Impact of twenty pesticides on soil carbon microbial functions and community composition

The effects of different halogenated-pyrethroid pesticides on soil microbial community

The application of pesticides increases crop yields but affects the structure and function of the soil microbial community. Halogens are common functional modification groups in chemical compounds, and innovative pesticides have been developed on the basis of these groups. However, the effects of different halogen substituents on soil microorganisms remain unclear. This study investigated the effects of three pyrethroid pesticides (deltamethrin, cypermethrin, and cyfluthrin) on the soil microbiota. Our results revealed that all these pesticides significantly reduced the stability of the bacterial communities and decreased bacterial diversity at high concentrations. Compared with deltamethrin (Br-) and cypermethrin (Cl-), low concentrations (0.5 mg/kg) of cyfluthrin (F-) increased soil bacterial diversity by 23.14 % and increased the potential for nitrogen fixation by 2.00 % and nitrification by 3.39 %, thus making it a relatively eco-friendly option. Our findings provide new insights into the potential ecological effects of halogenated pyrethroid pesticides on soil ecosystems.

Enhanced bioremediation of bensulfuron-methyl contaminated soil by Hansschlegelia zhihuaiae S113: Metabolic pathways and bacterial community structure

Bensulfuron-methyl (BSM), a widely used herbicide, can persist in soil and damag sensitive crops. Microbial degradation, supplemented with exogenous additives, provides an effective strategy to enhance BSM breakdown. Hansschlegelia zhihuaiae S113 has been shown to efficiently degrade this sulfonylurea herbicide. However, depending solely on a single strain for degradation proves inefficient and unlikely to achieve ideal remediation in practical applications. This study assessed the impact of various carbon sources on the degradation efficiency of S113 in BSM-polluted soil. Among these, glucose was the most effective, achieving a 98.7 % degradation rate after 9 d of inoculation. In addition, seven intermediates were detected during BSM degradation in soil through the cleavage of the phenyl ring ester bond, the pyrimidine rings, and urea bridge peptide bond, among other pathways. 2-amino-4,6-dimethoxy pyrimidine (ADMP), and 2-(aminosulfonylmethyl)-methyl benzoate(MSMB) were the primary intermediates. These metabolites were less toxic to maize, sorghum, and bacteria than the BSM. Community structure analysis indicated that variations in exogenous carbon sources and environmental pollutants significantly improved the ecological functions of soil microbial communities, enhancing pollutant degradation. Addition of carbon sources notably affected soil microbial community structure, modifying metabolic activities and interaction patterns. Specifically, glucose substantially increased the richness and diversity of soil bacterial communities. These findings offer valuable insights for field remediation practices and contributed to the development of more robust soil pollution management strategies.

Effects of nitrile compounds on the structure and function of soil microbial communities as revealed by metagenomes

The proliferation of nitrile mixtures has significantly exacerbated environmental pollution. This study employed metagenomic analysis to investigate the short-term effects of nitrile mixtures on soil microbial communities and their metabolic functions. It also examined the responses of indigenous microorganisms and their functional metabolic genes across various land use types to different nitrile stressors. The nitrile compound treatments in this study resulted in an increase in the abundance of Proteobacteria, Actinobacteria, and Firmicutes, while simultaneously reducing overall microbial diversity. The key genes involved in the denitrification process, namely, nirK, nosZ, and hao, were down-regulated, and NO3--N, NO2--N, and NH4+-N concentrations decreased by 7.7%-12.3%, 11.1%-21.3%, and 11.3%-30.9%, respectively. Notably, pond sludge samples exhibited a significant increase in the abundance of nitrogen fixation-related genes nifH, vnfK, vnfH, and vnfG following exposure to nitrile compounds. Furthermore, the fumarase gene fumD, which is responsible for catalyzing fumaric acid into malic acid in the tricarboxylic acid cycle, showed a substantial increase of 7.2-10.6-fold upon nitrile addition. Enzyme genes associated with the catechol pathway, including benB-xylY, dmpB, dmpC, dmpH, and mhpD, displayed increased abundance, whereas genes related to the benzoyl-coenzyme A pathway, such as bcrA, dch, had, oah, and gcdA, were notably reduced. In summary, complex nitrile compounds were found to significantly reduce the species diversity of soil microorganisms. Nitrile-tolerant microorganisms demonstrated the ability to degrade and adapt to nitrile pollutants by enhancing functional enzymes involved in the catechol pathway and fenugreek conversion pathway. This study offers insights into the specific responses of microorganisms to compound nitrile contamination, as well as valuable information for screening nitrile-degrading microorganisms and identifying nitrile metabolic enzymes.

Multimodel-based quantitative source apportionment and risk assessment of soil heavy metals: A reliable method to achieve regional pollution traceability and management

To strengthen the control of pollution sources and promote soil pollution management of agricultural land, this study constructed a comprehensive source apportionment framework, which significantly improved the reliability of potential source analysis compared with the traditional single model. The spatial distribution pattern of agricultural soil heavy metals (SHMs) content in Lintong, a typical river valley city in China, was determined and the degree of contamination was evaluated. A scientific source apportionment methodological framework was constructed through correlation analysis methods together with multiple source apportionment receptor models. Finally, the Monte Carlo simulation method was used to derive the results of the human health risk assessment (HHRA). The results revealed the following: (1) Agricultural soils were moderately and mildly polluted, accounting for 28.8 % and 71.2 % of the total number of sampling points, respectively. (2) The overall correlation of heavy metals (HMs) was strong according to the coupling analysis of the SHMs, in which a strong correlation (0.8-1) was reached among Cu, Ni, Pb, Cr and Zn, indicating that these HMs were most likely homologous or composite. (3) Multimodel analysis of the SHMs sources revealed that the first and second principal components were agricultural (41.36 %) and industrial (19.69 %) sources, respectively, and the remaining principal components were road traffic, natural factors, and atmospheric deposition or surface runoff, respectively. (4) The average comprehensive noncarcinogenic health risk indices for adults and children were 4.2259E-02 and 1.4194E-01, respectively, which were within the slight risk range, indicating that the risk caused by SHMs to the human body can be almost negligible. This study adopted a mixed method to reveal the risk of SHMs pollution and its sources, which provides some reference and technical support for traceability analysis, zoning control, and health risk studies of regional pollutants and is helpful for formulating scientific management measures and targeting control policies.

Impacts of organophosphate pesticide types and concentrations on aquatic bacterial communities and carbon cycling

Organophosphorus pesticides (OPPs) are important chemical stressors in aquatic ecosystems, and they attract increasing more attentions recently. However, the impacts of different OPPs on carbon cycling remain unclear, particularly for those functional-yet-uncultivable microbes. This study investigated the change in lake aquatic microbial communities in the presence of dichlorvos, monocrotophos, omethoate and parathion. All OPPs significantly inhibited biomass (p < 0.05) and the expression of carbon cycle-related cbbLG gene (p < 0.01), and altered aquatic microbial community structure, interaction, and assembly. Variance partitioning analysis showed a stronger impact of pesticide type on microbial biomass and community structure, where pesticide concentration played more significant roles in carbon cycling. From analysis of cbbLG gene and PICRUSt2, Luteolibacter and Verrucomicrobiaceae assimilated inorganic carbon through Wood-Ljungdahl pathway, whereas it was Calvin-Benson-Bassham cycle for Cyanobium PCC-6307. This work provides a deeper insight into the behavior and mechanisms of microbial community change in aquatic system in response to OPPs, and explicitly unravels the impacts of OPPs on their carbon-cycling functions.

Current insights into environmental acetochlor toxicity and remediation strategies

Acetochlor is a selective pre-emergent herbicide that is widely used to control annual grass and broadleaf weeds. However, due to its stable chemical structure, only a small portion of acetochlor exerts herbicidal activity in agricultural applications, while most of the excess remains on the surfaces of plants or enters ecosystems, such as soil and water bodies, causing harm to the environment and human health. In recent years, researchers have become increasingly focused on the repair of acetochlor residues. Compared with traditional physical and chemical remediation methods, microorganisms are the most effective way to remediate chemical pesticide pollution, such as acetochlor, because of their rich species, wide distribution, and diverse metabolic pathways. To date, researchers have isolated and identified many high-efficiency acetochlor-degrading strains, such as Pseudomonas oleovorans, Klebsiella variicola, Bacillus subtilus, Rhodococcus, and Methylobacillus, among others. The microbial degradation pathways of acetochlor include dechlorination, hydroxylation, N-dealkylation, C-dealkylation, and dehydrogenation. In addition, the microbial enzymes, including hydrolase (ChlH), debutoxylase (Dbo), and monooxygenase (MeaXY), responsible for acetochlor biodegradation are also being investigated. In this paper, we review the migration law of acetochlor in the environment, its toxicity to nontarget organisms, and the main metabolic methods. Moreover, we summarize the latest progress in the research on the microbial catabolism of acetochlor, including the efficient degradation of microbial resources, biodegradation metabolic pathways, and key enzymes for acetochlor degradation. At the end of the article, we highlight the existing problems in the current research on acetochlor biodegradation, provide new ideas for the remediation of acetochlor pollution in the environment, and propose future research directions.

Impacts of nano-acetamiprid pesticide on faba bean root metabolic response and soil health

The associated benefits and potential environmental risks of nanopesticides on plant and soil health, particularly in comparison with traditional pesticides, have not been systematically elucidated. Herein, we investigated the impacts of the as-synthesized nano-acetamiprid (Nano-Ace, 20 nm) at low (10 mg/L), medium (50 mg/L), high (100 mg/L) doses and the corresponding high commercial acetamiprid (Ace, 100 mg/L) on the physiological and metabolic response of faba bean (Vicia faba L.) plants, as well as on rhizosphere bacterial communities and functions over short-, medium- and long-term exposures. Overall, Nano-Ace exposure contributed to basic metabolic pathways (e.g., flavonoids, amino acids, TCA cycle intermediate, etc.) in faba bean roots across the whole exposure period. Moreover, Nano-Ace exposure enriched rhizosphere beneficial bacteria (e.g., Streptomyces (420.7%), Pseudomonas (33.8%), Flavobacterium (23.3%)) and suppressed pathogenic bacteria (e.g., Acidovorax (44.5%)). Additionally, Nano-Ace exposure showed a trend of low promotion and high inhibition of soil enzyme activities (e.g., invertase, urease, arylsulfatase, alkaline phosphatase) involved in soil C, N, S, and P cycling, while the inhibition was generally weaker than that of conventional Ace. Altogether, this study indicated that the redox-responsive nano-acetamiprid pesticide possessed high safety for host plants and soil health.

The effect of natural products used as pesticides on the soil microbiota: OECD 216 nitrogen transformation test fails to identify effects that were detected via q-PCR microbial abundance measurement

BACKGROUND

Natural products present an environmentally attractive alternative to synthetic pesticides which have been implicated in the off-target effect. Currently, the assessment of pesticide toxicity on soil microorganisms relies on the OECD 216 N transformation assay (OECD stands for the Organisation Economic Co-operation and Development, which is a key international standard-setting organisation). We tested the hypotheses that (i) the OECD 216 assay fails to identify unacceptable effects of pesticides on soil microbiota compared to more advanced molecular and standardized tests, and (ii) the natural products tested (dihydrochalcone, isoflavone, aliphatic phenol, and spinosad) are less toxic to soil microbiota compared to a synthetic pesticide compound (3,5-dichloraniline). We determined the following in three different soils: (i) ammonium (NH4 +) and nitrate (NO3 -) soil concentrations, as dictated by the OECD 216 test, and (ii) the abundance of phylogenetically (bacteria and fungi) and functionally distinct microbial groups [ammonia-oxidizing archaea (AOA) and bacteria (AOB)] using quantitative polymerase chain reaction (q-PCR).

RESULTS

All pesticides tested exhibited limited persistence, with spinosad demonstrating the highest persistence. None of the pesticides tested showed clear dose-dependent effects on NH4 + and NO3 - levels and the observed effects were <25% of the control, suggesting no unacceptable impacts on soil microorganisms. In contrast, q-PCR measurements revealed (i) distinct negative effects on the abundance of total bacteria and fungi, which were though limited to one of the studied soils, and (ii) a significant reduction in the abundance of both AOA and AOB across soils. This reduction was attributed to both natural products and 3,5-dichloraniline.

CONCLUSION

Our findings strongly advocate for a revision of the current regulatory framework regarding the toxicity of pesticides to soil microbiota, which should integrate advanced and well-standardized tools. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A risk entropy approach for linking pesticides and soil bacterial communities

Pesticides play a vital role in ensuring modern agricultural production, but also adversely affecting soil health. Microorganisms are the cornerstone of soil ecology, however, to date, there are few unified standards to measure the risk of soil pesticide residues to soil microbial community. To compensate for this gap, we collected soil samples from 55 orchards and monitored and risk-assessed 165 pesticides to microbial community in the soil. Results showed that a total of 137 pesticides were detected in all samples. Pesticide residues significantly influenced the microbial diversity and community structure in orchard soils, particularly fungicides and herbicides. The risk entropy of each pesticide was calculated in all samples and it was found that 60% of the samples had a "pesticide risk" (Risk quotient > 0.01), where the relative abundance significantly increased in 43 genera and significantly decreased in 111 genera (p < 0.05). Through multiple screens, we finally identified Bacillus and Sphingomonas as the most abundant sensitive genera under pesticide perturbation. The results showed that despite the complexity of the effects of pesticide residues on soils health, we could reveal them by identifying changes in soil bacterial, especially by the differences of microbial biomarkers abundance. The present study could provide new insights into the research strategy for pesticide pollution on soil microbial communities. ENVIRONMENTAL IMPLICATION: The risk of pesticide residues in soil needs to be quantified and standardized. We believe that microorganisms can be used as a marker to indicate soil pesticide residue risk. For this end, we investigated the residues of 165 pesticides in 55 orchard soil samples, calculated pesticide risk entropy and their effects on the soil microbial community. Through multiple analyzing and screening, we ultimately identified that, out of the 154 detected biomarkers, Bacillus and Sphingomonas were the most abundant sensitive genera under pesticide perturbation, which have the potential to be used as key biomarkers of soil microbiomes induced by pesticide perturbation.

Analysis and Functional Prediction of Core Bacteria in the Arabidopsis Rhizosphere Microbiome under Drought Stress

The effects of global warming, population growth, and economic development are increasing the frequency of extreme weather events, such as drought. Among abiotic stresses, drought has the greatest impact on soil biological activity and crop yields. The rhizosphere microbiota, which represents a second gene pool for plants, may help alleviate the effects of drought on crops. In order to investigate the structure and diversity of the bacterial communities on drought stress, this study analyzed the differences in the bacterial communities by high-throughput sequencing and bioinformatical analyses in the rhizosphere of Arabidopsis thaliana under normal and drought conditions. Based on analysis of α and β diversity, the results showed that drought stress had no significant effect on species diversity between groups, but affected species composition. Difference analysis of the treatments showed that the bacteria with positive responses to drought stress were Burkholderia-Caballeronia-Paraburkholderia (BCP) and Streptomyces. Drought stress reduced the complexity of the rhizosphere bacterial co-occurrence network. Streptomyces was at the core of the network in both the control and drought treatments, whereas the enrichment of BCP under drought conditions was likely due to a decrease in competitors. Functional prediction showed that the core bacteria metabolized a wide range of carbohydrates, such as pentose, glycans, and aromatic compounds. Our results provide a scientific and theoretical basis for the use of rhizosphere microbial communities to alleviate plant drought stress and the further exploration of rhizosphere microbial interactions under drought stress.

Actinomycetota, a central constituent microbe during long-term exposure to diazinon, an organophosphorus insecticide

Microbial biodegradation is a primary pesticide remediation pathway. Despite diazinon is one of the most frequently used organophosphate insecticides worldwide, its effect on soil microbial community remains obscure. We hypothesize that diazinon exposure reshapes microbial community, among them increased microbes may play a crucial role in diazinon degradation. To investigate this, we collected soil from an organic farming environment, introduced diazinon, cultivated it in a greenhouse, and then assessed its effects on soil microbiomes at three distinct time points: 20, 40, and 270 days after treatment (DAT). Results from HPLC showed that the level of diazinon was gradually degraded by 98.8% at 270 DAT when compared with day zero, whereas 16S rRNA gene analysis exhibited a significant reduction in the bacterial diversity, especially at the early two time points, indicating that diazinon may exert selection pressure to the bacteria community. Here, the relative abundance of phylum Actinomycetota increased at 20 and 40 DATs. In addition, the bacterial functional gene profile employing PICRUSt2 prediction also revealed that diazinon exposure induced the genomic function related to xenobiotics biodegradation and metabolism in soil, such as CYB5B, hpaC, acrR, and ppkA. To validate if bacterial function is caused by increased relative abundance in diazinon enriched soil, further bacteria isolation resulted in obtaining 25 diazinon degradation strains out of 103 isolates. Notably, more than 70% (18 out of 25) isolates are identified as phylum Actinomycetota, which empirically confirms and correlates microbiome and PICRUSt2 results. In conclusion, this study provides comprehensive information from microbiome analysis to obtaining several bacteria isolates responsible for diazinon degradation, revealing that the phylum Actinomycetota is as a key taxon that facilitates microbial biodegradation in diazinon spoiled soil. This finding may assist in developing a strategy for microbial detoxification of diazinon, such as using an Actinomycetota rich synthetic community (SynCom).

Role of Soil Microbiota Enzymes in Soil Health and Activity Changes Depending on Climate Change and the Type of Soil Ecosystem

The extracellular enzymes secreted by soil microorganisms play a pivotal role in the decomposition of organic matter and the global cycles of carbon (C), phosphorus (P), and nitrogen (N), also serving as indicators of soil health and fertility. Current research is extensively analyzing these microbial populations and enzyme activities in diverse soil ecosystems and climatic regions, such as forests, grasslands, tropics, arctic regions and deserts. Climate change, global warming, and intensive agriculture are altering soil enzyme activities. Yet, few reviews have thoroughly explored the key enzymes required for soil fertility and the effects of abiotic factors on their functionality. A comprehensive review is thus essential to better understand the role of soil microbial enzymes in C, P, and N cycles, and their response to climate changes, soil ecosystems, organic farming, and fertilization. Studies indicate that the soil temperature, moisture, water content, pH, substrate availability, and average annual temperature and precipitation significantly impact enzyme activities. Additionally, climate change has shown ambiguous effects on these activities, causing both reductions and enhancements in enzyme catalytic functions.

Combined pollution and soil microbial effect of pesticides and microplastics in greenhouse soil of suburban Tianjin, Northern China

Current-used pesticides (CUPs) and plastic films are essential materials used in greenhouse cultivation, which can lead to the residual accumulation of CUPs and microplastics (MPs) over time. The impact of CUPs and MPs on soil quality and food safety cannot be overlooked. However, the combined pollution resulting from CUPs and MPs in greenhouse soil remains poorly understood. In this study, we conducted a survey at 30 greenhouse sites in the Wuqing District of Tianjin, China, to investigate the pollution levels and characteristics of CUPs and MPs using QuEChERS combined with LC-MS/MS, and density extraction, 30% H2O2 digestion and micro-fourier transform infrared spectroscopy, respectively. Additionally, we aimed to evaluate the interactions among these two pollutants, soil physicochemical properties, and the bacterial community in the soil. CUPs were frequently detected in the examined soil samples; however, they posed no significant ecological risks due to their low levels. Furthermore, MPs, which predominantly comprised fragmented and fibrous polyethylene (PE) and polypropylene (PP) particles smaller than 1.0 mm, could potentially degrade into nanoplastics, which might subsequently enter the food chain and pose a serious threat to human health. We observed no substantial correlations between CUPs and MPs, except for a negative correlation between dimethomorph and film MPs. The soil pH and total organic carbon (TOC) exhibited interactions with both types of pollutants, whereas soil clay content (CC) only correlated with CUPs, and soil available nitrogen (AN) only correlated with MPs. The variability of soil bacterial communities among the 30 sampling sites was minimal, with the dominant genus being Bacillus. Soil pH, TOC, and CC collectively exerted a strong influence on the microbial community across all samples; however, the effects of CUPs and MPs on the soil microbial structure were marginal. These results contribute to a comprehensive understanding of the environmental stress and ecological risks associated with the combined pollution of CUPs and MPs.

Efficiency and ecological safety of herbicide haloxyfop-R-methyl on removal of coastal invasive plant Spartina alterniflora

Spartina alterniflora is a global invasive plant and has caused considerable damage to coastal wetland ecosystem. This study evaluated the efficiency and ecological safety of herbicide haloxyfop-R-methyl (HPME) in removing S alterniflora in Laizhou Bay. The results showed that the density of regenerated S. alterniflora after 10 months of application of 0.01, 0.02 and 0.03 g/m2 HPME decreased by 86.67 %, 99.16 % and 99.31 %, respectively. Moreover, seed abortion rates were 62.25 %, 92.24 % and 94.82 %, and weight of roots in HPME groups were 56.63 %, 59.99 %, and 40.10 % of those in the control group. After 4 days of application, HPME could not be detected in S. alterniflora and sediments. In addition, HPME did not change sediment physicochemical properties, macrozoobenthos community and microbial community structure during 16 days, but increased the density of native macrozoobenthos after 1 year. Therefore, HPME might be an effective and ecologically safe chemical for the eradication of S. alterniflora.

Imidacloprid-induced stress affects the growth of pepper plants by disrupting rhizosphere-plant microbial and metabolite composition

Overusing imidacloprid (IMI) has been found to impede secondary metabolism and hinder plant growth. The impact of IMI stress on the interaction between metabolites, rhizosphere, and plant-microbe dispersion through various pathways in pepper plants has not been extensively studied. This study investigated the effects of IMI on plant signaling components, secondary metabolic pathways, and microbial communities in the rhizosphere and phyllosphere. Here, the distribution of IMI and its metabolites (6-chloronicotinic acid, IMI-desnitro, 5-hydroxy-IMI, IMI-urea, and IMI-olefin) was primarily observed in the pepper plant leaves. A rise in IMI concentration had a more significant inhibitive effect on the metabolism of pepper leaves than on pepper roots. The findings of non-target metabolomics indicated that IMI exposure primarily suppresses secondary metabolism in pepper plants, encompassing flavones, phenolic acids, and phytohormones. Notably, the IMI treatment disrupted the equilibrium between plants and microbes by decreasing the population of microorganisms such as Vicinamibacteria, Verrucomicrobiae, Gemmatimonadetes, and Gammaproteobacteria in the phyllosphere, as well as Vicinamibacteria, Gemmatimonadetes, Gammaproteobacteria, and Alphaproteobacteria in the rhizosphere of pepper plants. The study demonstrates that overexposure to IMI harms microbial composition and metabolite distribution in the rhizosphere soil and pepper seedlings, inhibiting plant growth.

Nano-based smart formulations: A potential solution to the hazardous effects of pesticide on the environment

Inefficient usage, overdose, and post-application losses of conventional pesticides have resulted in severe ecological and environmental issues, such as pesticide resistance, environmental contamination, and soil degradation. Advances in nano-based smart formulations are promising novel methods to decrease the hazardous impacts of pesticide on the environment. In light of the lack of a systematic and critical summary of these aspects, this work has been structured to critically assess the roles and specific mechanisms of smart nanoformulations (NFs) in mitigating the adverse impacts of pesticide on the environment, along with an evaluation of their final environmental fate, safety, and application prospects. Our study provides a novel perspective for a better understanding of the potential functions of smart NFs in reducing environmental pollution. Additionally, this study offers meaningful information for the safe and effective use of these nanoproducts in field applications in the near future.

Repeated applications of fipronil, propyzamide and flutriafol affect soil microbial functions and community composition: A laboratory-to-field assessment

Pesticides play an important role in conventional agriculture by controlling pests, weeds, and plant diseases. However, repeated applications of pesticides may have long lasting effects on non-target microorganisms. Most studies have investigated the short-term effects of pesticides on soil microbial communities at the laboratory scale. Here, we assessed the ecotoxicological impact of fipronil (insecticide), propyzamide (herbicide) and flutriafol (fungicide) on (i) soil microbial enzymatic activities, (ii) potential nitrification, (iii) abundance of the fungal and bacterial community and key functional genes (nifH, amoA, chiA, cbhl and phosphatase) and (iii) diversity of bacteria, fungi, ammonia oxidizing bacteria (AOB) and archaea (AOA) after repeated pesticide applications in laboratory and field experiments. Our results showed that repeated applications of propyzamide and flutriafol affected the soil microbial community structure in the field and had significant inhibitory effects on enzymatic activities. The abundances of soil microbiota affected by pesticides recovered to levels similar to the control following a second application, suggesting that they might be able to recover from the pesticide effects. However, the persistent pesticide inhibitory effects on soil enzymatic activities suggests that the ability of the microbial community to cope with the repeated application was not accompanied by functional recovery. Overall, our results suggest that repeated pesticide applications may influence soil health and microbial functionalities and that more information should be collected to inform risk-based policy development.

Insights into the ubiquity, persistence and microbial intervention of imidacloprid

Imidacloprid, a neonicotinoid pesticide, is employed to increase crop productivity. Meanwhile, its indiscriminate application severely affects the non-target organisms and the environment. As an eco-friendly and economically workable option, the microbial intervention has garnered much attention. This review concisely outlines the toxicity, long-term environmental repercussions, degradation kinetics, biochemical pathways, and interplay of genes implicated in imidacloprid remediation. The studies have highlighted imidacloprid residue persistence in the environment for up to 3000 days. In view of high persistence, effective intervention is highly required. Bacteria-mediated degradation has been established as a viable approach with Bacillus spp. being among the most efficient at 30 ℃ and pH 7. Further, a comparative metagenomic investigation reveals dominant neonicotinoid degradation genes in agriculture compared to forest soils with distinctive microbial communities. Functional metabolism of carbohydrates, amino acids, fatty acids, and lipids demonstrated a significantly superior relative abundance in forest soil, implying its quality and fertility. The CPM, CYP4C71v2, CYP4C72, and CYP6AY3v2 genes that synthesize cyt p450 monooxygenase enzyme play a leading role in imidacloprid degradation. In the future, a systems biology approach incorporating integrated kinetics should be utilized to come up with innovative strategies for moderating the adverse effects of imidacloprid on the environment.

The Effects of Roundup™ on Benthic Microbial Assemblages

Given the wide usage of Roundup, a common herbicide, the impacts of its presence in ecological communities are of great interest. Many studies have investigated the effects of glyphosate, the active ingredient in Roundup, on different factions of an ecosystem including on animals, plants, microorganisms, and nutrients. The current study expanded upon these works using Roundup instead of glyphosate to provide a realistic application in which to observe the development of microbial assemblages and nutrient composition in two different habitats. Winogradsky columns were prepared using benthic material from a ditch and a pond. Varying concentrations of Roundup were introduced to the columns at the beginning of the study and microbial growth and nutrient compositions from each column were measured weekly. The results indicate that the presence of Roundup has varying effects on microorganisms and nutrients. While photosynthetic microbes were negatively impacted, a shift in the microbial composition to heterotrophic microbes indicates that these microorganisms were able to utilize some ingredients in Roundup as a nutrient source. Additionally, the temporal analysis of nutrient compositions indicated that microbes metabolize glyphosate starting with the phosphate moiety even when the other compounds in Roundup are present. While these trends were observed in both benthic habitats, the composition of the ecological community can affect its ability to utilize the ingredients in Roundup as a nutrient source.