samples obtained from four sites at Seybouse River in Algeria were carried out. The minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were determined in culture media with 12.5-3600 µg/mL of cadmium and copper salts. Metallothionein (MT) production was evaluated by spectrophotometry methodology. Trace metal element concentrations determined in the water samples revealed spatial variations for Cu and Cd. A total of 12 copper- and cadmium-resistant bacteria (KZ1-KZ12) were isolated from surface water in Seybouse River. Five isolates KZ2, KZ5, KZ8, KZ10 and KZ11 showed high values of minimum inhibitory concentration (MIC = 3600 µg/mL) for each heavy metal. High MBC of the strain toward Cu and Cd was found to be 3600 µg/mL. The MT concentration in five best isolates which showed high resistances increased with increasing metal concentration (r = 0.936, p = 0.006). High levels of MT are detected in bacterial strains exposed to Cd (51.66-90.53 nmol MT/g bacterial biomass). These indicated that the isolates can be used efficiently in removal of heavy metals in contaminated sites.

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## A novel Cyphos IL 104-based polymer inclusion membrane (PIM) probe to mimic biofilm zinc accumulation

**Authors:** Antico E, Fontas C, Vera R, Mostazo G, Salvado V, Guasch H

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 715:136938, 2020, DOI: 10.1016/j.scitotenv.2020.136938

**Abstract:** The presence of Zn in surface waters from abandoned mining zones is a critical issue since excess Zn concentrations may affect aquatic life and whole ecosystems. We present, for the first time, a simple tool based on a polymer inclusion membrane (PIM) intended to monitor Zn in river water by mimicking metal accumulation in the biofilm. The PIM-based probe contains a polymeric membrane prepared using cellulose triacetate (CFA, 50% w/ w) as the base polymer, nitrophenyloctyl ether (NPOE) as the plasticizer (20% w/w), and the ionic liquid (IL) Cyphos 104 as the extractant (30% w/w). The accumulation of Zn

in the acceptor phase (0.01 M HNO3) was evaluated for different free metal concentrations at 4 h accumulation time resulting in a good correlation between the free metal concentration and the accumulated one. We also found that the metal accumulated agrees with the free metal fraction upon addition of EDTA in the donor solution. The results for Zn accumulation with the PIM-based probe were found to be comparable to those obtained for a biofilm that was grown in a stream from an abandoned mine area and subsequently translocated to the laboratory and put in contact with Zn polluted stream water, so confirming the effectiveness of this new probe in mimicking Zn accumulation in the biofilm.

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## Amoxicillin removal by pre-denitrification membrane bioreactor (A/O-MBR): Performance evaluation, degradation by-products, and antibiotic resistant bacteria

**Authors:** Matsubara ME, Helwig K, Hunter C, Roberts J, Subtil EL, Coelho LHG

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 192:110258, 2020, DOI: 10.1016/j.ecoenv.2020.110258

**Abstract:** Membrane bioreactors (MBRs) are one of the treatment technologies with the potential to remove emerging compounds from wastewater. The present work evaluated the efficiency of an MBR pilot system in removing amoxicillin from synthetic wastewater using a continuous flow pre-denitrification MBR (A/O-MBR) pilot unit. The system operated in three phases: (1) synthetic wastewater and hydraulic retention time (HRT) of 40 h; (2) adding amoxicillin 100 µg L-1 to the influent, and (3) varying flowrate to HRT of 20 h.
Liquid chromatography coupled to high resolution mass spectrometry analysis confirmed the presence of five amoxicillin degradation by-products in the effluent. The addition of amoxicillin did not affect chemical oxygen demand (COD) or dissolved organic carbon (DOC) removal efficiencies. Respirometry showed that amoxicillin level did not inhibit heterotrophic bacteria metabolism. The change in HRT reduced the DOC removal (from 84% to 66%) but did not influence COD (94%) or total nitrogen (72%). The amoxicillin and by-products removal decreased from 80% to 54% with HRT change. Adsorption and biodegradation represented the largest removed fraction of the antibiotic in the A/O-MBR system (68%). Ecotoxicity assays showed P. fluorescens was more resistant and E. coli less resistant to amoxicillin residues at effluent sample matrix.

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## Effects of soil chemical properties and fractions of Pb, Cd, and Zn on bacterial and fungal communities

**Authors:** Pan XM, Zhang SR, Zhong QM, Gong GS, Wang GY, Guo X, Xu XX

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 715:136904, 2020, DOI: 10.1016/j.scitotenv.2020.136904

**Abstract:** Heavy metal contamination in soils poses a serious threat to microorganisms, which play important roles in soil biogeochemical process. However, the key fractions of heavy metals affecting soil microorganisms are still unclear. In this study, DNA sequencing, redundancy and variance partition analysis were performed to investigate the combined effects of heavy metal fractions and soil chemical properties on microbial communities in Pb, Cd, and Zn co-contaminated soils. The results showed that long-term exposure of microorganisms to these metals changed the richness, diversity, and structure of their communities. The bacterial and fungal Chao richness indexes decreased, but only the bacterial Shannon index improved with increasing metal concentrations. Moreover, soil available potassium and add-extractable Pb made the greatest contributions to variations in the bacterial community structure, while soil pH, water-extractable Pb and Zn were the dominant factors influencing the fungal community

structure. In addition, Marmoricola, Nocardioides, and Gibberella were sensitive to these metals. Overall, the effects of different heavy metal fractions on microorganisms varied significantly, and these metal fractions together with soil chemical properties determined the soil microbial communities.

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## Microbial degradation and other environmental aspects of microplastics/plastics

**Authors:** Yuan JH, Ma J, Sun YR, Zhou T, Zhao YC, Yu F

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 715:136968, 2020, DOI: 10.1016/j.scitotenv.2020.136968

**Abstract:** Microplastic (MP) pollution is a significant environmental concern due to the persistence of MPs and their potential adverse effects on biota. Most scientific studies have examined the distribution, ingestion, fate, behavior, amount, and effect of MPs. However, few studies have described the development of methods for the removal and remediation of MPs. Therefore, in this review, we summarize the recent literature regarding the microbial-mediated degradation of MPs and discuss the associated degradation characteristics and mechanisms. Different types and combinations of microorganisms, such as bacteria, fungi, bacterial consortia, and biofilms, that can degrade different MN are categorized. This article summarizes approximately 50 recent papers. Twelve and 6 papers reported that bacteria and fungi, respectively, can degrade MN. Nine articles indicated that bacterial consortia have the ability to degrade MN, and 6 articles found that biofilms can also utilize MN. Furthermore, to evaluate their associated degradation effects, the corresponding structural changes (i.e., macro size, surface morphology, and functional groups) in MPs after microbial degradation are examined. In addition, MP biodegradation is affected by microbial characteristics and environmental factors; therefore, the environmental factors (i.e., temperature, pH and strain activity) influencing MP degradation and the associated degradation effects (i.e., weight loss, degradation rate, and molecular weight change) are generalized. Furthermore, the mechanisms
associated with the microbial-mediated degradation of MPs are briefly discussed. Finally, prospects for the degradation of MPs using microbes and future research directions are envisioned. This review provides the first systematic summary of the microbial-mediated degradation of MN and provides a reference for future studies investigating effective means of MP pollution control.

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ERA / PUBLICATIONS
SCIENTIFIQUES / MICROBIOLOGIE ET PESTICIDES

Long-term application of Swedish sewage sludge on farmland does not cause clear changes in the soil bacterial resistome

Authors: Rutgersson et al.

Source: Environment International, 137, 2020, doi: 10.1016/j.envint.2019.105339.

**Abstract:** The widespread practice of applying sewage sludge (...) provides a potential route for human exposure to chemical contaminants (...) and dissemination of antibiotic resistant bacteria or resistance genes. To assess such risks, (...) an agricultural field trial (...) amended with semi-digested and digested sludge every four years since 1981 (...).

Antimicrobials or bioavailable metals (Cu and Zn) did not accumulate to levels of concern for environmental selection of antibiotic resistance, and no coherent signs, neither on short or long time scales, of enrichment of antibiotic-resistant bacteria or resistance genes were found (...). Only very few and slight differences in microbial community composition were observed after sludge amendment. (...)

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Fifteen-Year Application of Manure and Chemical Fertilizers Differently Impacts Soil ARGs and Microbial Community Structure

Authors: Wang F, Han W, Chen S, Dong W, Qiao M, Hu C and Liu B

Source: Front. Microbiol. 11:62, 2020, doi: 10.3389/fmicb.2020.00062

**Abstract:** (...) High-throughput quantitative PCR and sequencing technologies were employed to assess the effects of long-term manure or chemical fertilizer application on the distribution of ARGs and microbial communities. A total of 114 unique ARGs were successfully amplified from all soil samples. Manure application markedly increased the relative abundance and detectable numbers of ARGs, with up to 0.23 copies/16S rRNA gene and 81 unique ARGs. (...) In contrast, chemical fertilizers only moderately affected the diversity of ARGs and had no significant effect on the relative abundance of the total ARGs. (...) Furthermore, the application of manure and chemical fertilizers significantly affected microbial community structure, and variation partitioning analysis showed that microbial community shifts represented the major driver shaping the antibiotic resistome. (...)

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Do combined nanoscale polystyrene and tetracycline impact on the incidence of resistance genes and microbial community disturbance in *Enchytraeus crypticus*?

Authors: Ma et al.

Source: Journal of Hazardous Materials, 387, 2020, doi: 10.1016/j.jhazmat.2019.122012

**Abstract:** (...) The combined toxic effects of nanoplastic and its adsorbed pollutant on the soil fauna are still not well known. We used high-
throughput quantitative PCR to explore the effects of oral nanoscale polystyrene and tetracycline exposure on antibiotic resistance genes in the soil invertebrate *Enchytraeus crypticus*, and used bacterial 16S rRNA gene amplification sequencing to examine the response of the microbiome of *E. crypticus*. (...) Results showed that the number of ARGs, especially macrolide-lincosamide-streptogramin B (MLSB), tetracycline ARGs, as well as multidrug ARGs, increased with exposure to nanoscale polystyrene and tetracycline. (...). The exposure significantly perturbed the microbial community of *E. crypticus*. (...) After terminating exposure for 14 days, the diversity and abundance of ARGs were not completely restored, while the microbiome was not permanently changed but reversibly impacted.

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## Trophic transfer of pesticides: The fine line between predator-prey regulation and pesticide-pest regulation

**Authors:** Baudrot, V, Fernandez-de-Simon, J, Coeurdassier, M, Couval, G, Giraudoux, P, Lambin, X.

**Source:** J Appl Ecol. (57)4:806-818, 2020, doi: 10.1111/1365-2664.13578

**Abstract:** Understanding pesticide impacts on populations of target/non-target species and communities is a challenge to applied ecology. When predators that otherwise regulate pest densities ingest prey contaminated with pesticides, this can suppress predator populations by secondary poisoning. It is, however, unknown how species relationships and protocols of treatments (e.g. anticoagulant rodenticide [AR]) interact to affect pest regulation. To tackle this issue, we modelled a heuristic non-spatialized system including montane water voles, specialist vole predators (stoats, weasels) and a generalist predator (red fox) (...) we explored the impact of five farmer functional responses (defined by both

AR quantity and threshold vole density above which AR spreading is prohibited) (...).

(...) Keeping vole density below acceptable bounds by spreading AR while maintaining sufficient voles as prey resources led to less AR being applied and extended periods without AR in the environment, benefiting predators while avoiding episodes with high vole density. (...)

(...) Our model reveals the need to maintain refuges with sufficient non-poisoned voles for sustaining specialist mustelids, (...). We suggest that long periods without pesticide treatment are essential to maintain predator populations, and that practices of pesticides use that attempt to permanently suppress a pest over a large scale are counterproductive.

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## Azoxystrobin dissipation and its effect on soil microbial community structure and function in the presence of chlorothalonil, chlortetracycline and ciprofloxacin

**Authors:** Han et al.

**Source:** Env. Poll. 257:113578, 2020, doi: 10.1016/j.envpol.2019.113578

**Abstract:** The residual characteristics and the adsorption-desorption behaviors of azoxystrobin (AZO) as well as the soil ecological effects in the individual repeated treatments of AZO and its combination with chlorothalonil (CTL), chlortetracycline (CTC) and ciprofloxacin (CIP) were systematically studied in organic manure (OM)-amended soil under laboratory conditions.

CTL, CTC and CIP decreased the adsorption affinity of AZO in soil. The dissipation of AZO was inhibited to different degrees in the combined and repeated treatments with other compounds. Repeated treatments altered soil microbial functional diversity.
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Short-term application of mulch, roundup and organic herbicides did not affect soil microbial biomass or bacterial and fungal diversity

Authors: Bottrill et al

Source: Chemosphere 244:125436, 2020, doi: 10.1016/j.chemosphere.2019.125436

**Abstract:** Application of synthetic herbicides is currently the most widely used and cost-effective methods to assist with revegetation programs. However, the effects of short-term application of various conventional or biological herbicides or alternative strategies on soil microbiological diversity and functions need to be better characterized (...).

Soil microbial biomass was not affected by short-term herbicide application. Bacterial and fungal diversity (illumina sequencing) was not affected by short-term herbicide application. Basiodiomycota had one unidentified class found only in the mulch treatment.

Herbicides may have greater impact with long-term use. (...) We hypothesise that mulching may be a preferred treatment to facilitate weed control in riparian zone revegetation.

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A safety type of genetically engineered bacterium that degrades chemical pesticides

Authors: Li Q, Li J, Kang KL, Wu YJ

Source: AMB EXPRESS 10(1), 2020, DOI: 10.1186/s13568-020-00967-y

**Abstract:** Chemical pesticides are used widely and their residues are found in the environment. Pesticide pollution has become a global problem. To find an economical, effective and safety way to degrade residues of pesticides in environment, we constructed a genetically engineered bacterium (GEB) having the ability to degrade pesticides, emit green fluorescence and has a containment system by using a dual plasmid

expression system. One plasmid contains the genes of enhanced green fluorescent protein (EGFP) and carboxylesterase B1 (CarE B1), which were cloned downstream of lambda P-L promoter and expressed constitutively. The gene of CarE B1 encodes an insect-detoxifying enzyme possessing the degradability to organochloride pesticides, organophosphorus pesticides, carbamates, and pyrethoid insecticides. The other is the conditional suicide plasmid for containment system, in which the lethal gene used was the nuclease gene of Serratia marcescens without the leader-coding sequence and was placed downstream of T7 promoter. The GEB has wide prospects of application on cleanup of pesticide residues with its degradability to several pesticides and containment system.

Heavy Metals as a Factor Increasing the Functional Genetic Potential of Bacterial Community for Polycyclic Aromatic Hydrocarbon Biodegradation

Authors: Staninska-Pieta J, Czarny J, Piotrowska-Cyplik A... more

Source: MOLECULES 25(2), 2020, DOI: 10.3390/molecules25020319

**Abstract:** The bioremediation of areas contaminated with hydrocarbon compounds and heavy metals is challenging due to the synergistic toxic effects of these contaminants. On the other hand, the phenomenon of the induction of microbial secretion of exopolysaccharides (EPS) under the influence of heavy metals may contribute to affect the interaction between hydrophobic hydrocarbons and microbial cells, thus increasing the bioavailability of hydrophobic organic pollutants. The purpose of this study was to analyze the impact of heavy metals on the changes in the metapopulation structure of an environmental consortium, with particular emphasis on the number of copies of orthologous genes involved in exopolysaccharide synthesis pathways and the biodegradation of hydrocarbons. The results of the experiment
confirmed that the presence of heavy metals at concentrations of 50 mgL(-1) and 150 mgL(-1) resulted in a decrease in the metabolic activity of the microbial consortium and its biodiversity. Despite this, an increase in the biological degradation rate of polycyclic aromatic hydrocarbons was noted of 17.9% and 16.9%, respectively. An assessment of the estimated number of genes crucial for EPS synthesis and biodegradation of polycyclic aromatic hydrocarbons confirmed the relationship between the activation of EPS synthesis pathways and polyaromatic hydrocarbon biodegradation pathways. It was established that microorganisms that belong to the Burkholderiales order are characterized by a high representation of the analyzed orthologs and high application potential in areas contaminated with heavy metals and hydrocarbons.

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## Adsorption performance of *Bacillus licheniformis* sp. bacteria isolated from the soil of the Tigris River on mercury in aqueous solutions

**Authors:** Baran MF, Yildirim A, Acay H... more

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY, 2020, DOI: 10.1080/03067319.2020.1746779

**Abstract:** Mercury is known to be one of the most toxic heavy metals in the environment and is released into the water systems in significant quantities through natural events and industrial process activities. Many chemical materials are used as adsorbents in the removal of toxic metals from the environment and wastewaters. (...). In this study, *Bacillus licheniformis* in the soil isolated from the Tigris River was used as bio-sorbent. The mercury (Hg(II)) absorption behaviour of *Bacillus licheniformis* bacteria (BLB) was investigated using inductively coupled plasma mass spectrometry. The effects of equilibrium of adsorption time, temperature, adsorbent dosage and pH on the adsorption of Hg (II) onto BLB were determined. The maximum adsorption capacity of Hg (II) onto BLB was determined as 82.12 mg/g (T = 25 degrees C, pH 5, Co = 50 mg/L, m = 25 mg). The BLB was characterised using Fourier transform infrared spectroscopy analysis, thermal gravimetric analysis/differential thermal analysis, scanning electron microscopy analysis and energy-dispersive X-ray spectroscopy analysis. In addition, pseudo-first-order and pseudo-second-order kinetic models were applied. The equilibrium data for the adsorption of Hg(II) onto BLB were examined by the Langmuir and Freundlich isotherm models. The activation energy was calculated using the pseudo-second-order rate constant. These results suggested the BLB can be used as an efficient adsorbent for the removal of Hg(II) metal ions from wastewater. When the results of bio-sorption studies were examined, it was found that the bio-sorbent could be reused easily. The present study suggests that microorganism bio-sorbents are useful for the efficient removal of mercury from aqueous solutions.

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## Biochar and bacteria inoculated biochar enhanced Cd and Cu immobilization and enzymatic activity in a polluted soil

**Authors:** Tu C, Wei J, Guan F, Liu Y... more

**Source:** ENVIRONMENT INTERNATIONAL, 137, 2020, DOI: 10.1016/j.envint.2020.105576

**Abstract:** The application of biochar in the remediation of heavy metal contaminated soil has received increasing global attention during the past decade. Although there has been some review work on the mechanism of heavy metals stabilization by biochar, the effects and mechanisms of interaction between biochar and functional microbes such as heavy metal tolerant, adsorption and transformation microbial strains remains unclear. In this paper, maize biochar and a heavy metal-tolerant strain *Pseudomonas* sp. NT-2 were selected to investigate the dynamic effects and potential mechanisms of biochar and bacteria loaded biochar on the stabilization of Cd and Cu mixed contaminated soil by a 75-day pot experiment. The results showed that, compared to the single biochar amendment, the application of biochar inoculated with NT-2 strain at the rate of 5% significantly increased the soil pH at the initial stage of incubation, and followed by a slight decline to a neutral-alkaline range during the reaction. The addition of NT-2 loaded biochar
could also significantly increase the proportion of residual fraction of Cd and Cu, thus reduce the proportion of exchangeable and carbonate bound species in the soil, which lead to the decreasing of plant and human bioavailability of the metal in the soil indicated by DTPA and simulated human gastric solution extraction (UBM), respectively. Finally, the application of bacterial loaded biochar also markedly enhanced soil urease and catalase activities during the later stage of the incubation, and improved soil microbial community at the end of incubation, which indicates a recovery of soil function after the metal stabilization. The research results may provide some new insights into the development of functional materials and technologies for the green and sustainable remediation of heavy metal contaminated soil by the combination of biochar and functional microorganisms.

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# Bacterial response to sharp geochemical gradients caused by acid mine drainage intrusion in a terrace: Relevance of C, N, and S cycling and metal resistance

**Authors:** Sun WM, Sun XX, Li BQ... more

**Source:** ENVIRONMENT INTERNATIONAL 138, 2020, DOI: 10.1016/j.envint.2020.105601

**Abstract:** A unique terrace with sharp gradient of environmental conditions was selected to study the microbial response and survival strategies to the extreme environments introduced by acid mine drainage (AMD) contamination. A combination of geochemical analyses, metagenomic sequencing, ex-situ microcosm setups, and statistical analyses were used to investigate the environment-microbe interactions. The microbial communities and metabolic potentials along the terrace were studied by focusing on the genes associated with important biogeochemical processes (i.e., C, N, S cycling and metal resistance). Results show that the variations of geochemical parameters substantially shaped the indigenous microbial communities. Sharp environmental gradients also impacted the microbial metabolic potentials, especially for C, N, and S cycling. Although the relative abundances of carbon fixing genes did not significantly vary along the environmental

gradients, the taxa for carbon fixation varied significantly in more contaminated fields versus less contaminated fields, indicating the effects of AMD contamination on the autotrophic microbial communities. AMD input also influenced the N cycling, especially for nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA). In addition, ex situ experiments were undertaken to evaluate the effects of AMD contamination on nitrogen fixation rates. Random Forest (RF) analysis indicated that nitrate, pH, total N, TOC exhibited positive correlations with the rates of nitrogen fixation while total Fe, Fe(III), and sulfate showed negative effects. Two co-occurrence networks at taxonomic and genomic levels indicated that geochemical parameters such as pH, TOC, total N, total S, and total Fe substantially influenced the innate microbial communities and their metabolic potentials. The current study provides an understanding for microbial response to AMD contamination and lays the foundation for future potential AMD bioremediation.

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# Comparative assessment of polymeric and other nanoparticles impacts on soil microbial and biochemical properties

**Authors:** Xin XP, Zhao FL, Zhao HM... more

**Source:** GEODERMA 367, 2020, DOI: 10.1016/j.geoderma.2020.114278

**Abstract:** Interest has been generated in nanotechnology application in agricultural and food systems and understanding ecotoxicity of nanoparticles (NPs) is imperative for ecosystem health and food safety. This study compared the dose-effects of newly synthesized polysuccinimide NPs (PSI-NPs) with mull-walled carbon nanotubes (MWCNTs), nano-Ag and nano-TiO2, on soil microbiological and biochemical processes. The effects of NPs varied largely with the type and dose of NPs as well as soil properties. Of the tested NPs, PSI-NPs had no significant perturbance, while the rest of NPs decreased microbial biomass C and N (MBC and MBN), stimulated the microbial metabolic quotient (MMQ), and inhibited dehydrogenase (DA), urease (UA), and phosphatase (PA) activities. Significant
dose-effects of MWCNTs, nano-Ag and nano-TiO2 occurred, and the influences were more intensive at higher application rate (500 ppm). Irrespective of NP type and dose, the effects were severer in Spodosol soil than Alfisol soil. Principle component analysis (PCA) also confirmed that most of the measured indicators were not affected by PSI-NPs, partly affected by MWCNTs, but intensively influenced by nano-Ag and nano-TiO2. These results highlight the advantages of PSI-NPs over the other NPs for agricultural applications and could facilitate the development of guidelines in regulating NPs application in agroecosystems.

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## Potency of Phlebia species of white rot fungi for the aerobic degradation, transformation and mineralization of lindane

**Authors:** Xiao PF, Kondo R

**Source:** JOURNAL OF MICROBIOLOGY, 2020, DOI: 10.1007/s12275-020-9492-x

**Abstract:** The widespread use of the organochlorine insecticide lindane in the world has caused serious environmental problems. The main purpose of this paper is to investigate the potency of several Phlebia species of white rot fungi to degrade, transform and mineralize lindane, and to provide the feasibility of using white rot fungi for bioremediation at contaminated sites. Based on tolerance experiment results, Phlebia brevispora and Phlebia lindtneri had the highest tolerance to lindane and were screened by degradation tests. After 25 days of incubation, P. brevispora and P. lindtneri degraded 87.2 and 73.3% of lindane in low nitrogen medium and 75.8 and 64.9% of lindane in high nitrogen medium, respectively. Several unreported hydroxylation metabolites, including monohydroxylated, dehydroxylated, and trihydroxylated products, were detected and identified by GC/MS as metabolites of lindane. More than 10% of [C-14] lindane was mineralized to (CO2)-C-14 by two fungi after 60 days of incubation, and the mineralization was slightly promoted by the addition of glucose. Additionally, the degradation of lindane and the formation of

metabolites were efficiently inhibited by piperonyl butoxide, demonstrating that cytochrome P450 enzymes are involved in the fungal transformation of lindane. The present study showed that P. brevispora and P. lindtneri were efficient degraders of lindane; hence, they can be applied in the bioremediation process of lindane-contaminated sites.

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## Integration of earthworms and arbuscular mycorrhizal fungi into phytoremediation of cadmium-contaminated soil by Solanum nigrum L

**Authors:** Wang G, Wang L, Ma F, You YQ... more

**Source:** JOURNAL OF HAZARDOUS MATERIALS 389, 2020, DOI: 10.1016/j.jhazmat.2019.121873

**Abstract:** Arbuscular mycorrhizal fungi (AMF) and earthworms independently enhance plant growth, heavy metal (HM) tolerance, and HM uptake, thus they are potential key factors in phytoremediation. However, few studies have investigated their interactions in HM phytoextraction by hyperaccumulators. This study highlights the independent and interactive effects of earthworms and AMF on Solanum nigrum. Plants inoculated with either AMF or earthworms exhibited ameliorated growth via enhancement of productivity, metal tolerance, and phosphorus (P) acquisition. Co-inoculation with both had more pronounced effects on plant biomass and P acquisition in shoots, but not in roots, and in Cd-polluted soils it significantly promoted (P < 0.05) shoot biomass (20.7-134.6 %) and P content (20.4-112.0 %). AMF and earthworms increased Cd accumulation in plant tissues, but only AMF affected Cd partitioning between shoots and roots. Although AMF decreased root-to-shoot translocation of Cd at high Cd levels, this was counterbalanced by earthworms. Both AMF and its combination with earthworms enhanced Cd phytoavailability by altering Cd chemical fractions
and decreasing pH. Co-inoculation increased Cd removal amounts up to 149.3 % in 120 mg kg(-1) Cd-spiked soils. Interactions between the two organisms were synergistic in Cd phytoextraction. Thus, earthworm-AMF-plant symbiosis potentially plays an essential role in phytoremediation of HM-polluted soils.

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## Evaluation of seven chemical pesticides by mixed microbial culture (PCS-1): Degradation ability, microbial community, and *Medicago sativa* phytotoxicity

Authors: Li HY, Qiu YZ, Yao T... more

Source: JOURNAL OF HAZARDOUS MATERIALS 389, 2020, DOI: 10.1016/j.jhazmat.2019.121834

**Abstract:** Environmental problems caused by the large-scale use of chemical pesticides are becoming more and more serious, and the removal of chemical pesticides from the ecological environment by microbial degradation has attracted wide attention. In this study, using enrichment screening with seven chemical pesticides as the sole carbon source, a mixed microbial culture (PCS-1) was obtained from the continuous cropping of strawberry fields. The microbial community composition, degradation ability, and detoxification effect of PCS-1 was determined for the seven pesticides. Inoculation with PCS-1 showed significant degradation of and tolerance to the seven pesticides. Microbial community composition analysis indicated that Pseudomonas, Enterobacter, Aspergillus, and Rhodotorula were the dominant genera for the degradation of the seven pesticides by PCS-1. The concentration of the seven pesticides was 10 mg L-1 in hydroponic and soil culture experiments. The fresh weight, plant height, and root length of PCS-1-inoculated alfalfa (*Medicago sativa*) significantly increased compared with those of non-PCS-1-inoculated M. sativa. PCS-1 not only effectively degraded the residual content of the seven pesticides in water and soil but also reduced the pesticide residues in the roots, stems, and leaves of *M. sativa*. This study shows that PCS-1 may be important in environmental remediation involving the seven pesticides.

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## Design of Bacterial Strain-Specific qPCR Assays Using NGS Data and Publicly Available Resources and Its Application to Track Biocontrol Strains

Authors: Hernandez I, Sant C, Martinez R, Fernandez C

Source: FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.00208

**Abstract:** Biological control is emerging as a feasible alternative to chemical pesticides in agriculture. Measuring the microbial biocontrol agent (mBCA) populations in the environment is essential for an accurate environmental and health risk assessment and for optimizing the usage of an mBCA-based plant protection product. We hereby show a workflow to obtain a large number of qPCR markers suitable for robust strain-specific quantification. The workflow starts from whole genome sequencing data and consists of four stages: (i) identifying the strain-specific sequences, (ii) designing specific primer/probe sets for qPCR, and (iii) empirically verifying the performance of the assays. The first two stages involve exclusively computer work, but they are intended for researchers with little or no bioinformatic background: Only a knowledge of the BLAST suite tools and work with spreadsheets are required; a familiarity with the Galaxy environment and next-generation sequencing concepts are strongly advised. All bioinformatic work can be implemented using publicly available resources and a regular desktop computer (no matter the operating system) connected to the Internet. The workflow was tested with five bacterial strains from four different genera under development as mBCAs and yielded thousands of candidate markers and a triplex qPCR assay for each candidate mBCA. The qPCR assays were successfully tested in soils of different natures, water from different sources, and with samples from different plant tissues. The mBCA detection limits and population dynamics in the different matrices are similar to those in qPCR assays designed by other means. In summary, a new accessible, cost-effective, and robust workflow to
obtain a large number of strain-specific qPCR
markers is presented.

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Long-term application of
Swedish sewage sludge on
farmland does not cause clear
changes in the soil bacterial
resistome

Authors: Rutgersson C, Ebmeyer S, Lassen SB...
more

Source: ENVIRONMENT INTERNATIONAL 137,
2020, DOI: 10.1016/j.envint.2019.105339

**Abstract:** The widespread practice of applying sewage sludge to arable land makes use of nutrients indispensable for crops and reduces the need for inorganic fertilizer, however this application also provides a potential route for human exposure to chemical contaminants and microbial pathogens in the sludge. A recent concern is that such practice could promote environmental selection and dissemination of antibiotic resistant bacteria or resistance genes. Understanding the risks of sludge amendment in relation to antibiotic resistance development is important for sustainable agriculture, waste treatment and infectious disease management. To assess such risks, we took advantage of an agricultural field trial in southern Sweden, where land used for growing different crops has been amended with sludge every four years since 1981. We sampled raw, semi-digested and digested and stored sludge together with soils from the experimental plots before and two weeks after the most recent amendment in 2017. Levels of selected antimicrobials and bioavailable metals were determined and microbial effects were evaluated using both culture-independent metagenome sequencing and conventional culturing. Antimicrobials or bioavailable metals (Cu and Zn) did not accumulate to levels of concern for environmental selection of antibiotic resistance, and no coherent signs, neither on short or long time scales, of enrichment of antibiotic-resistant bacteria or resistance genes were found in soils amended with digested and stored sewage sludge in doses up to 12 metric tons per hectare. Likewise, only very few and slight differences in microbial community composition were observed after sludge amendment. Taken together, the

current study does not indicate risks of sludge
amendment related to antibiotic resistance
development under the given conditions.
Extrapolations should however be done with care
as sludge quality and application practices vary
between regions. Hence, the antibiotic
concentrations and resistance load of the sludge
are likely to be higher in regions with larger
antibiotic consumption and resistance burden
than Sweden.

Microbial Degradation of
Plastic in Aqueous Solutions
Demonstrated by CO2
Evolution and Quantification

Authors: Rose RS, Richardson KH, Latvanen EJ...

Source: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES 21(4), 2020, DOI: 10.3390/ijms21041176

**Abstract:** The environmental accumulation of plastics worldwide is a consequence of the durability of the material. Alternative polymers, marketed as biodegradable, present a potential solution to mitigate their ecological damage. However, understanding of biodegradability has been hindered by a lack of reproducible testing methods. We developed a novel method to evaluate the biodegradability of plastic samples based on the monitoring of bacterial respiration in aqueous media via the quantification of CO2 produced, where the only carbon source available is from the polymer. *Rhodococcus rhodochrous* and *Alcanivorax borkumensis* were used as model organisms for soil and marine systems, respectively. Our results demonstrate that this approach is reproducible and can be used with a variety of plastics, allowing comparison of the relative biodegradability of the different materials. In the case of low-density polyethylene, the study demonstrated a clear correlation between the molecular weight of the sample and CO2 released, taken as a measure of biodegradability.

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Effect of cadmium on the contamination on the rhizosphere bacterial diversity of *Echinocactus platyacanthus*

**Authors:** Carabali MMS, Garcia-Oliva F, Paez LEC, Lopez-Lozano NE

**Source:** RHIZOSPHERE 13, 2020, DOI: 10.1016/j.rhisph.2020.100187

**Abstract:** To better understand the mechanism of tolerance to heavy metals, it is relevant to analyze the effects of Cd contamination on the rhizospheric microbiota of plants with high tolerance to environmental stress such as cacti species. In this work, the effects of soil contamination with Cd on bacterial diversity, microbial carbon, abundance of diazotrophs in the soil, and on the photosynthetic efficiency and absorption of Cd of the candy barrel cactus (Echinocactus platyacanthus) were evaluated. Experimental pots sown with E. platyacanthus were contaminated with different concentrations of Cd+2. Changes in rhizospheric soil community were evaluated after 30 days of contamination. In general, soil contamination with Cd significantly changes the structure of the rhizospheric bacterial community which could have serious effects on the functioning of this community, especially in N mobilization. Despite the plant not showing signs of physiological stress reflected in the photosynthetic yield, revealing its high resistance to contamination with Cd, a slight increase in the electron transport rate at low Cd concentration was observed. This increase correlates with an increase in abundance of diazotrophs and microbial C, suggesting an interesting response by the entire system to the presence of low Cd concentration in the soil. In this work, we have demonstrated that the factors analyzed here can be indicators of the quality and health of the soil, being a complement to explaining the behavior of metals in the soil matrix, and thus be able to understand the mechanism of tolerance to Cd contamination in soil.

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A new assay of bacterial selection with Pb reveals an unexpected effect of Pb on

bacterial behavior: implications for remediation

**Authors:** Bouquet D, Lepinay A, Gaudin P, Jean-Soro L, Le Guern C, Lichtfouse E, Lebeau T

**Source:** ENVIRONMENTAL CHEMISTRY LETTERS, 2020, DOI: 10.1007/s10311-020-00986-y

**Abstract:** Soil pollution by lead (Pb) is a major health concern due to Pb toxicity. Phytoextraction could remove Pb, but this technique is limited by the low Pb mobility in soils. Pb mobility can be increased by bioaugmentation, which consists in adding selected bacteria in soil to increase Pb bioavailability. Nonetheless, many bioaugmentation and phytoextraction experiments have failed because bacterial selections did not take into account the presence of metals. Therefore, we developed a microplate assay with Pb-enriched growth media for the rapid selection of bacterial strains. Selection criteria included the ability of bacteria to grow in soils, to promote plant growth and to increase Pb availability. Results show that 100-250 μM Pb induced a decrease of production of indole acetic acid (IAA), a plant growth promotor, by up to 49% for *Cupriavidus metallidurans*, compared to the control without Pb. This finding implies that application in real soil conditions with *C. metallidurans* would have probably failed, thus strengthening the value of our selection method in the presence of Pb. By contrast, 100-250 μM Pb induced a 8.5-11-fold higher degradation of aminocyclopropane carboxylic acid (ACC) by *C. metallidurans*. Surprisingly, *Pseudomonas putida* did not degrade ACC without Pb, but degraded ACC at 100-250 μM Pb. This observation means that Pb activates ACC degradation, which should reduce plant stress because ACC is the precursor of the ethylene phytohormone. Overall, our selection method in the presence of Pb allows to reveal new bacterial properties, which would not have been disclosed by current methods that do not take into account the effect of metals. Our method allows also to test simultaneously about 200 bacterial isolates. In addition, our findings show for the first time that Pb changes the production of IAA and the degradation of ACC.

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Cadmium Pollution Impact on the Bacterial Community of
# Haplic Cambisols in Northeast China and Inference of Resistant Genera

**Authors:** Duan CW, Liu Y, Zhang HG, Chen GY, Song, JF

Source: JOURNAL OF SOIL SCIENCE AND PLANT NUTRITION, 2020, DOI: 10.1007/s42729-020-00201-5

**Abstract:** Modern industry and agriculture has aggravated heavy metal pollution of soils, of which cadmium (Cd) is among the common most toxic and widely distributed pollutants. Bacteria are a major group of microorganisms and the most abundantly occurring in soils. In Northeastern China, many mining sites occur whose soils need reclamation and Cd pollution has commonly existed. Haplic Cambisols is the zonal forest soil here. Yet, how Cd contamination may affect the bacterial characteristics and chemical properties of Haplic Cambisols is still unknown. Here, we applied different concentrations of Cd contamination to Haplic Cambisols and monitored the resulting changes to bacterial community structure and diversity, as well as the general soil environments; we then inferred Cd-resistant bacteria to provide theoretical support for microbial remediation of Cd-contaminated Haplic Cambisols in Northeast China. Haplic Cambisols were treated with different concentrations of CdCl2 solutions (0 [CK], 1, 5, 25, 50, 75, 100 mg kg(-1)), respectively expressed as T1, T2, T3, T4, T5, and T6) and incubated for 50 days, and then bacterial community composition was identified, and the pH, organic matter, hydrolytic nitrogen, available phosphorus, potassium, and cadmium contents of the soils were measured. Adding higher concentrations of Cd usually significantly increased the richness and diversity of the bacterial community in Haplic Cambisols in terms of both species and abundance with the effects of some treatments being not significant, and this effect varied with Cd concentration. Applying Cd significantly influenced the bacterial community's structure and its metabolic functioning. Cd also influenced bacterial diversity via several key soil environmental factors, namely the pH, organic matter, and hydrolytic nitrogen contents. Pseudolabrys, Ralstonia, Reyranella, Afipia, Pelomonas, Rhizomicrobium, and Bradyrhizobium within Proteobacteria; Rhodanobacter from Bacteroidetes; and Nitrobacter within Nitrospirae were the main resistant bacteria. Higher concentrations of Cd increased the bacterial

community richness and diversity of Haplic Cambisols, as well as the relative abundance of their main bacterial populations. The Cd-resistant genera were inferred, and relative abundances of Ralstonia, Bradyrhizobium, Rhizomicrobium, and Afipia were the highest.

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# Bacteria affect Sb(III, V) adsorption and oxidation on birnessite

**Authors:** Du HH, Tao J, Yang RJ, Lei M, Tie BQ... more

Source: JOURNAL OF SOILS AND SEDIMENTS, 2020, DOI: 10.1007/s11368-020-02607-1

**Abstract:** Purpose The adsorption-oxidation of Sb on manganese oxide plays an important role in controlling Sb mobility and fate in soils and sediments. Widespread organic substances such as microbes may greatly affect this process, and deserve a careful investigation. This study examines the adsorption and oxidation of Sb(III, V) on birnessite, a typical manganese oxide, with and without Bacillus cereus cells. Materials and methods Adsorption isotherms were conducted to explore the adsorption capacity of Sb to the birnessite-bacteria composite. X-ray photoelectron spectroscopy (XPS) was applied to determine the valence state of Mn and the adsorbed Sb species. Results and discussion The SEM results show that birnessite adheres to the outer surface of bacterial cells, and the aggregation of minerals occurs to a lesser extent in the presence of cells. Batch adsorption results show a much larger Sb adsorption on individual birnessite than on bacteria, and the measured Sb adsorption to the birnessite-bacteria composite is larger than that predicted assuming additive, i.e., the sum of the end-member metal adsorptivities. On birnessite, Sb(III) is predominately oxidized to Sb(V) according to the XPS analysis, and the presence of bacteria hinders this oxidation reaction. Conclusions We propose that microbe-birnessite association favors the immobilization of Sb on solid phases, but can inhibit the oxidation of Sb(III) to Sb(V), which is of great significance
for evaluating the toxicity, bio-availability, and mobility of Sb in both natural and contaminated environments.

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Physiological responses of Morus alba L. in heavy metal(loid)-contaminated soil and its associated improvement of the microbial diversity

**Authors:** Zeng P, Huang FL, Guo ZH, Xiao XY, Peng C

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 27(4): 4294-4308, 2020, DOI: 10.1007/s11356-019-07124-4

**Abstract:** Woody plants have considerable application potential in the phytoremediation schemes, owing to their long-lived large biomass and prosperous root systems in heavy metal(loid)-contaminated soil. Under greenhouse conditions, the physiological response characteristics and phytoremediation possibility of Morus alba L. and its associated improvement of the bacterial and arbuscular mycorrhizal fungal (AMF) diversities in heavy metal(loid) co-contaminated soils were investigated. The results showed that the cultivated *M. alba* L. plant exhibited significant tolerance against the heavy metal(loid)s in co-contaminated soil and that the microbial diversities were improved notably. The contents of malondialdehyde (MDA) in *M. alba* L. leaves decreased with cultivation from 90 to 270 days, while the superoxide dismutase, peroxidase and catalase activities were maintained at normal levels to eliminate the production of lipid peroxides. The chemical compositions (e.g. amino acids, carbohydrates and proteins) in the root of *M. alba* L. fluctuated slightly throughout the cultivation period. Meanwhile, Cd, Pb and Zn were majorly concentrated in the *M. alba* L. roots, and the maximum contents were 23.4, 7.40 and

615.5 mg/kg, respectively. According to the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis results, the influence of *M. alba* L. on the rhizosphere AMF community was greater than that on the bacteria community. Meanwhile, the bacterial and AMF Shannon diversity indexes in the contaminated soil were enhanced by 18.7-22.0% and 7.14-16.4%, respectively, with the presence of *M. alba* L. Furthermore, the correlations between the availability of As, Cd, Pb, and Zn and Shannon diversity indexes of the bacterial and AMF communities were significantly (p &60; 0.05) positive with the phytoremediation of *M. alba* L. Therefore, *M. alba* L. can be suggested as a potential plant candidate for ecological remediation and for simultaneously improving the activity and diversity of microorganisms in contaminated soils.

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Impacts of antimony and arsenic co-contamination on the river sedimentary microbial community in an antimony-contaminated river

**Authors:** Xu R, Sun XX, Han F, Li BQ... more

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 713, 2020, DOI: 10.1016/j.scitotenv.2019.136451

**Abstract:** Antimony (Sb) and arsenic (As) are toxic elements that occur widely in trace soil concentrations. Expansion of mining activities has increased Sb and As pollution, thus posing a severe threat to human welfare and ecological systems worldwide. Knowledge regarding the composition and adaptation of the microbial communities in these metal(loid) contaminated sites is still limited. In the current study, samples along a river flowing through the world's largest Sb mining area (Xikuangshan) were selected to investigate the microbial response to different Sb or As species. A comprehensive analysis of geochemical parameters, high-throughput sequencing, and statistical methods were applied to reveal the different effects of Sb and As on sedimentary microorganisms. Results suggested that the majority of the Sb and As fractions were not bioavailable. The Sb extractable fraction had a stronger effect on the microbial community compared with its As counterpart. Random forest
analyses indicated that the easily exchangeable Sb fraction and specifically sorbed surface-bound fraction were the two most selective variables shaping microbial community diversity. A total of 11 potential keystone phyla, such as bacteria associated with the Bacteroidetes, Proteobacteria, and Firmicutes, were identified according to a molecular ecological network analysis. Strong correlations (vertical bar R > 0.7, P < 0.05) were identified among the indigenous microbial community and pH (negative), sulfate (negative), and exchangeable Sb fraction (positive). Bacteria associated with the genera Geobacter, Phormidium, Ignavibacterium, Desulfobulbus, Ferruginibacter, Fluviicola, Methylotenera, and Scytonema, were predicted to tolerate or metabolize the Sb extractable fraction.

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## Sub-Arctic Field Degradation of Metsulfuron-Methyl in Two Alaskan Soils and Microbial Community Composition Effects

**Authors:** Tomco PL, Seefeldt SS, Rodriguez-Baisi K, Hatton JJ, Duddleston KN

**Source:** WATER AIR AND SOIL POLLUTION 231:4, 2020, DOI: 10.1007/s11270-020-04528-8

**Abstract:** Metsulfuron-methyl is a sulfonylurea herbicide, primarily with postemergence activity but also with occasional pre-emergent activity, used for control of weeds and woody plants on agricultural lands and natural areas. The active ingredient is popular in Alaska as Ally XP formulation; little is known about its high-latitude environmental behavior and potential adverse impacts on soil health in cold regions. Our study determined field degradation rates at two experimental farms in Alaska and assessed whether laboratory-incubated soil amended at 1x or 100x label rates would adversely impact microbial community diversity. DT50 was observed at 4.12-5.13 days, with the compound below 1 µg/kg detection limit at 90 days. Interestingly, this is faster than the reported range of field half-lives in the literature (7-42 days). Microbial community composition was not affected by MSM at both 1x and 100x rates. High-latitude regions exhibit extreme summer

photoperiods that may exacerbate the MSM degradation/dissipation rate; we postulate that timing of application may have large impacts on MSM attenuation.

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## Influence of multi-walled carbon nanotubes on the microbial biomass, enzyme activity, and bacterial community structure in 2,4-dichlorophenol-contaminated sediment

**Authors:** Song B, Gong JL, Tang WW... more

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 713, 2020, DOI: 10.1016/j.scitotenv.2020.136645

**Abstract:** The rise in manufacture and use of carbon nanotubes has aroused the concern about their potential risks associated with coexisting pollutants in the aquatic environment. 2,4-dichlorophenol (2,4-DCP), with a high toxicity to many aquatic organisms, is a widespread pollutant resulting from the extensive use of pesticides and preservatives. In this article, the adsorption of 2,4-DCP by riverine sediment and the responses of sediment microbial community to 2,4-DCP were studied in the presence of multi-walled carbon nanotubes (MWCNTs). Adding MWCNTs significantly increased the adsorption amount of sediment for 2,4-DCP from 0.541 to 1.44 mg/g as the MWCNT concentration increased from 0 to 15 mg/g. The responses of sediment microbial community were determined after one-month exposure to MWCNTs at different concentrations (0.05,0.5, 5, and 50 mg/g). The microbial biomass carbon in the sediment contaminated with 2,4-DCP increased in the presence of 5 mg/g of MWCNTs (from 0.06 to 0.11 mg/g), but not significantly changed at other MWCNT concentrations. For the sediments contaminated with 2,4-DCP, the presence of MWCNTs made no difference to urease activity, while the dehydrogenase activity slightly increased with the
addition of 5 mg/g of MWCNTs and decreased in the presence of 50 mg/g of MWCNTs. The changes of sediment bacterial communities were further determined by 16S rRNA gene sequencing. Based on the weighted UniFrac distance between communities, the clustering analysis suggested that the contamination of 2,4-DCP affected the bacterial community structure in a greater degree than that caused by MWCNTs at relatively low concentrations (&#60;= 5 mg/g). Bacteroidetes, Planctomycetes, and Nitrospirae were feature bacterial phyla to reflect the effects of MWCNTs and 2,4-DCP on sediment bacterial community. These results may contribute to the understanding of microbial community response to co-exposure of MWCNTs and 2,4-DCP and the assessment of associated ecological risks.

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Effects of electron donors on
the degradation of
hexachlorocyclohexane and
microbial community in
submerged soils

Authors: Zhao Y, Zhang Y, Wang J, Hou JY... more

Source: JOURNAL OF SOILS AND SEDIMENTS 20(4):2155-2165, 2020, DOI: 10.1007/s11368-020-02593-4

**Abstract:** Purpose Hexachlorocyclohexane (HCH) is a pesticide that is persistent in aerobic but not in anaerobic conditions. The aim of this investigation was to elucidate the impacts of different electron donors on the degradation of hexachlorocyclohexane and their relationships with the microbial community in submerged soils. Materials and methods Soil samples were collected from a pesticides-polluted site which was previously used for long-term storage of pesticides since the 1960s. Residual amounts of HCHs in submerged soils were assessed to evaluate the efficiency of the added electron donors after incubation. Changes in microbial community were monitored during incubation. Results and discussion The efficiencies of removal of HCHs by Fe-0, Fe-0 + straw and glucose treatments were 63.8%, 40.3%, and 22.0%, compared with 5.4% by the control. Soil redox potential decreased rapidly following addition of Fe-0 and became anaerobic, but there was no significant decrease in redox potential following

the addition of glucose. Principal coordinates analysis (PCoA) confirms that the electron donors greatly affected the soil bacterial community. Furthermore, community composition analysis shows that Firmicutes was the dominant phylum after addition of carbon sources (straw and glucose) but Proteobacteria were dominant in the control and the Fe-0 treatment. Prauserella, Actinobacteria, and Streptomyces showed highly significant increases in the Fe-0 treatment and were positively correlated with total HCH residues. Conclusions These findings indicate that the addition of organic materials (straw and glucose) had a gradual effect on the degradation of HCH while Fe-0 acted rapidly. Elucidation of the relationships between electron donors and soil microbial communities will help in the bioremediation of HCH-contaminated sites.

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Pesticide application inhibit
the microbial carbonic
anhydrase-mediated carbon
sequestration in a soil
microcosm

Authors: Nathan VK, Jasna V, Parvathi A

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 27(4):4468-4477, 2020, DOI: 10.1007/s11356-019-06503-1

**Abstract:** Heterotrophic system for carbon sequestration is gaining importance in the recent decades. Carbonic anhydrase (CA) is a major enzyme involved in carbon sequestration and biomineralization process. In this paper, we evaluate the effect of pesticide on CA activity using inhibitory assay. 2,4-D, being one of the most extensively used pesticide, being deleterious to soil health, its usage should be minimized to regain the soil health. Maximum inhibitory constant (K-i) was observed for 5% 2,4-D (49.53 mM) followed by 5% glyphosate (43.92 mM). The maximum Km increase with increase in pesticide concentration by 3.05-fold was in case of glyphosate which was higher than that of 2,4-D (2.08-fold) and dichlorvos (2.38-fold). Moreover, we evaluated the carbon sequestration using CA enzyme in the soil microcosm. In the present study, we identified the negative impact of 2,4-D on carbonic anhydrase produced by *Bacillus halodurans* PO15. The inhibition was a mixed type
and had significantly lowered the carbon reduction to about 2.38 +/- 0.17% in a soil microcosm study. Based on the molecular docking, the inhibition was contributed due to weak H-bonding interaction with amino acid residues (Gly65, Gly95, Val147, Ser150 and Gly65, Ser146, and Ser150).

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# Challenges with Verifying Microbial Degradation of Polyethylene

Authors: Montazer Z, Najafi MBH, Levin DB

Source: POLYMERS 12(1), 2020, DOI: 10.3390/polym12010123

**Abstract:** Polyethylene (PE) is the most abundant synthetic, petroleum-based plastic materials produced globally, and one of the most resistant to biodegradation, resulting in massive accumulation in the environment. Although the microbial degradation of polyethylene has been reported, complete biodegradation of polyethylene has not been achieved, and rapid degradation of polyethylene under ambient conditions in the environment is still not feasible. Experiments reported in the literature suffer from a number of limitations, and conclusive evidence for the complete biodegradation of polyethylene by microorganisms has been elusive. These limitations include the lack of a working definition for the biodegradation of polyethylene that can lead to testable hypotheses, a non-uniform description of experimental conditions used, and variations in the type(s) of polyethylene used, leading to a profound limitation in our understanding of the processes and mechanisms involved in the microbial degradation of polyethylene. The objective of this review is to outline the challenges in polyethylene degradation experiments and clarify the parameters required to achieve polyethylene biodegradation. This review emphasizes the necessity of developing a biochemically-based definition for the biodegradation of polyethylene (and other synthetic plastics) to simplify the comparison of results of experiments focused for the microbial degradation of polyethylene.

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# Phytostabilization of Polluted Military Soil Supported by Bioaugmentation with PGP-Trace Element Tolerant Bacteria Isolated from *Helianthus petiolaris*

Authors: Saran A, Imperato V, Fernandez L, Gkorezis, P... more

Source: AGRONOMY-BASEL 10(2), 2020, DOI: 10.3390/agronomy10020204

**Abstract:** Lead (Pb) and cadmium (Cd) are major environmental pollutants, and the accumulation of these elements in soils and plants is of great concern in agricultural production due to their toxic effects on crop growth. Also, these elements can enter into the food chain and severely affect human and animal health. Bioaugmentation with plant growth-promoting bacteria (PGPB) can contribute to an environmentally friendly and effective remediation approach by improving plant survival and promoting element phytostabilization or extraction under such harsh conditions. We isolated and characterised Pb and Cd-tolerant root-associated bacteria from *Helianthus petiolaris* growing on a Pb/Cd polluted soil in order to compose inoculants that can promote plant growth and also ameliorate the phytostabilization or phytoextraction efficiency. One hundred and five trace element-tolerant rhizospheric and endophytic bacterial strains belonging to eight different genera were isolated from the aromatic plant species Helianthus petiolaris. Most of the strains showed multiple PGP-capabilities, ability to immobilise trace elements on their cell wall, and promotion of seed germination. *Bacillus paramycoides* ST9, *Bacillus wiedmannii* ST29, *Bacillus proteolyticus* ST89, *Brevibacterium frigoritolans* ST30, *Cellulosimicrobium cellulans* ST54 and *Methylobacterium* sp. ST85 were selected to perform bioaugmentation assays in greenhouse
microcosms. After 2 months, seedlings of sunflower (H. annuus) grown on polluted soil and inoculated with B. proteolyticus ST89 produced 40% more biomass compared to the non-inoculated control plants and accumulated 20 % less Pb and 40% less Cd in the aboveground plant parts. In contrast, B. paramycoides ST9 increased the bioaccumulation factor (BAF) of Pb three times and of Cd six times without inhibiting plant growth. Our results indicate that, depending on the strain, bioaugmentation with specific beneficial bacteria can improve plant growth and either reduce trace element mobility or enhance plant trace element uptake.

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## Sulfate-reducing bacteria (SRB) can enhance the uptake of silver-containing nanoparticles by a wetland plant

**Authors:** Niu ZS, Yang Y, Tou FY, Guo XP... more

**Source:** ENVIRONMENTAL SCIENCE-NANO 7(3):912-92), 2020, DOI: 10.1039/c9en01162e

**Abstract:** The presence of sulfate-reducing bacteria (SRB) can reduce the bioavailability of toxic metal ions (e.g., Ag+) to plants via mediating the formation of metal sulfide precipitates; however, it remains largely elusive if SRB can also affect the phyto-uptake of metal nanoparticles (e.g., Ag-0-NPs). In the current study, the bioavailability of Ag-0-NPs to a model wetland plant, *Scirpus triqueter*, was investigated in the presence/absence of SRB. Comparative experiments were conducted using 0.01-10 mg L-1 Ag-0-NPs and silver ions. In addition to quantifying the total dissolved Ag concentrations, we analyzed the average sizes and particle concentrations of Ag-containing NPs (Ag-NPs) in plant tissues, including both roots and stems, after the designated treatments. The results show that although the presence of SRB can reduce the uptake of total Ag by 37% during the exposure of the plant to Ag ions, it can significantly enhance the uptake of total Ag during exposure of the plant to Ag-0-NPs, likely by transforming Ag-0-NPs into Ag-sulfide NPs with smaller particle sizes. Transmission electron microscopy data revealed that biogenic secondary Ag-sulfide particles smaller than 10 nm in size form in the vicinity of

pristine Ag-0-NPs. These NPs are likely generated from the parent Ag-0-NPs via a dissolution-diffusion-sulfidation process. Moreover, the phyto-uptake of Ag-0-NPs of various sizes (i.e., 20, 40 and 80 nm) in the presence/absence of SRB also confirmed a size dependent pattern, with more silver identified in the plant exposed to smaller Ag-NPs. The combined results suggest that the enhanced bioavailability of Ag-NPs to *Scirpus triqueter* in the presence of SRB is mainly attributed to the formation of secondary biogenic NPs with minute size. This result points to the importance of complex, coupled interactions between aqueous solutions, bacteria, plants, and labile NPs.

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## Comparative Genomics of a Paddy Field Bacterial Isolate Ochrobactrum sp. CPD-03: Analysis of Chlorpyrifos Degradation Potential

**Authors:** Nayak T, Panda AN, Kumari K, Adhya TK, Raina

**Source:** INDIAN JOURNAL OF MICROBIOLOGY 2020, DOI: 10.1007/s12088-020-00864-9

**Abstract:** Ochrobactrum genus is known to catabolize aromatic compounds. This study reports a complete genome sequence of Ochrobactrum sp. CPD-03 (similar to 4.6 Mb of chromosomal features) responsible for chlorpyrifos (CP) isolated form a paddy field (20.3588 degrees N, 85.8333 degrees E) in Bhubaneswar, India. A comparative genomics approach was performed between CPD-03 and eight closely related genomes of other Ochrobactrum strains in order to deepen our knowledge, to establish its phylogenetic and functional relationships. The involvement of CP degrading genes indicated a versatile role of CPD-03 in additional field trails. This research would provide the genetic information for its use in natural environment for the depletion of organophosphorus (OP) compounds.

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## Influence of the herbicide haloxyfop-R-methyl on
## bacterial diversity in rhizosphere soil of *Spartina alterniflora*

**Authors:** Liang QY, Yan ZZ, Li XZ

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 194, 2020, DOI: 10.1016/j.ecenv.2020.110366

**Abstract:** Haloxyfop-R-methyl (haloxyfop) can efficiently control *Spartina alterniflora* in coastal ecosystems, but its effect on soil microbial communities is not known. In the present study, the impact of the haloxyfop on rhizosphere soil bacterial communities of *S. alterniflora* over the dissipation process of the herbicide has been studied in a coastal wetland. The response of the bacterial community in the rhizoplane (iron plaque) of *S. alterniflora* subjected to haloxyfop treatment was also investigated. Results showed that the persistence of haloxyfop in the rhizosphere soil followed an exponential decay with a half-life of 2.6-4.9 days, and almost all of the haloxyfop dissipated on Day 30. The diversity of rhizosphere soil bacteria was decreased at the early stages (Days 1, 3 & 7) and recovered at late stages (Days 15 & 30) of the haloxyfop treatment. Application of haloxyfop treatment increased the relative abundance of the genera *Pseudomonas*, *Acinetobacter*, *Pontibacter*, *Shewanella* and *Aeromonas*. Strains isolated from these genera can degrade herbicides efficiently, which possibly played a role in the degradation of haloxyfop. The rhizoplane bacterial diversity was reduced on Day 15 while being vastly enhanced on Day 30. Soil variables, including the electric conductivity, redox potential, and soil moisture, along with the soil haloxyfop residue, jointly shape the bacterial community in rhizosphere soil.

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## Optimized bioleaching of copper by indigenous cyanogenic bacteria isolated from the landfill of e-waste

**Authors:** Arab B, Hassanpour F, Arshadi M, Yaghmaei S, Hamedi J

**Source:** JOURNAL OF ENVIRONMENTAL MANAGEMENT 261, 2020, DOI: 10.1016/j.jenvman.2020.110124

**Abstract:** In this study, indigenous cyanogenic bacterial strains were isolated on nutrient, minimal salt, and soil extract media at various culture conditions from two distinct landfills of e-waste, Iran. Based on their cyanide formation profiles, five most potent isolates were selected for optimization and to this end, the influence of the most effective factors on cyanide production including pH, glycine concentration and temperature were assessed using one-factor at a time method (OFAT). Initial pH of 7, glycine concentration of 2 g/L and temperature of 30 degrees C were obtained as optimal conditions for most of the isolates. Additionally, two bioleaching processes were applied for each bacteria to detect the effect of optimal conditions on bioleaching and to assay their potential in the mobilization of copper. Under optimal conditions and pulp density of 1 g/L, copper recoveries were recorded as 96.73%, 82.49%, 81.17%, 41.72%, and 31.52% by S22, N13, N37, N23, and N41 respectively during 10 days which is approximately 1.5-5 times higher than the recovery obtained without optimization. During the optimization and the bioleaching process, the pH fluctuation of the flasks was monitored which validated the activity of the microorganisms.

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## Construction of a Tetracycline Degrading Bacterial Consortium and Its Application Evaluation in Laboratory-Scale Soil Remediation

**Authors:** Wu XL, Gu YC, Wu XY, Zhou XY... more

**Source:** MICROORGANISMS 8(2), 2020, DOI: 10.3390/microorganisms8020292

**Abstract:** As an environmental pollutant, tetracycline (TC) can persist in the soil for years and damage the ecosystem. So far, many methods have been developed to handle the TC contamination. Microbial remediation, which involves the use of microbes to biodegrade the pollutant, is considered cost-efficient and more suitable for practical application in soil. This study isolated several strains from TC-contaminated soil and constructed a TC-degrading bacterial consortium containing *Raoultella* sp. XY-1 and *Pandoraea* sp. XY-2, which exhibited better
growth and improved TC degradation efficiency compared with single strain (81.72% TC was biodegraded within 12 days in Lysogeny broth (LB) medium). Subsequently, lab-scale soil remediation was conducted to evaluate its effectiveness in different soils and the environmental effects it brought. Results indicated that the most efficient TC degradation was recorded at 30 degrees C and in soil sample Y which had relatively low initial TC concentration (around 35 mg/kg): TC concentration decreased by 43.72% within 65 days. Soil properties were affected, for instance, at 30 degrees C, the pH value of soil sample Y increased to near neutral, and soil moisture content (SMC) of both soils declined. Analysis of bacterial communities at the phylum level showed that Proteobacteria, Bacteroidetes, Acidobacteria, and Chloroflexi were the four dominant phyla, and the relative abundance of Proteobacteria significantly increased in both soils after bioremediation. Further analysis of bacterial communities at the genus level revealed that Raoultella sp. XY-1 successfully proliferated in soil, while Pandoraea sp. XY-2 was undetectable. Moreover, bacteria associated with nitrogen cycling, biodegradation of organic pollutants, soil biochemical reactions, and plant growth were affected, causing the decline in soil bacterial diversity. Variations in the relative abundance of tetracycline resistance genes (TRGs) and mobile gene elements (MGEs) were investigated, the results obtained indicated that tetD, tetG, tetX, intI1, tnpA-04, and tnpA-05 had higher relative abundance in original soils, and the relative abundance of most TRGs and MGEs declined after the microbial remediation. Network analysis indicated that tnpA may dominate the transfer of TRGs, and Massilia, Alkanibacter, Rhizomicrobium, Xanthomonadales, Acidobacteriaceae, and Xanthomonadaceae were possible hosts of TRGs or MGEs. This study comprehensively evaluated the effectiveness and the ecological effects of the TC-degrading bacterial consortium in soil environment.

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Effects of soil heavy metal pollution on microbial activities and community diversity in different land use types in mining areas

Authors: Zhao XQ, Sun Y, Huang J, Wang H, Tang D

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020, DOI: 10.1007/s11356-020-08538-1

**Abstract:** Microbial activities and community structures play crucial roles in the soil environment and can be served as effective indicators to assess the ecological influence of heavy metal pollution in soil. This article selected soil samples from five land use types (mining area, mineral processing area, heap mining area, tailing area, and vegetable area) in the Shizishan mining area in Tongling, Anhui Province, China. The physicochemical properties, pollution characteristics, enzyme activities (catalase, urease, alkaline phosphatase, neutral phosphatase, cellulase, and sucrase), microbial biomass carbon (MBC), basal respiration (SBR), and metabolic entropy (qCO2) in soil were determined and compared, and the relationship between environmental factors and the microbial activities and community diversity was analyzed. The results showed that, according to the Nemerow's Pollution Index (P-N), the values were the heap mining area (24.47) > mineral processing area (12.55) > mining area (9.81) > tailings area (6.02) > vegetable area (4.51). With the increase of heavy metal contamination in the sampling area, the six enzyme activities, MBC and SBR decreased, but the qCO2 increased. Principal coordinate analysis (PCoA) and canonical correlation analysis (CCA) showed that the land use types, soil moisture content (MC), heavy metal content, pH, MBC, SBR, and qCO2 were significantly affected by the microbial community. The most dominant phyla were Proteobacteria (34.73%), Bacteroidetes (9.25%), Acidobacteria (8.99%), and Chloroflexi (8.68%) at the phylum (0.01) level by a total of 18 phyla. It was also found that Firmicutes and Phormidium were more tolerant to heavy metals. These results contributed to an insight into key environmental variables shaping the microbial activities, community structure, and diversity under various land use types in mining area.

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Tetracyclines Mode of Action and their Bacterial Mechanisms of Resistance

Authors: Roberts MC
**Source:** BACTERIAL RESISTANCE TO ANTIBIOTICS - FROM MOLECULES TO MAN, JOHN WILEY,

Ed. Bonev BB, Brown NM 101-124, 2020

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## Urban and agricultural soils in Southern California are a reservoir of carbapenem-resistant bacteria

**Authors:** Lopez NV, Farsar CJ, Harmon DE, Ruiz C

**Source:** MICROBIOLOGYOPEN 2020, DOI: 10.1002/mbo3.1034

**Abstract:** Carbapenems are last-resort beta-lactam antibiotics used in healthcare facilities to treat multidrug-resistant infections. Thus, most studies on identifying and characterizing carbapenem-resistant bacteria (CRB) have focused on clinical settings. (...) Here, we have surveyed 11 soil samples from 9 different urban or agricultural locations in the Los Angeles-Southern California area to determine the prevalence and characteristics of CRB in these soils. All samples tested contained CRB with a frequency of &#60;10 to 1.3 x 10(4) cfu per gram of soil, with most agricultural soil samples having a much higher relative frequency of CRB than urban soil samples. Identification and characterization of 40 CRB from these soil samples revealed that most of them were members of the genera Cupriavidus, Pseudomonas, and Stenotrophomonas. Other less prevalent genera identified among our isolated CRB, especially from agricultural soils, included the genera Enterococcus, Bradyrhizobium, Chromobacter, and Planomicrobium. Interestingly, all of these carbapenem-resistant isolates were also intermediate or resistant to at least 1 noncarbapenem antibiotic. Further characterization of our isolated CRB revealed that 11 Stenotrophomonas, 3 Pseudomonas, 1 Enterococcus, and 1 Bradyrhizobium isolates were carbapenemase producers. Our findings show for the first time that both urban and agricultural soils in Southern California are an underappreciated reservoir of bacteria resistant to carbapenems and other antibiotics, including carbapenemase-producing CRB.

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## On the contribution of reclaimed wastewater irrigation to the potential exposure of humans to antibiotics, antibiotic resistant bacteria and antibiotic resistance genes - NEREUS COST Action ES1403 position paper

**Authors:** Pina B, Bayona JM, Christou A... more

**Source:** JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 8(1), 2020, DOI: 10.1016/j.jece.2018.01.011

**Abstract:** Antibiotic resistance (AR) is becoming a worldwide threat due to the increasing occurrence of antibiotic-resistant pathogenic bacterial strains. There is a general consensus about the potential implications of the use of antibiotics in livestock on the onset of antibiotic resistant bacteria (ARB), mainly through meat consumption. However, the ever-increasing use of reclaimed wastewater (RWW) in agriculture may also contribute significantly to the non-accounted exposure to antibiotics, ARB, and antibiotic resistance genes (ARGs). This position paper aims at evaluating the current knowledge concerning the occurrence of antibiotics, ARBs, and ARGs in edible parts of different common crops irrigated with RWW. We will discuss which regulations on the use of RWW may contribute to the minimization of the prevalence of these contaminants in crops, and provide recommendations on how to minimize the impact of these practices.

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## Co-effect of minerals and Cd(II) promoted the formation of bacterial biofilm and consequently enhanced the sorption of Cd(II)

**Authors:** Xu SZ, Xing YH, Liu S... more

**Source:** ENVIRONMENTAL POLLUTION 258, 2020, DOI: 10.1016/j.envpol.2019.113774
**Abstract:** Heavy metal pollution is very common in soils. Soils are complex systems including minerals, bacteria, and various other substances. In Cd(II) contaminated soil, the combined effects of clay minerals and heavy metals on bacterial biofilm and Cd(II) adsorption are unappreciated. Our study showed that the combination of clay minerals (goethite, kaolinite, and montmorillonite) and heavy metals promoted Serratia marcescens S14 biofilm development significantly more than clay minerals or Cd(II) alone. The amount of biofilm after binary treatment with clay minerals and Cd(II) was 2.3-73 times than that in control. Mineral-induced cell death and the expression of the firnA, bsmA, and eps were key players in biofilm formation. Binary treatment with montmorillonite and Cd(II) significantly enhanced biofilm development and consequently increased the adsorption of Cd(II). Cd(II) removal is the result of co-adsorption of bacteria and minerals. Bacterial biofilm played an important role in Cd(II) adsorption. MR spectroscopy showed the components of biofilm were not affected by minerals and revealed the functional groups -OH, -NH, -CH2, -SH, -COO participated in Cd(II) immobilization. Our findings are of fundamental significance for understanding how minerals and Cd(II) affect biofilms and thereby enhance Cd(II) adsorption and predicting the mobility and fate of heavy metals in heavy metal-contaminated soil.

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Removal of Heavy Metals
Zinc, Lead, and Cadmium by
Biomineralization of Urease-
Producing Bacteria Isolated
from Iranian Mine Calcareous
Soils

Authors: Jalilvand N, Akhgar A, Alikhani HA...
more

Source: JOURNAL OF SOIL SCIENCE AND PLANT NUTRITION 20(1):206-219, 2020, DOI: 10.1007/s42729-019-00121-z

**Abstract:** One appropriate strategy for refining heavy metals could be based on bioprecipitation by ureolytic bacteria. The study was conducted to isolate urease-producing bacteria from the contaminated soils and evaluate the potential of selected isolates in biomineralization of heavy

metals. To this end, four isolates which had the greatest urease production, calcite precipitation, and endurance to the heavy metals were obtained from contaminated areas during the screening steps. These isolates along with Sporosarcina pasteurii were used to bioprecipitate zinc (Zn), lead (Pb), and cadmium (Cd) from solutions with concentrations of 100, 300, and 500 mM of these metals' ions. Amount of heavy metal precipitates formed by these bacteria were compared. Among these isolates, *Stenotrophomonas rhizophila* (A323) and *Variovorax boronicumulans* (C113) produced the highest carbonate minerals of heavy metals. *S. rhizophila* removed 96.25%, 71.3%, and 63.91% of Pb, Cd, and Zn, respectively, after 72 h of incubation. Also, *V. boronicumulans* removed 95.93% of Pb, 73.45% of Cd, and 73.81% of Zn after having the same amount of time for incubation. *S. pasteurii* eliminated 98.71% of Pb, 97.15% of Cd, and 94.83% of Zn. The presence of lead, zinc, cadmium, and carbon as well as oxygen in precipitates formed from biomineralization of heavy metals was confirmed by energy dispersive spectroscopy (EDS). The *S. pasteurii* produced higher amounts of metal carbonates. Nevertheless, the use of selected bacteria in bioremediation of contaminated sites may be more effective due to the stability of these bacteria in high concentrations of Pb, Zn, and Cd.

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Isotope Fractionation (delta C-13, delta N-15) in the Microbial Degradation of Bromoxynil by Aerobic and Anaerobic Soil Enrichment Cultures

Authors: Knossow N, Siebner H, Bernstein A

Source: JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 68(6):1546-1554, 2020, DOI: 10.1021/acs.jafc.9b07653

**Abstract:** Bromoxynil is an increasingly applied nitrile herbicide. Under aerobic conditions, hydration, nitrilation, or hydroxylation of the nitrile group commonly occurs, whereas under anaerobic conditions reductive dehalogenation is common. This work studied the isotope effects associated with these processes by soil cultures. The aerobic soil enrichment culture presented a significant increase in Stenotrophomonas, Pseudomonas, Chryseobacterium, Achromobacter, Azospirillum, and Arcticibacter,
and degradation products indicated that nitrile hydratase was the dominant degradation route. The anaerobic culture was dominated by Proteobacteria and Firmicutes phyla with a significant increase in Dethiosulfatibacter, and degradation products indicated reductive debromination as a major degradation route. Distinct dual-isotope trends (delta C-13, delta N-15) were determined for the two routes: a strong inverse nitrogen isotope effect (epsilon(N) = 10.56 +/- 0.36 parts per thousand) and an insignificant carbon isotope effect (epsilon(C) = 0.37 +/- 0.36 parts per thousand) for the aerobic process versus a negligible effect for both elements in the anaerobic process. These trends differ from formerly reported trends for the photodegradation of bromoxynil and enable one to distinguish between the processes in the field.

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Effects of modified nanoscale carbon black on plant growth, root cellular morphogenesis, and microbial community in cadmium-contaminated soil

Authors: Cheng JM, Sun ZH, Li XR, Yu YQ

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020, DOI: 10.1007/s11356-020-08081-z

**Abstract:** Previous researches have confirmed that modified nanoscale carbon black (MCB) can decrease the bioavailability of heavy metals in soil and accumulation in plant tissues, resulting in the increase of biomass of plant. However, as a nanoparticle, the effects of MCB on plant cell morphology and microbial communities in Cd-contaminated soil are poorly understood. This study, through greenhouse experiments, investigated the effects of MCB as an amendment for 5 mg center dot kg(-1) Cd-contaminated soil on plant growth, plant cellular morphogenesis, and microbial communities. Two types of plants, metal-tolerant plant ryegrass (*Lolium multiflorum*), and hyperaccumulator plant chard (*Beta vulgaris* L. var. cicla) were selected. The results indicated that adding MCB to Cd-contaminated soil, the dry biomass of shoot ryegrass and chard increased by 1.07 and 1.05 times, respectively, comparing with control group (the treatment without MCB). Meanwhile, the

physiological characteristics of plant root denoted that adding MCB reduced the damage caused by Cd to plants. The acid phosphatase activity of soils treated with MCB was higher and the dehydrogenase activity was lower than control group during whole 50 days of incubation, while the urease and catalase activity of soils treated with MCB were higher than control group after 25 days of incubation. When compared with the treatment without MCB, the abundances of nitrogen-functional bacteria (Rhodospirillum and Nitrospira) and phosphorus-functional bacteria (Bradyrhizobium and Flavobacterium) increased but that of nitrogen-functional bacteria, Nitrososphaera, declined. The presence of MCB resulted in increased microbial community abundance by reducing the bioavailability of heavy metals in soil, while increasing the abundance of plants by increasing the amount of available nitrogen in soil. The result of this study suggests that MCB could be applied to the in-situ immobilization of heavy metal in contaminated soils because of its beneficial effects on plants growth, root cellular morphogenesis, and microbial community.

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Significance of soil microbe in microbial-assisted phytoremediation: an effective way to enhance phytoremediation of contaminated soil

Authors: Yang Y, Liu Y, Li Z, Wang Z, Li C, Wei H

Source: INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY 2020, DOI: 10.1007/s13762-020-02668-2

**Abstract:** Soil contamination is an increasing global problem. Efforts are underway to minimize the release of contaminants and develop effective bioremediation strategies. Contaminated soil can be treated by phytoremediation that is dependent on the contaminant and soil properties and plant growth rate. In recent decades, soil microbes have been used successfully to enhance the capacity of plants to tolerate, remove and/or degrade contaminants. This paper reviews the principles and applications of microbe-assisted phytoremediation, including the factors that influence phytoremediation, and the mechanisms
of microbial remediation. Inoculation with specific contaminant-degrading bacteria and plant growth-promoting rhizobacteria is effective in enhancing phytoremediation. However, in the context of serious and complicated cases of environmental pollution exacerbated by climate change, it is critical to increase the knowledge about the mechanisms of microbe-assisted phytoremediation to underpin the selection of most appropriate phytoremediation approaches.

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## Long-term effects of chlorothalonil on microbial denitrification and N2O emission in a tea field soil

Authors: Su XX, Wang YY, Peng GL, He Q

Source: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020, DOI: 10.1007/s11356-020-07679-7

**Abstract:** Pesticide chlorothalonil is widely applied in tea agroecosystem, potentially disturbing soil microbial-mediated nitrogen cycle. The underlying toxicity mechanism, however, is not well explored. Here, we investigated the long-term effects of chlorothalonil on soil microbial denitrification and N2O emission pattern in a tea field after 40 days of exposure. Results showed that chlorothalonil inhibited denitrification process but remarkably promoted N2O emission by 380-830%. Chlorothalonil significantly inhibited N2O reductase activity but did not affect nosZ abundance. Our results further revealed that chlorothalonil influenced soil denitrification by directly suppressing microbial electron transport system activity, and decreasing electron donor nicotinamide adenine dinucleotide (NADH) and energy source adenosine triphosphate (ATP) levels. Additionally, chlorothalonil also downregulated denitrifying functional genes (narG, nirS, and norB) and declined the relative abundances of potential denitrifiers (i.e., Pseudomonas and Streptomyces). Stepwise regression and path modeling suggested that nitrate reductase was the most significant factor in explaining denitrification rate under chlorothalonil applications. This study provides important information for revealing the chronic impacts of pesticide on tea soil denitrification and N2O emission on the basis of electron transport mechanism. Most significantly, N2O emission is

underestimated in chlorothalonil-treated soils, which suggests that future estimations of N2O emission from agricultural lands should take account of pesticide dependency conditions.

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## Soil exposed to silver nanoparticles reveals significant changes in community structure and altered microbial transcriptional profiles

Authors: Meier MJ, Dodge AE, Samarajeewa AD, Beaudette LA

Source: ENVIRONMENTAL POLLUTION 258, 2020, DOI: 10.1016/j.envpol.2019.113816

**Abstract:** Anthropogenic activities can disrupt soil ecosystems, normally resulting in reduced soil microbial health. Regulatory agencies need to determine the effects of uncharacterized substances on soil microbial health to establish the safety of these chemicals if they end up in the environment. Previous work has focused on measuring traditional ecotoxicological endpoints within the categories of microbial biomass, activity, and community structure/diversity. Because these tests can be labor intensive, lengthy to conduct, and cannot measure changes in individual gene functions, we wanted to establish whether metatranscriptomics could be used as a more sensitive endpoint and provide a perspective on community function that is more informative than taxonomic identification of microbes alone. We spiked a freshly collected sandy loam soil (Vulcan, Alberta, Canada) with 0, 60, 145, 347, 833, and 2000 mg kg(-1) of silver nanoparticles (AgNPs), a known antagonist of microorganisms due to its propensity for dissolution of toxic silver ions. Assessments performed in our previous work using traditional tests demonstrated the toxicity of AgNPs on soil microbial processes. We expanded this analysis with genomics-based tests by measuring changes in community taxonomic structure and function using 16S rDNA profiling and metatranscriptomics. In addition to identifying bacterial taxa affected by AgNPs, we found that genes involved in heavy metal resistance (e.g., the CzcA efflux pump) and other toxicity response pathways were highly upregulated in the presence of silver.
response analysis using BMDExpress2 software successfully modeled many physiologically relevant genes responding to low concentrations of AgNPs. We found that the transcriptomic point of departure (BMD50) was lower than the IC50s calculated using the traditional tests in our previous work. These results suggest that dose-response modeling of metatranscriptomic gene expression is a useful tool in soil microbial health assessment.

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# Arbuscular Mycorrhizal Fungi (AMF) from Heavy Metal-Contaminated Soils: Molecular Approach and Application in Phytoremediation

Authors: Kumar S, Saxena S

**Source:** BIOFERTILIZERS FOR SUSTAINABLE AGRICULTURE AND ENVIRONMENT, Edited by: Giri B, Prasad R, Wu QS, Varma A, Book Series: Soil Biology 55:489-500, 2019, DOI: 10.1007/978-3-030-18933-4_22

**Abstract:** Discharge of effluents from textile industry into river and agricultural land is one of the major global problems. The discharge of dye-containing effluents directly into the water makes it toxic for environment and living organisms. Currently available physical and chemical processes do not remove toxic chemicals, dyes, and detergents completely from the environment. It is now known that biological organisms like Arbuscular mycorrhizal fungi (AMF), in association with different plant species grown under contaminated soils, enhance uptake of heavy metals. However, very limited knowledge is available with community composition of tolerant mycorrhizal species/strains associated with heavy metal accumulator plants. Therefore, the present chapter deals with identification of novel approaches for diagnosis of mycorrhizal species from complex environmental soil. Furthermore, this chapter suggests more sustainable approaches for reclamation of heavy metals by AMF associated with the heavy metal accumulator plants.

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# Tolerance of dark septate endophytic fungi (DSE) to agrochemicals in vitro

Authors: Spagnoletti FN, Chiocchio VM

**Source:** REVISTA ARGENTINA DE MICROBIOLOGIA
52(1):43-49, 2020, DOI:
10.1016/j.ram.2019.02.003

**Abstract:** Dark septate endophytes (DSE) are a heterogeneous group of fungi, mostly belonging to the Phylum Ascomycota, that are involved in a mutualistic symbiosis with plant roots. The aim of this study is to evaluate the behavior of two strains of DSE isolated from wheat roots of two cropping areas in the province of Buenos Aires, Argentina, against some agrochemicals. Of all the isolates obtained, two strains were identified as *Alternaria alternata* and *Cochliobolus* sp. These DSE were found to be tolerant to glyphosate, carbendazim and cypermethrin when evaluated at the recommended agronomic dose (AD), 2 AD and, in some cases, 10 AD. This work contributes to the study of the biology of this group of fungi and their tolerance in the presence of xenobiotics widely used in agriculture.

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# Temporal effects of repeated application of biogas slurry on soil antibiotic resistance genes and their potential bacterial hosts

Authors: Liu C, Chen YX, Li XH, Zhang YR... more

**Source:** ENVIRONMENTAL POLLUTION, 258, 2020, DOI: 10.1016/j.envpol.2019.113652

**Abstract:** Biogas slurry, a liquid end product of animal manure fermentation, is widely used as fertilizer in crop fields. Land application may introduce antibiotics and related resistance genes from livestock production into agricultural soil. Nevertheless, changes in antimicrobial resistance in soil where biogas slurry has been repeatedly applied are not fully understood. In the present study, 13 veterinary antibiotics were analyzed in soils that were repeatedly sprayed with biogas slurry, and simultaneously, temporal changes in antibiotic resistance genes (ARGs) and bacterial
community composition were investigated using a real-time quantitative PCR assay and MiSeq sequencing. Long-term repeated application of biogas slurry did not result in excessive accumulation of antibiotic residuals in the soil but increased the abundance of ARGs and facilitated ARG transfer among potential hosts. Although the quantitative PCR assay showed a decreasing trend for the relative abundance of ARGs over time, a relevance network analysis revealed highly complex bacteria-ARG co-occurrence after long-term application, which implied that repeated application might intensify horizontal gene transfer (HGT) of ARGs among different bacterial hosts in soil. The increased relative abundance of the intI1 gene supported the shift in ARG-bacteria co-occurrence. Furthermore, ordination analysis showed that the distributions of antibiotic resistance bacteria (ARB) and ARGs were closely related to application duration than to the influence of antibiotic residuals in the biogas slurry-treated soil environment. Additionally, natural level of ARG abundance in untreated soils indirectly suggested the presence/absence of antibiotics was not a key determinant causing the spread of antimicrobial resistance. This study provides improved insight into the effects of long-term repeated application of biogas slurry on the shift in ARG abundances and bacteria-ARG co-occurrence in soils, highlighting the need to focus on the influence of changed soil environment on the ARG transfer.

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## Evaluation of degradation of a novel sulfone bactericide in soils: identification of degradation product and kinetics study

**Authors:** Meng XG, Long XF, Wang N, Pan SZ... more

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY 17(2):891-902, 2020, DOI: 10.1007/s13762-019-02523-z

**Abstract:** Fubianezuofeng is a novel bactericide that shows good inhibitory activity on rice bacterial leaf streak and leaf blight. In this study, the probable influencing factors such as light, soil moisture, soil types, temperature, soil

sterilization, and soil organic matter on this bactericide degradation were investigated. The results showed that the degradation experiments of Fubianezuofeng follow the first-order kinetics equation. The rate of degradation was remarkably affected by the types of soil with the degradation half-life t(1/2) 3.89, 5.21, 4.56, 7.22, 213.05, and 137.29 h for Tianjin, Hefei, Guiyang, Nanning, Harbin, and Changsha soils, respectively. The high moisture and increased temperature can accelerate its degradation rate in soil. Moreover, the degradation rate was faster under non-sterilized condition (t(1/2) 9.24 days) than under sterilized condition (t(1/2) 31.51 days) and removed organic matter from soil (t(1/2) 57.76 days). And the degradation under ultraviolet light (t(1/2) 0.47 days) was the fastest followed by xenon light (t(1/2) 5.42 days) and dark condition (t(1/2) 9.24 days). Finally, the major degradation product, named 2-(4-fluorobenzyl)-5-methoxy-1,3,4-oxadiazole, was identified by ultra-high-performance liquid chromatography equipped with high-resolution mass spectrometry, and the probable mechanism and degradation pathway of FBEZF under the present experimental conditions were proposed in soil. This research can be helpful for the security evaluation of FBEZF and provide some useful data for further investigations and developments on sulfone pesticides in the agricultural and environmental field. Graphic abstract

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## Inoculation with abscisic acid (ABA)-catabolizing bacteria can improve phytoextraction of heavy metal in contaminated soil

**Authors:** Lu Q, Weng YN, You Y, Xu QR, Li HY... more

**Source:** ENVIRONMENTAL POLLUTION 257, 2020, DOI: 10.1016/j.envpol.2019.113497

**Abstract:** Promotion of plant capacity for accumulation of heavy metals (HMs) is one of the key strategies in enhancing phytoremediation in contaminated soils. Here we report that, *Rhodococcus qingshengii*, an abscisic acid (ABA)-catabolizing bacteria, clearly boosts levels of Cd, Zn, and Ni in wild-type Arabidopsis by 47, 24, and 30%, respectively, but no increase in Cu was
noted, when compared with non-inoculated Arabidopsis plants in contaminated growth substrate. Furthermore, when compared with wild-type plants, *R.qingshengii*-induced increases in Cd, Zn, and Ni concentrations were more pronounced in abi1/hab1/abi2 (ABA-sensitive mutant) strains of Arabidopsis, whereas little effect was observed in snrk2.2/2.3 (ABA insensitive mutant). This demonstrates that metabolizing ABA might be indispensable for R. qingshengii to improve metal accumulation in plants. Bacterial inoculation significantly elevated the expression of Cd, Zn, and Ni-related transporters; whereas the transcript levels of Cu transporters remained unchanged. This result may be a reasonable explanation for why the uptake of Cd, Zn, and Ni in plants was stimulated by bacterial inoculation, while no effect was observed on Cu levels. From our results, we clearly demonstrate that *It qingshengii* can increase the accumulation of Cd, Zn, and Ni in plants via an ABA-mediated HM transporters-associated mechanism. Metabolizing ABA in the plants by ABA-catabolizing bacterial inoculation might be an alternative strategy to improve phytoremediation efficiency in HMs contaminated soil.

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## Bioremediation of Oxamyl Compounds by Algae: Description and Traits of Root-Knot Nematode Control

**Authors:** El-Ansary MSM, Hamouda RAF, Ahmed-Farid OA

**Source:** WASTE AND BIOMASS VALORIZATION, 2020, DOI: 10.1007/s12649-020-00950-5

**Abstract:** Safety of environment and human health has newly become crucial factors when selecting crops production programs. With regard to nematicides, oxamyl is a systematic nematicide widely used for the control of soil nematodes. Accelerated biodegradation of the oxamyl, utilized at the recommended dose in soil cultured by banana plants and coupled with root-knot nematode (RKN, Meloidogyne incognita), was observed using algal bioassay studies. However, algae play an important role in maintaining micro and macro elements availability, plant biochemical process, nitrogen fixation, photosynthesis and rebate the harmful effect of

pesticides through degradation. For this reason, algae such as: *Chlorella vulgaris*, *Scenedesmus obliquus*, *Anabaena oryza* and *Nostoc muscorum* have been used to determine the degradability enhancement of oxamyl by an accelerated biodegradation process. All oxamyl-degrading species showed a highly effective to enhance biodegradation of oxamyl compound. Memorable, the alga *S. obliquus* was the most successful one for oxamyl degradation that denoted by the least residue in plant was 25% and oxamyl degradation in untreated soil by algae was 100% and had an active promoting effect on plant health. Unlike, the incorporated application of alga, *C. vulgaris* was the most successful action in diminishing the nematode, juveniles2 count in soil (57.55%) and galls count on roots (52.87%).

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## The toxic factor of copper should be adjusted during the ecological risk assessment for soil bacterial community

**Authors:** Chen JW, Zhang H, Li JJ, Liu Y... more

**Source:** ECOLOGICAL INDICATORS, 111, 2020, DOI: 10.1016/j.ecolind.2020.106072

**Abstract:** The toxic factor (TF) is a key parameter commonly used to evaluate the potential ecological risk index (RI) of heavy metals. However, it remains largely unknown whether this traditional TF is applicable to the ecological risk assessment of heavy metal to soil microorganisms, which are essential to ecological functions and ecosystem sustainability. Here, based on the TF values of 5 and 30 for copper (Cu) and cadmium (Cd), respectively, we constructed soil microcosms to establish a gradient of ecological risk levels, and different combinations of Cu and Cd concentrations were used at each ecological risk level. We found that bacterial abundance and functional diversity significantly decreased and the metal resistance gene (MRG) abundances increased with the increasing RI level. At the same RI level, the bacterial abundance and functional diversity decreased while MRG abundances increased with increasing Cu concentrations, suggesting that the ecological risk to soil bacterial community was more relevant to Cu, rather than Cd. The traditional TF of Cu used to calculate the RI might be underestimated if it is used for evaluation of the risk to soil bacteria. Our
calibration analysis revealed that the TF of Cu should be adjusted to 6 during the assessment of the RI for soil bacterial community in heavy-metal contaminated area.

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## Amelioration of chromium and heat stresses in Sorghum bicolor by Cr6+ reducing-thermotolerant plant growth promoting bacteria

**Authors:** Bruno LB, Karthik C, Ma Y, Kadirvelu K... more

**Source:** CHEMOSPHERE 244, 2020, DOI: 10.1016/j.chemosphere.2019.125521

**Abstract:** Climatic factors particularly increased atmospheric temperature (IAT) greatly alters plant microbe and heavy metal interactions and subsequently reduces plant growth and phytoremediation efficiency. The aim of the study was to assess the effects of inoculation of chromium reducing-thermotolerant plant growth promoting bacteria (CRT-PGPB) on plant growth, physiological responses and chromium (Cr) uptake by Sorghum bicolor under IAT condition. Three potential CRT-PGPB strains were isolated from Cr contaminated sites and identified as Bacillus cereus TCR17, Providencia rettgeri TCR21 and Myroides odoratimimus TCR22 through molecular characterization. These strains displayed the potential to reduce Cr6+ to Cr3+, produce siderophores, indole-3-acetic acid and solubilize phosphate. Inoculation of S. bicolor with CRT-PGPB increased plant growth, antioxidant status (superoxide dismutase, catalase and ascorbate peroxidase) and decreased proline and malondialdehyde contents in plants under Cr, IAT and Cr + IAT stress indicate that PGPB helped plants to reduce stress induced oxidative damage. Irrespective of IAT stress, inoculation of CRT-PGPB decreased the accumulation of Cr in plants compared with uninoculated control suggest that CRT-PGPB might have the potential to improve phytostabilization process in Cr contaminated soils. Furthermore, gene expression studies confirmed that inoculation of TCR21 down-regulated the expression of proline synthesis gene (p5cs1) and up-regulated the expression of antioxidant related genes (sod, apx1 and cat) and stress tolerance genes (SHsp). Our results showed

that CRT-PGPB exhibiting potential to tolerate Cr, temperature, produce plant beneficial metabolites and reduce Cr6+ to Cr3+, can be exploited as potential inoculants for improving plant growth and phytoremediation process in Cr contaminated soil under IAT condition.

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## Microbial diversity in soils from antimony mining sites: geochemical control promotes species enrichment

**Authors:** Deng RJ, Tang ZE, Hou BL, Ren BZ... more

**Source:** ENVIRONMENTAL CHEMISTRY LETTERS 2020, DOI: 10.1007/s10311-020-00975-1

**Abstract:** Elevated soil concentrations of antimony (Sb) and co-contaminants are frequently encountered where antimony has been mined on a large scale. For instance, the Xikuangshan antimony mine in central South China has sustained, over many centuries, dispersed and spatially variable input of toxic elements into the soil ecosystem. We utilized this unique environment to assess the impact of geochemical conditions on soil microbiology. Geochemical conditions were assessed by monitoring absolute and available fractions of toxic elements and disrupted soil properties. Soil microbiology was studied by high-throughput sequencing and statistical analysis, including principle component analysis and canonical correspondence analysis. Results show that Sb concentrations were ranged from 970 to more than 24,000 mg/kg. As concentrations were three times higher than the regional background values and ten times higher for Pb, 590 times higher for Cd and 30 times higher for Hg. About 5-10% of the total soil Sb was environmentally mobile. Microbial diversity was high, and soil properties such as pH, organic matter, iron and sulfate controlled the absolute microbial activity. We identified strong positive and negative correlations with specific bacterial taxonomic groups which show: (1) an intolerance of available fractions for all elements, e.g., Gemmatimonas, Pirellula, Spartobacteria; (2) a good tolerance of available fractions for all elements, e.g., Povalibacter, Spartobacteria; and (3) a mixed response, tolerating available Sb, Hg and Cd and inhibition by As, Pb, e.g., Escherichia/Shigella and Arthrobacter, and in
reverse, e.g., Gemmatimonas and Sphingomonas. The site hosts great diversity dominated by Gram-negative organisms, many with rod (bacillus) morphologies but also some filamentous forms, and a wide range of metabolic capabilities: anaerobes, e.g., Saccharibacteria, metal oxidizing, e.g., Geobacter, chemoautotrophs, e.g., Gemmata, and sulfur reducing, e.g., Desulfuromonas. The bioremediation potential of Arthrobacter and Escherichia/Shigella for Sb control is highlighted.

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## Effective bioremediation of heavy metal-contaminated landfill soil through bioaugmentation using consortia of fungi

**Authors:** Hassan A, Periathamby A, Ahmed A... more

**Source:** JOURNAL OF SOILS AND SEDIMENTS 20(1):66-80, 2020, DOI: 10.1007/s11368-019-02394-4

**Abstract:** Purpose Heavy metals' contamination of soil is a serious concern as far as public health and environmental protection are concerned. As a result of their persistent and toxic properties, heavy metals need to be removed from contaminated environments using an efficient technology. This study is aimed to determine the heavy metals' (Ni, Pb, and Zn) bioremoval capacity of consortia of filamentous fungi from landfill leachate-contaminated soil.

**Materials and methods** Three different groups of consortia of fungi, namely all isolated fungi, Ascomycota, and Basidiomycota, were employed for the bioremediation of the contaminated soil. A total of thirteen fungal species were used to make up the three consortia. The setup was kept for 100 days during which regular watering was carried out. Soil subsamples were collected at day 20, day 60, and 100 for monitoring of heavy metal concentration, fungal growth, and other physicochemical parameters.

**Results and discussion** Highest tolerance index of 1.0 was recorded towards Ni and Zn concentrations. The maximum metal bioremoval efficiency was observed for soil bioaugmented with the all isolated fungi for Ni and Pb with the

removal efficiencies as 52% and 44% respectively. However, 36% was realized as the maximum removal for Zn, and was for Ascomycota consortium-treated soil. The order for the heavymetal removal for Ni and Pb is all isolated fungi > Basidiomycota > Ascomycota, while for Zn is Basidiomycota > all isolated fungi > Ascomycota. Spectra analysis revealed the presence of peaks (1485-1445 cm(-1)) only in the consortia-treated soil which corresponded to the bending of the C-H bond which signifies the presence of methylene group.

Conclusions Soil treated using bioaugmentation had the best heavy metal removal as compared to that of the control. This suggests the contribution of fungal bioaugmentation in the decontamination of heavy metal-contaminated soil.

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## Azoxystrobin dissipation and its effect on soil microbial community structure and function in the presence of chlorothalonil, chlortetracycline and ciprofloxacin

**Authors:** Han LX, Liu YL, Fang K, Zhang XL, Liu T... more

**Source:** ENVIRONMENTAL POLLUTION 257, 2020, DOI: 10.1016/j.envpol.2019.113578

**Abstract:** The residual characteristics and the adsorption-desorption behaviors of azoxystrobin (AZO) as well as the soil ecological effects in the individual repeated treatments of AZO and its combination with chlorothalonil (CTL), chlortetracycline (CTC) and ciprofloxacin (CIP) were systematically studied in organic manure (OM)-amended soil under laboratory conditions. The presence of CTL, CTC, and CIP, both individually and combined, decreased the sorption affinity of AZO with the Freundlich adsorption and desorption coefficient decreasing by 0.3-24.2%, and CTC and CIP exhibited greater adverse effects than CTL. AZO dissipated slowly and the residues significantly accumulated during ten repeated treatments. The dissipation of AZO was inhibited to different degrees in the combined treatments. Biolog analysis revealed that the soil microbial functional diversity in the
OM-soil + AZO and OM-soil + AZO + CTL treatments was higher than that in the OM-soil treatment during the former three repeated treatments, but which was inhibited during the latter seven repeated treatments. The soil microbial functional diversity in the OM-soil + AZO + CTC, OM-soil + AZO + CIP and OM-soil + AZO + CTL + CTC + CIP treatments was inhibited during the ten repeated treatments compared with OM-soil treatment. Metagenomic results showed that all repeated treatments significantly increased the relative abundance of Actinobacteria, but significantly decreased that of Proteobacteria and Firmicutes during the ten repeated treatments. Furthermore, the relative abundance of soil dominant bacterial genera Rhodococcus, Mycobacterium and Arthrobacter in all the repeated treatments significantly increased by 1.5-1283.9% compared with the OM-soil treatment. It is concluded that coexistence of CTL, CTC and CIP, both individually and combined, with AZO can inhibit the dissipation of AZO, reduce the adsorption affinity of AZO on soil, and alter the soil microbial community structure and functional diversity.

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Metal-Tolerant Fungal Communities Are Delineated by High Zinc, Lead, and Copper Concentrations in Metalliferous Gobi Desert Soils

**Authors:** Kerfahi D, Ogwu MC, Ariunzaya D... more

**Source:** MICROBIAL ECOLOGY 79(2):420-431, 2020, DOI: 10.1007/s00248-019-01405-8

**Abstract:** The soil fungal ecology of the southern Gobi region of Mongolia has been little studied. We utilized the ITS1 region from soil DNA to study

possible influences soil metal concentrations on soil fungal community variation. In the sample network, a distinctive fungal community was closely associated with high zinc (Zn), lead (Pb), and copper (Cu) concentrations. The pattern of occurrence suggests that high metal concentrations are natural and not a product of mining activities. The metal-associated fungal community differs little from the "normal" community in its major OTUs, and in terms of major fungal guilds and taxa, and its distinctiveness depends on a combination of many less common OTUs. The fungal community in the sites with high metal concentrations is no less diverse than that in areas with normal background levels. Overall, these findings raise interesting questions of the evolutionary origin and functional characteristics of this apparently "metal-tolerant" community, and of the associated soil biota in general. It is possible that rehabilitation of metal-contaminated mined soils from spoil heaps could benefit from the incorporation of fungi derived from these areas.

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Short-term application of mulch, roundup and organic herbicides did not affect soil microbial biomass or bacterial and fungal diversity

**Authors:** Bottrill D, Ogbourne SM, Citerne N, Smith T... more

**Source:** CHEMOSPHERE 244, 2020, DOI: 10.1016/j.chemosphere.2019.125436

**Abstract:** Application of synthetic herbicides is currently the most widely used and cost-effective methods to assist with revegetation programs. However, the effects of short-term application of herbicides such as Roundup, acetic acid, BioWeed (TM) and Slasher (R) as compared with mulch, on soil microbial biomass and microbial diversity remain unknown. This study examined the effects of short-term herbicide application on soil microbial biomass, C:N ratio, and fungal and bacterial communities at months 2 and 8 following initiation of treatment application. No effects of treatments on soil pH, C:N and microbial biomass were found. No segregation among treatments in the community structure of bacteria and fungi was observed. However, the fungal phylum
Basidiomycota had one unidentified class, which was only found in the mulch treatment, suggesting the C quality in the mulch treatment may differ compared with the other treatments. The dry and hot conditions experienced throughout the study period may have resulted in fast degradation of the herbicides and may have minimised the impacts of the herbicides on microbial diversity and community structure. Given that the research was undertaken at a single site and over only a short time frame, the results should be extrapolated with caution. Herbicides may have greater impact with long-term use. Future research will need to assess the revegetation success of each treatment and determine if the observed change in Basidiomycota profile and C quality identified in this study becomes significant over the long-term. We hypothesise that mulching may be a preferred treatment to facilitate weed control in riparian zone revegetation.

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## Design of a degenerate primer pair to target a bacterial functional community: The hppd bacterial gene coding for the enzyme targeted by herbicides, a study case

**Authors:** Thiour-Mauprivez C, Devers-Lamrani M, Mounier A, Beguet J, Spor A, Calvayrac C, Barthelmebs L, Martin-Laurent

**Source:** JOURNAL OF MICROBIOLOGICAL METHODS 170, 2020, DOI: 10.1016/j.mimet.2020.105839

**Abstract:** The present work aimed to design a degenerate primer pair to target a large part of the hppd soil bacterial community, possibly affected by herbicides. We validated these primers by qPCR and high-throughput sequencing analysis of soil samples.

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## Study on degradation of chlorpyrifos-methyl and utilization of chlorpyrifos-methyl drading vacterium, *Bacillus vallismortis* CM-11

**Authors:** Zhu JW, Meng ZL, Zhao Y

**Source:** FRESENIUS ENVIRONMENTAL BULLETIN 29(3):1316-1321, 2020

**Abstract:** A strain CM-11 capable of highly degrading chlorpyrifos-methyl was isolated from soil. The strain CM-11 was identified as *Bacillus vallismortis* based on 16S rRNA and analysis of morphology, physiological and biochemical characters. The optimal pH value and temperature were 6.8-7.2 and 30-35 square. The 6d degradation rate of 100 mg/L chlorpyrifos-methyl by strain CM-11 was at about 99.6% in inorganic salt medium. The strain CM-11 could hydrolyze chlorpyrifos-methyl to 3,5,6-trichloro-2-pyridinol (TCP), but it could only slowly degrade TCP. The combined applications of the strain CM-11 and the strain TBE-6 was considered an effective means for degrading chlorpyrifos-methyl, because the strain TBE-6 could rapidly degrade TCP. The degradation rate of chlorpyrifos-methyl (100mg/L) by the strain CM-11 and the strain TBE-6 could reach about 100% in 5d. This study may provide theoretic basis and reference for prevention and control of pesticides pollution.

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## Temporal dynamics of earthworm (*Eisenia fetida*) microbial communities after cadmium stress based on a compound mathematical model

**Authors:** Ning YC, Zhou HR, Wang SB... more

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020, DOI: 10.1007/s11356-020-08122-7

**Abstract:** Soil cadmium (Cd) pollution has received increasing attention from scholars. In the field of Cd pollution remediation, there is an urgent need to study the combined bioremediation technology of earthworms and
microbes. (...) After different Cd stress times, the regulation process between the microbial communities in the earthworms and in the soil was studied. Canonical correlation analysis and the TOPSIS method were combined to establish a mathematical model for data analysis, and the changes in the carbon source utilization intensity by microbes were analysed. The results showed that in the short-term stress tests, the regulation process could be divided into five stages. Specifically, after 1-3 days of stress, the microbial community in the earthworms regulated the soil microbial community, but on the 3rd day, the regulation was weakened. On the 4th day, the soil microbial community was affected not only by the microbes in the earthworms but also by the increasing intensity of Cd stress. After 5 days of stress, the microbial communities in the earthworms and the soil were both greatly affected by Cd poisoning, and the microbes transitioned from stable to declining. At 6-7 days, the microbes in the earthworms gained control over those in the soil once again, and the Cd-tolerant microbes began to appear and proliferate. At 8-10 days, the regulation of the soil microbes by the earthworm microbes weakened, while the Cd-tolerant population in the soil microbial communities gradually evolved at this stage to adapt to the increasing Cd stress. The long-term stress tests showed that the difference between the microbial communities in the soil and in the earthworms increased, and there was almost no regulation between them.

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## Mercury alters the rhizobacterial community in Brazilian wetlands and it can be bioremediated by the plant-bacteria association

**Authors:** Mariano C, Mello IS, Barros BM... more

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020, DOI:10.1007/s11356-020-07913-2

**Abstract:** This study examined how soil mercury contamination affected the structure and functionality of rhizobacteria communities from *Aeschynomene fluminensis* and *Polygonum acuminatum* and how rhizobacteria mediate metal bioremediation. The strains were isolated

using culture-dependent methods, identified through 16S rDNA gene sequencing, and characterized with respect to their functional traits related to plant growth promotion and resistance to metals and antibiotics. The bioremediation capacity of the rhizobacteria was determined in greenhouse using corn plants. The isolated bacteria belonged to the phyla *Actinobacteria*, *Deinococcus-Thermus*, *Firmicutes*, and *Proteobacteria*, with great abundance of the species *Microbacterium trichothecenolyticum*. The rhizobacteria abundance, richness, and diversity were greater in mercury-contaminated soils. Bacteria isolated from contaminated environments had higher minimum inhibitory concentration values, presented plasmids and the merA gene, and were multi-resistant to metals and antibiotics. *Enterobacter* sp. C35 and M. trichothecenolyticum_C34 significantly improved (Dunnett's test, p < 0.05) corn plant growth in mercury-contaminated soil. These bacteria helped to reduce up to 87% of the mercury content in the soil, and increased the mercury bioaccumulation factor by up to 94%. Mercury bioremediation mitigated toxicity of the contaminated substrate. *Enterobacter* sp. C35, *Bacillus megaterium* C28, and *Bacillus mycoides* C1 stimulated corn plant growth and could be added to biofertilizers produced in research and related industries.

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## Heavy metals, antibiotics and nutrients affect the bacterial community and resistance genes in chicken manure composting and fertilized soil

**Authors:** Deng WW, Zhang AY, Chen SJ... more

**Source:** JOURNAL OF ENVIRONMENTAL MANAGEMENT Volume: 257, 2020, DOI: 10.1016/j.jenvman.2019.109980

**Abstract:** Succession of bacterial communities involved in the composting process of chicken manure, including first composting (FC), second composting (SC) and fertilizer product (Pd) and fertilized soil (FS), and their associations with nutrients, heavy metals, antibiotics and antibiotic resistance genes (ARGs) were investigated.
Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant phyla observed during composting. Overall, potential pathogenic bacteria decreased from 37.18% (FC) to 3.43% (Pd) and potential probiotic taxa increased from 5.77% (FC) to 7.12% (Pd). Concentrations of heavy metals increased after second composting (SC), however, no significant differences were observed between FS and CS groups. Alpha diversities of bacterial communities showed significant correlation with heavy metals and nutrients. All investigated antibiotics decreased significantly after the composting process. The certain antibiotics, heavy metals, or nutrients was significantly positive correlated with the abundance of ARGs, highlighting that they can directly or indirectly influence persistence of ARGs. Overall, results indicated that the composting process is effective for reducing potential pathogenic bacteria, antibiotics and ARGs. The application of compost lead to a decrease in pathogens and ARGs, as well as an increase in potentially beneficial taxa and nutrients in soil.

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## The combined effects of treated wastewater irrigation and plastic mulch cover on soil and crop microbial communities

**Authors:** Obayomi O, Edelstein M, Safi J, Mihiret M... more

**Source:** BIOLOGY AND FERTILITY OF SOILS 2020, DOI: 10.1007/s00374-020-01442-3

**Abstract:** Global water scarcity necessitates the use of treated wastewater (TWW) for various purposes, including agricultural irrigation, yet this water may introduce various contaminants to the soil and crops. Therefore, application of TWW irrigation was sanctioned by barriers (drip irrigation and plastic mulch) to reduce risks to consumers; however, barriers' effect on soil

health is controversial. We hypothesized that the combination of TWW irrigation with plastic mulch barrier would alter the soil microbial community (bacteria and protists), while TWW irrigation alone would have a negligible effect. To test our hypothesis, we compared the response of soil and crop (cucumbers and melons) microbiomes to water qualities (TWW and potable water (PW) applied by drip irrigation in combination with plastic mulch during two growing seasons. The abundance, diversity, composition, and predicted functions of the water, soil, and crop microbial communities were analyzed in 230 samples, concomitant to monitoring the physicochemical parameters. TWW had significantly higher nutrients and salinity than PW but did not differ in pH. TWW-irrigated soils were significantly more saline than PW-irrigated soils, particularly under plastic cover, but all other physiochemical parameters were similar. The microbial communities significantly differed between water qualities, yet these differences did not carry to the irrigated soils or crops, regardless of the use of plastic mulch. Moreover, limited migration was detected between communities in the different matrices. Our results imply that short-term irrigation with TWW and the use of plastic mulch has negligible impact on soil and crop microbiomes.

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## Do combined nanoscale polystyrene and tetracycline impact on the incidence of resistance genes and microbial community disturbance in *Enchytraeus crypticus*?

**Authors:** Ma J, Sheng GD, Chen QL, O'Connor P

**Source:** JOURNAL OF HAZARDOUS MATERIALS
Volume: 387, 2020, DOI: 10.1016/j.jhazmat.2019.122012

**Abstract:** It has been proved that nanoplastics can effectively adsorb pollutants and thus influence their behavior and availability. The combined toxic effects of nanoplastic and its adsorbed pollutant on the soil fauna are still not well known. We used high-throughput quantitative PCR
to explore the effects of oral nanoscale polystyrene and tetracycline exposure on antibiotic resistance genes in the soil invertebrate *Enchytraeus crypticus*, and used bacterial 16S rRNA gene amplification sequencing to examine the response of the microbiome of *E. crypticus*. After 14 days of tetracycline and nanoscale polystyrene exposure, we terminated exposure and monitored the restoration of ARGs and microbiome in the *E. crypticus*. Results showed that the number of ARGs, especially macrolide-lincosamide-streptogramin B (MLSB), tetracycline ARGs, as well as multidrug ARGs, increased with exposure to nanoscale polystyrene and tetracycline. The abundance of Aminoglycoside and Beta_Lactamase ARGs in *E. crypticus* also significantly increased. The exposure significantly perturbed the abundance of families Microbacteriaceae, Streptococcaceae, Enterobacteriaceae, Rhodocyclaceae and Sphinomonadaceae. After terminating exposure for 14 days, the diversity and abundance of ARGs were not completely restored, while the microbiome was not permanently changed but reversibly impacted.

Microbial and Viral Communities and Their Antibiotic Resistance Genes Throughout a Hospital Wastewater Treatment System

**Authors:** Petrovich ML, Zilberman, Kaplan A, Eliraz GR, Wang YB, Langenfeld K, Duhaime M, Wigginton K, Poretsky R, Avisar D... more

**Source:** FRONTIERS IN MICROBIOLOGY 11, 2020, DOI: 10.3389/fmicb.2020.00153

**Abstract:** Antibiotic resistance poses a serious threat to global public health, and antibiotic resistance determinants can enter natural aquatic systems through discharge of wastewater effluents. Hospital wastewater in particular is expected to contain high abundances of antibiotic resistance genes (ARGs) compared to municipal

wastewater because it contains human enteric bacteria that may include antibiotic-resistant organisms originating from hospital patients, and can also have high concentrations of antibiotics and antimicrobials relative to municipal wastewater. Viruses also play an important role in wastewater treatment systems since they can influence the bacterial community composition through killing bacteria, facilitating transduction of genetic material between organisms, and modifying the chromosomal content of bacteria as prophages. However, little is known about the fate and connections between ARGs, viruses, and their associated bacteria in hospital wastewater systems. To address this knowledge gap, we characterized the composition and persistence of ARGs, dsDNA viruses, and bacteria from influent to effluent in a pilot-scale hospital wastewater treatment system in Israel using shotgun metagenomics. Results showed that ARGs, including genes conferring resistance to antibiotics of high clinical relevance, were detected in all sampling locations throughout the pilot-scale system, with only 16% overall depletion of ARGs per genome equivalent between influent and effluent. The most common classes of ARGs detected throughout the system conferred resistance to aminoglycoside, cephalosporin, macrolide, penam, and tetracycline antibiotics. A greater proportion of total ARGs were associated with plasmid-associated genes in effluent compared to in influent. No strong associations between viral sequences and ARGs were identified in viral metagenomes from the system, suggesting that phage may not be a significant vector for ARG transfer in this system. The majority of viruses in the pilot-scale system belonged to the families Myoviridae, Podoviridae, and Siphoviridae. Gammaproteobacteria was the dominant class of bacteria harboring ARGs and the most common putative viral host in all samples, followed by Bacilli and Betaproteobacteria. In the total bacterial community, the dominant class was Betaproteobacteria for each sample. Overall, we found that a variety of different types of ARGs and viruses were persistent throughout this hospital wastewater treatment system, which can be released to the environment through effluent discharge.

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Rhizoremediation of Cu(II) ions from contaminated soil
## using plant growth promoting bacteria: an outlook on pyrolysis conditions on plant residues for methylene orange dye biosorption

**Authors:** Yaashikaa PR, Kumar PS, Varjani S, Saravanan A

**Source:** BIOENGINEERED 11(1):175-187, 2020, DOI: 10.1080/21655979.2020.1728034

**Abstract:** Rhizoremediation is one of the most accepted, cost-effective bioremediation techniques focusing on the application of rhizospheric microorganisms in combination with plants for the remediation of organic and inorganic pollutants from the contaminated sites. This work focuses on isolation and identification of metal resistant bacteria to grow on medium with the copper ion concentration of 1500 mg/L. The resistant isolate was identified as *Pantoea dispersa* by a 16S rRNA sequencing. The bioaccumulation of Cu(II) ions in plant is high at the concentration of Cu(II) ion is 125 mg/L in soil. In *Sphaeranthus indicus* the Cu(II) ion translocation factor has expanded with an expansion of grouping of Cu(II) ion in the soil and the most extreme TF factor was acquired at the centralization of Cu(II) ion is 150 mg/L in soil. Surface morphology of biochar was characterized by Scanning Electron Microscopy (SEM) analysis. The adsorption performance of biochar (Sphaeranthus indicus biomass) and mechanism for the removal of Cu(II) ion were investigated. This study resolves that pyrolysis is promising technology for the conversion of metal ion contaminated plant residues from phytoremediation into valuable products.

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## Isolation of urease-producing bacteria and their effects on reducing Cd and Pb accumulation in lettuce (Lactuca sativa L.)

**Authors:** Wang TJ, Wang SL, Tang XC, Fan XP, Yang S, Yao LG, Li YD, Han H

**Source:** ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 27(8):8707-8718, 2020, DOI: 10.1007/s11356-019-06957-3

**Abstract:** Excess Cd and Pb in agricultural soils enter the food chain and adversely affect all organisms. Therefore, it is important to find an eco-friendly way to reduce heavy metal accumulation in vegetables. We used urea agar plates to isolate urease-producing bacteria from the rhizosphere soil of lettuce in Cd- and Pb-contaminated farmland and investigated their ability to produce urease and immobilize heavy metals. The effects of these strains on the biomass, quality, and Cd and Pb accumulation of lettuce were also studied. The results showed that two urease-producing bacteria, *Enterobacter bugandensis* TJ6 and *Bacillus megaterium* HD8, were screened from the rhizosphere soil of lettuce. They had a high ability to produce urease (44.5 mS cm(-1) min(-1) OD600-1 and 54.2 mS cm(-1) min(-1) OD600-1, respectively) and IAA (303 mg L-1 and 387 mg L-1, respectively). Compared with the control, inoculation with strains TJ6 and HD8 reduced the Cd (75.3-85.8%) and Pb (74.8-87.2%) concentrations and increased the pH (from 6.92 to 8.13-8.53) in solution. A hydroponic experiment showed that the two strains increased the biomass (31.3-55.2%), improved the quality (28.6-52.6% for the soluble protein content and 34.8-88.4% for the vitamin C (Vc) content), and reduced the Cd (25.6-68.9%) and Pb (48.7-78.8%) contents of lettuce shoots (edible tissue). In addition, strain HD8 had a greater ability than strain TJ6 to reduce lettuce Cd and Pb uptake and water-soluble Cd and Pb levels in solution. These data show that the urease-producing bacteria protect lettuce against Cd and Pb toxicity by extracellular adsorption, Cd and Pb immobilization, and increased pH. The effects of heavy metal immobilization by the two strains can guarantee vegetable safety in situ for the bioremediation of heavy metal-polluted farmland.

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## Uranium tolerant phosphate solubilizing bacteria isolated from Gogi, a proposed uranium mining site in South India
**Authors:** Sowmya S, Rekha PD, Yashodhara I, Karunakara N, Arun AB

**Source:** APPLIED GEOCHEMISTRY 114, 2020, DOI: 10.1016/j.apgeochem.2020.104523

**Abstract:** Remediation of uranium contamination presents a significant environmental problem worldwide. Bioremediation has gained increasing importance as a feasible and eco-friendly strategy. Uranium tolerant phosphate solubilizing bacteria are considered as important candidates in the development of bioremediation technology. In this context, we have isolated bacteria from a proposed uranium mining site, Gogi in the Bhima river belt of Karnataka (South India) with special reference to phosphate solubilizers. Out of 270 bacteria isolated, 14 isolates solubilized 148.5-1226.6 mgL(-1) phosphate from 5 g L-1 tri-calcium phosphate accompanied by drop in media pH from an initial 6.9 to pH values between 3.9 and 6.3. Phylogenetic analysis of 14 phosphate solubilizing bacteria by 16S rRNA gene sequencing grouped them into three phyla, namely Firmicutes, Proteobacteria and Actinobacteria. When tested for uranium sensitivity, 12 of the 14 phosphate solubilizing isolates showed significant (p &\#60; 0.01) tolerance to uranium (4.1%-26.1%) compared to the reference strain *Escherichia coli* ATCC 25922(T). This demands further in-depth studies on microbial inhabitants from such complex environmental conditions that could provide better agents and insights for remediation technology.

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## Characteristics and in situ remediation effects of heavy metal immobilizing bacteria on cadmium and nickel co-contaminated soil

**Authors:** Wang Y, Luo Y, Zeng GQ, Wu XD, Wu B, Li X, Xu H

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 192, 2020, DOI: 10.1016/j.ecoenv.2020.110294

**Abstract:** Cadmium (Cd) and nickel (Ni) in soil have caused serious environmental problems and increased healthy risks to humans and biota, it is vital important and necessary to develop effective methods to resolve the combined contaminated

problems. In this study, strains L5 and L6 with good heavy metal resistant and immobilizing capacities were isolated from Cd and Ni contaminated soil. Bacterial characteristic experiment illustrated that many functional groups (-OH, -NH2 and -COO et al.) were distributed on the surface of 1.5 and L6. Under the stress of heavy metals, bacterial appearances were distorted. The pot experiment indicated that the concentrations of HOAc-extractable Cd and Ni in soil reduced 6.26-15.33% and 13.31-19.53% with the inoculation of L5 and L6. In addition, the immobilization rates on Cd and Ni improved 61.27-128.50% and 23.69-39.66% with re-inoculation of strains L5 and L6 at 30 days, respectively. After inoculation of strains L5 and L6 for 60 days, the activities of FDA hydrolysis, acid phosphatase, urease, invertase and dehydrogenase in soil increased obviously. Furthermore, bacterial diversity indexes and community structure of soil were also improved. Thus, given the beneficial remediation effects of the isolated strains, L5 and L6 have great potentials for heavy metals contaminated soil remediation.

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## Quantifying the Mineralization of C-13-Labeled Cations and Anions Reveals Differences in Microbial Biodegradation of Herbicidal Ionic Liquids between Water and Soil

**Authors:** Wilms W, Wozniak-Karczewska M, Niemczak M, Lisiecki P, Zgola-Grzeskowiak A, Lawniczak L, Framski G, Pernak J, Owsianiak M, Vogt C... more

**Source:** ACS SUSTAINABLE CHEMISTRY & ENGINEERING 8(8):3412-3426, 2020, DOI: 10.1021/acssuschemeng.9b07598

**Abstract:** Characterization of the biodegradability of herbicidal ionic liquids (HILs) using the industry standard activated sludge methodology is thought to be insufficient to fully
understand the biodegradation of HILs in the environment because cations and anions of the HILs may have different potential for biodegradation in aquatic and terrestrial systems. To test this hypothesis, we conducted laboratory microcosm experiments using C-13-labeled cations and anions forming benzyldodecyldimethylammonium 4-chloro-2-methylphenoxyacetate ([C-12-BA][MCPA]) and evaluated their biodegradation potential in soil with a known history of herbicide exposure, and in water (mineral medium) augmented with microorganisms present in activated sludge. The biodegradability of the cation and anion was found to depend on the test system (water or soil). The cation was mineralized in water, whereas the anion was fully utilized in soil. These results suggest that performing biodegradation tests using differently C-13-labeled species of the target HIL and mimicking various environmental compartments (e.g., soil, activated sludge) is needed to provide a better understanding of the fate of HILs in the environment. They also indicate that biodegradation kinetic parameters of HILs derived from experiments performed in aqueous systems should not be used to estimate biodegradation rates in terrestrial environments.

## Microbial inoculant and garbage enzyme reduced cadmium (Cd) uptake in *Salvia miltiorrhiza* (Bge.) under Cd stress

**Authors:** Wei XM, Cao P, Wang G, Han JP

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 192, 2020, DOI: 10.1016/j.ecoenv.2020.110311

**Abstract:** The uptake and accumulation of cadmium (Cd) in *Salvia miltiorrhiza* (Bge.) negatively affects the quality of its harvested roots, and seriously threatens human health. This study investigates the effect of a microbial inoculant (MI) and garbage enzyme (GE) on Cd uptake, the accumulation of bioactive compounds, and the community composition of microbes in the rhizosphere soil of *S. miltiorrhiza* under Cd stress. *S. miltiorrhiza* seedlings were transplanted to Cd-contaminated pots and

irrigated with an MI, GE, a combination of an MI and GE (MIGE) or water (control). The results indicated that treatments with an MI, GE or MIGE can reduce Cd uptake in *S. miltiorrhiza*. The MIGE treatment had greater efficiency in reducing Cd uptake than the control (reduction by 37.90%), followed by the GE (25.31%) and MI (5.84%) treatments. Treatments with an MI, GE and MIGE had no significant impact on fresh and dry root biomass. Relative to the control, the MI treatment had the highest efficiency in increasing the accumulation of total tanshinones (an increase of 40.45%), followed by the GE treatment (40.08%), with the MIGE treatment (9.90%) treatment not having a more favorable effect than the separate application of an MI or GE. The salvianolic acid content for all groups was higher than the standard prescribed by Chinese pharmacopoeia, notwithstanding a slightly lower level in the treated groups relative to the control. In addition, metagenomic analysis indicated changes in the relative abundance of soil microbes associated with the bioremediation of heavy metals. The relative abundances of Brevundimonas, Microbacterium, Cupriavidus and Aspergillus were significantly greater in the treated groups than in the Control. These results suggest that using MI and GE, either separately or together, may not only improve the quality of *S. miltiorrhiza* but may also facilitate the microbial remediation of soil contaminated with Cd.

## Impact of pesticide monocrotophos on microbial populations and histology of intestine in the Indian earthworm Lampito mauritii (Kinberg)

**Authors:** Kavitha V, Anandhan R, Alharbi N, Kadaikunnan S, Khaled JM, Almanaa TN, Govindarajan M

**Source:** MICROBIAL PATHOGENESIS, 139, 2020, DOI: 10.1016/j.micpath.2019.103893

**Abstract:** Soil contamination has enlarged over the decades due to intensive use of pesticides and chemical fertilizers in agronomy. Earthworms are significant organisms in the soil community. Earthworms are the major role in soil fertility in most ecological system and the production of biogenic structures. Moreover, earthworm gut mucus enhances the beneficial soil microorganism potential biological activities. They are used as
model organisms for assessing the ecological risks of chemicals. Enrichment of essential nutrients in soil through earthworm is a cost-effective and eco-friendly approach. In India, the organophosphorus pesticide monocrotophos is commonly used to control agricultural pests. Hence, it is important to study the effect of monocrotophos on the gut microbiota in *Lampito mauritii*. A 15-day exposure to a low (1/10th of the LC50 after 96 h i.e., 0.093 ppm kg(-1)) and high sublethal concentration (1/3rd of the LC50 after 96 h i.e., 0.311 ppm kg(-1)) of monocrotophos led to reduced proliferation of the gut microbiota in *L. mauritii*. However, exposure for 30 days led to a recuperation of the microbial populations to near control values. Among the eight bacterial and five fungal species that inhabit the gut of *L. mauritii*, only six bacterial and three fungal species were able to survive after exposure to monocrotophos. In addition to the study, histopathological changes were observed in the intestine of *L. mauritii* after application of lower sublethal concentration of monocrotophos. Severe pathological changes such as vacuolization, degenerated nuclei, damaged villi and congestion of the blood sinuses were noticed in the intestine on 1st and, 5th day of the experiment. But in 30th day the damages were slowly recovered due to degradation of monocrotophos by the presence of some pesticides degrading bacterial and fungal species and regenerative capability of chloragogen cells in the intestine. The results suggested that reduced microbial populations and pathological damages in intestine were observed during the application of monocrotophos. So, the monocrotophos have several harmful impacts on earthworms.

# Soil Microbial Communities in Diverse Agroecosystems Exposed to the Herbicide Glyphosate

**Authors:** Kepler RM, Schmidt DJE, Yarwood SA, Cavigelli MA, Reddy KN, Duke SO, Bradley CA, Williams MM, Buyer JS, Maul JE

**Source:** APPLIED AND ENVIRONMENTAL MICROBIOLOGY 86(5), 2020, DOI: 10.1128/AEM.01744-19

**Abstract:** Despite glyphosate's wide use for weed control in agriculture, questions remain about the

herbicide's effect on soil microbial communities. The existing scientific literature contains conflicting results, from no observable effect of glyphosate to the enrichment of agricultural pathogens such as *Fusarium* spp. We conducted a comprehensive field-based study to compare the microbial communities on the roots of plants that received a foliar application of glyphosate to adjacent plants that did not. The 2-year study was conducted in Beltsville, MD, and Stoneville, MS, with corn and soybean crops grown in a variety of organic and conventional farming systems. By sequencing environmental metabarcode amplicons, the prokaryotic and fungal communities were described, along with chemical and physical properties of the soil. Sections of corn and soybean roots were plated to screen for the presence of plant pathogens. Geography, farming system, and season were significant factors determining the composition of fungal and prokaryotic communities. Plots treated with glyphosate did not differ from untreated plots in overall microbial community composition after controlling for other factors. We did not detect an effect of glyphosate treatment on the relative abundance of organisms such as *Fusarium* spp.

**IMPORTANCE** Increasing the efficiency of food production systems while reducing negative environmental effects remains a key societal challenge to successfully meet the needs of a growing global population. The herbicide glyphosate has become a nearly ubiquitous component of agricultural production across the globe, enabling an increasing adoption of no-till agriculture. Despite this widespread use, there remains considerable debate on the consequences of glyphosate exposure. In this paper, we examine the effect of glyphosate on soil microbial communities associated with the roots of glyphosate-resistant crops. Using metabarcoding techniques, we evaluated prokaryotic and fungal communities from agricultural soil samples (n = 768). No effects of glyphosate were found on soil microbial communities associated with glyphosate-resistant corn and soybean varieties across diverse farming systems.

# Zinc resistance of six dark septate endophytic fungi and the growth response of tomato

**Authors:** Lin LC
**Source:** APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 18(1):389-400, 2020, DOI: 10.15666/aeer/1801_389400

**Abstract:** Dark septate endophytic fungi (DSEF) can promote the growth response of host plants and can increase their resistance to heavy metals. In this study, six isolated DSEFs were proven to be able to form microsclerotia with plants. The objective of this study was to investigate the promoting and inoculation effects of these six DSEFs. Molecular analysis showed that the DSEFs may be new additions to the fungal flora of Taiwan and may be new species in the world. Screening and selection of Zn-resistant DSEFs showed that only two strains, CkDB5 and RrtHH10, were Zn-resistant. Evaluation of the Zn resistance range of CkDB5 and RrtHH10 revealed that the former presented lower EM50 values than the latter, and that both strains showed the same minimum inhibitory concentration values. As the Zn concentration increased, twisting and looping of the mycelial morphology of the strains was observed. Resynthesis experiments proved that CkDB5 and RrtHH10 could promote the growth response of tomato. The biomasses of CkDB5-inoculated plants was up to four times higher than that of the controls. This study showed that, of the six DSEFs, only CkDB5 and RrtHH10 showed Zn-resistance. CkDB5 is a fungus with particularly high Zn resistance, and it could facilitate tomato growth.

## Effects of soil chemical properties and fractions of Pb, Cd, and Zn on bacterial and fungal communities

**Authors:** Pan XM, Zhang SR, Zhong QM, Gong, GS, Wang GY, Guo X, Xu XX

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 715, 2020, DOI: 10.1016/j.scitotenv.2020.136904

**Abstract:** Heavy metal contamination in soils poses a serious threat to microorganisms, which play important roles in soil biogeochemical process. However, the key fractions of heavy metals affecting soil microorganisms are still unclear. In this study, DNA sequencing, redundancy and variance partition analysis were performed to investigate the combined effects of heavy metal fractions and soil chemical properties on microbial communities in Pb, Cd, and Zn co-contaminated soils. The results showed that long-term exposure of microorganisms to these metals changed the richness, diversity, and structure of their communities. The bacterial and fungal Chao richness indexes decreased, but only the bacterial Shannon index improved with increasing metal concentrations. Moreover, soil available potassium and add-extractable Pb made the greatest contributions to variations in the bacterial community structure, while soil pH, water-extractable Pb and Zn were the dominant factors influencing the fungal community structure. In addition, Marmoricola, Nocardioides, and Gibberella were sensitive to these metals. Overall, the effects of different heavy metal fractions on microorganisms varied significantly, and these metal fractions together with soil chemical properties determined the soil microbial communities. (C) 2020 Elsevier B.V. All rights reserved.

## Optimization of Paraquat degradation with microbial consortium from contaminated soil using statistic method

**Authors:** Teerakun M, Reungsang A, Chaowarat, M, Saraphirom P

**Source:** INTERNATIONAL JOURNAL OF GEOMATE 18(68):73-79, 2020, DOI: 10.21660/2020.68.5676

**Abstract:** Paraquat is one of non-selective herbicides, widely used in Thailand and other countries that can be used to prevent and mitigate problems with weeds that have become resistant. It has a broad spectrum of weed knockdown herbicide which can be easily distributed in an aquatic environment due to its high solubility in water. The aim of the research is to study the optimization condition for biodegradation of paraquat by microbial consortium using an orthogonal array design in culture media. The microbial consortium which can degrade paraquat were isolated from cassava rhizosphere soil with a historic area of using paraquat in Kalasin, Thailand Analysis of the 16S rDNA gene sequences compared with the database
in Gen Bank demonstrated that microbial consortium showed the similarity with Sphingomicrobium marinum (97%), Ferrovibrio xuzhouensis (93%), Azospirillum lipoferum (93%), Altererythrobacter xinjiangensis (94%), Xanthobacter autofrophicus (92%) and Azospirillum amazonense (99%). To achieve the biodegradation experiments, orthogonal arrays design was investigated, with the three independent variables: glucose concentration (1-20 g/L), paraquat concentration (10-100 mg/L) and inoculum concentration (110%). The biodegradation consortium was done triplicate in 250 mL Erlenmeyer flask at 30 degrees C 150 rpm for 35 days. Paraquat biodegradation was reported as biodegradation percentage. The results demonstrated that the optimum concentrations of glucose, paraquat, and inoculum for paraquat biodegradation were 1 g/L, 10 mg/L, and 5%, respectively. The paraquat removal efficiency of 95.69% was achieved under the optimal condition.

## A slurry microcosm study on the interaction between antibiotics and soil bacterial community

**Authors:** Dong XH, Rao DW, Tian LJ, Wang QZ, Yang K

**Source:** HELIYON 6(2), 2020, DOI: 10.1016/j.heliyon.2020.e03348

**Abstract:** Antibiotics released in the environment have attracted great attention. The environmental emission control of antibiotics should be based on the degree of their negative impacts on the environment and ecology. Here, we conducted a series of soil slurry microcosm experiments to investigate the interactions between antibiotics and the soil bacterial community. In the soil slurry, distinctive behaviors were observed for different antibiotics. Betalactams (ampicillin and ceftriaxone) experienced fast biodegradation. Kanamycin was adsorbed on soil particles soon after its addition. Nalidixic acid was stable throughout the experimental period (164 h). The main inactivation mechanism of tetracycline was deduced to be hydrolysis. Bacterial communities in slurries with or without antibiotic-treatment were profiled via high-throughput Illumina

sequencing of the 16S rRNA gene. Unstable (ceftriaxone) and adsorbed (kanamycin) antibiotics show minor or negligible influences on the soil bacterial community. Stable antibiotics (nalidixic acid and tetracycline) have significantly affected the structure of the bacterial community. Most of enriched bacterial genera by various antibiotics belong to the same phylum, Proteobacteria. Inhibited bacterial phyla by nalidixic acid are Firmicutes and Bacteroidetes, while those inhibited by tetracycline are Firmicutes, Bacteroidetes and Cyanobacteria. According to the PICRUSt prediction of metagenome, influence of antibiotics on overall metabolic function of the bacterial community is rather limited. This study has provided valuable information, from a phylogenetic viewpoint, about the influence of high concentration of antibiotics on soil bacterial community.

## Role of extracellular polymeric substance (EPS) in toxicity response of soil bacteria *Bacillus* sp. S3 to multiple heavy metals

**Authors:** Zeng Weimin, Li Fang, Wu Chenchen... more

**Source:** BIOPROCESS AND BIOSYSTEMS ENGINEERING 43(1):153-167, 2020, DOI: 10.1007/s00449-019-02213-7

**Abstract:** Heavy metal resistant bacteria are of great interest because of their potential use in bioremediation. Understanding the survival and adaptive strategies of these bacteria under heavy metal stress is important for better utilization of these bacteria in remediation. The objective of this study was to investigate the role of bacterial extracellular polymeric substance (EPS) in detoxifying against different heavy metals in *Bacillus* sp. S3, a new hyper antimony-oxidizing bacterium previously isolated from contaminated mine soils. The results showed that *Bacillus* sp. S3 is a multi-metal resistant bacterial strain, especially to Sb(III), Cu(II) and Cr(VI). Toxic Cd(II), Cr(VI) and Cu(II) could stimulate the secretion of EPS in *Bacillus* sp. S3, significantly enhancing the adsorption and detoxification capacity of heavy metals. Both Fourier transform infrared
spectroscopy (FTIR) and three-dimensional excitation-emission matrix (3D-EEM) analysis further confirmed that proteins were the main compounds of EPS for metal binding. In contrast, the EPS production was not induced under Sb(III) stress. Furthermore, the TEM-EDX micrograph showed that Bacillus sp. S3 strain preferentially transported the Sb(III) to the inside of the cell rather than adsorbed it on the extracellular surface, indicating intracellular detoxification rather than extracellular EPS precipitation played an important role in microbial resistance towards Sb(III). Together, our study suggests that the toxicity response of EPS to heavy metals is associated with difference in EPS properties, metal types and corresponding environmental conditions, which is likely to contribute to microbial-mediated remediation.

## Microsegmented flow-assisted miniaturized culturing for isolation and characterization of heavy metal-tolerant bacteria

**Authors:** Cao J, Kalensee F, Guenther PM, Koehler JM

**Source:** INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY 17(1):1-16, 2020, DOI: 10.1007/s13762-019-02424-1

**Abstract:** Soils are complex ecosystem, and their function in the environment is mainly determined by the microbial communities. Metal-tolerant micro-organisms have an important function in the formation of soil and the development of microbial communities in all areas where heavy metals are released by natural erosion processes or by human activities. The investigation of dose-dependent growth and behaviour is an essential part of the search for heavy metal-tolerant microorganism communities and their characterization. In this study, next-generation sequencing was used for the analysis of soil sample and reduced communities and droplet-based microfluidics was used to assess the growth behaviour of unknown bacterial communities and single strains in response to different heavy metal ions. Highly resolved dose-response functions of

the bacterial communities reflect the specific character in their concentration-dependent response to different culture media and heavy metals of copper, nickel and cobalt. Besides the characterization of community responses, they allowed to characterize newly isolated strains. Concentration-dependent growth patterns of the micro-organisms in the droplets could be observed. The investigation demonstrates the potential of droplet-based microfluidics for miniaturized eco-toxicological studies and their suitability for the discovery of novel strains with special tolerance features.

## Incorporation of cyclodiene pesticides and their polar metabolites to model membranes of soil bacteria

**Authors:** Wojcik Aneta, Perczyk Paulina, Wydro Pawel, Broniatowski Marcin

**Source:** JOURNAL OF MOLECULAR LIQUIDS 298:112019, 2020, DOI: 10.1016/j.molliq.2019.112019

**Abstract:** The world-wide application of cyclodiene pesticides (CP) lead to severe pollution of arable land and because of the long half-lives they will be for many decades present in the soil. The only reasonable way of the elimination of these chemicals from the soil is bioremediation - the introduction to the soil of decomposer microorganisms strains capable of CP degradation. CP are highly hydrophobic and exhibit large membrane activity; thus, they can be incorporated to the cellular membrane and retained therein. The presence of CP and their metabolites in the cellular membrane of the decomposer organism can lead to severe alterations of its function and in consequence to the death of the decomposer cell. Microorganisms protect themselves changing the phospholipid composition of their membranes. To shed light on the correlation between the membrane composition and its interactions with CP and their metabolites we applied Langmuir monolayers as
versatile models of decomposers' membranes. By the proper selection of phospholipids we prepared different models of cellular membranes of Gram-negative and Gram-positive bacteria. The model membranes were doped by four most frequently applied CP and their common metabolite. The combined application of microscopic, diffractometric and spectroscopic methods proved that CP can be incorporated into the model membranes and that the membrane activity of endosulfan is comparable with endrin - one of the most toxic pesticides. The penetration tests and spectroscopic studies proved also the possibility of the uptake of the polar CP metabolites by the model membranes from the aqueous subphase.

## Fire Phoenix facilitates phytoremediation of PAH-Cd co-contaminated soil through promotion of beneficial rhizosphere bacterial communities

**Authors:** Dai Yuanyuan, Liu Rui, Zhou Yuemei, Li Na, Hou Liqun... more

**Source:** ENVIRONMENT INTERNATIONAL 136:UNSP 105421, 2020, DOI: 10.1016/j.envint.2019.105421

**Abstract:** Pot experiments were conducted in a growth chamber to evaluate the phytoremediation efficiency and rhizosphere regulation mechanism of Fire Phoenix (a mixture of Festuca L.) in polycyclic aromatic hydrocarbon-cadmium (PAH-Cd) co-contaminated soils. Plant biomass, removal rates of PAHs and Cd, soil enzyme activity, and soil bacterial community were determined. After 150 days of planting, the removal rates of the total 4 PAHs and Cd reached 64.57% and 40.93% in co-contaminated soils with low-PAH (104.79-144.87 mg.kg(-1)), and 68.29% and 25.40% in co-contaminated soils with high-PAH (169.17-197.44 mg.kg(-1)), respectively. The polyphenol oxidase (PPO) activity decreased in soils having Fire Phoenix, while the dehydrogenase (DHO) activity increased as the changes of DHO activity had a strong positive correlation with the removal rates of PAHs and Cd

in the low-PAH soils ($r = 0.862$ ($P < 0.006$) and $0.913$ ($P < 0.002$), respectively). Meanwhile, successive changes in the bacterial communities were detected using high-throughput 454 GS-FLX pyrosequencing of the 16S rRNA, and these changes were especially apparent for the co-contaminated soils with the low PAH concentration. The Fire Phoenix could promote the growth of Mycobacterium, Dokdonella, Gordonia and Kaistobacter, which played important roles in PAHs degradation or Cd dissipation. These results indicated that Fire Phoenix could effectively motivate the soil enzyme and bacterial community and enhance the potential for phytoremediation of PAH-Cd co-contaminated soils.

## Effects of pesticide residues on bacterial community diversity and structure in typical greenhouse soils with increasing cultivation years in Northern China

**Authors:** Wang Chao-Nan, Wu Rui-Lin, Li Yu-Yan, Qin Yi-Fan, Li Yi-Long... more

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 710:136321, 2020, DOI: 10.1016/j.scitotenv.2019.136321

**Abstract:** The understanding of soil microbiome is important for sustainable cultivation, especially under greenhouse conditions. Here, we investigated the changes in soil pesticide residues and microbial diversity and community structure at different cultivation years under a greenhouse system. The 9-to-14 years sites were found to have the least diversity/rich microbial population as compared to sites under 8 years and over 16 years, as analyzed with alpha diversity index. In total, 42 bacterial phyla were identified across soils with different pesticide residues and cultivation ages. Proteobacteria, Acidobacteria, and Bacteroidetes represented the dominant phyla, that accounted for 34.2-43.4%, 9.7-19.3% and 92-16.5% of the total population, respectively. Our data prove that certain pesticides contribute to variation in soil microbial community and that soil bacteria respond
differently to cultivation years under greenhouse conditions. Thus, this study provides an insight into microbial community structure changes by pesticides under greenhouse systems and natural biodegradation may have an important part in pesticides soil decontamination.

# Exploring bacterial community composition in Mediterranean deep-sea sediments and their role in heavy metal accumulation

**Authors:** Jroundi Fadwa, Martinez-Ruiz Francisca, Merroun Mohamed L, Teresa Gonzalez-Munoz Maria

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT 712:135600, 2020, DOI: 10.1016/j.scitotenv.2019.135660

**Abstract:** The role of microbial processes in bioaccumulation of major and trace elements has been broadly demonstrated. However, microbial communities from marine sediments have been poorly investigated to this regard. In marine environments, particularly under high anthropogenic pressure, heavy metal accumulation increases constantly, which may lead to significant environmental issues. A better knowledge of bacterial diversity and its capability to bioaccumulate metals is essential to face environmental quality assessment. The oligotrophic westernmost Mediterranean, which is highly sensitive to environmental changes and subjected to increasing anthropogenic pressure, was selected for this study. A sediment core spanning the last two millennia was sampled at two intervals, with ages corresponding to 140 (S1) and 1400 (S2) yr BP. High-throughput sequencing showed an abundance of Bacillus, Micrococcus, unclassified members of Planococcaceae, Anaerolineaceae, Planctomycetaceae, Microlunatus, and Microbacterium in both intervals, with slight differences in their abundance, along with newly detected ones in S2, i.e., Propionibacterium, Fictibacillus, Thalassobacillus, and Bacteroides. Canonical correspondence analysis (CCA) and co-occurrence patterns confirmed strong correlations among the taxa and the environmental parameters, suggesting either shared and preferred environmental conditions, or the performance of functions similar to or complementary to each

other. These results were further confirmed using culture-dependent methods. The diversity of the culturable bacterial community revealed a predominance of Bacillus, and Micrococcus or Kocuria. The interaction of these bacterial communities with selected heavy metals (Cu, Cr, Zn and Pb) was also investigated, and their capacity of bioaccumulating metals within the cells and/or in the extracellular polymeric substances (EPS) is demonstrated. Interestingly, biomineralization of Pb resulted in the precipitation of Pb phosphates (pyromorphite). Our study supports that remnants of marine bacterial communities can survive in deep-sea sediments over thousands of years. This is extremely important in terms of bioremediation, in particular when considering possible environmentally friendly strategies to bioremediate inorganic contaminants.

# Responses of bacterial communities in wheat rhizospheres in different soils to di-n-butyl and di(2-ethylhexyl)phthalate contamination

**Authors:** Gao Minling, Zhang Ze, Dong Youming... more

**Source:** GEODERMA 362:114126, 2020, DOI: 10.1016/j.geoderma.2019.114126

**Abstract:** Di-n-butyl phthalate (DBP) and di(2-ethylhexyl)phthalate (DEHP) are commonly used as plasticizers to enhance the flexibility of plastic products. They are universal pollutants and well-known endocrine disruptors, and their effects on rhizosphere organisms have aroused great concern. In the present study, the effects of DBP and DEHP contamination on bacterial community structure and functions in wheat rhizospheres in fluvo-aquic, cinnamon, and brown soils were investigated using Illumina HiSeq 2500 sequencing. Operational taxonomic unit richness and bacterial diversity were decreased in DEHP-contaminated fluvo-aquic and brown soils, but not in DEHP-contaminated cinnamon and DBP-polluted soils. The relative abundance of some families was positively associated with soil pH, total nitrogen content (TN), and soil organic matter (SOM), and negatively correlated with DBP/DEHP concentration. The relative abundances of families that can extremely effectively degrade DBP/DEHP were enhanced by
DBP/DEHP pollution, whereas the relative abundances of some genera that are beneficial to soil health were reduced in the DBP/DEHP-polluted soils. Soil pH, TN, and SOM were crucial in determining the fate and effect of PAEs in the soil ecosystems. In conclusion, DBP/DEHP pollution alters the rhizosphere bacterial community structure and affects microbial metabolic behavior and functional diversity during wheat growth.

## The utilization of biomineralization technique based on microbial induced phosphate precipitation in remediation of potentially toxic ions contaminated soil: A mini review

**Authors:** Jiang Luhua, Liu Xueduan, Yin Huaqun... more

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 191:110009, 2020, DOI: 10.1016/j.ecoenv.2019.110009

**Abstract:** In recent years, many studies have been devoted to investigate the application of microbial induced phosphate precipitation (MIPP) process for potentially toxic element polluted soil remediation. MIPP biomineralization technique exhibits a great potential to efficiently remediate polluted soil considering its low cost, green and ecofriendly process, and simple in operation. This paper represented a review on the state of the art of polluted soil remediation based on MIPP technique. Briefly, certain defined criteria on targeted microbe selection was discussed; an overall review on the utilization of MIPP process for toxic ions biomineralization in soil was provided: influencing factors reported in the literature, such as pH, temperature, humic substances, coexisting ions, effective microbial population, and enzyme activity, were then comprehensively reviewed; finally; a special emphasis was given to enhance MIPP remediation performance in soil in future research.

## Effect of the veterinary ionophore monensin on the structure and activity of a tropical soil bacterial community

**Authors:** Granados-Chinchilla Fabio, Arias-Andre, Maria de Jesus, Fernandez Montes de Oca Maria Laura, Rodriguez Cesar

**Source:** JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART B-PESTICIDES FOOD CONTAMINANTS AND AGRICULTURAL WASTES 55(2):127-134, 2020, DOI: 10.1080/03601234.2019.1673612

**Abstract:** Monensin (MON) is a coccidiostat used as a growth promoter that can reach the environment through fertilization with manure from farm animals. To verify whether field-relevant concentrations of this drug negatively influence the structure and activity of tropical soil bacteria, plate counts, CO2 efflux measurements, phospholipid fatty acids (PLFA) and community-level physiological profiling (CLPP) profiles were obtained for soil microcosms exposed to 1 or 10 mg kg(-1) of MON across 11 days. Although 53% (1 mg kg(-1)) to 40% (10 mg kg(-1)) of the MON concentrations added to the microcosms dissipated within 5days, a subtle concentration-dependent decrease in the number of culturable bacteria (&#60;1 log CFU g(-1)), reduced (-20 to -30%) or exacerbated (+25%) soil CO2 effluxes, a marked shift of non-bacterial fatty acids, and altered respiration of amines (1.22-fold decrease) and polymers (1.70-fold increase) were noted in some of the treatments. These results suggest that MON quickly killed some microorganisms and that the surviving populations were selected and metabolically stimulated. Consequently, MON should be monitored in agronomic and environmental systems as part of One Health efforts.

## Associative effects of lignin-derived biochar and arbuscular mycorrhizal fungi applied to soil polluted from
# Pb-acid batteries effluents on barley grain safety

**Authors:** Khan Muhammad Asaf, Mahmood-ur-Rahman, Ramzani Pia Muhammad Adnan, Zubair Muhammad, Rasool Bilal, Khan Muhammad Kamran, Ahmed Ammar, Khan Shahbaz Ali, Turan Veysel, Iqbal Muhammad

**Source:** SCIENCE OF THE TOTAL ENVIRONMENT
710:136294, 2020, DOI: 10.1016/j.scitotenv.2019.136294

**Abstract:** While disobeying environmental regulations of Pakistan, several Pb-acid batteries recycling and repairing units discharge their effluents into water canals that irrigate arable fields. Resultantly, serious ecological risks, as well as human health hazards through consumption of edible crops grown on such Pb-polluted soils have been reported. In this experiment, we observed associative effects of amending a soil polluted from Pb-add batteries effluents (SPB) with arbuscular mycorrhizal fungi (AMF) and lignin-derived biochar (LBC) on barley grain safety to human health. The SPB was treated with AMF inoculum (a consortium of four AMF species), lignin (IN), and 113C, as sole treatments and AMF inoculum with LN and LBC. Barley parameters involving Pb distribution in grain and other parts, grain biochemistry, and nutrition were assessed. Likewise. Pb bioavailability in SPB, AMF root colonization, soil enzymes, microbial biomass carbon (MBC), and AMP produced total glomalin related soil protein (TGSP) were also scoped. Additionally, human renal cells (HEK 293) cytotoxicity test was performed by opting barley grain-related Pb concentrations. Results show that LBC + AMF significantly reduced grain Pb concentrations below the critical limit [4.67 mg kg(-1) (WHO/FAO standard)], AMF colonization, MBC, soil enzymology, and TGSP, compared to control. Likewise, rest barley parameters were also improved in this treatment Contrary to other treatments, grain produced on LBC + AMF did not result in (a) cell apoptosis, (b) cell distortion and (c) cohesion loss. Immobilization of Pb in SPB was due to the dilution effect of Pb adsorption on LBC, AMF mycelium and TGSP which resulted in a significant drop of grain Pb concentrations below the critical limit and ultimately no harm to HEK 293 cells. Our findings endorse that grain produced at LBC + AMF treatment are safer for human consumption and will not pose health risks. The LBC + AMF application can remediate SPB for safer cereal production.

# Effects of Soil Amendments on Microbial Activities in a Typical Cd-Contaminated Purple Field Soil, Southwestern China

**Authors:** Wang Wenqiang, Zhou Fengwu, Chang Yajun, Cui Jian, He Dongyi, Du Jinmeng, Chan Andy, Yao Dongrui, Li Yong, Chen Zhiyuan... more

**Source:** BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 104(3):380-385, 2020, DOI: 10.1007/s00128-020-02786-0

**Abstract:** In this study, three soil amendments (inorganic, liming, or organic-inorganic materials) were used in a Cd-contaminated purple field soil to investigate their impacts on soil Cd availability, enzyme (urease, catalase, sucrase, and acid phosphatase) activities, microbial biomass (carbon/nitrogen) and type (bacteria, fungi, and actinomycetes) in mustard and corn trials. Results showed that soil amendments generally decreased soil exchangeable Cd, fungi and bacterial populations while increasing the activities of all the four soil enzymes tested, microbial biomass carbon and populations of actinomycetes ($p < 0.05$). Soil pH and microbial biomass nitrogen did not exhibit any significant response ($p > 0.05$) whereas stronger effects appeared in soil organic matter and available nutrients (nitrogen, phosphorous and potassium; $p < 0.05$). However, only soil available phosphorous significantly correlated with soil microbial activity in both mustard and corn trails ($p < 0.05$). Thus, application of phosphorous-containing amendments should be considered for promoting soil health in the remediation of the Cd-contaminated purple soils.

Biodegradation of
Organophosphorus
Compounds Predicted by
Enzymatic Process Using
Molecular Modelling and
Observed in Soil Samples
Through Analytical
Techniques and
# Microbiological Analysis: A Comparison

**Authors:** Cardozo Monique, de Almeida Joyce S, F D, Cavalcante Samir F de A, Salgado Jacqueline RS, Goncalves Arlan S, Franca, Tanos CC, Kuca Kamil, Bizzo Humberto R

**Source:** MOLECULES 25(1):58, 2020, DOI: 10.3390/molecules25010058

**Abstract:** Organophosphorus compounds (OP) are chemicals widely used as pesticides in different applications such as agriculture and public health (vector control), and some of the highly toxic forms have been used as chemical weapons. After application of OPs in an environment, they persist for a period, suffering a degradation process where the biotic factors are considered the most relevant forms. However, to date, the biodegradation of OP compounds is not well understood. There are a plenty of structure-based biodegradation estimation methods, but none of them consider enzymatic interaction in predicting and better comprehending the differences in the fate of OPs in the environment. It is well known that enzymatic processes are the most relevant processes in biodegradation, and that hydrolysis is the main pathway in the natural elimination of OPs in soil samples. Due to this, we carried out theoretical studies in order to investigate the interactions of these OPs with a chosen enzyme—the phosphotriesterase. This one is characteristic of some soils' microorganisms, and has been identified as a key player in many biodegradation processes, thanks to its capability for fast hydrolyzing of different OPs. In parallel, we conducted an experiment using native soil in two conditions, sterilized and not sterilized, spiked with specific amounts of two OPs with similar structure-paraoxon-ethyl (PXN) and O-(4-nitrophenyl) O-ethyl methylphosphonate (NEMP). The amount of OP present in the samples and the appearance of characteristic hydrolysis products were periodically monitored for 40 days using analytical techniques. Moreover, the number of microorganisms present was obtained with plate cell count. Our theoretical results were similar to what was achieved in experimental analysis. Parameters calculated by enzymatic hydrolysis were better for PXN than for NEMP. In soil, PXN suffered a faster hydrolysis than NEMP, and the cell count for PXN was higher than for NEMP, highlighting the higher microbiological toxicity of the latter. All these results pointed out that theoretical study can offer a better comprehension of the possible mechanisms

involved in real biodegradation processes, showing potential in exploring how biodegradation of OPs relates with enzymatic interactions.

# Enhanced bioremediation of lindane-contaminated soils through microbial bioaugmentation assisted by biostimulation with sugarcane filter cake

**Authors:** Raimondo Enzo E, Aparicio Juan D, Bigliardo Ana L, Fuentes Maria S, Benimeli Claudia S

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 190:110143, 2020, DOI: 10.1016/j.ecoenv.2019.110143

**Abstract:** Lindane is a toxic and persistent organochlorine pesticide, whose extensive use generated its accumulation in different environmental matrices. Bioremediation is a promising technology that can be used combining bioaugmentation and biostimulation processes to soil restoration. The aim of the present work was to determine the conditions of maximum lindane removal by bioaugmentation with an actinobacteria consortium and biostimulation with sugarcane filter cake (SCFC). The assays were carried out on lindane-contaminated silty loam (SLS), clayey (CS), and sandy (SS) soils. Through complete factorial designs, the effects of three abiotic factors (moisture content, proportion and size of SCFC particles) were evaluated on lindane removal. In addition, a response optimizer determined the optimal conditions for pesticide removal in bioaugmented and biostimulated soils, in the range of levels studied for each factor. In these conditions, bioaugmentation of biostimulated soils increased the pesticide removal (SLS: 61.4%, CS: 70.8%, SS: 86.3%), heterotrophic microbial counts, and soil
enzymatic activities, and decreased lindane T-1/2, regarding the non-bioaugmented biostimulated controls, after 14 days of assay. The values of these parameters confirmed the efficiency of the bioremediation process. Finally, the viability of the four strains was demonstrated at the end of the assay. The results indicate that the simultaneous application of bioaugmentation with the actinobacteria consortium and biostimulation with SCFC constitutes a promising tool for restoring soils contaminated with lindane, by using the optimal conditions obtained through the factorial designs.

## Variation in soil microbial population and enzyme activities under faba bean as affected by pentachlorophenol

**Authors:** Siczek Anna, Frac Magdalena, Gryta Agata, Kalembasa Stanislaw, Kalembasa Dorota

**Source:** APPLIED SOIL ECOLOGY 150:UNSP 103466, 2020, DOI: 10.1016/j.apsoil.2019.103466

**Abstract:** Pentachlorophenol (PCP) is a widely detectable toxic chemical with a detrimental effect on the functioning of ecosystems. A field trial was undertaken to study its effects on the activities, metabolic and genetic diversifies, as well as soil bacterial and fungal community composition. The seeds of faba bean (Vicia faba L.) were either treated (PCP) or left untreated (Control) with pentachlorophenol before sowing. During the vegetative period, soil samples were taken three times from the rhizosphere in order to assess the influence of PCP on soil enzymatic activity, metabolic diversity (Biolog EcoPlate), community of ammonia-oxidizing archaea (DGGE and t-RFLP) and the fungal and bacterial microbiome (NGS). PCP treatment led to a considerable reduction in the activities of enzymes connected with the N cycle (protease and urease) and showed a significant negative correlation with them (r = -0.934 and - 0.716, respectively). Dehydrogenase and respiration activities were also reduced by PCP. In contrast to other enzymes analysed, PCP significantly increased acid phosphomonoesterase activity compared to the Control (r = 0.850). PCP also decreased the carbon utilization efficiency of indigenous microbes and caused the lower utilization of amines, amides and carboxylic

acids. The amount of isolated DNA was lower in PCP-treated soil than in the Control. The technique of t-RFLP fingerprinting revealed the changes caused by contamination and new specific fragments were observed in PCP-contaminated soil. Additionally, pentachlorophenol changed more fungal than bacterial structures in the faba bean rhizosphere. For most of the analysis parameters, the effect of PCP was notable during the entire analysis period of faba bean growth (from 5-6 leaves to pod formation). The results demonstrated the harmful effect of PCP on soil activity and changes in soil microorganism genetic diversity, which could result in the deterioration of the environment for soil function and processes as well as for plant growth.

## Development of microbial communities in organochlorine pesticide contaminated soil: A post-reclamation perspective

**Authors:** Balazs Helga E, Schmid Christoph AO, Podar Dorina, Hufnagel Gudrun, Radl Viviane, Schroeder Peter

**Source:** APPLIED SOIL ECOLOGY 150:UNSP 103467, 2020, DOI: 10.1016/j.apsoil.2019.103467

**Abstract:** In order to meet constantly increasing demands for land without damaging pristine environments like forests or grasslands, reclamation and re-purposing of historically contaminated areas should become a priority. Successful reclamation goes hand in hand with the soil functional recovery potential and with resilient microbial communities capable of performing the necessary ecosystem services. In this context, we designed a greenhouse pot experiment as a mock reclamation situation, where traces of lindane at hazard threshold and twice the concentration accepted for waste deposits are left in the soil after conventional clean-up by excavation and land filling. We assessed the effects of lindane at 50 and 100 mg kg(-1) regarding crop growth and nutrient turnover (with focus on the nitrogen cycle) as two key parameters for soil functions. The bulk and rhizosphere soil bacterial community composition were chosen as parameters for soil resilience in lindane contamination conditions. Lindane severely affected plant growth and development.
The potential nitrogen fixation, quantified as nifH gene copy number, suffered direct negative effects of lindane contamination in bulk soil, which could represent an additional obstacle for phytoremediation. Changes in rhizosphere bacterial community composition were related to lindane toxic effects towards the plants, which might have supported the growth of opportunists and saprophytes. In bulk soil, the bacterial community shifted towards lindane tolerant taxa like Sphingomonas and Porphyrobacter that are interesting with regard to their applications in bioremediation. We concluded that lindane at hazard threshold concentration left in soil after clean-up has negative effects both soil functionality, and the recovery of the bacterial communities to their original composition when lindane resistant plant crops are not involved.

## Biodegradation and biotransformation of pentachlorophenol by wood-decaying white rot fungus *Phlebia acanthocystis* TMIC34875

**Authors:** Xiao Pengfei, Kondo Ryuichiro

**Source:** JOURNAL OF WOOD SCIENCE 66(1):2, 2020, DOI: 10.1186/s10086-020-1849-6

**Abstract:** Pentachlorophenol (PCP) has been introduced into the environment mainly as a wood preservative and biocide. The degradation and transformation of PCP in liquid culture by wood-decaying fungus capable of degrading organochlorine pesticides was investigated in this study. The results of tolerance test showed that the tolerance level of *Phlebia acanthocystis* to PCP in potato dextrose agar medium was higher than that of other Phlebia species. At the end of 10 days of incubation, P. acanthocystis was able to remove 100% and 76% of PCP (25 µM) in low-nitrogen and potato dextrose broth media, respectively. The decrease of PCP in *P. acanthocystis* culture is accompanied by the formation of pentachloroanisole and p-tetrachlorohydroquinone via methylation and oxidation reactions. Moreover, the p-tetrachlorohydroquinone formed is rapidly converted to methylated products including tetrachloro-4-methoxyphenol and tetrachloro-1,4-dimethoxybenzene. The activities of lignin

peroxidase and manganese peroxidase were found to increase in extracellular fluid from fungal culture treated with high-concentration PCP, with maximum values of 169.6 U/L and 73.4 U/L, respectively. The in vitro degradation of PCP and p-tetrachlorohydroquinone was confirmed using extracellular fluid of *P. acanthocystis*, suggested that the methylation of both compounds is related to extracellular enzymes. Degradation of PCP was efficiently inhibited by piperonyl butoxide or 1-aminobenzotriazole, demonstrating that cytochrome P450 monooxygenase is involved in fungal transformation of PCP, particularly in the oxidation of PCP to p-tetrachlorohydroquinone. Additionally, *P. acanthocystis* mineralized 9.3% of the PCP to (CO2)-C-14 in low-nitrogen culture during 42 days. Results obtained in the present study are in favor of the use of *P. acanthocystis* as a microbial tool of remediation of PCP-contaminated sites.

## Impacts of Cu and sulfadiazine on soil potential nitrification and diversity of ammonia-oxidizing archaea and bacteria

**Authors:** Liao Qiang, Li Mingzhu, Dong Yuanpeng, Wu Mi, Meng Zilin, Zhang Qian, Liu Aiju

**Source:** ENVIRONMENTAL POLLUTANTS AND BIOAVAILABILITY 31(1):60-69, 2019, DOI: 10.1080/26395940.2018.1564629

**Abstract:** Soil potential nitrification rate (PNR) and diversity of ammonia-oxidizing microbes were investigated in spiked soils with Cu and Sulfadiazine (SDZ). An obvious decrease of PNR was observed with the increase of Cu and SDZ concentrations in the soil. Real-time fluorescence quota PCR result showed that AOA and AOB were slightly stimulated at the gene level in both contaminated soils. Sequential analysis indicated that 200 mg kg(-1) Cu could improve AOA diversity but reduce AOB diversity, but 5 mg kg(-1) SDZ caused a decrease of both AOA and AOB diversity. Microbial community's analysis also found that 200 mg kg(-1) Cu and 5 mg kg(-1) SDZ had different influence on the populations of AOA and AOB. It could be concluded that Cu and SDZ might have a different ecological effect mechanism on soil potential nitrification and ammonia-oxidizing microbial communities.
# Hydrogeochemical and microbiological effects of simulated recharge and drying within a 2D meso-scale aquifer

**Authors:** Regnery Julia, Li Dong, Lee Jonghyun, Smits Kathleen M, Sharp Jonathan O

**Source:** CHEMOSPHERE 241:UNSP 125116, 2020, DOI: 10.1016/j.chemosphere.2019.125116

**Abstrac:** tOscillating cycles of dewatering (termed drying) and rewetting during managed aquifer recharge (MAR) are used to maintain infiltration rates and could also exert an influence on subsurface microbial structure and respiratory processes. Despite this practice, little knowledge is available about changes to microbial community structure and trace organic chemical biodegradation potential in MAR systems under these conditions. A biologically active two-dimensional (2D) synthetic MAR system equipped with automated sensors (temperature, water pressure, conductivity, soil moisture, oxidation-reduction potential) and embedded water and soil sampling ports was used to test and model these important subsurface processes at the meso-scale. The fate and transport of the antiepileptic drug carbamazepine, the antibiotics sulfamethoxazole and trimethoprim, and the flame retardant tris (2-chloroethyl) phosphate were simulated using the finite element analysis model, FEFLOW. All of these compounds exhibit moderate to poor biodegradability in MAR systems. Within the operational MAR scenario tested, three episodic drying cycles spanning between 18 and 24 days were conducted over a period of 184 days. Notably, cessation of flow and partial dewatering of the 2D synthetic aquifer during dry cycles caused no measurable decrease in soil moisture content beyond the near-surface layer. The episodic flow introduction and dewatering cycles in turn had little impact on overall trace organic chemical biotransformation behavior and soil microbial community structure. However, spatial differences in oxidation-reduction potential and soil moisture were both identified as significant environmental predictors for microbial community structure in the 2D synthetic aquifer.

# Association between antibiotic residues, antibiotic resistant bacteria and antibiotic resistance genes in anthropogenic wastewater - An evaluation of clinical influences

**Authors:** Voigt AM, Zacharias N, Timm C, Wasser F, Sib E, Skutlarek D, Parcina M, Schmithausen RM, Schwartz T, Hembach N ... more

**Source:** CHEMOSPHERE 241:UNSP 125032, 2020, DOI: 10.1016/j.chemosphere.2019.125032

**Abstract:** The high use of antibiotics in human and veterinary medicine has led to a wide spread of antibiotics and antimicrobial resistance into the environment. In recent years, various studies have shown that antibiotic residues, resistant bacteria and resistance genes, occur in aquatic environments and that clinical wastewater seems to be a hot spot for the environmental spread of antibiotic resistance. Here a representative statistical analysis of various sampling points is presented, containing different proportions of clinically influenced wastewater. The statistical analysis contains the calculation of the odds ratios for any combination of antibiotics with resistant bacteria or resistance genes, respectively. The results were screened for an increased probability of detecting resistant bacteria, or resistance genes, with the simultaneous presence of antibiotic residues. Positive associated sets were then compared, with regards to the detected median concentration, at the investigated sampling points. All results show that the sampling points with the highest proportion of clinical wastewater always form a distinct cluster concerning resistance. The results shown in this study lead to the assumption that ciprofloxacin is a good indicator of the presence of multidrug resistant *P. aeruginosa* and extended spectrum beta-lactamase (ESBL)-producing *Klebsiella* spec., *Enterobacter* spec. and *Citrobacter* spec., as it positively relates with both parameters. Furthermore, a precise relationship between carbapenemase genes and meropenem, regarding the respective sampling sites, could be obtained. These results highlight the role of clinical wastewater for the dissemination and development of multidrug resistance.
# Antibiotic Residues and Antibiotic-Resistant Bacteria in Pig Slurry Used to Fertilize Agricultural Fields

**Authors:** Rasschaert Geertrui, Van Elst Daan, Colson Lander, Herman Lieve, De Carvalho Ferreira Helena Cardoso, Dewulf Jeroen, Decrop Johan, Meirlaen Jurgen, Heyndrickx Marc, Daeseleire Els

**Source:** ANTIBIOTICS-BASEL 9(1):34, 2020, DOI: 10.3390/antibiotics9010034

**Abstract:** Pig manure may contain antibiotic residues, antibiotic-resistant bacteria or pathogens, which may reach the environment upon fertilization. During this study, 69 antibiotic residues belonging to 12 classes were quantified in 89 pig slurry samples. These samples were also studied for the presence of Salmonella and for E. coli resistant to meropenem, colistin, ciprofloxacin, or cefotaxim. The obtained isolates were further tested for antibacterial susceptibility. No antibiotic residues were detected in four samples, whereas in the other samples, up to 12 antibiotics were found. The most frequently detected antibiotic residues were doxycycline, sulfadiazine, and lincomycin. Doxycycline was found in the highest concentration with a mean of 1476 µg/kg manure (range: 18-13632 µg/kg). Tylosin and oxytetracycline were found with mean concentrations of 784 µg/kg (range: 17-5599 µg/kg) and 482 µg/kg (range: 11-3865 µg/kg), respectively. Lincomycin, had a mean concentration of 177 µg/kg manure (range: 9-3154 µg/kg). All other 18 antibiotic residues were found with mean concentrations of less than 100 µg/kg manure. Fifty-one slurry samples harbored Salmonella; 35% of the Salmonella isolates were sensitive to a panel of 14 antibiotics, whereas the other 65% were resistant up to five antibiotics. For E. coli, 52 manure samples contained E. coli isolates which were resistant to ciprofloxacin and 22 resistant to cefotaxime. All ciprofloxacin and cefotaxime-resistant isolates were multi-resistant, with resistance up to nine and eight antibiotics, respectively. This research indicates that pig slurry used for fertilization often contains antibiotic residues and antibiotic-resistant bacteria, including pathogens.

# Characterization of tetracycline effects on microbial community, antibiotic resistance genes and antibiotic resistance of Aeromonas spp. in gut of goldfish *Carassius auratus* Linnaeus

**Authors:** Jia Jia, Cheng Mengqian, Xue Xue, Guan Yongjing Wang Zaizhao

**Source:** ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 191:110182, 2020, DOI: 10.1016/j.ecoenv.2020.110182

**Abstract:** The gut of aquatic animals was a significant niche for dissemination of antibiotic resistance genes (ARGs) and direct response of living conditions. In this study, the gut microbiota of goldfish *Carassius auratus* Linnaeus was sampled at 7 days and 21 days after treatment with tetracycline at 0.285 and 2.85 µg L-1 to investigate the influences on the microbial structure and antibiotic resistance. The proportion of tetracycline resistance bacteria was 1.02% in the control group, while increased to 23.00%, 38.43%, 62.05% in groups of high concentration for 7 days (H7), low concentration for 21 days (L21) and high concentration for 21 days (H21), respectively. Compared to the control group, the diversity of isolated Aeromonas spp. was decreased in the treatment groups and the minimal inhibitory concentration (MIC) of resistant isolates was enhanced from 32 to 256 μg mL(-1) with the treatment of tetracycline in time- and dose-dependent manners. Furthermore, the abundance of most genes was increased in treatment groups and efflux genes mainly responded to the stress of tetracycline with an average level of 1.0 x 10(-2). After treatment with tetracycline, the predominant species were changed both at phylum and genus levels. The present study explored the impact of tetracycline on gut microbiota of goldfish at environmentally realistic concentrations for the first time and our findings will provide a reference for characterizing the microbiome of fish in the natural environment.
# Rapid elimination of foodborne and environmental fungal contaminants by benzo analogs

Authors: Kim et al

Source: J Sci Food Agric, 2020, DOI: 10.1002/jsfa.10288

**Abstract:** Contamination of food or the environment by fungi, especially those resistant to conventional fungicides or drugs, represents a hazard to human health. The objective of this study is to identify safe, natural antifungal agents that can remove fungal pathogens or contaminants rapidly from food and / or environmental sources. Fifteen antifungal compounds (nine benzo derivatives as candidates; six conventional fungicides as references) were investigated. (...) when OG, CA, and 2H5M were examined in commercial food matrices, organic apple, or grape juices, only CA maintained a similar level of antifungal activity, compared with a PBS bioassay. trans-Cinnamaldehyde showed higher antifungal activity (...). trans-Cinnamaldehyde could be developed as a potent antifungal agent in food processing or soil sanitation by reducing the time / cost necessary for fungal removal. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

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# Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan

Authors: Kanwal et al

Source: Environ Sci Pollut Res Int 27(11):12293-12307, 2020, doi: 10.1007/s11356-020-07649-z

**Abstract:** In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. (...)

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# Content of essential and non-essential elements in wild animals from western Ukraine and the health risks associated with meat and liver consumption

Source: Pilarczyk et al.

Source: Chemosphere 244, 2020, DOI: 10.1016/j.chemosphere.2019.125506.

**Abstract:** (...) The purpose of the work was to determine the levels of selected toxic and non-toxic elements in the tissues of free-living animals (...) to assess the health risks associated with meat and liver consumption. The test material comprised muscle, liver and kidney samples taken from 12 wild boar (Sus scrofa), 10 roe deer (Capreolus capreolus), 8 hares (Lepus europaeus L.). The permissible concentration of Pb was