thiencarbazone-methyl is a herbicide applied on various grasses and weeds. This triazolinone pesticide may be present in soil and water after application posing deleterious effects on environment and human health. The degradation of thiencarbazone-methyl was scrutinized by the pure bacterial strains including *Streptococcus pneumonia* (SP), *Escherichia coli* (EC) and *Streptococcus pyogenes* (SPy). Individual bacterial suspension was prepared with herbicide solution and evaluated for a duration of 28 days. Time-dependent sampling was performed to investigate thiencarbazone-methyl degradation after specific days interval. Biotransformed samples were extracted and analyzed by UV-Vis spectrophotometer and GC-MS. Biodegradation percentage achieved by SP, Spy and EC, after 28 days, was 31, 40 and 65, respectively. *E. coli* (R-

2= 0.91) displayed greatest potential among all the strains to degrade the herbicide. Significant residues formed included methyl 4-isocyanatosulfonyl-5-methylthiophene-3-carboxylate, 4-methanesulfonyl-benzenesulfonic acid amide and methyl 3-sulfamoylthiophene-2-carboxylate. Current research elucidated the effectiveness of using bacterial strains for the bioremediation of pesticides in environment.

Accès au document

## Influence of Microbial Inoculation on Heavy Metals Absorption of Three Reforestation Species

**Authors:** Morong LJM, Aggangan NS

**Source:** PHILIPPINE JOURNAL OF CROP SCIENCE 44:18-27 - Special Issue: SI, 2019

**Abstract:** Pterocarpus indicus, Acacia mangium and Eucalyptus urophylla are fast growing tree species that thrive in diverse environments and have the potential to rehabilitate heavy metals (HM) contaminated areas i.e. mined-out areas. To determine the effect of microbial inoculation on the absorption and translocation of HMs, three treatments consisting of no microbial inoculants, mycorrhiza and mycorrhiza+NFB were applied to three reforestation species following a 2-factor experiment in RCBD. The bioconcentration factor (BCF) values indicate that *P. indicus*, *A. mangium* and *E. urophylla* accumulated higher HMs in their roots with respect to their corresponding rhizosphere soil, therefore reducing the availability of HMs in the environment. Among the tree species *P. indicus* inoculated with mycorrhiza+NFB seems to be the best bioremediation species and most effective in reducing HM in soil having had the highest BCF for Cd, Pb and Cu. Moreover, even with just mycorrhizal treatment, *P. indicus* was still able to effectively exclude Cu having shown the highest translocation factor (TF) for Cu. All the three reforestation species, however, when inoculated with microbial fertilizers have the potential to remediate Cu, Pb and Cd laden soils
and are recommended to be utilized in
bioremediation of HM contaminated sites. It is
also recommended that inoculants be tested on
plants used as food in HM contaminated areas to
determine their effects on their HM absorption to
address the possibility of HM entry in the food
chain.

Accès au document

Optimization of microbial
assisted phytoremediation of
soils contaminated with
pesticides

Authors: Nurzhanova A, Mukasheva T, Berzhanova R and more ...

Source: INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2020, DOI: 10.1080/15226514.2020.1825330

**Abstract:** 580 microbial strains were isolated from the rhizosphere of the plants *Cucurbita pepo* L. and *Xanthium strumarium* grown on soil contaminated with dichlorodiphenyltrichloroethane (DDT) and its metabolites. During the cultivation, two bacterial strains were selected because of their ability to grow on media containing 0.5-5.0 mg L (-1) of dichlorodiphenyldichloroethylene (DDE) as the sole carbon source. They were identified as *Bacillus vallismortis* and *Bacillus aryabhattai*. Both of these species were shown to have a high capacity for the utilization of DDE - more than 90% of which was consumed after 21 days of cultivation. Laboratory experiments were carried out then to assess the possibility of using these strains for the decontamination of organochlorine pesticides (OCPs) contaminated soils. Inoculation of *C. pepo* and *X. Strumarium* with our isolates *B. Vallismortis* and *B. Aryabhattai* resulted in a reduction of the pollutant stress to the plants as shown by an increase both in aboveground and in root biomass. The microorganisms enhanced the uptake and phytostabilization potential of *C. pepo* and *X. strumarium* and can be applied for the treatment of DDE contaminated soils.

Accès au document

Trifolium repens-Associated
Bacteria as a Potential Tool
to Facilitate
Phytostabilization of Zinc and
Lead Polluted Waste Heaps

Authors: Olenska E, Imperato V, Malek W and more ...

Source: PLANTS-BASEL 9, 8, 2020, DOI: 10.3390/plants9081002

**Abstract:** Heavy metals in soil, as selective agents, can change the structure of plant-associated bacterial communities and their metabolic properties, leading to the selection of the most-adapted strains, which might be useful in phytoremediation. *Trifolium repens*, a heavy metal excluder, naturally occurs on metal mine waste heaps in southern Poland characterized by high total metal concentrations. The purpose of the present study was to assess the effects of toxic metals on the diversity and metabolic properties of the microbial communities in rhizospheric soil and vegetative tissues of *T. repens* growing on three 70-100-years old Zn-Pb mine waste heaps in comparison to Trifolium-associated bacteria from a non-polluted reference site. In total, 113 cultivable strains were isolated and used for 16S rRNA gene Sanger sequencing in order to determine their genetic affiliation and for in vitro testing of their plant growth promotion traits. Taxa richness and phenotypic diversity in communities of metalliferous origin were significantly lower (< 0.0001) compared to those from the reference site. Two strains, *Bacillus megateriumBolR EW3_A03* and *Stenotrophomonas maltophiliaBolN EW3_B03*, isolated from a Zn-Pb mine waste heap which tested positive for all examined plant growth promoting traits and which showed co-tolerance to Zn, Cu, Cd, and Pb can be considered as potential facilitators of phytostabilization.

Accès au document
# A Newly Discovered Humic-Reducing Bacterium, *Pseudomonas geniculata* PQ01, Isolated From Paddy Soil Promotes Paraquat Anaerobic Transformation

**Authors:** Wu CY, Wu XY, Chen SS, Wu DM

**Source:** FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.02003

**Abstract:** Due to toxicity and persistence of paraquat (a widely used herbicide), eco-friendly remediation approaches to its contamination and effective antidotes to its poisoning have been highly desired and raised increasing concerns. Paraquat degradation was lesser in aerobic soil in comparison with anaerobic soil, and humic-reducing microorganisms (HRMs) play a key role in paraquat anaerobic transformation process. However, the degradation pathways and related mechanisms remain poorly understood. In this study, we investigated the specific interaction mechanisms of the paraquat transformation processes mediated by a humic-reducing strain under anaerobic conditions. A strain of pure culture, designated as PQ01, was successfully isolated from paddy soil using anaerobic enrichment procedure, and identified as *Pseudomonas geniculata* using phenotypic and phylogenetic analysis. Sucrose, glucose, pyruvate, formic acid, and acetic acid were shown to be favorable electron donors for the reduction of anthrahydroquinone-2,6-disulfonate (AQDS) reduction by PQ01. The strain also had the ability of reducing Fe(III) (hydr)oxides in the presence of sucrose with efficiencies in the order of ferrihydrite > alpha-FeOOH/gamma-FeOOH > gamma-Fe2O3 > alpha-Fe2O3. In the "PQ01 + paraquat + AQDS + sucrose" system, AQDS reduction and paraquat biotransformation by strain PQ01 occurred simultaneously, and the presence of sucrose significantly enhanced the biotransformation. Specific mechanisms of the electron transfer processes are promoted by both

PQ01 and AQDS, and proceed in two aspects: (1) paraquat served as electron donor in the anaerobic reduction of AQDS by strain PQ01; (2) AQDS was reduced by PQ01 anaerobic metabolism to produce AH(2)QDS, which can directly react with paraquat under anaerobic conditions to generate a single crystal compound (molecular formula of the unit structure is C26H20N2O8S2), causing the paraquat to decline dramatically. In conclusion, this main mechanism included the microbial reduction of AQDS to AH (2)QDS, followed by the abiotic reaction between AH(2)QDS and paraquat. This study reported the new characteristics of P. geniculata capable of reducing humics analogs, Fe(III) (hydr)oxides, and paraquat, and proposed a novel electron transformation mechanism of the HRMs' mediated degradation of organic contaminants.

Accès au document

# Biodegradation of organophosphorus pesticide chlorpyrifos by *Sphingobacterium* sp. C1B, a psychrotolerant bacterium isolated from apple orchard in Himachal Pradesh of India

**Authors:** Verma S, Singh D, Chatterjee S

**Source:** EXTREMOPHILES, 2020, DOI: 10.1007/s00792-020-01203-y

**Abstract:** A psychrotolerant *Sphingobacterium* sp. was isolated from the apple orchard situated in the Kufri region of Shimla, Himachal Pradesh, India using an enrichment culture technique having chlorpyrifos (CP) as the sole source of carbon and energy. Based on biochemical characterization and 16S rRNA analysis, the strain was identified as *Sphingobacterium* sp. C1B. The bacterium C1B was able to degrade chlorpyrifos ≥ 42 ppm and ≥ 36 ppm within 14 days at 20 degrees C and 15 degrees C, respectively. The strain was also able to degrade chlorpyrifos ≤ 35 ppm at 28 degrees C within 14
days. The enzyme organophosphorus hydrolase might be responsible for the initial degradation of CP by the strain C1B. Based on the HPLC and GCMS analysis, a probable degradation pathway has been proposed, which followed the path from chlorpyrifos to 3,5,6-trichloro-2-pyridinol to benzene, 1,3-bis (1,1-dimethylethyl) and then entered into the TCA cycle. Our current study revealed that the bacterium C1B was found to be a useful strain for the degradation of pesticide chlorpyrifos in the cold climatic environment.

Accès au document

Lead (Pb)-resistant bacteria inhibit Pb accumulation in dill (Anethum graveolens L.) by improving biochemical, physiological, and antioxidant enzyme response of plants

Authors: Rahbari A, Fatemi H, Pour BE and more
...

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI: 10.1007/s11356-020-10851-8

**Abstract:** The accumulation of heavy metal in the soil is a serious concern for sustainable food production due to their toxic effects on plants and other living things. The strategies are required on urgent bases for the management of metal-contaminated soils. Thus, the microbes from the genus Pseudomonas were characterized for different traits and lead (Pb)-resistant ability and their effects were assessed on growth, photosynthesis, antioxidant capacity, and Pb uptake by dill (Anethum graveolens L.). Furthermore, soil basal respiration and induced respiration in soil were also assessed under microbes and Pb stress. Among the tested three strains, Pseudomonas P159 and P150 were more tolerant to Pb stress than Pseudomonas P10, whereas P159 showed the highest values for phosphorus (P), siderophore, auxin, and

hydrogen cyanide production. The bacterial inoculation increased the plant shoot dry weights, carbohydrates, proline, and chlorophyll contents under Pb stress. The catalase (CAT) and peroxidase (POD) activities of the plants were higher in bacterial-treated plants than control. The bacterial inoculation decreased Pb concentration in plants, and the response varied with the type of microbes. The bacterial strains enhanced the soil basal and induced respiration than respective Pb treatments alone. Overall, Pseudomonas P159 is potentially suitable for the remediation of Pb-contaminated soils.

Accès au document

Efficient biodegradation of DEHP by CM9 consortium and shifts in the bacterial community structure during bioremediation of contaminated soil

Authors: Bai, NL., Li, SX., Zhang, JQ., and more
...

Source: ENVIRONMENTAL POLLUTION 266, 2, 2020, DOI: 10.1016/j.envpol.2020.115112

**Abstract:** Di(2-ethylhexyl) phthalate (DEHP), the most extensively used plasticizer in plastic formulations, is categorized as a priority environmental contaminant with carcinogenic, teratogenic, and mutagenic toxicities. Many isolated microorganisms exhibit outstanding performance as pure cultures in the laboratory but are unable to cope with harsh environmental conditions in the field. In the present study, a microbial consortium (CM9) with efficient functionality was isolated from contaminated farmland soil. CM9 could consistently degrade 94.85% and 100.00% of DEHP (1000 mg/L) within 24 h and 72 h, respectively, a higher efficiency than those of other reported pure and mixed microorganism cultures. The degradation efficiencies of DEHP and di-n-butyl phthalate were significantly higher than those of dimethyl
phthalate and diethyl phthalate (p &#60; 0.05). The primary members of the CM9 consortium were identified as Rhodococcus, Niabella, Sphingopyxis, Achromobacter, Tahibacter, and Xenophilus. The degradation pathway was hypothesized to include both de-esterification and beta-oxidation. In contaminated soil, bioaugmentation with CM9 and biochar markedly enhanced the DEHP removal rate to 87.53% within 42 d, compared to that observed by the indigenous microbes (49.31%) (p &#60; 0.05). During simulated bioaugmentation, the dominant genera in the CM9 consortium changed significantly over time, indicating their high adaptability to soil conditions and contribution to DEHP degradation. Rhodococcus, Pigmentiphaga and Sphingopyxis sharply decreased, whereas Tahibacter, Terrimonas, Niabella, Unclassifiedj Caulobacteraceae, and Allorhizobium-Neorhizobium-Pararhizobium- Rhizobium showed considerable increases. These results provide a theoretical framework for the development of in situ bioremediation of phthalate (PAE)-contaminated soil by composite microbial inocula.

Accès au document

Characterization of the
Belowground Microbial
Community in a Poplar-
Phytoremediation Strategy of
a Multi-Contaminated Soil

**Authors:** Barra Caracciolo A, Grenni P, Garbini GL and more ...

**Source:** FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.02073

**Abstract:** Due to their widespread use in industrial applications in recent decades, Polychlorobiphenyls (PCBs) and heavy metals (HMs) are the most common soil contaminants

worldwide, posing a risk for both ecosystems and human health. In this study, a poplar-assisted bioremediation strategy has been applied for more than 4 years to a historically contaminated area (PCBs and HMs) in Southern Italy using the Monviso poplar clone. This clone was effective in promoting a decrease in all contaminants and an increase in soil quality in terms of organic carbon and microbial abundance. Moreover, a significant shift in the structure and predicted function of the belowground microbial community was also observed when analyzing both DNA and cDNA sequencing data. In fact, an increase in bacterial genera belonging to Proteobacteria able to degrade PCBs and resist HMs was observed. Moreover, the functional profiling of the microbial community predicted by PICRUSt2 made it possible to identify several genes associated with PCB transformation (e.g., bphAa, bphAb, bphB, bphC), response to HM oxidative stress (e.g., catalase, superoxide reductase, peroxidase) and HM uptake and expulsion (e.g., ABC transporters). This work demonstrated the effectiveness of the poplar clone Monviso in stimulating the natural belowground microbial community to remove contaminants and improve the overall soil quality. It is a practical example of a nature based solution involving synergic interactions between plants and the belowground microbial community.

Accès au document

Potential Plant Growth-Promoting Bacteria with Heavy Metal Resistance

**Author:** Efe D

**Source:** CURRENT MICROBIOLOGY, 2020, DOI: 10.1007/s00284-020-02208-8

**Abstract:** Plant growth-promoting (PGP) bacteria commonly have many strategies to cope with heavy metal toxicity. Heavy metal-resistant PGP bacteria can be used to improve the growth of plants in heavy metal contaminated soils. In this study, the soil samples were collected from the lead-zinc mineral deposits in Gumushane Province, Turkey. Nine bacterial isolates were obtained on the nutrient agar medium
supplemented with 100 mg/mL zinc and lead. All of the isolates were screened in terms of plant growth-promoting characteristics including production of indole-3-acetic acid and siderophore, nitrogen fixation and phosphate solubilisation. Nine bacteria were identified as *Bacillus cereus*, *Bacillus atrophaeus*, *Bacillus pumilus*, *Bacillus amyloliquefaciens*, *Bacillus tropicus*, *Bacillus subtilis*, *Bacillus halotolerans*, *Bacillus vallismortis*, and *Enterococcus mundtii* by classical and 16S rDNA-PCR assays. In addition, these isolates were evaluated for their response to three heavy metals (lead, zinc, copper) dominant in the soil samples and minimal inhibitory concentration (MIC) of the heavy metals was determined with plate dilution method. Consequently, the bacterial isolates in this study possess plant growth-promoting traits and can ameliorate heavy metal contaminated soil. *E.mundtii* was reported to be found in heavy metal contaminated soil for the first time. This study is the first report about PGP characteristics (IAA production and phosphate solubilisation) of *B.vallismortis*.

Accès au document

Biodegradation of Pesticides
at the Limit: Kinetics and
Microbial Substrate Use at
Low Concentrations

Authors: Wirsching J, Pagel H, Ditterich F and
more ...

Source: FRONTIERS IN MICROBIOLOGY 11, 2020,
DOI: 10.3389/fmicb.2020.02107

**Abstract:** The objective of our study was to test whether limited microbial degradation at low pesticide concentrations could explain the discrepancy between overall degradability demonstrated in laboratory tests and their actual persistence in the environment. Studies on pesticide degradation are often performed using unrealistically high application rates seldom

found in natural environments. Nevertheless, biodegradation rates determined for higher pesticide doses cannot necessarily be extrapolated to lower concentrations. In this context, we wanted to (i) compare the kinetics of pesticide degradation at different concentrations in arable land and (ii) clarify whether there is a concentration threshold below which the expression of the functional genes involved in the degradation pathway is inhibited without further pesticide degradation taking place. We set up an incubation experiment for four weeks using 14C-ring labeled 2-methyl-4-chlorophenoxyacetic acid (MCPA) as a model compound in concentrations from 30 to 20,000 μg kg (-1) soil. To quantify the abundance of putative microorganisms involved in MCPA degradation and their degradation activity, tfdA gene copy numbers (DNA) and transcripts (mRNA) were determined by quantitative real-time PCR. Mineralization dynamics of MCPA derived-C were analyzed by monitoring 14CO(2) production and 14C assimilation by soil microorganisms. We identified two different concentration thresholds for growth and activity with respect to MCPA degradation using tfdA gene and mRNA transcript abundance as growth and activity indices, respectively. The tfdA gene expression started to increase between 1,000 and 5,000 μg MCPA kg (-1) dry soil, but an actual increase in tfdA sequences could only be determined at a concentration of 20,000 μg. Accordingly, we observed a clear shift from catabolic to anabolic utilization of MCPA-derived C in the concentration range of 1,000 to 5,000 μg kg (-1). Concentrations ≥ 1,000 μg kg(-1) were mainly associated with delayed mineralization, while concentrations ≤ 1,000 μg kg(-1) showed rapid absolute dissipation. The persistence of pesticides at low concentrations cannot, therefore, be explained by the absence of functional gene expression. Nevertheless, significant differences in the degradation kinetics of MCPA between low and high pesticide concentrations illustrate the need for studies investigating pesticide degradation at environmentally relevant concentrations.

Accès au document
Performance of microbial
induced
carbonate
precipitation
for
immobilizing Cd in water and
soil

Authors: Peng DH, Qiao SY, Luo Y and more ...

Source: JOURNAL OF HAZARDOUS MATERIALS 400, 2020, DOI: 10.1016/j.jhazmat.2020.123116

**Abstract:** Microbial induced carbonate precipitation (MICP) is known as a significant process for remediating heavy metals contaminated environment. In this study, a novel Cd-resistant ureolytic bacteria was isolated and identified as Enterobacter sp. Its performances for immobilizing Cd in solution and soil were systematically discussed at different treatment conditions. Results showed that initial pH and Cd concentration were important parameters to influence Cd removal rate. The maximal Cd removal rate in solution reached 99.50 % within 7 days by MICP. The precipitation produced in Cd removal process were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer to understand the removal mechanism. Analyses showed that Cd removal mechanism of CJW-1 was predominately via biominerals including calcites and vaterites to absorb Cd2+. Cd immobilization tests demonstrated that the highest Cd-immobilization rate in soil could reach 56.10 %. Although all treatments contribute to soil pH, fertility, and enzyme activities improvement, oyster shell wastes (OS) had a better effect on soil cation exchange capacity. All treatments had negative effects on soil respiration and bacterial community, but OS can alleviate such adverse influence. Our results emphasized that Cd-resistant ureolytic bacteria strain CJW-1 combined with OS had excellent ability and reuse value to remediate Cd-contaminated environment.

Accès au document

Fungal bioremediation of soil
co-contaminated with
petroleum hydrocarbons and
toxic metals

Authors: Li QW, Liu JC, Gadd GM

Source: APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, 2020, DOI: 10.1007/s00253-020-10854-y

**Abstract:** Much research has been carried out on the bacterial bioremediation of soil contaminated with petroleum hydrocarbons and toxic metals but much less is known about the potential of fungi in sites that are co-contaminated with both classes of pollutants. This article documents the roles of fungi in soil polluted with both petroleum hydrocarbons and toxic metals as well as the mechanisms involved in the biotransformation of such substances. Soil characteristics (e.g., structural components, pH, and temperature) and intracellular or excreted extracellular enzymes and metabolites are crucial factors which affect the efficiency of combined pollutant transformations. At present, bioremediation of soil co-contaminated with petroleum hydrocarbons and toxic metals is mostly focused on the removal, detoxification, or degradation efficiency of single or composite pollutants of each type. Little research has been carried out on the metabolism of fungi in response to complex pollutant stress. To overcome current bottlenecks in understanding fungal bioremediation, the potential of new approaches, e.g., gradient diffusion film technology (DGT) and metabolomics, is also discussed.

Accès au document

The Fate of Lead (Pb) in
Multitrophic Interactions
Among Bacteria, Fungi, and
Bacterivorous Soil Nematodes
Authors: Iqbal N, Ahmed S, Pervez A and more
...

Source: CLEAN-SOIL AIR WATER, 2020, DOI: 10.1002/clen.202000307

**Abstract:** Contamination of potentially toxic metals poses threats to living organisms due to prolonged existence in an ecosystem. The effects of toxic metals on soil microbes have broadly been reported but the study on interactions among soil micro- and macro-organisms under metal stress needs to be elaborated. In current study, the immobilization of lead (Pb) is investigated by using five resistant microbial strains; (2) *Bacillus cereus*, (1) *Bacillus subtilis*, (1) *Brevundimonas naejangsanensis*, and (1) fungal strain *Fusarium equiseti* isolated from contaminated soil of Hattar, Pakistan. Bacterial and fungal strains and their consortia are tested in the presence/absence of nematodes for Pb immobilization in a medium containing 250 mg L⁻¹Pb. Single bacterial strains immobilize Pb up to 72%, while in the presence of nematodes, bacterial immobilization potential decreases. An increased Pb immobilization up to 185 mg L⁻¹ is found when bacterial and fungal consortia are inoculated with nematodes. The maximum 80% Pb immobilization is found in bacterial-bacterial combinations with nematodes. This study, reveals that inoculation of bacterial-bacterial consortia in the presence of nematodes enhanced bacterial growth via feeding resulting in higher Pb immobilization. These resistant microbial strains can thus be used to treat contaminated sites for better ecosystem functioning.

Accès au document

Accelerated Biodegradation
of the Agrochemical
Ametoctradin by Soil-Derived
Microbial Consortia

Authors: Whittington HD, Singh M, Ta C, Azcarate-Peril MA, Bruno-Barcena JM

Source: FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.01898

**Abstract:** Pesticide-resistant plant pathogens are an increasing threat to the global food supply and have generated a need for novel, efficacious agrochemicals. The current regulatory process for approving new agrochemicals is a tedious but necessary process. One way to accelerate the safety evaluation process is to utilize in vitro systems to demonstrate pesticide degradation by soil microbes prior to ex vivo soil evaluations. This approach may have the capability to generate metabolic profiles free of inhibitory substances, such as humic acids, commonly present in ex vivo soil systems. In this study, we used a packed-bed microbial bioreactor to assess the role of the natural soil microbial community during biodegradation of the triazolopyrimidine fungicide, ametoctradin. Metabolite profiles produced during in vitro ametoctradin degradation were similar to the metabolite profiles obtained during environmental fate studies and demonstrated the degradation of 81% of the parent compound in 72 h compared to a half-life of 2 weeks when ametoctradin was left in the soil. The microbial communities of four different soil locations and the bioreactor microbiome were compared using high throughput sequencing. It was found that biodegradation of ametoctradin in both ex vivo soils and in vitro in the bioreactor correlated with an increase in the relative abundance of Burkholderiales, well characterized microbial degraders of xenobiotic compounds.

Accès au document

Microbial Consortium of
PGPR, Rhizobia and
Arbuscular Mycorrhizal
Fungus Makes Pea Mutant
SGECd(t) Comparable with
Indian Mustard in Cadmium
Tolerance and Accumulation
**Authors:** Belimov AA, Shaposhnikov Al, Azarova TS and more ...

**Source:** PLANTS-BASEL 9, 8, 2020, DOI: 10.3390/plants9080975

**Abstract:** Cadmium (Cd) is one of the most widespread and toxic soil pollutants that inhibits plant growth and microbial activity. Polluted soils can be remediated using plants that either accumulate metals (phytoextraction) or convert them to biologically inaccessible forms (phytostabilization). The phytoremediation potential of a symbiotic system comprising the Cd-tolerant pea (Pisum sativum L.) mutant SGECd(t) and selected Cd-tolerant microorganisms, such as plant growth-promoting rhizobacterium *Variovorax paradoxus* 5C-2, nodule bacterium *Rhizobium leguminosarum* bv.viciae RCAM1066, and arbuscular mycorrhizal fungus Glomussp. 1Fo, was evaluated in comparison with wild-type pea SGE and the Cd-accumulating plant Indian mustard (Brassica juncea L. Czern.) VIR263. Plants were grown in pots in sterilized uncontaminated or Cd-supplemented (15 mg Cd kg (-1)) soil and inoculated or not with the microbial consortium. Cadmium significantly inhibited growth of uninoculated and particularly inoculated SGE plants, but had no effect on SGECd(t) and decreased shoot biomass of *B. juncea*. Inoculation with the microbial consortium more than doubled pea biomass (both genotypes) irrespective of Cd contamination, but had little effect on *B. juncea* biomass. Cadmium decreased nodule number and acetylene reduction activity of SGE by 5.6 and 10.8 times, whereas this decrease in SGECd(t) was 2.1 and 2.8 times only, and the frequency of mycorrhizal structures decreased only in SGE roots. Inoculation decreased shoot Cd concentration and increased seed Cd concentration of both pea genotypes, but had little effect on Cd concentration of *B. juncea*. Inoculation also significantly increased concentration and/or accumulation of nutrients (Ca, Fe, K, Mg, Mn, N, P, S, and Zn) by Cd-treated pea plants, particularly by the SGECd(t) mutant. Shoot Cd concentration of SGECd(t) was twice that of SGE, and the inoculated SGECd(t) had approximately similar Cd accumulation capacity as compared with *B. juncea*. Thus,

plant-microbe systems based on Cd-tolerant micro-symbionts and plant genotypes offer considerable opportunities to increase plant HM tolerance and accumulation.

Accès au document

Bioremediation of toxic metals in mining site of Zamfara metropolis using resident bacteria (*Pantoea agglomerans*): A optimization approach

**Authors:** Audu KE, Adeniji SE, Obidah J

**Source:** HELIYON 6, 8, 2020, DOI: 10.1016/j.heliyon.2020.e04704

**Abstract:** Background: Various clean-up techniques for heavy metals have been suggested and practiced for its biosorption from the contaminated or pollutant soil by using chemical and physical methods. But most of the methods are hazardous to the environment and expensive. This study was on how to determine the potential of resident bacteria in the removal of heavy metals from contaminated soils in Abare situated in Anka Local Government of Zamfara State, Nigeria. Thus, this study employed bioremediation technique for removal of heavy metals. Results: The preparation of Culture media and Isolation of bacteria of the different contaminated soils were achieved by spread plate method. Whereas, concentrations of the heavy metals (Lead (Pb), Copper (Cu) and Iron (Fe)) were determined by Atomic absorption spectrophotometer (AAS. *Pantoea agglomerans* was used for biosorption experiment. The concentrations of Pb ranged between 1.328 +/- 0.493 to 2.326 +/- 2.093 mg/L, Cu 0.234 +/- 0.117 to 1.054 +/- 1.486 mg/L and Fe 18.498 +/- 11.462 to 27.754 +/- 57.510 mg/L. The optimum temperature for biosorption condition was found to be 35 degrees C. More so, the optimum pH of (7) was observed for maximum biosorption of Pb and Cu ions by Pantoea agglomerans which may
be attributed to homeostatic phenomenon and
the availability of metal binding sites on the
biosorbents. Metal uptake biosorption
percentage revealed that Pantoea agglomerans
absorbed 99.6% of Pb, 60% of Cu and 96% of Fe.
Conclusion: This study revealed that Pantoea
agglomerans potential for bioremediation of the
three metals.

Accès au document

Remediation potential of
immobilized bacterial strain
with biochar as carrier in
petroleum hydrocarbon and
Ni co-contaminated soil

Authors: Li X, Wang YX, Luo T and more ...

Source: ENVIRONMENTAL TECHNOLOGY 2020,

DOI: 10.1080/09593330.2020.1815858

**Abstract:** The remediation of organic pollutant-heavy metal co-contaminated soil is a great challenge. Immobilized microorganism technology (IMT) is a potential approach to remediate co-contaminated soil. In this study, we evaluated the feasibility of IMT for the remediation of petroleum hydrocarbon-heavy metal nickel (Ni) co-contaminated soil. The Ni resistant and hydrocarbon-degrading bacteria strain *Citrobacter* sp. was added to co-contaminated soil by immobilizing on corncob biochar. The potential performance in biodegradation of petroleum hydrocarbon and changing the mobility and speciation of nickel (Ni) in soil were determined, with consideration of the influences of the soil properties and dehydrogenase activity. The results demonstrated that the degradation rate of petroleum hydrocarbons by immobilized microorganisms group (IM) was 45.52%, significantly higher than that of the free bacteria (30.15%), biochar (25.92%) and blank group (18.47%) (P\&#60;:0.05). At the same time, IM was more effective in immobilizing Ni in the soil by transforming available Ni to a stable fraction with a maximum residual concentration

increasing by 101.50 mg center dot kg (-1), and
the carcinogenic nickel sulfide was not detected
after remediation in IM. IM exhibited a higher
level of soil dehydrogenase activity (0.3956 mu g
center dot mL (-1) center dot h(-1) center dot g(-
1)) than that of free bacteria (0.2878 mu g
center dot mL(-1)center dot h(-1)center dot g(-
1)). A linear correlation was found between the
petroleum pollutants degradation rate and
dehydrogenase activity (P < 0.05). This study
indicates the effectiveness and potential of IMT
application in degrading petroleum hydrocarbon
and immobilizing heavy metals in co-
contaminated soil.

Accès au document

Effects of root endophytic
fungus, *Microdochium bolleyi*
on cadmium uptake,
translocation and tolerance
by *Hordeum vulgare* L.

Authors: Shadmani L, Jamali S, Fatemi A

Source: BIOLOGIA 2020, DOI: 10.2478/s11756-020-00598-5

**Abstract:** Endophytic fungi can have a positive impact on phytoremediation of heavy metals, but the effects of endophytic fungus *Microdochium bolleyi* on extraction of Cd by barley, have not been previously examined. Therefore, the objective of the present study was to assess the effects of *M. bolleyi* (strain B26) on cadmium (Cd) tolerance, accumulation and translocation by barley (*Hordeum vulgare* L.) (Sararood cultivar) under Cd stress. Barley plants were inoculated with B26 in Cd-added sands (0,
10, 30, 60 mg Cd kg (-1) sand), and the various attributes of growth along with the amount of Cd in barley were investigated after two months. The results indicated that fungal inoculation significantly improved (p < 0.05) plant growth in the presence of Cd by enhancing factors of plant growth; shoot length increased by 8.93%, 11.61% and 5.59%, root length by 26.47%, 12.39% and 13.95%, dry root biomass by 6.35%, 8.57% and 28.57%, dry shoot biomass by 11.39%, 8.25% and 4.81% in soil containing 10, 30 and 60 mg Cd kg (-1), respectively. The increases in chlorophyll content were 16.74% and 9.97% under 10 and 30 mg Cd kg (-1) treatments, in turn. In terms of Cd accumulation, fungal inoculation increased the amount of Cd in the barley roots, by 44%, 27.95% and 25.18% in soil containing 10, 30 and 60 mg Cd kg (-1), respectively, but it remained the same in plant leaves whether the plants were inoculated or not. The results suggested B26 can be exploited to improve the potential of barley for the remediation of Cd contaminated sites.

Accès au document

## Poly-gamma-glutamic acid-producing bacteria reduced Cd uptake and effected the rhizosphere microbial communities of lettuce

**Authors:** Wang XH, Dong GY, Liu XW and more ...

**Source:** JOURNAL OF HAZARDOUS MATERIALS 398, 2020, DOI: 10.1016/j.jhazmat.2020.123146

**Abstract:** Poly-gamma-glutamic acid (gamma-PGA) could efficiently stabilize heavy metals in the environment. This study characterized the effects of two plant growth-promoting and gamma-PGA-producing bacteria *Bacillus subtilis* W7 and *Bacillus amyloliquefaciens* W25 on Cd immobilization and gamma-PGA production in soil filtrate and on the biomass and Cd uptake by lettuce in Cd-contaminated soil, the impact of these strains on the rhizosphere soil bacterial community was also evaluated. The strains reduced Cd concentration (16-75 %) in soil

filtrate and strain W25 had a higher ability of producing gamma-PGA and immobilizing Cd than strain W7. Compared with the control, the strains significantly increased the biomass (41-85 %) and reduced Cd uptake (19-41 %) by lettuce, reduced available Cd content (25-37 %) and increased the relative abundance of gamma-PGA-producing bacteria (24-30 %) in Cd-contaminated soil, among which the effects of strain W25 were better than that of strain W7. Besides, these isolates also increased soil pH value, urease activity and the relative abundance of plant growth-promoting and metal-immobilizing bacteria such as Sphingomonas and Bacillus. In summary, the two strains reduced soil available Cd and lettuce Cd uptake by increasing the pH value, urease activity and the abundance of gamma-PGA-producing bacteria, and regulating bacterial community structure in rhizosphere soil.

Accès au document

## Impact of a synthetic fungicide (fosetyl-Al and propamocarb-hydrochloride) and a biopesticide (*Clonostachys rosea*) on soil bacterial, fungal, and protist communities

**Authors:** Fournier B, Santos SP, Gustavsen JA and more ...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 738, 2020, DOI: 10.1016/j.scitotenv.2020.139635

**Abstract:** The use of synthetic pesticides in agriculture is increasingly debated. However, few studies have compared the impact of synthetic pesticides and alternative biopesticides on non-target soil microorganisms playing a central role in soil functioning.

We conducted a mesocosm experiment and used high-throughput amplicon sequencing to test the
impact of a fungal biopesticide and a synthetic fungicide on the diversity, the taxonomic and functional compositions, and co-occurrence patterns of soil bacterial, fungal and protist communities.

Neither the synthetic pesticide nor the biopesticide had a significant effect on microbial a-diversity. However, both types of pesticides decreased the complexity of the soil microbial network. The two pesticides had contrasting impacts on the composition of microbial communities and the identity of key taxa as revealed by microbial network analyses. The biopesticide impacted keystone taxa that structured the soil microbial network. The synthetic pesticide modified biotic interactions favouring taxa that are less efficient at degrading organic compounds. This suggests that the biopesticides and the synthetic pesticide have different impact on soil functioning. Altogether, our study shows that pest management products may have functionally significant impacts on the soil microbiome even if microbial alpha-diversity is unaffected. It also illustrates the potential of high-throughput sequencing analyses to improve the ecotoxicological risk assessment of pesticides on non-target soil microorganisms.

Accès au document

## Responses of microbial communities and metabolic activities in the rhizosphere during phytoremediation of Cd-contaminated soil

**Authors:** Liu CJ, Lin H, Li B and more ...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 202, 2020, DOI: 10.1016/j.ecoenv.2020.110958

**Abstract:** Phytoremediation is an effective way to repair heavy metal contaminated soil and rhizosphere microorganisms play an important role in plant regulation. Nevertheless, little information is known about the variation of

microbial metabolic activities and community structure in rhizosphere during phytoremediation. In this study, the rhizosphere soil microbial metabolic activities and community structure of *Trifolium repens* L. during Cdcontaminated soil phytoremediation, were analyzed by Biolog EcoPlateTM and high-throughput sequencing. The uptake in the roots of *Trifolium repens* L. grown in 5.68 and 24.23 mg/kg Cd contaminated soil was 33.51 and 84.69 mg/kg respectively, causing the acid-soluble Cd fractions decreased 7.3% and 5.4%. Phytoremediation significantly influenced microbial community and *Trifolium repens* L. planting significantly increased the rhizosphere microbial population, diversity, the relative abundance of plant growth promoting bacteria (Kaistobacter and Flavisolibacter), and the utilization of difficultly metabolized compounds. The correlation analysis among substrate utilization and microbial communities revealed that the relative abundance increased microorganisms possessed stronger carbon utilization capacity, which was beneficial to regulate the stability of plant-microbial system. Collectively, the results of this study provide fundamental insights into the microbial metabolic activities and community structure during heavy metal contaminated soil phytoremediation, which may aid in the bioregulation of phytoremediation.

Accès au document

## Zinc tolerant plant growth promoting bacteria alleviates phytotoxic effects of zinc on maize through zinc immobilization

**Authors:** Jain D, Kour R, Bhojiya AA, and more ...

**Source:** SCIENTIFIC REPORTS 10, 1, 2020, DOI: 10.1038/s41598-020-70846-w

**Abstract:** The increasing heavy metal contamination in agricultural soils has become a
serious concern across the globe. The present study envisages developing microbial inoculant approach for agriculture in Zn contaminated soils. Potential zinc tolerant bacteria (ZTB) were isolated from zinc (Zn) contaminated soils of southern Rajasthan, India. Isolates were further screened based on their efficiency towards Zn tolerance and plant growth promoting activities. Four strains viz. ZTB15, ZTB24, ZTB28 and ZTB29 exhibited high degree of tolerance to Zn up to 62.5 mM. The Zn accumulation by these bacterial strains was also evidenced by AAS and SEM-EDS studies. Assessment of various plant growth promotion traits viz., IAA, GA (3), NH3, HCN, siderophores, ACC deaminase, phytase production and P, K, Si solubilization studies revealed that these ZTB strains may serve as an efficient plant growth promoter under in vitro conditions. Gluconic acid secreted by ZTB strains owing to mineral solubilization was therefore confirmed using high performance liquid chromatography. A pot experiment under Zn stress conditions was performed using maize (Zea mays) variety (FEM-2) as a test crop. Zn toxicity reduced various plant growth parameters ; however, inoculation of ZTB strains alleviated the Zn toxicity and enhanced the plant growth parameters. The effects of Zn stress on antioxidant enzyme activities in maize under in vitro conditions were also investigated. An increase in superoxide dismutase, peroxidase, phenylalanine ammonia lyase, catalase and polyphenol oxidase activity was observed on inoculation of ZTB strains. Further, ZIP gene expression studies revealed high expression in the ZIP metal transporter genes which were declined in the ZTB treated maize plantlets. The findings from the present study revealed that ZTB could play an important role in bioremediation in Zn contaminated soils.

Accès au document

Responses of microbial
communities and metabolic
activities in the rhizosphere

during phytoremediation of
Cd-contaminated soil

Authors: Liu CJ, Lin H, Li B and more ...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 202, 2020, DOI: 10.1016/j.ecoenv.2020.110958

**Abstract:** Phytoremediation is an effective way to repair heavy metal contaminated soil and rhizosphere microorganisms play an important role in plant regulation. Nevertheless, little information is known about the variation of microbial metabolic activities and community structure in rhizosphere during phytoremediation. In this study, the rhizosphere soil microbial metabolic activities and community structure of *Trifolium repens* L. during Cd contaminated soil phytoremediation, were analyzed by Biolog EcoPlateTM and high-throughput sequencing. The uptake in the roots of *Trifolium repens* L. grown in 5.68 and 24.23 mg/kg Cd contaminated soil was 33.51 and 84.69 mg/kg respectively, causing the acid-soluble Cd fractions decreased 7.3% and 5.4%. Phytoremediation significantly influenced microbial community and Trifolium repensL. planting significantly increased the rhizosphere microbial population, diversity, the relative abundance of plant growth promoting bacteria (Kaistobacter and Flavisolibacter), and the utilization of difficultly metabolized compounds. The correlation analysis among substrate utilization and microbial communities revealed that the relative abundance increased microorganisms possessed stronger carbon utilization capacity, which was beneficial to regulate the stability of plant-microbial system. Collectively, the results of this study provide fundamental insights into the microbial metabolic activities and community structure during heavy metal contaminated soil phytoremediation, which may aid in the bioregulation of phytoremediation.

Accès au document
# Evaluation of organic carbon and microbial inoculum for bioremediation of acid mine drainage

**Authors:** Ruehl MD, Hiibel SR

**Source:** MINERALS ENGINEERING 157, 2020, DOI: 10.1016/j.mineng.2020.106554

**Abstract:** Acid mine drainage (AMD) from abandoned mines cause environmental harm and requires cost-effective, passive remediation techniques. Mining activities expose mineral surfaces to oxidation, which accelerates the release and mobilization of acidity, sulfate, and metal ions in AMD. Sulfate-reducing bioreactors (SRBRs) are an attractive means to treat AMD by reducing sulfate, increasing pH, and precipitating metals as metal sulfides. Twelve SRBRs were constructed and operated for 12 months to evaluate AMD bioremediation performance as a function of carbon source and inoculum. Several locally-sourced waste organic materials were characterized by carbon fractionation; two mixtures with the same carbon profile but originating from different sources were used as organic substrates. Microbial communities from two different soil types were used to inoculate the bioreactors. The use of cow manure, corncob, and pinewood as the carbon source and soil from a local pond shore as the inoculum resulted in the greatest bioremediation efficiency, with a pH increase from 2.85 to 6.80 and removals of 82% for total Fe2+, &#62; 86% for Cu2+, &#62; 88% for Zn2+, and &#62; 65% for SO42-. The source of inoculum was found to impact bioremediation startup, with sulfate reduction observed 20 days earlier in high performing inocula. The carbon source was found to impact long-term bioremediation efficiency, with 24% more SO42- and 38% more Fe2+ removed by the best performing carbon sources. Altogether, the combination of manure as a carbon source and marina soil as an inoculum resulted in the highest bioremediation efficiency. The high metal and sulfate removals combined with pH increases to near neutral,

validate the use of SRBRs as an effective method for long-term AMD bioremediation.

Accès au document

## Insight into plant-bacteria-fungi interactions to improve plant performance via remediation of heavy metals: an overview

**Authors:** Kazemalilou S, Delangiz N, Lajayer BA, Ghorbanpour M

**Source:** book chapter: MOLECULAR ASPECTS OF PLANT BENEFICIAL MICROBES IN AGRICULTURE, Edited by: Sharma, V; Salwan, R; AlAni, LKT: 123-132, 2020, DOI: 10.1016/B978-0-12-818469-1.00010-9

Accès au document

Endophytic bacteria stimulate mercury phytoremediation by modulating its bioaccumulation and volatilization

**Authors:** Mello IS, Targanski S, Pietro-Souza W, and more ...

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 202, 2020, DOI: 10.1016/j.ecoenv.2020.110818

**Abstract:** The quantification, efficiency, and possible mechanisms of mercury phytoremediation by endophytic bacteria are poorly understood. Here we selected 8 out of 34 previously isolated endophytic bacterial strains with a broad resistance profile to metals and 11 antibiotics: Acinetobacter baumannii Bacl43, Bacillus sp. Bacl34, Enterobacter sp. Bacl14, Klebsiella pneumoniae Bacl20, Pantoea sp.
Bacl23, *Pseudomonas* sp. Bacl7, *Pseudomonas* sp. Bacl38, and *Serratia marcescens* Bacl56. Except for *Klebsiella pneumoniae* Bacl20, the other seven bacterial strains promoted maize growth on a mercury-contaminated substrate. *Acinetobacter baumannii* Bacl43 and *Bacillus* sp. Bacl34 increased total dry biomass by approximately 47%. The bacteria assisted mercury remediation by decreasing the metal amount in the substrate, possibly by promoting its volatilization. The plants inoculated with *Serratia marcescens* Bacl56 and *Pseudomonas* sp. Bacl38 increased mercury volatilization to 47.16% and 62.42%, respectively. Except for *Bacillus* sp. Bacl34 and *Pantoea* sp. Bacl23, the other six bacterial strains favored mercury bioaccumulation in plant tissues. Endophytic bacteria-assisted phytoremediation contributed to reduce the substrate toxicity assessed in different model organisms. The endophytic bacterial strains selected herein are potential candidates for assisted phytoremediation that shall help reduce environmental toxicity of mercury contaminated soils.

Accès au document

## Efficient fungal and bacterial facilitated remediation of thiencarbazone methyl in the environment

**Authors:** Ahmad KS, Gul P, Gul MM

**Source:** ENVIRONMENTAL RESEARCH 188, 2020, DOI: 10.1016/j.envres.2020.109811

**Abstract:** Triazole herbicide, Thiencarbazone-methyl (TCM) applied on different crops for weedicidal activity is associated with an inherent toxicity towards bladder and urinary functionality. TCM has been first time explored for its biodegradative behavior utilizing microbes, previously isolated from soils. Simulated bio-transformation assemblies of five fungal strains; *Aspergillus fiavus* (AF), *Penicillium chrysogenum* (PC), *Aspergillus niger* (AN), *Aspergillus terrus* (AT), *Aspergillus fumigants* (AFu) and two bacterial strains:

*Xanthomonas citri* (XC), *Pseudomonas syringae* (PS), were utilized. 10 mg/L TCM concentration was set up utilizing each microbe and analysed for 42 days. TCM bio-degradation was evaluated by UV-Visible spectrophotometry and gas chromatography mass spectroscopy. *Aspergillus terrus* (R-2 = 0.86) and *Penicillium chrysogenum* (R-2 = 0.88) exhibited highest capability to metabolize TCM while forming intermediate metabolites including ; 2,4-dihydro-[1,2,4] triazol-3-one, semicarbazide and urea, methyl 4-isocyanatosulfonyl-5-methylthiophene-3-carboxylate. TCM degradation by all strains AF, AFu, AN, PC, AT, PS and XC was found to be 74, 74, 81, 95, 98, 90 and 95%, respectively after 42 days elucidating the effectiveness of all the utilized strains in degrading TCM. Current investigations can impact vital bioremediation approaches for pesticides mitigation from the ecological compartments. Furthermore, present research can be extended to the optimization of the bio-deteriorative assays to be employed on the practical scale for the successful management of environment through sustainable and cost effective ways.

Accès au document

## Phytomanagement Reduces Metal Availability and Microbial Metal Resistance in a Metal Contaminated Soil

**Authors:** Xue K, Van Nostrand JD, Zhou JZ and more...

**Source:** FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.01899

**Abstract:** Short rotation coppice (SRC) with metal tolerant plants may attenuate the pollution of excessive elements with potential toxicity in soils, while preserving soil resources and functionality. Here, we investigated effects of 6 years phytomanagement with willow SRC on properties including heavy metal levels, toxicity tested by BioTox, microbial biomass, enzyme activities, and functional gene abundances measured by GeoChip of soils contaminated by
As, Cd, Pb and Zn, as compared to the same soils under non-managed mixed grassland representing no intervention treatment (Unt). Though metal total concentrations did not differ by SRC and Unt, SRC soils had lower metal availability and toxicity, higher organic carbon, microbial biomass, phosphatase, urease and protease activities, as compared to Unt soils. Significantly reduced abundances of genes encoding resistances to various metals and antibiotics were observed in SRC, likely attributed to reduced metal selective pressure based on less heavy metal availability and soil toxicity. SRC also significantly reduced abundances of genes involved in nitrogen, phosphorus, and sulfur cycles, possibly due to the willow induced selection. Overall, while the SRC phytomanagement did not reduce the total heavy metal concentrations in soils, it decreased the heavy metal availability and soil toxicity, which in turn led to less metal selective pressure on microbial communities. The SRC phytomanagement also reduced the abundances of nutrient cycling genes from microbial communities, possibly due to intense plant nutrient uptake that depleted soil nitrogen and phosphorus availability, and thus site-specific practices should be considered to improve the soil nutrient supply for phytomanagement plants.

Accès au document

## Application of a simazine degrading bacterium, *Arthrobacter ureafaciens* XMJ-Z01 for bioremediation of simazine pollution

**Authors:** Zhu JW, Zhao Y, Fu L and more ...

**Source:** WATER AND ENVIRONMENT JOURNAL, 2020, DOI: 10.1111/wej.12560

**Abstract:** A bacterium named XMJ-Z01 is screened from soil and identified as *Arthrobacter ureafaciens*, which can efficiently degrade simazine. The strain XMJ-Z01 is highly resistant to simazine and can tolerate simazine at a level

of not less than 2000 mg/L. The degradation efficiency of simazine (100 mg/L) in liquid medium by strain XMJ-Z01 can reach about 99.1% in 7 days. Adding a small amount of fresh soil during the degradation of simazine (in culture medium) by strain XMJ-Z01 can improve the degradation efficiency. The use of strain XMJ-Z01 in simazine-contaminated farmland will accelerate the degradation of simazine residues in the soil and reduce its leakage into the deep soil; in addition, it is also beneficial to reduce the adverse effects of simazine on soil enzyme. Therefore, it is considered that strain XMJ-Z01 can be used for bioremediation of simazine pollution in soil.

Accès au document

## Characterization and bioremediation potential of nickel-resistant endophytic bacteria isolated from the wetland plant *Tamarix chinensis*

**Authors:** Chen J, Li N, Han S, Sun YK and more ...

**Source:** FEMS MICROBIOLOGY LETTERS 367, 12, 2020, DOI: 10.1093/femsle/fnaa098

**Abstract:** Wetlands have been proposed as a sink for pollutants such as heavy metals. Wetland plants play a significant role in the phytoremediation of heavy metals. Here, we isolated and characterized three novel nickel (Ni)-resistant endophytic bacteria (NiEB) from the wetland plant *Tamarix chinensis*. The NiEB were identified as *Stenotrophomonas* sp. S20, *Pseudomonas* sp. P21 and *Sphingobium* sp. S42. All isolates tolerated 50 mg L-1 Ni, with isolates S20 and P21 being more tolerant to Ni at up to 400 mg L-1. Moreover, isolate S42 removed 33.7% of nickel sulfate from the water by forming white
precipitates. The three isolates exhibited different plant growth-promoting (PGP) traits related to the production of indole acetic acid (IAA), siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Phytotoxicity studies revealed that the growth of the wetland plants in a high Ni concentration (200 mg L-1) recovered after co-incubation with isolate S42. Overall, this study presents the first report of NiEB isolation from wetland plants and provides novel insights into the diverse functions of endophytic bacteria in a plant host with the potential to improve Ni phytoremediation.

Accès au document

A hyperaccumulator plant *Sedum alfredii* recruits Cd/Zn-tolerant but not Pb-tolerant endospheric bacterial communities from its rhizospheric soil

**Authors:** Wu Y, Ma LY, Zhang XC and more ...

**Source:** PLANT AND SOIL DOI: 10.1007/s11104-020-04684-0

**Abstract:** Aims For a metal hyper accumulator plant *Sedum alfredii*, the recruitment of unique rhizospheric bacterial communities from bulk soils has been well studied. However, in the root-soil interface, the knowledge on the establishment of endospheric microbiomes from rhizospheric soil is still scarce. Methods In this study, we combined culture-independent that was 16S rRNA gene amplicon sequencing, and culture-dependent methods that included bacterial isolation, heavy metal tolerance and plant growth-promoting traits. Results The Cd/Zn concentrations in endosphere were significantly higher than in soil, while Pb concentration in endosphere was significantly lower than in soil.

The alpha-diversity in rhizosphere soils was higher than in root endosphere, and the compartments as a major determinant revealed 85.9% of the taxa variations. The relative abundance of Proteobacteria increased in endosphere compared to rhizosphere. The difference of Cd/Zn tolerance between endospheric and rhizospheric isolates was not obvious, while the Pb tolerance of endospheric isolates significantly decreased compared to rhizosphere. Conclusions : The results suggest that S. alfredii recruits Cd/Zn-tolerant but not Pb-tolerant endospheric bacterial communities from its rhizospheric soil. The difference in the microbial structure and function in the root-soil interface might be related to the selective absorption of metals in S. alfredii.

Accès au document

Bacterial bioaugmentation enhances hydrocarbon degradation, plant colonization and gene expression in diesel-contaminated soil

**Authors:** Ummara U, Noreen Si, Afzal M, Ahmad P

**Source:** PHYSIOLOGIA PLANTARUM 2020, DOI: 10.1111/ppl.13171

**Abstract:** Environmental contamination by hydrocarbons is a major problem, and hydrocarbon accumulation in soil poses hazardous threat to ecosystems. Phytoremediation, which involves plants, is an encouraging technique for the removal of hydrocarbons from polluted soil and water. The purpose of this investigation was to examine whether bacterial inoculation enhanced the phytoremediation of hydrocarbons in diesel-contaminated soil vegetated with maize (Zea maysL.). The two cultivars of maize, MMRI Yellow and Pearl White, were planted in diesel-polluted soil (0, 1.5, 2.5, and 3.5 g diesel kg(-)
1) soil), and inoculated with the consortium of three alkane-degrading bacterial strains, *Arthrobacter oxydans* ITRH49, *Pseudomonas* sp. ITRI73 and *Pseudomonas* sp. MixRI75. Bacterial inoculation enhanced plant growth and hydrocarbon degradation. Between two cultivars, MMRI Yellow showed better growth and hydrocarbon degradation in the presence and absence of bacterial inoculation. Maximum hydrocarbon degradation (80%) was observed in the soil having minimum concentration of diesel (1.5 g kg(-1)soil), and vegetated with bacterial inoculated MMRI Yellow maize cultivar. Furthermore, more bacterial colonization, and abundance and expression of the alkane hydroxylase gene (alkB) were observed in the root interior than in the rhizosphere and shoot interior of the plants. The bacteria-mediated phytoremediation of soil contaminated with hydrocarbons suggested that the collective use of plants and bacteria was the most beneficial approach for the reclamation of diesel-contaminated soil in comparison with vegetation alone.

Accès au document

## The modulation of sugarcane growth and nutritional profile under aluminum stress is dependent on beneficial endophytic bacteria and plantlet origin

**Authors:** Labanca ERG, Andrade SAL, Kuramae E. E, Silveira APD

**Source:** APPLIED SOIL ECOLOGY 156, 2020, DOI: 10.1016/j.apsoil.2020.103715

**Abstract:** Plant growth-promoting bacteria (PGPB) are claimed to not only improve plant fitness but also alleviate plant stress. In this study, we evaluated the effect of five PGPB strains on plantlet growth and nutrient and aluminum (Al) uptake under acid soil conditions characterized by low P and K nutrient availability

and high metal and aluminum (Al) bioavailability, which may represent a stress condition for crop plants. The PGPB strains were inoculated in sugarcane plantlets produced by meristem tissue culture (MCPs) or one-bud stalks (O-BSPs) and cultivated in soil at 37% Al saturation and pH 4.0. Biomass accumulation and Al and nutrient content in roots and shoots were determined after 30 days of growth. Bacterial inoculation increased root and shoot biomass. However, the magnitudes of these increases were dependent on bacterial strain and plantlet origin. The inoculated plantlets exhibited increased Al content and shifts in Al allocation and calcium (Ca) and boron (B) content among different plant parts (root or shoot), and these changes also depended on plantlet origin and the inoculated strain. The higher Ca uptake of inoculated MCPs and higher B uptake of inoculated O-BSPs may have contributed to reducing the damage caused by excessive Al content. The beneficial microbes also caused changes in plant uptake of micronutrients and slightly reduced macronutrient content. Pseudomonas fluorescens (IAC/BECa 141), Kosakonia radicincitans (IAC/BECa 95), Paraburkholderia tropica (IAC/BECa 135) and Herbaspirillum frisingense (IAC/BECa 152) showed potential for alleviating Al stress in sugarcane plantlets.

Accès au document

## Acclimatization of a newly isolated bacteria in monomer tere-phthalic acid (TPA) may enable it to attack the polymer poly-ethylene tere-phthalate (PET)

**Authors:** Kumar, V., Maitra, SS., Singh, R., Burnwal, DK.

**Source:** JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 8, 4, 2020, DOI: 10.1016/j.jece.2020.103977
**Abstract:** Environmental persistence of polyethylene terephthalate (PET) has become a vexing problem. PET is a very popular polymer for many desirable properties, especially as a food grade polymer. It is being produced in large quantities and the entire production is not recycled. A large quantity of PET is finding its way to the Municipal Solid Waste (MSW) dumps and even to rivers as microplastics. There are various methods for PET degradation, among which bio-degradation is most environmentally friendly and technologically suitable. Some metagenomic studies have been conducted for isolation of PET degrading bacteria/enzymes. However, all previous studies deal with bacteria directly isolated from contaminated sites. We have isolated one such bacteria Rhococcus sp. SSM1 from a PET rich MSW dump of New Delhi. However, we did not use the bacteria directly for PET degradation. We forced the bacteria to grow on the monomer terephthalic acid (TPA), the monomer, as the only carbon source for generations. Surprisingly, the Rhococcus sp. SSM1 acclimatized to grow on TPA, was able to attack PET flims, the polymer, resulting in some degradation of the material. This was evidenced by presence of more TPA concentration than supplied at certain time of fermentation and many heavy molecules (heavier than TPA) in the fermentation media which can only come only by degradation of PET. This is a new paradigm in biodegradation research, where acclimatization in the monomer enables a bacteria to attack the polymer. However, we are not claiming that the bacteria can biodegrade bulk PET. It is perhaps surviving on TPA and attacking the surface of the polymer, which is microscopically rough. Bacteria may be recognizing some protruding fingers di, tri or n-mers of TPA from polymer surface and attacking them.

Accès au document

Structure of microbial
communities in amended and
unamended acid-generating
mine wastes along gradients

of soil amelioration and
revegetation

Authors: Asemaninejad A, Munford K, Watmough S and more ....

Source: APPLIED SOIL ECOLOGY 155, 2020, DOI: 10.1016/j.apsoil.2020.103645

**Abstract:** Understanding the structure of microbial communities in acidic, metal contaminated tailings and waste rock in cool, continental northern temperate climates is important for identifying their potential for use in phytostabilization and bioremediation programs. In this study, microbial community compositions across two large mine waste sites in the Sudbury basin, Ontario Canada were analyzed along gradients of barren-to-vegetated tailings and waste rock. Microbial communities were less diverse, more homogenous, and mainly chemolithoautotrophic in barren sites, transitioning to more diverse communities of organoheterotrophs, nitrogen-fixing/plant-growth promoting bacteria, and ectomycorrhizal fungi in the vegetated areas. Co-occurrence analyses of microbial communities demonstrated higher levels of association among microbial groups in the barren tailings, which were related to the extreme environmental and chemical conditions and restricted anabolic nutrient availability of the substrates. We also show that vegetation and plant-derived organic matter in the tailings are associated with the shifts observed in the structure of microbial communities towards more soil-like communities. These changes in microbial communities can improve soil fertility through increased rates of heterotrophic decomposition of plant-derived organic matter, and sequentially further aid in the establishment of vegetation. These findings will help develop phytostabilization approaches in mine tailings and waste rock in cool, continental northern temperate and boreal climates.

Accès au document
# Microbial approach for alleviation of potentially toxic elements in agricultural soils

**Authors:** Alves LD, Nunes FC, Santos ID and more ...

**Source:** Book chapter: CLIMATE CHANGE AND SOIL INTERACTIONS Edited by: Prasad, MNV; Pietrzykowski, M: 271-303, 2020, DOI: 10.1016/B978-0-12-818032-7.00010-2

Accès au document

# Microbial insights into the biogeochemical features of thallium occurrence: A case study from polluted river sediments

**Authors:** Wang J, She JY, Zhou YC and more...

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 739, 2020, DOI: 10.1016/j.scitotenv.2020.139957

**Abstract:** Thallium (Tl) is a trace element with extreme toxicity. Widespread Tl pollution in riverine systems, mainly due to escalating mining and smelting activities of Tl-bearing sulfide minerals, has attracted increasing attention. Insights into the function of the microbial communities with advanced characterization tools are critical for understanding the biogeochemical cycle of Tl. Herein, microbial communities and their adaptive evolution strategies in river sediments from a representative Tl-bearing pyrite mine area in southern China were profiled via 16S rRNA gene sequence analysis and shotgun metagenomic analysis. In total, 64 phyla and 778 genera of microorganisms were observed in the studied

sediments. The results showed that pH, Tl, Pb, Zn and total organic carbon (TOC) had a significant influence on microbial community structure. Some important reductive microorganisms (such as Erysipelothrix, Geobacter, desulfatiferula, desulfatihabadium and fusibacter) were involved in the biogeochemical cycle of Tl. The study suggested that relevant C, N and S cycle genes were the main metabolic paths of microorganisms surviving in the high Tl-polluted environment. The findings were critical for establishment, operation and regulation in the microbial treatment of Tl containing or related wastewater.

Accès au document

# The Immobilization of Soil Cadmium by the Combined Amendment of Bacteria and Hydroxyapatite

**Authors:** Zeng XX, Xu H, Lu J, and more ...

**Source:** SCIENTIFIC REPORTS 10, 1, 2020, DOI: 10.1038/s41598-020-58259-1

**Abstract:** The remediation of heavy metal-contaminated soils has attracted increased attention worldwide. The immobilization of metals to prevent their uptake by plants is an efficient way to remediate contaminated soils. This work aimed to seek the immobilization of cadmium in contaminated soils via a combination method. Flask experiments were performed to investigate the effects of hydroxyapatite (HAP) and the *Cupriavidus* sp. strain ZSK on soil pH and DTPA-extractable cadmium. Pot experiments were carried out to study the effects of the combined amendment on three plant species. The results showed that HAP has no obvious influence on the growth of the strain. With increasing concentrations of HAP, the soil pH increased, and the DTPA-extractable Cd decreased. Via the combined amendment of the
strain and HAP (SH), the DTPA-extractable Cd in the soil decreased by 58.2%. With the combined amendment of the SH, the cadmium accumulation in ramie, dandelion, and daisy decreased by 44.9%, 51.0%, and 38.7%, respectively. Moreover, the combined amendment somewhat benefitted the growth of the three plant species and significantly decreased the biosorption of cadmium. These results suggest that the immobilization by the SH combination is a potential method to decrease the available cadmium in the soil and the cadmium accumulation in plants.

Accès au document

# Diversity of Metal-Resistant and Tensoactive-Producing Culturable Heterotrophic Bacteria Isolated from a Copper Mine in Brazilian Amazonia

**Authors:** Domingues VS, Monteiro AD, Lopes JDL and more ...

**Source:** SCIENTIFIC REPORTS 10, 1, 2020, DOI: 10.1038/s41598-020-62780-8

**Abstract:** Bacterial extracellular polymeric substances (EPSs) present diverse properties of biotechnological interest, such as surface modification, metal adsorption and hydrophobic substances solubilization through surface tension reduction. Thus, there is a growing demand for new producing strains and structurally variable biomolecules with different properties. One approach for scanning this biodiversity consists of exploring environments under selective pressures. The aim of this study was to evaluate the composition of culturable heterotrophic bacterial communities from five different sites from a copper mine in the Amazon biome by an enrichment technique to obtain metal resistant

bacteria (lead, arsenic, cadmium, copper and zinc) capable of producing EPSs. The bacterial densities at the sites varied from 2.42 x 10(3) to 1.34 x 10(8) NMP mL (-1) and the 77 bacterial isolates obtained were classified in four divisions, beta-Proteobacteria (16.88%), gamma-Proteobacteria (7.29%), Firmicutes (61%) and Actinobacteria (12.98%). Bacillus, Alcaligenes, and Lysinibacillus were the most dominant among the 16 observed genera, but the relative frequency of each varied according to the sample and the metal used in the enrichment culture. 58% of the bacterial strains (45) could produce EPSs. From these, 33 strains showed emulsifying activity (E-24), and 9 of them reached values higher than 49%. Only *Actinomyces viscosus* E3.Pb5 and *Bacillus subtilis* group E3. As2 reduced the medium surface tension to values lower than 35 mN m(-1). It was possible to confirm the high presence of bacteria capable of producing EPSs with tensoactive properties in Amazon copper mines and the evolutionary pressure exerted by the heavy metals during enrichment. These molecules can be tested as an alternative for use in processes that involve the removal of metals, such as the bioremediation of contaminated environments.

Accès au document

# Responses of soil and earthworm gut bacterial communities to heavy metal contamination

**Authors:** Liu Pe, Yang Y, Li M

**Source:** ENVIRONMENTAL POLLUTION 265, PT A, A, 2020, DOI: 10.1016/j.envpol.2020.114921

**Abstract:** The large accumulation of heavy metals in the soil surrounding steel factories has become a severe environmental problem. However, few studies have focused on how the earthworm gut microbiota responds to heavy metals in the soil. This study used research sites at a steel factory in Nanjing, China, to investigate how the soil bacterial community and earthworm gut microbiota respond differently to
heavy metal contamination using Illumina high-throughput sequencing targeting 16S rRNA genes. The bacterial community of earthworm guts showed a distinct structure compared with that of the soil, featuring a higher relative abundance of Proteobacteria (45.7%) and Bacteroidetes (18.8%). The bacterial community in the earthworm gut appeared more susceptible to heavy metal contamination compared with the soil community. For example, we identified 38 OTUs (Operational taxonomic units) significantly influenced by contamination among 186 abundant OTUs in the soil, whereas 63 out of the 127 abundant OTUs in the earthworm gut were altered significantly under contamination. This susceptibility may be partly explained by the lower alpha diversity and distinct microbial interactions in the gut. In addition, the accumulation of heavy metals also stimulated the growth of potential plant growth promoting bacteria (PGPB) in the earthworm gut, especially those related to indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) production, which may potentially benefit the phyto-remediation of heavy metals. These results contribute to our understanding of the soil biota and its interactions under heavy metal contamination and may provide further insights into the phytoremediation of metal-contaminated soil.

Accès au document

Effect of biochar on Cd and pyrene removal and bacteria communities variations in soils with culturing ryegrass (*Lolium perenne* L.)

Authors: Li GR, Chen FK, Jia SY and more ...

Source: ENVIRONMENTAL POLLUTION 265, PT A, A, 2020, DOI: 10.1016/j.envpol.2020.114887

**Abstract:** Organic contaminations and heavy metals in soils cause large harm to human and environment, which could be remedied by planting specific plants. The biochars produced

by crop straws could provide substantial benefits as a soil amendment. In the present study, biochars based on wheat, corn, soybean, cotton and eggplant straws were produced. The eggplant straws based biochar (ESBC) represented higher Cd and pyrene adsorption capacity than others, which was probably owing to the higher specific surface area and total pore volume, more functional groups and excellent crystallization. And then, ESBC amendment hybrid Ryegrass (*Lolium perenne* L.) cultivation were investigated to remediate the Cd and pyrene co-contaminated soil. With the leaching amount of 100% (v/w, mL water/g soil) and Cd content of 16.8 mg/kg soil, dosing 3% ESBC (wt%, biochar/soil) could keep 96.2% of the Cd in the 10 cm depth soil layer where the ryegrass root could reach, and it positively help root adsorb contaminations. Compared with the single planting ryegrass, the Cd and pyrene removal efficiencies significantly increased to 22.8% and 76.9% by dosing 3% ESBC, which was mainly related with the increased plant germination of 80% and biomass of 1.29 g after 70 days culture. When the ESBC dosage increased to 5%, more free radicals were injected and the ryegrass germination and biomass decreased to 65% and 0.986 g. Furthermore, when the ESBC was added into the ryegrass culture soil, the proportion of Cd and pyrene degrading bacteria Pseudomonas and Enterobacter significantly increased to 4.46% and 3.85%, which promoted the co-contaminations removal. It is suggested that biochar amendment hybrid ryegrass cultivation would be an effective method to remediate the Cd and pyrene co-contaminated soil.

Accès au document

*Bacillus aryabhattai* FACU: A promising bacterial strain capable of manipulate the glyphosate herbicide residues

Authors: Elarabi NI, Abdelhadi AA, Ahmed RH and more ...
**Source:** SAUDI JOURNAL OF BIOLOGICAL SCIENCES 27(9):2207-2214, 2020, DOI: 10.1016/j.sjbs.2020.06.050

**Abstract:** Glyphosate is a commonly used organophosphate herbicide that has an adverse impact on humans, mammals and soil microbial ecosystems. The redundant utilize of glyphosate to control weed growth cause the pollution of the soil environment by this chemical. The discharge of glyphosate in the agricultural drainage can also cause serious environmental damage and water pollution problems. Therefore, it is important to develop methods for enhancing glyphosate degradation in the soil through bioremediation. In this study, thirty bacterial isolates were selected from an agro-industrial zone located in Sadat City of Monufia Governorate, Egypt. The isolates were able to grow in LB medium supplemented with 7.2 mg/ml glyphosate. Ten isolates only had the ability to grow in a medium containing different concentrations of glyphosate (50, 100, 150, 200 and 250 mg/ml). The FACU3 bacterial isolate showed the highest CFU in the different concentrations of glyphosate. The FACU3 isolate was Gram-positive, spore-forming and rod-shape bacteria. Based on API 50 CHB/E medium kit, biochemical properties and 16S rRNA gene sequencing, the FACU3 isolate was identified as Bacillus aryabhattai. Different bioinformatics tools, including multiple sequence alignment (MSA), basic local alignment search tool (BLAST) and primer alignment, were used to design specific primers for goxB gene amplification and isolation. The goxB gene encodes FAD-dependent glyphosate oxidase enzyme that responsible for biodegradation process. The selected primers were successfully used to amplify the goxB gene from Bacillus aryabhattai FACU3. The results indicated that the Bacillus aryabhattai FACU3 can be utilized in glyphosate-contaminated environments for bioremediation. According to our knowledge, this is the first time to isolate of FAD-dependent glyphosate oxidase (goxB) gene from Bacillus aryabhattai. (C) 2020 Published by Elsevier B.V. on behalf of King Saud University.

Accès au document

Effects of liquid digestate on
the valence state of
vanadium in plant and soil
and microbial community
response

Authors: Aihemaiti A, Gao YC, Liu L and more ...

**Source:** ENVIRONMENTAL POLLUTION 265, PT A, A, 2020, DOI: 10.1016/j.envpol.2020.114916

**Abstract:** Liquid digestate containing high levels of nutrients and humic and fatty acids can affect vanadium species and their plant uptake. To elucidate the effects of liquid digestate on the valence state of vanadium in soil and plant tissue, as well as its effects on the microbial community and soil properties, we grew green bristlegrass (Setaria viridis), a native plant capable of growing in vanadium mining areas, in vanadium-contaminated soils sampled from a mining area and treated it with 5% and 10% liquid digestate for 90 d, respectively. Changes in the concentrations of pentavalent (V[V]) and tetravalent (V[IV]) vanadium in the soils and the shoots and roots of bristlegrass and the soil microbial abundance were measured. The results showed that vanadium existed mainly in the form of V(IV) in the soil but accumulated mainly in the form of V(V) in the bristlegrass. Liquid digestate markedly reduced V(V) concentrations in the soils (by up to 45%) and in the shoots and roots of green bristlegrass (by up to 98%). Liquid digestate enhanced the abundance of Bacteroidetes, which can reduce V(V) to lower valence state. Microbial reduction and phosphorus immobilization were responsible for downregulating V(V) concentrations in the plant and soil. The liquid digestate can be used to enhance in situ bioremediation of vanadium-contaminated soil in mining area.

Accès au document
ERA / PUBLICATIONS
SCIENTIFIQUES /
PESTICIDES ET FAUNE
SAUVAGE

Multiscale habitat mediates pest reduction by birds in an intensive agricultural region

**Authors:** Heath SK, and Long RF

**Source:** Ecosphere 10(10):e02884, 2019, DOI: 10.1002/ecs2.2884

**Abstract:** (...) Effectiveness of local habitat enhancement and subsequent pest reduction services can be mediated by the amount of habitat at larger scales. We tested whether the presence and increase of local and landscape scale bird habitat increased avian predator abundance and pest reduction by birds. We surveyed birds and performed a sentinel prey exclosure experiment in walnut orchards in the Sacramento Valley, California, USA—comparing predation probability between orchards with (n = 10) and without (n = 10) woody habitat in uncultivated orchard margins. (...)

Accès au document

Birds suppress pests in corn but release them in soybean crops within a mixed prairie/agriculture system

**Authors:** Garfinkel MB, Minor ES, Whelan CJ

**Source:** The Condor, 122(2):1-12, 2020, DOI: 10.1093/condor/duaa009

**Abstract:** Birds provide ecosystem services (pest control) in many agroecosystems (...). We studied indirect effects of insectivorous birds on

corn and soybean crops in fields adjacent to a prairie in Illinois (USA). (...) We used bird-excluding cages over crops to examine the net effect of birds on corn and soybean grain yield. We also conducted DNA metabarcoding to identify arthropod prey in fecal samples from captured birds. (...) We estimated that birds in this system provided a service worth approximately US $275 ha-1 in corn yield gain, and a disservice valued at approximately $348 ha-1 in soybean yield loss. (...).

Accès au document

Yellow-legged gull eggs (Larus michahellis) as persistent organic pollutants and trace metal bioindicator for two nearby areas with different human impact

**Authors:** Viñas L, Besada V, Pérez-Fernández B, Bode A

**Source:** Environmental Research, 190:110026, 2020, DOI: 10.1016/j.envres.2020.110026

**Abstract:** The concentration of different persistent organic pollutants (POPs including chlorinated and brominated compounds) and trace metals and metalloids (As, Cd, Cu, Cr, Pb, Hg, Ni, and Zn) was examined in eggs from two colonies of yellow-legged gulls. (...) Statistically significant differences for the two colonies were observed for Hg, the sum of 7 CBs, the sum of DDTs y and the sum of 9 PBDEs, with values that could be causing some toxic effects (...) The estimated isotopic niche was also calculated, based on δ15N and δ13C, for the two colonies, pointing to a wider diet in the Cíes colony when compared to the diet in the Vigo colony. (...)

Accès au document
# Glyphosate-based herbicides influence antioxidants, reproductive hormones and gut microbiome but not reproduction: A long-term experiment in an avian model

**Authors:** Ruuskanen S, Rainio MJ, Gómez-Gallego C, Selenius O, Salminen S, Collado MC, Saikkonen K, Saloniemi I, Helander M

Sources: ENVIRONMENTAL POLLUTION, 2020, DOI:10.1016/j.envpol.2020.115108

**Abstract:** Glyphosate-based herbicides (GBHs) residues may expose non-target organisms to health risks, yet the developmental and cumulative effects of GBHs on physiology and reproduction remain poorly understood. We present the first long-term study on the effects of subtoxic GBH exposure (160 mg/kg) on multiple key physiological biomarkers (...), gut microbiome, reproductive hormones, and reproduction in an avian model (...) Japanese quail females and males (Cotumix japonica) (...) Future studies are needed to characterize the effects on reproductive physiology in more detail. (...)

Accès au document

Exposure Impacts of Environmentally Relevant Concentrations of a Glufosinate Ammonium Herbicide Formulation on Larval Development and Thyroid Histology of *Xenopus laevis*

**Authors:** Babalola OO, Truter JC, Archer E, van Wyk JH et al

Source: ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 2020, DOI: 10.1007/s00244-020-00758-3

**Abstract:** (...) These complex activities of thyroid hormones are prone to disruption by agricultural pesticides, often leading to modulation of growth and the reproductive system in particular. (...) In this study, the standardized Xenopus Metamorphosis Assay protocol was used to assess the potential thyroid-modulatory properties of the Glufosinate ammonium Basta formulation, at relevant environmental concentrations (...) The present study confirmed that this Basta formulation interacts with the thyroid axis and therefore potentially pose health hazard to amphibian (...)

Accès au document

# Cypermethrin- and fipronil-based insecticides cause biochemical changes in *Physalaemus gracilistadpoles*

**Authors:** Rutkoski CF, Macagnan N, Folador A, Skovronski VJ et al

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 2020, DOI:10.1007/s11356-020-10798-w

**Abstract:** Insecticides used for agricultural pest control, as cypermethrin-based insecticide (CBI) and fipronil-based insecticide (FBI), are constant threats to non-target aquatic organisms. This study aimed to investigate the effect of different concentrations of cypermethrin and fipronil on neurotoxicity and oxidative stress in *Physalaemus gracilis*. (...) both insecticides promoted oxidative stress and neurotoxic effects in *P. gracilis* tadpoles. (...)

Accès au document
## Organochlorine pesticide residues in feathers of four bird species from western part of Turkey

**Authors:** Arikan K, Turan SL

**Source:** TURKISH JOURNAL OF ZOOLOGY 2020, DOI: 10.3906/zoo-2005-52

**Abstract:** (...) The purpose of the study was to investigate OCP residue levels in wild birds from Aegean, Marmara, Mediterranean, and Central Anatolia geographical regions of Turkey. Feather samples (n = 80) of four bird species in four regions (...) Feather samples were analysed using GC/MS and scanned for 23 pesticide congeners. (...) Regions and birds differed significantly as well as among themselves in terms of total residue levels (...)

Accès au document

## A micronucleus assay detects genotoxic effects of herbicide exposure in a protected butterfly species

**Authors:** Santovito A, Audisio M, Bonelli S

**Source:** Ecotoxicology 2020, DOI: 10.1007/s10646-020-02276-3

**Abstract:** (...) We investigated, by micronucleus (MN) assay, the genotoxic effect of glyphosate, a common herbicide, on *L. dispar* larvae. (...) In a control/treatment experiment, we extracted epithelial cells from last-instar larvae fed with *Rumex* spp. plants sprayed with a solution containing 3.6 g/L of glyphosate, and from larvae fed with unsprayed plants. (...) For the first time, a MN assay was used in order to evaluate the genomic damage on a phytophagous invertebrate at the larval stage. (...)

Accès au document

## Legacy and Contaminants of Emerging Concern in Tree Swallows Along an Agricultural to Industrial Gradient: Maumee River, Ohio

**Authors:** Custer CM, Custer TW, Dummer PM, Schultz S, Tseng CY, Karouna-Renier N, Matson CW

**Source:** Environ Toxicol Chem 2020, DOI: 10.1002/etc.4792

**Abstract:** Exposure to multiple classes of contaminants, both legacy and contaminants of emerging concern (CECs), were assessed in tree swallow (*Tachycineta bicolor*) tissue and diet samples from 6 sites along the Maumee River, Ohio, USA, to understand both exposure and possible effects of exposure to those CECs for which there are little avian data. The 6 sites represented a gradient from intensive agriculture upstream to highly urbanized and industrial landscapes downstream (...) This is one of the most comprehensive assessments to date of exposure and effects of a wide variety of CECs in birds.

Accès du document

## Genotoxicity in American kestrels in an agricultural landscape in the Baja California peninsula, Mexico

**Authors:** Frixione MG, Rodríguez-Estrella R

**Sources:** Environ Sci Pollut Res 2020, DOI: 10.1007/s11356-020-10392-0

**Abstract:** Raptors as top predators have been used as effective sentinels of environmental stressors in agricultural areas worldwide. Pollutants in agricultural areas have negative
effects on top predator populations. Biomarkers such as erythrocyte nuclear abnormalities have been used as an effective measure of genotoxicity caused by exposure—particularly short-term exposure—to pollutants. We took blood samples from 54 wild specimens of American kestrel (Falco sparverius), (...). We found a high frequency of abnormalities in numerous individuals, similar to those found in raptors from highly polluted areas. (...).

Accès au document

ERA / PUBLICATIONS

SCIENTIFIQUES /

PESTICIDES / CLIMAT

et VdT / ENCHY

## Ecotoxicology of strobilurin fungicides

Strobilurin fungicides (SFs), a class of new fungicides, use strobilurin A as a lead compound. However, with excessive production and usage, the SF residues in soil and aquatic ecosystems may lead to environmental pollution. The mechanism of action (MOA) of SFs is respiratory inhibition of fungal mitochondria. (...)

Accès au document

## Sub-Lethal Effects of Pesticides on the DNA of Soil Organisms as Early Ecotoxicological Biomarkers

This review describes the researches performed in the last years to assess the impact of pesticide sub-lethal doses on soil microorganisms and non-target organisms in agricultural soil ecosystems. (...)

Accès au document

## A two years field experiment to assess the impact of two fungicides on earthworm communities and their recovery

Recent EFSA (European Food Safety Authority) reports highlighted that the ecological risk assessment of pesticides needed to go further by taking more into account the impacts of chemicals on biodiversity under field conditions. We assessed the effects of two commercial formulations of fungicides separately and in mixture, i.e., (...) copper oxychloride (...) epoxiconazole (...) dimoxystbin (...) on earthworms at 1, 6, 12, 18 and 24 months after the application (...) in field situations.

Accès au document

## A biological characteristic extrapolation of compound toxicity for different developmental stage species with toxicokinetic-toxicodynamic model

Intraspecific difference in toxicity brings uncertainty to ecological risk assessment (ERA) and water quality criteria (WQC) of chemicals. Here, we compared intraspecies sensitivity to toxicants for *Mesocyclops ieuckarti* of which toxicity data was obtained from published literatures, and zebrafish *Danio rerio* of which toxicity data was done in this study. (...)

Accès au document
## What are the effects of PFAS exposure at environmentally relevant concentrations?

(...) little data exists on the effects of exposure to PFAS at environmentally relevant concentrations and this hampers the effective management of these compounds. This paper reviews current research on the occurrence and ecotoxicology of PFAS at environmentally relevant doses to assess their potential biological impacts.

Accès au document

## Transcriptome, bioaccumulation and toxicity analyses of earthworms (*Eisenia fetida*) affected by trifloxystrobin and trifloxystrobin acid

As a promising fungicide, the potential environmental risk of trifloxystrobin (TFS) and its main metabolism trifloxystrobin acid (TFSA) in soil environment should be given special attention. The present study investigated the potential risks of TFS and TFSA in soil environment to earthworms (*Eisenia fetida*) through measuring several biomarkers.

Accès au document

## Novel Pesticide Risk Indicators for Aquatic Organisms and Earthworms

There are many approaches of pesticide risk assessment. Despite their variation in difficulty and information complexity, all of them are intended to predict the actual pesticide risk as accurately as possible, i.e., to predict the behavior and hazard of a pesticide in the

environment with high precision. The aim of this study was to develop a risk indicator of pesticide's negative impact on soil and aquatic organisms.

Accès au document

## Biochemical response, histopathological change and DNA damage in earthworm (*Eisenia fetida*) exposed to sulfentrazone herbicide

(...) we know little about the impact of sulfentrazone on ecologically important soil earthworms such as Eisenia fetida. Thus, we investigated the toxicity of sulfentrazone (0.2, 1.0 and 5.0 mg/kg in soil) on *E. fetida* at day 7, 14, 21 and 28. We investigated the effects of sulfentrazone on oxidative stress, histopathological change, and DNA damage in earthworms. (...)

Accès au document

## Sub-lethal effects of the pesticide imazalil on the earthworm *Eisenia andrei*: reproduction, cytotoxicity, and oxidative stress

Although considered an emerging contaminant and detected in the environment, the systematic and penetration fungicide imazalil ((RS)-1-(beta-allyloxy-2,4-dichlorophenylethyl) imidazole) has received relatively little scientific attention with regard to its possible negative effects in the environment. Only a few toxicological studies have assessed the potential environmental effect of imazalil and its impact on organisms. In this context, the aim of the present study is to evaluate the effects of different concentrations of the pesticide imazalil on the
earthwormEisenia andreiin acute contact and chronic tests in natural soil.

Accès au document

Interactive effect of glyphosate-based herbicides and organic soil layer thickness on growth and reproduction of the tropical earthworm *Pontoscolex corethrurus* (Muller, 1857)

Glyphosate-based herbicides (GBHs) have negative effects on the fitness parameters of earthworms; however, these effects may vary from one commercial product to another and between different recommended doses. Additionally, frequent applications of GBHs may decrease the thickness of the topsoil layer due to increased soil erosion through vegetation reduction. To investigate the effects of frequent applications of GBHs, and their interactive effect on the performance of *P. corethrurus*, we performed a two-factor experiment (...)

Accès au document

More frequent droughts slow down litter decomposition across European agroecosystems and increase the importance of earthworm functional diversity

Effects of increasing rainfall variability and weather extremes on litter decomposition are still uncertain, especially in agroecosystems, where the functional structure of soil communities is already affected. We conducted a mesocosm experiment to evaluate the impacts of different rain regimes and land management on litter mass loss and earthworm ecological groups (epigeic, endogeic and anecic) across European agroecosystems.

Accès au document

DROIT ET POLITIQUE

DE

L'ENVIRONNEMENT

Drinking Water Directive

On 1 February 2018 the Commission proposed the recast of Council Directive 98/83/EC on the quality of water intended for human consumption (the ‘Drinking Water Directive’). The proposal aimed to update parameters set over 20 years ago, correct shortcomings and introduce access to water in response to the first ever European citizens’ initiative ‘Right2Water’.

After intense negotiations, an agreement was found between the co-legislators in December 2019, and in February 2020 the ENVI Committee approved the outcome of the negotiations. The Council adopted its first reading on 23 October 2020. The adoption of the EP second reading is foreseen in December Plenary.

The agreed text will ensure that tap water across the EU is safe to drink. Under the new rules, the quality standards for drinking water are brought up to date, a cost-effective risk-based approach to monitoring water quality is introduced as well as hygienic requirements for materials in contact with drinking water.

The recast also addresses growing concern about the effects of endocrine disruptors, pharmaceuticals and microplastics on human health by introducing a watch list mechanism which will allow to follow up, in a dynamic and
flexible way, on new knowledge about these substances and their relevance for human health.

Accès au document

## Reducing agricultural ammonia emissions: benefits and costs

Ammonia (NH3) emissions associated with the agriculture sector contribute to the production of fine particulate matter (PM2.5) pollution and may be associated with premature mortality. This study assesses the economic costs and benefits associated with reducing emissions in the agricultural sector. To do this, it uses emissions data from 2016 to assess the costs and benefits of achieving the 2020 ammonia emission reduction commitments, as set out in the National Emission reduction Commitments Directive (NECD) 2016/2284/

EU1, in relation to four abatement options. The results suggest that compliance with the directive may be associated with significant reductions in premature mortality, and that the economic benefits of avoiding premature mortality might outweigh the costs of abatement.

Environment 5th October 2020 / Issue 549

Source: Giannakis, E., Kushta, J., Bruggeman. A. and Lelieveld J. (2020). Costs and benefits of agricultural ammonia emission abatement options for compliance with European air quality regulations. Environmental Sciences Europe 31: 93. https://doi.org/10.1186/s12302-019-0275-0

Accès au document

## Impact des polluants en mélange: un appel à projets de recherche est ouvert

Actu-environnement 07/10/20

Clôture : 01/12/2020

L'Ademe ouvre, jusqu'au 1er décembre 2020, un appel à projets de recherche dans le cadre du « Programme impacts 2020 ». L'objectif est de soutenir des projets de recherche et de développement portant sur l'impact des mélanges de polluants sur le vivant. Les projets devront porter sur les effets sanitaires d'une exposition aux polluants de l'air ; les micro-organismes pathogènes, les agents biologiques, les virus ; la pollution des sols ; l'économie circulaire et les filières à retenir ; la santé des sols, l'agriculture urbaine et les projets alimentaires territoriaux ou encore l'approche territoriale d'évaluation du risque lié à des expositions multiples. Ils pourront bénéficier d'une subvention allant de 45 000 à 200 000 € par projet pour une durée de trois ans maximum.

Accès au document

## Qualité de l'air : l'Ademe regroupe ses programmes de recherche dans l'appel à propositions unique Aqacia

Actu-environnement 17/09/20

Le 16 septembre, l'Agence de la transition écologique (Ademe) a lancé le premier appel à propositions de recherche (APR) de son nouveau programme « amélioration de la qualité de l'air : comprendre, innover, agir » (Aqacia). Les candidatures sont ouvertes jusqu'au 27 novembre 2020. Ce programme « a pour ambition de faire émerger des projets de recherche & développement orientés vers la compréhension et l'amélioration de la qualité de l'air intérieur et extérieur », résume l'Ademe. Il prend le relais de différents programmes de recherche : Primequal,
Cortea, Aactair-volet R&D et partiellement d'Impacts-volet Air. [...]

Accès au document

## REGLEMENTATION / DROIT

Limites maximales applicables aux résidus de 1,4diaminobutane, de 1méthylcyclopropène, d'acétate d'ammonium, de bifénazate, de chlorantraniliprole, de chlorméquat, de cyprodinil, de chaux, de mandipropamide, de poivre, de pyridaben, de la substance «répulsifs: farine de sang», d'extraits d'algues et de chlorhydrate de triméthylamine, présents dans ou sur certains produits

RÈGLEMENT (UE) 2020/1565 DE LA COMMISSION du 27 octobre 2020 modifiant les annexes II, III et IV du règlement (CE) n° 396/2005 du Parlement européen et du Conseil en ce qui concerne les limites maximales applicables aux résidus de 1,4diaminobutane, de 1méthylcyclopropène, d'acétate d'ammonium, de bifénazate, de chlorantraniliprole, de chlorméquat, de cyprodinil, de chaux, de mandipropamide, de

poivre, de pyridaben, de la substance «répulsifs: farine de sang», d'extraits d'algues et de chlorhydrate de triméthylamine, présents dans ou sur certains produits

Numéro officiel : UE/2020/1565

Liens juridiques : Modification Règlement CE/396/2005 23/02/2005

Accès au document

Limites maximales applicables aux résidus de bupirimate, de carfentrazone-éthyle, d'éthirimol et de pyriofénone présents dans ou sur certains produits

RÈGLEMENT (UE) 2020/1566 DE LA COMMISSION du 27 octobre 2020 modifiant les annexes II et III du règlement (CE) n° 396/2005 du Parlement européen et du Conseil en ce qui concerne les limites maximales applicables aux résidus de bupirimate, de carfentrazone-éthyle, d'éthirimol et de pyriofénone présents dans ou sur certains produits

Numéro officiel : UE/2020/1566

Liens juridiques : Modification le 17/05/2021 Règlement CE/396/2005 23/02/2005

Accès au document

Démarches ou pratiques ayant des incidences favorables sur la réduction de l'usage et des impacts de produits phytopharmaceutiques
Arrêté du 16 octobre 2020 fixant la liste des démarches ou pratiques ayant des incidences favorables sur la réduction de l'usage et des impacts de produits phytopharmaceutiques permettant l'exemption prévue au 2° du III de l'article L. 254-6-2 du code rural et de la pêche maritime

Numéro officiel : AGRG2027130A

Accès au document

## Activité « application en prestation de service de produits phytopharmaceutiques » : référentiel de certification

Arrêté du 16 octobre 2020 relatif au référentiel de certification prévu à l'article R. 254-3 du code rural et de la pêche maritime pour l'activité « application en prestation de service de produits phytopharmaceutiques »

Numéro officiel : AGRG2027132A

Liens juridiques : Abrogation le 01/01/2021
Arrêté 17/07/2014 NOR AGRG1403129A

Abrogation le 01/01/2021 Arrêté 25/11/2011 NOR AGRG1132074A

Accès au document

## Distribution de produits phytopharmaceutiques à des utilisateurs non professionnels : référentiel de certification

Arrêté du 16 octobre 2020 relatif au référentiel de certification prévu à l'article R. 254-3 du code rural et de la pêche maritime pour l'activité « distribution de produits phytopharmaceutiques à des utilisateurs non professionnels »

Numéro officiel : AGRG2027138A

Liens juridiques : Abrogation le 01/01/2021
Arrêté 25/11/2011 NOR AGRG1132064A

Accès au document

## Distribution de produits phytopharmaceutiques à des utilisateurs professionnels : référentiel de certification

Arrêté du 16 octobre 2020 relatif au référentiel de certification prévu à l'article R. 254-3 du code rural et de la pêche maritime pour l'activité « distribution de produits phytopharmaceutiques à des utilisateurs professionnels »

Numéro officiel : AGRG2027143A

Liens juridiques : Modification le 01/01/2021
Arrêté 06/01/2016 NOR AGRG1528365A

Abrogation le 01/01/2021 Arrêté 25/11/2011 NOR AGRG1132069A

Accès au document

## Référentiel de certification pour l'activité « conseils stratégique et spécifique à l'utilisation de produits phytopharmaceutiques »

Arrêté du 16 octobre 2020 relatif au référentiel de certification pour l'activité « conseils stratégique et spécifique à l'utilisation de produits phytopharmaceutiques »

Numéro officiel : AGRG2027149A

Liens juridiques : Abrogation le 01/01/2021
Arrêté 25/11/2011 NOR AGRG1132072A
Prolongation de l'approbation des substances actives : amidosulfuron, bifénox, chlorotoluron, clofentézine, clomazone, cyperméthrine, daminozide, deltaméthrine, dicamba, difénoconazole, diflufénican, fenoxaprop-P, fenpropidine, fludioxonyl, flufénacet, fosthiazate, indoxacarbe, lénacile, MCPA, MCPB, nicosulfuron, huiles de paraffine, piclorame, prosulfocarbe, soufre, triflusulfuron et tritosulfuron

RÈGLEMENT D'EXÉCUTION (UE) 2020/1511 DE LA COMMISSION du 16 octobre 2020 modifiant le règlement d'exécution (UE) n° 540/2011 en ce qui concerne la prolongation de l'approbation des substances actives «amidosulfuron», «bifénox», «chlorotoluron», «clofentézine», «clomazone», «cyperméthrine», «daminozide», «deltaméthrine», «dicamba», «difénoconazole», «diflufénican», «fenoxaprop-P», «fenpropidine», «fludioxonyl», «flufénacet», «fosthiazate», «indoxacarbe», «lénacile», «MCPA», «MCPB», «nicosulfuron», «huiles de paraffine», «piclorame», «prosulfocarbe», «soufre», «triflusulfuron» et «tritosulfuron»

Numéro officiel : UE/2020/1511

Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

## Mise sur le marché des produits phytopharmaceutiques : approbation de la substance active thiophanate-méthyl non renouvelée

RÈGLEMENT D'EXÉCUTION (UE) 2020/1498 DE LA COMMISSION du 15 octobre 2020 relatif au non-renouvellement de l'approbation de la substance active «thiophanate-méthyl», 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/2020/1498

Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

Accès au document

## Autorisation de l'Union pour la famille de produits biocides «Iodine based products - CID LINES NV»

RÈGLEMENT D'EXÉCUTION (UE) 2020/1187 DE LA COMMISSION du 7 août 2020 accordant une autorisation de l'Union pour la famille de produits biocides «Iodine based products - CID LINES NV»

Numéro officiel : UE/2020/1187

Accès au document
## Teneurs maximales en 3-monochloropropanediol (3-MCPD), en esters d'acides gras de 3-MCPD et en esters d'acides gras de glycidol dans certaines denrées alimentaires

RÈGLEMENT (UE) 2020/1322 DE LA COMMISSION du 23 septembre 2020 modifiant le règlement (CE) n° 1881/2006 en ce qui concerne les teneurs maximales en 3-monochloropropanediol (3-MCPD), en esters d'acides gras de 3-MCPD et en esters d'acides gras de glycidol dans certaines denrées alimentaires

Numéro officiel : UE/2020/1322

Liens juridiques : Modification Règlement
CE/1881/2006 19/12/2006

Accès au document

## Avis aux opérateurs sur les décrets biocides

Avis aux opérateurs sur les décrets biocides pris en application de l'article 76 de la loi n° 2018-938 du 30 octobre 2018 pour l'équilibre des relations commerciales dans le secteur agricole et alimentaire et une alimentation saine, durable et accessible à tous (EGAlim)

Numéro officiel : TREP2024632V

Accès au document

## Teneurs maximales en 3-monochloropropanediol (3-MCPD), en esters d'acides gras de 3-MCPD et en esters d'acides gras de glycidol dans certaines denrées alimentaires

RÈGLEMENT (UE) 2020/1322 DE LA COMMISSION du 23 septembre 2020 modifiant le règlement (CE) n° 1881/2006 en ce qui concerne les teneurs maximales en 3-monochloropropanediol (3-MCPD), en esters d'acides gras de 3-MCPD et en esters d'acides gras de glycidol dans certaines denrées alimentaires

Numéro officiel : UE/2020/1322

Liens juridiques : Modification Règlement
CE/1881/2006 19/12/2006

Accès au document

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

RÈGLEMENT D'EXÉCUTION (UE) 2020/1263 DE LA COMMISSION du 10 septembre 2020 portant approbation de la substance active «hydrogénocarbonate de sodium» 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/2020/1263

Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011
## Non-renouvellement de l'approbation de la substance active fenamiphos

RÈGLEMENT D'EXÉCUTION (UE) 2020/1246 DE LA COMMISSION du 2 septembre 2020 concernant le non-renouvellement de l'approbation de la substance active «fenamiphos», 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/2020/1246

Liens juridiques : Modification Règlement d'exécution UE/540/2011 25/05/2011

## PUBLICATIONS DU RESEAU ECOTOX

### Differential side-effects of *Bacillus thuringiensis* bioinsecticide on non-target *Drosophila* flies

**Authors:** Babin A, Nawrot-Esposito MP, Gallet A, Gatti JL, Poirie M

**Source:** SCIENTIFIC REPORTS 10(1):16241, 2020, DOI: 10.1038/s41598-020-73145-6

**Abstract:** Bioinsecticides based on *Bacillus thuringiensis* (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-

target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (similar to 10(6) Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at &#62; ; = 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.

### Synergetic effect of antibiotic mixtures on soil bacterial N2O-reducing communities

**Authors:** Roosevelt-Amsaleg C, David V, Alliot F, Guigon E, Crouzet O, Laverman AM

**Source:** ENVIRONMENTAL CHEMISTRY LETTERS
Early Access: OCT 2020, DOI: 10.1007/s10311-020-01117-3

**Abstract:** Antibiotics released in agricultural soils alter soil bacterial communities, inducing antimicrobial resistance and, in turn, canceling the efficiency of antibiotic drugs used for human and animal health. In soils, antibiotic impact on
nitrogen cycling is poorly known, notably when
antibiotic mixtures are applied. We hypothesized
that the impact of antibiotic mixtures would
have higher effects on denitrification. We
exposed soil denitrifying bacteria enrichments to
tetracycline, ofloxacin, sulfamethoxazole and
tylosin, either applied single or as mixture of
three antibiotics, during 7 days under
denitrifying conditions. We measured the
minimum inhibitory concentration of the N2O-
reducing capacity of the bacterial enrichment,
we deduced the half maximal effective
concentration (EC50) from the experimental data
and from the concentration addition hypothesis,
and we quantified nosZ gene abundances. Results
show that single antibiotic exposure inhibited
N2O-reduction only for tetracycline at 64 mg/L.
Inhibition by antibiotic mixtures always exceeded
the modeled inhibition calculated by
concentration addition. At high-antibiotic
exposure, nosZ gene clade I denitrifiers remained
abundant, of 10(7)-10(8) copies/ ng DNA. NosZ gene
clade II denitrifiers increased with antibiotic
concentrations. Our findings reveal for the first
time the synergistic effects of antibiotic
mixtures on soil nitrogen cycling.

Accès au document

Transfer and Transcriptomic
Profiling in Liver and Brain of
European Eels (Anguilla
anguilla) After Diet-borne
Exposure to Gold
Nanoparticles

**Authors:** Perrier F, Bertucci A, Pierron F, Feurtet-Mazel A, Simon O, Klopp C, Candaudap F, Pokrovski O, Etcheverria B, Mornet S, Baudrimont M

**Source:** ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Early Access, 2020, DOI: 10.1002/etc.4858

**Abstract:** A nanometric revolution is underway, promising technical innovations in a wide range

of applications and leading to a potential boost
in environmental discharges. The propensity of
nanoparticles (NPs) to be transferred throughout
trophic chains and to generate toxicity was
mainly assessed in primary consumers, whereas a
lack of knowledge for higher trophic levels
persists. The present study focused on a
predatory fish, the European eel (Anguilla
anguilla) exposed to gold NPs (AuNPs; 10 nm,
polyethylene glycol-coated) for 21 d at 3
concentration levels in food: 0 (NP0), 1 (NP1),
and 10 (NP10) mg Au kg(-1). Transfer was
assessed by Au quantification in eel tissues, and
transcriptomic responses in the liver and brain
were revealed by a high-throughput RNA-
sequencing approach. Eels fed at NP10 presented
an erratic feeding behavior, whereas Au
quantification only indicated transfer to intestine
and kidney of NP1-exposed eels. Sequencing of
RNA was performed in NP0 and NP1 eels. A total
of 258 genes and 156 genes were significantly
differentially transcribed in response to AuNP
trophic exposure in the liver and brain,
respectively. Enrichment analysis highlighted
modifications in the immune system-related
processes in the liver. In addition, results
pointed out a shared response of both organs
regarding 13 genes, most of them being involved
in immune functions. This finding may shed light
on the mode of action and toxicity of AuNPs in
fish. Environ Toxicol Chem 2020;00:1-12. (c) 2020
SETAC

Accès au document

A maternal effect influences
sensitivity to chlorpyrifos
pesticide in the pest moth
*Spodoptera littoralis*

Authors: Bagni T, Siaussat D, Maria A, Couzi P, Maibeche M, Massot M

Source: ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 204:111052, 2020, DOI: 10.1016/j.ecoenv.2020.111052

Abstract: Transgenerational effects on sensitivity to pesticides are poorly studied. This study
investigated the transgenerational influences of maternal body mass in the major pest moth *Spodoptera littoralis*, with a focus on sensitivity to chlorpyrifos pesticide. In 147 clutches of a laboratory strain of *S. littoralis*, we compared larval mortality between control larvae and larvae treated with chlorpyrifos. Because of the classic positive relationships between offspring size and maternal size and between offspring size and offspring quality, sensitivity to chlorpyrifos was predicted to be lower in larvae of larger mothers. Surprisingly, we found the opposite result, with higher pesticide toxicity in larvae of larger mothers. This result is partly explained by the lack of a relationship between larval mass and larval sensitivity to chlorpyrifos. This means that another offspring characteristic linked to maternal size should have affected larval sensitivity to chlorpyrifos. More generally, knowledge of the effects of the traits and ecological environments of mothers on offspring sensitivity to pesticides remains limited. Ecotoxicologists should pay more attention to such maternal effects on sensitivity to pesticides, both in pests and non-target species.

Accès au document

## Keep and promote biodiversity at polluted sites under phytomanagement

**Authors:** Garbisu C, Alkorta I, Kidd P, Epelde L, Mench M

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH Early Access, 2020, DOI: 10.1007/s11356-020-10854-5

**Abstract:** The phytomanagement concept combines a sustainable reduction of pollutant linkages at risk-assessed contaminated sites with the generation of both valuable biomass for the (bio)economy and ecosystem services. One of the potential benefits of phytomanagement is the possibility to increase biodiversity in polluted sites. However, the unique biodiversity present in some polluted sites can be severely impacted by the implementation of phytomanagement

practices, even resulting in the local extinction of endemic ecotypes or species of great conservation value. Here, we highlight the importance of promoting measures to minimise the potential adverse impact of phytomanagement on biodiversity at polluted sites, as well as recommend practices to increase biodiversity at phytomanaged sites without compromising its effectiveness in terms of reduction of pollutant linkages and the generation of valuable biomass and ecosystem services.

Accès au document

## Behavior of metallurgical zinc contamination in coastal environments: A survey of Zn from electroplating wastes and partitioning in sediments

**Authors:** Tonha MS, Garnier J, Araujo DF, Cunha BCA, Machado W, Dantas E, Araujo R, Kutter VT, Bonnet MP, Seyler P

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 743:140610, 2020, DOI: 10.1016/j.scitotenv.2020.140610

**Abstract:** The contamination of coastal environments by metallurgical wastes involves multiple biogeochemical processes; accordingly, understanding metal behavior and risk evaluation of contaminated areas, such as Sepetiba Bay (Rio de Janeiro, Brazil), remains challenging. This study coupled Zn isotopic analyses with sequential extractions (BCR) to investigate the mechanisms of Zn transfer between legacy electroplating waste and the main environments in Sepetiba Bay. This metallurgical waste showed a light bulk isotopic signature (delta (66/64) Znbulk(JMC) = +0.30 +/- 0.01 parts per thousand 2 s, n = 3) that was not distinct from the lithogenic geochemical baseline, but was different from signature of mangrove sediment considered as anthropogenic end member (delta(66/64) Zn-JMC = +0.86 +/- 0.15 parts per thousand) in a previous isotopic study in this
area. Zn isotopic compositions of sediment samples (ranging from +0.20 to +0.98 parts per thousand) throughout the bay fit a mixing model involving multiple sources, consistent with previous studies. In the metallurgic zone, the exchangeable/carbonate fraction (ZnF1) exhibited high Zn concentrations (ZnF1 9840 mg g(-1)) and a heavy isotopic composition (delta(66/64) ZnF1(JMC) = +1.10 +/- 0.01 parts per thousand). This finding showed that, in some cases, the bulk isotopic signature of waste is not the most relevant criterion for evaluating trace metal dispersion in the environment. Indeed, based on the BCR. it was observed that part of the anthropogenic metallurgical Zn was redistributed from the exchangeable/carbonate fraction in the waste to the surrounding mangrove sediment. Then, this contaminated sediment with heavy delta(66/64) Zn values was exported to other coastal environments. In Septiba Bay, contaminated sediments revealed a large concentration of ZnF1 fraction (up to 400 mg g(-1)) with a heavy Zn isotopic signature. This signature also matched the Zn isotopic signature of oysters in Septiba Bay reported by other studies; hence, measurement of the isotopic exchangeable/carbonate fraction has important implications for tracing the transfer of anthropogenic Zn to biota. (C) 2020 Elsevier B.V. All rights reserved.

Accès au document

## Reprint of: The effect of the Music Day event on community drug use

**Authors:** Devault DA, Peyre A, Jaupitre O, Daveluy A, Karolak S

**Source:** FORENSIC SCIENCE INTERNATIONAL 314:110355, 2020, DOI: 10.1016/j.forsciint.2020.110355

**Abstract:** Illicit drugs consumption can be back-calculated based on the analysis of drug residues in wastewater using the wastewater-based epidemiology method. The Music Day, held on June 21 in France since 1982, has grown to global

proportions and is now celebrated as World Music Day. This large outdoor event takes place in many cities with people allowed to play music in the streets. As psychotropic drugs are often associated with music events, the goal of this study is to investigate the use of illicit drugs on this day in Bordeaux, the fifth largest urban area in France. Daily sampling campaigns of composite wastewater were carried out for seven days in two wastewater treatment plants in Bordeaux in 2017 (Music Day) and 2018.

World Music Day in Bordeaux has no observable effect on illicit drug consumption even if this event has massive public participation: this is the first report of the absence of an illicit drug consumption increase in a festival of such magnitude, corroborating the effect of others' views and opinions, because this event takes place publicly in the street and not among peers. Different hypothesizes are put forward to explain this fact: inappropriate type of event for drug consumption, effect of other festivals, and influence of the event's timing on a weekday. (C) 2020 Elsevier B.V. All rights reserved.

Accès au document

## Multi-scale impact of chronic exposure to environmental concentrations of chlordecone in freshwater cnidarian, *Hydra circumcincta*

**Authors:** Colpaert R, Villard PH, de Jong L, Mambert M, Benbrahim K, Abraldes J, Cerini C, Pique V, Robin M, Moreau X

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH Early Access, 2020, DOI: 10.1007/s11356-019-06859-4

**Abstract:** Chlordecone (CLD) is an organochlorine pesticide widely used in the past to control pest insects in banana plantations in the French West Indies. Due to its persistence in the environment, CLD has contaminated the soils where it has
been spread, as well as the waters, and is still present in them. The objective of our study was to evaluate the effects of chronic exposure to environmentally relevant CLD concentrations in an animal model, the freshwater hydra (Hydra circumcincta). In a multi-marker approach, we have studied the expression of some target stress genes, the morphology, and the asexual reproduction rates. Our data showed that exposure to low concentrations of chlordecone leads to (i) a modulation of the expression of target genes involved in oxidative stress, detoxification, and neurobiological processes, and (ii) morphological damages and asexual reproduction impairment. We have observed non-monotonic dose-response curves, which agree with endocrine-disrupting chemical effects. Thus, "U-shaped" dose-response curves were observed for SOD, GRed, Hym355, and potentially GST gene expressions ; inverted "U-shaped" curves for GPx and CYP1A gene expressions and reproductive rates; and a biphasic dose-response curve for morphological damages. Therefore, in the range of environmental concentrations tested, very low concentrations of CLD can produce equally or more important deleterious effects than higher ones. Finally, to our knowledge, this study is the first one to fill the lack of knowledge concerning the effects of CLD inHydra circumcincta and confirms that this diploblastic organism is a pertinent freshwater model in the risk assessment.

Accès au document

Phytol, (E)-nerolidol and
spathulenol from Stevia
rebaudiana leaf essential oil
as effective and eco-friendly
botanical insecticides against
*Metopolophium dirhodum*

Authors: Benelli G, Pavela R, Drenaggi E, Desneux N, Maggi F

**Source:** INDUSTRIAL CROPS AND PRODUCTS 155:112844, 2020, DOI: 10.1016/j.indcrop.2020.112844

**Abstract:** Stevia rebaudiana (Asteraceae) is a medicinal plant of economic importance in the food market for the manufacture of natural sweeteners, namely steviol glycosides. The plant biomass used on an industrial level may also be the source of an essential oil (EO) of potential interest for developing novel insecticides. Here, the leaf EO chemical composition of S. rebaudiana growing in central Italy was analysed by gas chromatography-mass spectrometry (GC-MS). The EO insecticidal efficacy was evaluated against the aphid *Metopolophium dirhodum* (Hemiptera: Aphididae), a major pest of cereals. The EO composition was dominated by sesquiterpenes, i.e. caryophyllene oxide (20.7 %), spathulenol (14.9 %) and (E)-nerolidol (8.0 %), and diterpenes, i.e. phytol (9.2 %). The EO was effective against M. dirhodum aphids, showing an LC 50(90) of 5.1 and 10.8 mL L-1, respectively. The efficacy of the EO major constituents, namely caryophyllene oxide, spathulenol, (E)-nerolidol and phytol was also tested against M. dirhodum. Phytol was the most effective aphicide (LC50(90) = 1.4(4.2) mL L-1), followed by (E)-nerolidol (LC50(90) = 3.5(9.3) mL L-1) and spathulenol (LC50(90) = 4.3(7.5) mL L-1). The EO was minimally toxic towards non-target Eisenia fetida adults and Harmonia axyridis larvae and adults. Overall, phytol, (E)-nerolidol and spathulenol can be considered further for developing effective and eco-friendly green insecticides against aphids.

Accès au document

Contribution of chemical
inputs on the trace elements
concentrations of surface
soils in urban allotment
gardens

Authors: Joimel S, Cortet J, Consales JN, Branchu P, Haudin CS, Morel JL, Schwartz C
**Source:** JOURNAL OF SOILS AND SEDIMENTS Early Access sept, 2020, DOI: 10.1007/s11368-020-02784-z

**Abstract:** Purpose Urban soil contamination by heavy metals is one of the foremost challenges for urban soil quality, especially in the urban agriculture context. Urban gardening is a common practice in many industrialized and developing countries. How sources of soil contamination relate to inputs and influence the heavy metal content in soils, however, is not established yet. Materials and methods This study aims to assess the potential of pesticide applications (such as Bordeaux mixture) on soil quality. A set of 104 allotment gardens was selected in three cities in France, and topsoil was sampled and analyzed. Results and discussion The four most abundant metals in urban vegetable garden topsoils were Zn, Pb, Cu, and Cr. The past and/or present industrial and urban activities are not the only cause of the metal contamination in urban vegetable garden soils. Gardens, where pesticides such as the Bordeaux mixture are being used showed significantly higher total Cu values in soils (78 mg kg(-1)) compared with 49 mg kg(-1) for untreated gardens). Conclusions Even though the risk of metal contamination through vegetable consumption is usually considered low, we clearly identified indicators of anthropogenic Cd, Cu, Pb, and Zn pollution due to pesticides inputs. This link was particularly strong between the use of Bordeaux mixture and increases Cu levels.

Accès au document

Emerging polar pollutants in
groundwater: Potential
impact of urban stormwater
infiltration practices

**Authors:** Pinasseau L, Wiest L, Volatier L, Mermillod-Blondin F, Vulliet E

**Source:** ENVIRONMENTAL POLLUTION
266(2):115387, 2020, DOI: 10.1016/j.envpol.2020.115387

**Abstract:** The quality of groundwater (GW) resources is decreasing partly due to chemical contaminations from a wide range of activities, such as industrial and agricultural enterprises and changes in land-use. In urban areas, one potential major pathway of GW contamination is associated with urban water management practices based on stormwater runoff infiltration systems (SIS). Data on the performance of the upper layer of soil and the unsaturated zone of infiltration basins to limit the contamination of GW by hydrophilic compounds are lacking. With this aim, the impact of infiltration practices on GW contamination was assessed for 12 pesticides and 4 pharmaceuticals selected according to their ecotoxicological relevance and their likelihood of being present in urban stormwater and GW. For this purpose, 3 campaigns were conducted at 4 SIS during storm events. For each campaign, passive samplers based on the use of EmporeTM disk were deployed in GW wells upstream and downstream of SIS, as well as in the stormwater runoff entering the infiltration basins. Upstream and downstream GW contaminations were compared to evaluate the potential effect of SIS on GW contamination and possible relationships with stormwater runoff composition were examined. Our results showed two interesting opposite trends: (i) carbendazim, diuron, fluopyram, imidacloprid and lamotrigine had concentrations significantly increasing in GW impacted by infiltration, indicating a contribution of SIS to GW contamination, (ii) atrazine, simazine and 2,4,6-triisopropylbenzenesulfonate exhibited concentrations significantly decreasing with infiltration due to a probable dilution of historic GW contaminants with infiltrated stormwater runoff. The other 7 contaminants showed no general trend. This study demonstrates that passive samplers deployed in GW wells enabled the capture of emerging polar pollutants present at very low concentrations and allowed the assessment of infiltration practices on GW quality. New data on GW and urban stormwater are provided for poorly studied hazardous compounds. (C) 2020 Elsevier Ltd. All rights reserved.

Accès au document
Analysis of surface water
reveals land pesticide
contamination: an
application for the
determination of
chlordecone-polluted areas
in Guadeloupe, French West
Indies

Authors: Rochette R, Bonnal V, Andrieux P, Cattan P

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH Early Access Sept, 2020, DOI: 10.1007/s11356-020-10718-y

**Abstract:** In Guadeloupe, the use between 1972 and 1993 of chlordecone, an organochlorine insecticide, has permanently contaminated the island's soil, thus contaminating the food chain at its very beginning. There is today a strong societal requirement for an improved mapping of the contaminated zones. Given the extent of the areas to be covered, carrying out soil tests on each plot of the territory would be a long and expensive process. In this article, we explore a method of demarcating polluted areas. The approach adopted consists in carrying out, using surface water analyses, a hydrological delimitation that makes it possible to distinguish contaminated watersheds from uncontaminated ones. The selection of sampling points was based on the spatial analysis of the actual and potential contamination data existing at the beginning of the study. The approach was validated by soil analyses, after having compared the contamination data of the watersheds with the soil contamination data of the plots within them. The study thus made it possible to highlight new contaminated areas and also those at risk of contamination and to identify the plots to be targeted as a priority during future analysis campaigns by State services.

Accès au document

Impact of a synthetic
fungicide (fosetyl-Al and
propamocarb-hydrochloride)
and a biopesticide
(Clonostachys rosea) on soil
bacterial, fungal, and protist
communities

Authors: Fournier B, Dos Santos SP, Gustavsen JA, Imfeld G, Lamy F, Mitchell EAD, Mota M, Noll D, Planchamp C, Heger TJ

Source: SCIENCE OF THE TOTAL ENVIRONMENT
738:139635, 2020, DOI: 10.1016/j.scitotenv.2020.139635

**Abstract:** The use of synthetic pesticides in agriculture is increasingly debated. However, few studies have compared the impact of synthetic pesticides and alternative biopesticides on non-target soil microorganisms playing a central role in soil functioning.

We conducted a mesocosm experiment and used
high-throughput amplicon sequencing to test the
impact of a fungal biopesticide and a synthetic
fungicide on the diversity, the taxonomic and
functional compositions, and co-occurrence
patterns of soil bacterial, fungal and protist
communities.

Neither the synthetic pesticide nor the
biopesticide had a significant effect on microbial
a-diversity. However, both types of pesticides
decreased the complexity of the soil microbial
network. The two pesticides had contrasting
impacts on the composition of microbial
communities and the identity of key taxa as
revealed by microbial network analyses. The
biopesticide impacted keystone taxa that
structured the soil microbial network. The
synthetic pesticide modified biotic interactions
favouring taxa that are less efficient at
degrading organic compounds. This suggests that
the biopesticides and the synthetic pesticide
have different impact on soil functioning.
Altogether, our study shows that pest
management products may have functionally
significant impacts on the soil microbiome even if microbial alpha-diversity is unaffected. It also illustrates the potential of high-throughput sequencing analyses to improve the ecotoxicological risk assessment of pesticides on non-target soil microorganisms.

## Do rainfall characteristics affect the export of copper, zinc and synthetic pesticides in surface runoff from headwater catchments?

**Authors:** Imfeld G, Meite F, Wiegert C, Guyot B, Masbou J, Payraudeau S

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT
741:140437, 2020, DOI: 10.1016/j.scitotenv.2020.140437

**Abstract:** Rainfall and runoff characteristics may influence off-site export of pesticides into downstream aquatic ecosystems. However, the relationship between rainfall characteristics and pesticide export from small headwater catchments remains elusive due to confounding factors including the application dose and timing and the variation of pesticide stocks in soil. Here we examined the impact of rainfall characteristics on the export of copper (Cu), zinc (Zn) and 12 legacy and currently used synthetic pesticides in surface runoff from a headwater vineyard catchment. Cluster analysis of rainfall intensity, depth and duration of 78 events revealed four distinct rainfall categories, i.e., Small, Long, Moderate and Intense (p < 0.001). Event mean concentrations of pesticides did not differ among rainfall categories (p > 0.05). In contrast, event loads of both dissolved and solid-bound Cu and Zn significantly differed among rainfall categories (p < 0.001). Rainfall depth and intensity significantly correlated with both Cu and Zn loads in runoff (rho(s) = 0.33 to 0.92, p < 0.002), and might be the main drivers of Cu and Zn export at the catchment scale. In contrast, rainfall depth, intensity or duration did not influence the loads of synthetic pesticides in runoff, even when weekly variations of pesticide stocks in the soil were accounted for.

However, intense rainfall-runoff events, that can fragment soil, may control the export of persistent and hydrophobic legacy pesticides stocks in the soil, such as simazine and tetraclozole. Our results show that rainfall characteristics controlled the off-site export of Cu, Zn and legacy synthetic pesticides in a small headwater catchment, whereas the application timing drove the export of currently used synthetic pesticides in runoff. We anticipate our results to be a preliminary step to forecast the influence of regional rainfall patterns on the export of both metallic and synthetic pesticides by surface runoff from small agricultural headwater catchments.

## Direct and indirect effects of multiple environmental stressors on fish health in human-altered rivers

**Authors:** Petitjean Q, Jean S, Cote J, Larcher T, Angelier F, Ribout C, Perrault A, Laffaille P, Jacquin L

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT
742:140657, 2020, DOI: 10.1016/j.scitotenv.2020.140657

**Abstract:** Freshwater fish face multiple challenges in human-altered rivers such as trace metal contamination, temperature increase and parasitism. These multiple stressors could have unexpected interactive effects on fish health due to shared physiological pathways, but few studies investigated this question in wild fish populations. In this study, we compared 16 populations of gudgeon (Gobio occitaniae) distributed along perturbation gradients in human-altered rivers in the South of France. We tested the effects of single and combined stressors (i.e., metal contamination, temperature, parasitism) on key traits linked to fish health across different biological levels using a Structural Equation Modelling approach. Parasitism and temperature alone had limited deleterious effects on fish health. In contrast, fish living in metal-contaminated sites had higher stocks in the soil were accounted for.
metal bioaccumulation and higher levels of cellular damage in the liver through the induction of an inflammatory response. In addition, temperature and contamination had interactive negative effects on growth. These results suggest that trace metal contamination has deleterious effects on fish health at environmentally realistic concentrations and that temperature can modulate the effects of trace metals on fish growth. With this study, we hope to encourage integrative approaches in realistic field conditions to better predict the effects of natural and anthropogenic stressors on aquatic organisms.

## Screening of potential uranium protein targets in fish ovaries after chronic waterborne exposure: Differences and similarities between roach and zebrafish

**Authors:** Frelon S, Simon O, Eb-Levadoux Y, Mounicou S

**Source:** JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 222:106365, 2020, DOI: 10.1016/j.jenvrad.2020.106365

**Abstract:** Concentration of uranium (U), a naturally encountered radioactive element in earth's crust, can be enhanced in freshwater ecosystems (µg.L-1 - mg.L-1) due to various anthropogenic activities. The consequent aquatic organism exposure to U leads to its accumulation in all organs, particularly in the gonad, and in subcellular fractions (mainly the cytosol); then it is known to affect fish at several biological levels, and more particularly, at a reproduction endpoint, with a decrease in the total number of eggs, spawn events and larvae survival. The understanding of U reprotoxicity requires the fine knowledge of its speciation at molecular level, i.e., its interaction with cytosolic biomolecules. In this study, we focus on the U-protein interactions in gonads. A non-denaturating extraction protocol combined with

size exclusion chromatography (SEC) allowed the separation of metal-protein complexes in ovaries of U-contaminated wild roaches before their elemental detection (ICP MS). This enables unprecedented information to be obtained about U distribution in ovaries of autochthonous fish, *Rutilus rutilus*, which is different in some points from that obtained in the model species, Danio rerio under controlled laboratory conditions at a similar concentration level. Finally, the ability to transpose results from model to autochthonous fish was briefly discussed.

## Microbiome-Aware Ecotoxicology of Organisms: Relevance, Pitfalls, and Challenges

**Authors:** Duperron S, Halary S, Gallet A, Marie B

**Source:** FRONTIERS IN PUBLIC HEALTH 8:407 2020, DOI: 10.3389/fpubh.2020.00407

**Abstract:** Over the last 15 years, the advent of high-throughput "omics" techniques has revealed the multiple roles and interactions occurring among hosts, their microbial partners and their environment. This microbiome revolution has radically changed our views of biology, evolution, and individuality. Sitting at the interface between a host and its environment, the microbiome is a relevant yet understudied compartment for ecotoxicology research. Various recent works confirm that the microbiome reacts to and interacts with contaminants, with consequences for hosts and ecosystems. In this paper, we thus advocate for the development of a "microbiome-aware ecotoxicology" of organisms. We emphasize its relevance and discuss important conceptual and technical pitfalls associated with study design and interpretation. We identify topics such as functionality, quantification, temporality, resilience, interactions, and prediction as major challenges and promising venues for microbiome research applied to ecotoxicology.
# Dose reconstruction supports the interpretation of decreased abundance of mammals in the Chernobyl Exclusion Zone

**Authors:** Beaugelin-Seiller K, Garnier-Laplace J, Della-Vedova C, Metivier JM, Lepage H, Mousseau TA, Moller AP

**Source:** SCIENTIFIC REPORTS 10(1):14083, 2020, DOI: 10.1038/s41598-020-70699-3

**Abstract:** We re-analyzed field data concerning potential effects of ionizing radiation on the abundance of mammals collected in the Chernobyl Exclusion Zone (CEZ) to interpret these findings from current knowledge of radiological dose-response relationships, here mammal response in terms of abundance. In line with recent work at Fukushima, and exploiting a census conducted in February 2009 in the CEZ, we reconstructed the radiological dose for 12 species of mammals observed at 161 sites. We used this new information rather than the measured ambient dose rate (from 0.0146 to 225 mu Gy h(-1)) to statistically analyze the variation in abundance for all observed species as established from tracks in the snow in previous field studies. All available knowledge related to relevant confounding factors was considered in this re-analysis. This more realistic approach led us to establish a correlation between changes in mammal abundance with both the time elapsed since the last snowfall and the dose rate to which they were exposed. This relationship was also observed when distinguishing prey from predators. The dose rates resulting from our re-analysis are in agreement with exposure levels reported in the literature as likely to induce physiological disorders in mammals that could explain the decrease in their abundance in the CEZ. Our results contribute to informing the Weight of Evidence approach to demonstrate effects on wildlife resulting from its field exposure to ionizing radiation.

# High-multiplexed monitoring of protein biomarkers in the sentinel *Gammarus fossarum* by targeted scout-MRM assay, a new vision for ecotoxicoproteomics

**Authors:** Faugere J, Gouveia D, Ayciriex S, Chaumot A, Almunia C, Francois A, Armengaud J, Lemoine, JM, Geffard O, Degli-Esposti D, Salvador A

**Source:** JOURNAL OF PROTEOMICS 226:103901, 2020, DOI: 10.1016/j.jprot.2020.103901

**Abstract:** Ecotoxicoproteomics employs mass spectrometry-based approaches centered on proteins of sentinel organisms to assess for instance, chemical toxicity in fresh water. In this study, we combined proteogenomics experiments and a novel targeted proteomics approach free from retention time scheduling called Scout-MRM. This methodology will enable the measurement of simultaneously changes in the relative abundance of multiple proteins involved in key physiological processes and potentially impacted by contaminants in the freshwater sentinel Gammarus fossarum. The development and validation of the assay were performed to target 157 protein biomarkers of this non-model organism. We carefully chose and validated the transitions to monitor using conventional parameters (linearity, repeatability, LOD, LOQ). Finally, the potential of the methodology is illustrated by measuring 277 peptide-plex assay (831 transitions) in sentinel animals exposed in natura to different agricultural sites potentially exposed to pesticide contamination. Multivariate data analyses highlighted the modulation of several key proteins involved in feeding and molting. This multiplex-targeted proteomics assay paves the way for the discovery and the use of a large panel of novel protein biomarkers in emergent ecotoxicological models for environmental monitoring in the future.

**Biological significance:** The study contributed to the development of Scout-MRM for the high-
throughput quantitation of a large panel of proteins in the Gammarus fossarum freshwater sentinel. Increasing the number of markers in ecotoxicoproteomics is of most interest to assess the impact of pollutants in freshwater organisms. The development and validation of the assay enabled the monitoring of a large panel of reporter peptides of exposed gammarids. To illustrate the applicability of the methodology, animals from different agricultural sites were analysed. The application of the assay highlighted the modulation of some biomarker proteins involved in key physiological pathways, such as molting, feeding and general stress response. Increasing multiplexing capabilities and field test will provide the development of diagnostic protein biomarkers for emergent ecotoxicological models in future environmental biomonitoring programs.

## Sublethal exposure to deltamethrin impairs maternal egg care in the European earwig *Forficula auricularia*

**Authors:** Meunier J, Dufour J, Van Meyel S, Rault M, Lecureuil C

**Source:** CHEMOSPHERE 258:127383, 2020, DOI: 10.1016/j.chemosphere.2020.127383

**Abstract:** The application of pesticides typically leads to lethal and sublethal exposure of non-target insects. Whereas our current understanding of these sublethal effects typically focuses on reproductive and physiological parameters, recent works emphasize that sublethal effects on behaviors such as maternal care could be of major importance in non-target species. However, it remained unknown whether these sublethal effects occur in insects. Here, we tested if exposure to sublethal doses of deltamethrin - a pyrethroid insecticide commonly used in crops - alters the expression of maternal egg care in females of the European earwig *Forficula auricularia*, a predator insect and pest control. Our results first reveal that

deltamethrin exposure impaired the expression of three forms of maternal egg care : It decreased the likelihood of mothers to gather their otherwise scattered clutch of eggs, increased the time during which the female abandoned the clutch after a predator attack and reduced egg grooming duration. These sublethal effects did not reflect a lower activity of deltamethrin-exposed females, as these females increased their expression of self-grooming, and deltamethrin exposure did not affect females' exploration and mobility. Finally, we found that the negative effects of deltamethrin on egg care did not modify egg development, hatching rate and juvenile weight, possibly due to the transient effects of deltamethrin on maternal behaviors. Overall, our results reveal that sublethal exposure to a pesticide may diminish maternal egg care in a natural pest control and call for the integration of this measurement in assays on pesticides application. (C) 2020 Elsevier Ltd. All rights reserved.

## A two years field experiment to assess the impact of two fungicides on earthworm communities and their recovery

**Authors:** Amosse J, Bart S, Brulle F, Tebby C, Beaudouin R, Nelieu S, Lamy I, Pery ARR, Pelosi C

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 203:110979, 2020, DOI: 10.1016/j.ecoenv.2020.110979

**Abstract:** Recent EFSA (European Food Safety Authority) reports highlighted that the ecological risk assessment of pesticides needed to go further by taking more into account the impacts of chemicals on biodiversity under field conditions. We assessed the effects of two commercial formulations of fungicides separately and in mixture, i.e., Cuprafor Micro (R) (containing 500 g kg(-1) copper oxychloride) at 4 (C1, corresponding to 3.1 mg kg(-1) dry soil of