Enhanced Cypermethrin Degradation Kinetics and Metabolic Pathway in Bacillus thuringiensis Strain SG4

Biodegradation of monocrotophos, cypermethrin & fipronil by Proteus myxofaciens VITVJ1: A plant - microbe based remediation

Current study was focused on the degradation of pesticides such as Monocrotophos, Cypermethrin & Fipronil (M, C & F) using phyto and rhizoremediation strategies. The isolate Proteus myxofaciens (VITVJ1) obtained from agricultural soil was capable of degrading M, C & F. The bacteria exhibited resistance to all the pesticides (M, C & F) up to 1500 ppm and was also capable of forming biofilms. The degraded products identified using Gas Chromatography-Mass Spectroscopy (GC-MS) and FTIR was further used for deriving the degradation pathway. The end product of M, C & F was acetic acid and 3-phenoxy benzoic acid which was confirmed by the presence of functional groups such as C=O and OH. Seed germination assay revealed the non-toxic nature of the degraded products with increased germination index in the treatments augmented with degraded products. The candidate genes such as opdA gene, Est gene and MnP1gene was amplified with the amplicon size of 700bp, 1200bp and 500bp respectively. P. myxofaciens not only degraded M, C & F, but was also found to be a plant growth promoting rhizobacteria. Since, it was capable of producing Indole Acetic acid (IAA), siderophore and was able to solubilize insoluble phosphate. Therefore, VITVJ1 upon augmentation to the rhizoremediation setup aided the degradation of pesticides with increase in plant growth as compared to that of the phytoremediation setup. To our knowledge this is the first study where P. myxofaciens has been effectively used for the degradation of three different classes of pesticides, which could also enhance the growth of plants and simultaneously degrade M, C & F.

Synergistic insights into pesticide persistence and microbial dynamics for bioremediation

Rampant use of fertilizers and pesticides for boosting agricultural crop productivity has proven detrimental impact on land, water, and air quality globally. Although fertilizers and pesticides ensure greater food security, their unscientific management negatively impacts soil fertility, structure of soil microbiome and ultimately human health and hygiene. Pesticides exert varying impacts on soil properties and microbial community functions, contingent on factors such as their chemical structure, mode of action, toxicity, and dose-response characteristics. The diversity of bacterial responses to different pesticides presents a valuable opportunity for pesticide remediation. In this context, OMICS technologies are currently under development, and notable advancements in gene editing, including CRISPR technologies, have facilitated bacterial engineering, opening promising avenues for reducing toxicity and enhancing biological remediation. This paper provides a holistic overview of pesticide dynamics, with a specific focus on organophosphate, organochlorine, and pyrethroids. It covers their occurrence, activity, and potential mitigation strategies, with an emphasis on the microbial degradation route. Subsequently, the pesticide degradation pathways, associated genes and regulatory mechanisms, associated OMICS approaches in soil microbes with a special emphasis on CRISPR/Cas9 are also being discussed. Here, we analyze key environmental factors that significantly impact pesticide degradation mechanisms and underscore the urgency of developing alternative strategies to diminish our reliance on synthetic chemicals.

Response of Soil Microbiota, Enzymes, and Plants to the Fungicide Azoxystrobin

The present study was aimed at assessing the impact of azoxystrobin-a fungicide commonly used in plant protection against pathogens (Amistar 250 SC)-on the soil microbiota and enzymes, as well as plant growth and development. The laboratory experiment was conducted in three analytical terms (30, 60, and 90 days) on sandy clay (pH-7.0). Azoxystrobin was applied to soil in doses of 0.00 (C), 0.110 (F) and 32.92 (P) mg kg-1 d.m. of soil. Its 0.110 mg kg-1 dose stimulated the proliferation of organotrophic bacteria and actinobacteria but inhibited that of fungi. It also contributed to an increase in the colony development index (CD) and a decrease in the ecophysiological diversity index (EP) of all analyzed groups of microorganisms. Azoxystrobin applied at 32.92 mg kg-1 reduced the number and EP of microorganisms and increased their CD. PP952051.1 Bacillus mycoides strain (P), PP952052.1 Prestia megaterium strain (P) bacteria, as well as PP952052.1 Kreatinophyton terreum isolate (P) fungi were identified in the soil contaminated with azoxystrobin, all of which may exhibit resistance to its effects. The azoxystrobin dose of 0.110 mg kg-1 stimulated the activity of all enzymes, whereas its 32.92 mg kg-1 dose inhibited activities of dehydrogenases, alkaline phosphatase, acid phosphatase, and urease and stimulated the activity of catalase. The analyzed fungicide added to the soil at both 0.110 and 32.92 mg kg-1 doses inhibited seed germination and elongation of shoots of Lepidium sativum L., Sinapsis alba L., and Sorgum saccharatum L.

Microbial detoxification of chlorpyrifos, profenofos, monocrotophos, and dimethoate by a multifaceted rhizospheric Bacillus cereus strain PM38 and its potential for the growth promotion in cotton

Bacillus genera, especially among rhizobacteria, are known for their ability to promote plant growth and their effectiveness in alleviating several stress conditions. This study aimed to utilize indigenous Bacillus cereus PM38 to degrade four organophosphate pesticides (OPs) such as chlorpyrifos (CP), profenofos (PF), monocrotophos (MCP), and dimethoate (DMT) to mitigate the adverse effects of these pesticides on cotton crop growth. Strain PM38 exhibited distinct characteristics that set it apart from other Bacillus species. These include the production of extracellular enzymes, hydrogen cyanide, exopolysaccharides, Indol-3-acetic acid (166.8 μg/mL), siderophores (47.3 μg/mL), 1-aminocyclopropane-1-carboxylate deaminase activity (32.4 μg/mL), and phosphorus solubilization (162.9 μg/mL), all observed at higher concentrations. This strain has also shown tolerance to salinity (1200 mM), drought (20% PEG-6000), and copper and cadmium (1200 mg/L). The amplification of multi-stress-responsive genes, such as acdS, ituC, czcD, nifH, sfp, and pqqE, further confirmed the plant growth regulation and abiotic stress tolerance capability in strain PM38. Following the high-performance liquid chromatography (HPLC) analysis, the results showed striking compatibility with the first kinetic model. Strain PM38 efficiently degraded CP (98.4%), PF (99.7%), MCP (100%), and DMT (95.5%) at a concentration of 300 ppm over 48 h at 35 °C under optimum pH conditions, showing high coefficients of determination (R2) of 0.974, 0.967, 0.992, and 0.972, respectively. The Fourier transform infrared spectroscopy (FTIR) analysis and the presence of opd, mpd, and opdA genes in the strain PM38 further supported the potential to degrade OPs. In addition, inoculating cotton seedlings with PM38 improved root length under stressful conditions. Inoculation of strain PM38 reduces stress by minimizing proline, thiobarbituric acid-reactive compounds, and electrolyte leakage. The strain PM38 has the potential to be a good multi-stress-tolerant option for a biological pest control agent capable of improving global food security and managing contaminated sites.

Microbial degradation of the benzimidazole fungicide carbendazim by Bacillus velezensis HY-3479

Carbendazim (methyl benzimidazol-2-ylcarbamate: MBC) is a fungicide of the benzimidazole group that is widely used in the cultivation of pepper, ginseng, and many other crops. To remove the remnant carbendazim, many rhizobacteria are used as biodegradation agents. A bacterial strain of soil-isolated Bacillus velezensis HY-3479 was found to be capable of degrading MBC in M9 minimal medium supplemented with 250 mg/L carbendazim. The strain had a significantly higher degradation efficiency compared to the control strain Bacillus subtilis KACC 15590 in high-performance liquid chromatography (HPLC) analysis, and HY-3479 had the best degradation efficiency of 76.99% at 48 h. In gene expression analysis, upregulation of carbendazim-degrading genes (mheI, hdx) was observed in the strain. HY-3479 was able to use MBC as the sole source of carbon and nitrogen, but the addition of 12.5 mM NH4NO3 significantly increased the degradation efficiency. HPLC analysis showed that the degradation efficiency increased to 87.19% when NH4NO3 was added. Relative gene expression of mheI and hdx also increased for samples with NH4NO3 supplementation. The enzyme activity of the carbendazim-degrading enzyme and the 2-aminobenzimidazole-degrading enzyme was found to be highly present in the HY-3479 strain. It is the first reported B. velezensis strain to biodegrade carbendazim (MBC). The biodegradation activity of strain HY-3479 may be developed as a useful means for bioremediation and used as a potential microbial agent in sustainable agriculture.

Quantitative proteomic analysis reveals the mechanism and key esterase of β-cypermethrin degradation in a bacterial strain from fermented food

Beta-cypermethrin (β-CY) residues in food are an important threat to human health. Microorganisms can degrade β-CY residues during fermentation of fruits and vegetables, while the mechanism is not clear. In this study, a comprehensively investigate of the degradation mechanism of β-CY in a food microorganism was conducted based on proteomics analysis. The β-CY degradation bacteria Gordonia alkanivorans GH-1 was derived from fermented Pixian Doubanjiang. Its crude enzyme extract could degrade 77.11% of β-CY at a concentration of 45 mg/L within 24 h. Proteomics analysis revealed that the ester bond of β-CY is broken under the action of esterase to produce 3-phenoxy benzoic acid, which was further degraded by oxidoreductase and aromatic degrading enzyme. The up-regulation expression of oxidoreductase and esterase was confirmed by transcriptome and quantitative reverse transcription PCR. Meanwhile, the expression of esterase Est280 in Escherichia coli BL21 (DE3) resulted in a 48.43% enhancement in the degradation efficiency of β-CY, which confirmed that this enzyme was the key enzyme in the process of β-CY degradation. This study reveals the degradation mechanism of β-CY by microorganisms during food fermentation, providing a theoretical basis for the application of food microorganisms in β-CY residues.

Studies on photocatalytic mineralization of organic pesticides by bimetallic Cu-Zn nanoparticles derived from Zingiber officinale Roscoe (ginger) using green chemistry approach

Compared to monometallic nanoparticles, bimetallic nanoparticle synthesis and characterization have attracted more attention due to their superior environmental protection properties. In this study, we discuss the preparation and characterization of Cu-Zn bimetallic nanoparticles using Zinger extract, as well as their potential role in photocatalytic degradation of carbendazim, chlorpyrifos, monocrotophos, and cypermethrin. Surface properties were assessed with SEM and TEM, while UV-VIS, XRD, FTIR, and fluorescence spectroscopy were used to characterize the materials. It was observed that higher pH conditions were more conducive to the development of stable Cu-Zn BMNPs with diameters ranging from 60 to 100 nm. UV-VIS spectroscopy showed that the Cu-Zn bimetallic nanoparticles photodegraded 53-95% of the pesticides, monocrotophos, chlorpyrifos, and carbendazim during the 24-72-h incubation period. A number of pesticides may be photocatalytically degraded by primary reactive radicals produced by nanoparticles. We propose that the use of bimetallic nanoparticles could be one alternative strategy for pesticide mineralization.

Mycotransformation of Commercial Grade Cypermethrin Dispersion by Aspergillus terreus PDB-B Strain Isolated from Lake Sediments of Kulamangalam, Madurai

A fungal isolate Aspergillus terreus PDB-B (accession number: MT774567.1), which could tolerate up to 500 mg/L of cypermethrin, was isolated from the lake sediments of Kulamangalam tropical lake, Madurai, and identified by internal transcribed spacer (ITS) sequencing followed by phylogenetic analysis. The biotransformation potential of the strain was compared with five other strains (A, J, UN2, M1 and SM108) as a consortium, which were tentatively identified as Aspergillus glaucus, Aspergillus niger, Aspergillus flavus, Aspergillus terreus, and Aspergillus flavus, respectively. Batch culture and soil microcosm studies were conducted to explore biotransformation using plate-based enzymatic screening and GC-MS. A mycotransformation pathway was predicted based on a comparative analysis of the transformation products (TPs) obtained. The cytotoxicity assay revealed that the presence of (3-methylphenyl) methanol and isopropyl ether could be relevant to the high rate of lethality.

Bacillus sp. as a microbial cell factory: Advancements and future prospects

Bacillus sp. is one of the most distinctive gram-positive bacteria, able to grow efficiently using cheap carbon sources and secrete a variety of useful substances, which are widely used in food, pharmaceutical, agricultural and environmental industries. At the same time, Bacillus sp. is also recognized as a safe genus with a relatively clear genetic background, which is conducive to the industrial production of target metabolites. In this review, we discuss the reasons why Bacillus sp. has been so extensively studied and summarize its advances in systems and synthetic biology, engineering strategies to improve microbial cell properties, and industrial applications in several metabolic engineering applications. Finally, we present the current challenges and possible solutions to provide a reliable basis for Bacillus sp. as a microbial cell factory.

Pseudomonas aeruginosa based concurrent degradation of beta-cypermethrin and metabolite 3-phenoxybenzaldehyde, and its bioremediation efficacy in contaminated soils

Beta-cypermethrin is one of the widely used pyrethroid insecticides, and problems associated with the accumulation of its residues have aroused public attention. Thus, there is an urgent need to effectively remove the beta-cypermethrin that is present in the environment. Biodegradation is considered a cost-effective and environmentally friendly method for removing pesticide residues. However, the beta-cypermethrin-degrading microbes that are currently available are not optimal. In this study, Pseudomonas aeruginosa PAO1 was capable of efficiently degrading beta-cypermethrin and its major metabolite 3-phenoxybenzaldehyde in water/soil environments. Strain PAO1 could remove 91.4% of beta-cypermethrin (50 mg/L) in mineral salt medium within 120 h. At the same time, it also possesses a significant ability to metabolize 3-phenoxybenzaldehyde-a toxic intermediate of beta-cypermethrin. The Andrews equation showed that the maximum substrate utilization concentrations of beta-cypermethrin and 3-phenoxybenzaldehyde by PAO1 were 65.3558 and 49.6808 mg/L, respectively. Box-Behnken design-based response surface methodology revealed optimum conditions for the PAO1 strain-based degradation of beta-cypermethrin as temperature 30.6 °C, pH 7.7, and 0.2 g/L inoculum size. The results of soil remediation experiments showed that indigenous micro-organisms helped to promote the biodegradation of beta-cypermethrin in soil, and beta-cypermethrin half-life in non-sterilized soil was 6.84 days. The bacterium transformed beta-cypermethrin to produce five possible metabolites, including 3-phenoxybenzyl alcohol, methyl 2-(4-hydroxyphenoxy)benzoate, diisobutyl phthalate, 3,5-dimethoxyphenol, and 2,2-dimethyl-1-(4-phenoxyphenyl)propanone. Among them, methyl 2-(4-hydroxyphenoxy)benzoate and 3,5-dimethoxyphenol were first identified as the intermediate products during the beta-cypermethrin degradation. In addition, we propose a degradation pathway for beta-cypermethrin that is metabolized by strain PAO1. Beta-cypermethrin could be biotransformed firstly by hydrolysis of its carboxylester linkage, followed by cleavage of the diaryl bond and subsequent metabolism. Based on the above results, P. aeruginosa PAO1 could be a potent candidate for the beta-cypermethrin-contaminated environmental bioremediation.

Antioxidants improve β-cypermethrin degradation by alleviating oxidative damage and increasing bioavailability by Bacillus cereus GW-01

Microbial degradation of pesticide residues has the potential to reduce their hazards to human and environmental health. However, in some cases, degradation can activate pesticides, making them more toxic to microbes. Here we report on the β-cypermethrin (β-CY) toxicity to Bacillus cereus GW-01, a recently described β-CY degrader, and effects of antioxidants on β-CY degradation. GW-01 exposed to β-CY negatively affected the growth rate. The highest maximum specific growth rate (μm) appeared at 25 mg/L β-CY. β-CY induced the oxidative stress in GW-01. The activities of superoxide dismutase (SOD), catalyse (CAT), and glutathione-S-transferase (GST) were significantly higher than that in control (p < 0.01); but they are decreased as growth phase pronged, which is contrary to the β-CY degradation by GW-01 cells obtaining from various growth phase. Ascorbic acid (Vc), tea polyphenols (TP), and adenosine monophosphate (AMP) improved the degradation through changing the physiological property of GW-01. TP and AMP prompted the expression of gene encoding β-CY degradation in GW-01, while Vc does the opposite. Biofilm formation was significantly inhibited by β-CY, while was significantly enhanced by certain concentrations of TP and AMP (p < 0.05); while cell surface hydrophobicity (CSH) was negatively associated with β-CY concentrations from 25 to 100 mg/L, and these 4 antioxidants all boosted the CSH. Cells grown with β-CY had lower levels of saturated fatty acids but increased levels of some unsaturated and branched fatty acids, and these antioxidants alleviated the FA composition changes and gene expression related with FA metabolism. We also mined transcriptome analyses at lag, logarithmic, and stationary phases, and found that β-CY induced oxidative stress. The objective of this study was to elaborate characteristics in relation to the microbial resistance of pesticide poisoning and the efficiency of pesticide degradation, and to provide a promising method for improving pesticide degradation by microbes.

New roles for Bacillus thuringiensis in the removal of environmental pollutants

For a long time, the well-known Gram-positive bacterium Bacillus thuringiensis (Bt) has been extensively studied and developed as a biological insecticide for Lepidoptera and Coleoptera pests due to its ability to secrete a large number of specific insecticidal proteins. In recent years, studies have found that Bt strains can also potentially biodegrade residual pollutants in the environment. Many researchers have isolated Bt strains from multiple sites polluted by exogenous compounds and characterized and identified their xenobiotic-degrading potential. Furthermore, its pathway for degradation was also investigated at molecular level, and a number of major genes/enzymes responsible for degradation have been explored. At present, a variety of xenobiotics involved in degradation in Bt have been reported, including inorganic pollutants (used in the field of heavy metal biosorption and recovery and precious metal recovery and regeneration), pesticides (chlorpyrifos, cypermethrin, 2,2-dichloropropionic acid, etc.), organic tin, petroleum and polycyclic aromatic hydrocarbons, reactive dyes (congo red, methyl orange, methyl blue, etc.), and ibuprofen, among others. In this paper, the biodegrading ability of Bt is reviewed according to the categories of related pollutants, so as to emphasize that Bt is a powerful agent for removing environmental pollutants.

Biological treatment of triclosan using a novel strain of Enterobacter cloacae and introducing naphthalene dioxygenase as an effective enzyme

In recent years, triclosan (TCS) has been widely used as an antibacterial agent in personal care products due to the spread of the Coronavirus. TSC is an emerging contaminant, and due to its stability and toxicity, it cannot be completely degraded through traditional wastewater treatment methods. In this study, a novel strain of Enterobacter cloacae was isolated and identified that can grow in high TCS concentrations. Also, we introduced naphthalene dioxygenase as an effective enzyme in TCS biodegradation, and its role during the removal process was investigated along with the laccase enzyme. The change of cell surface hydrophobicity during TCS removal revealed that a glycolipid biosurfactant called rhamnolipid was involved in TCS removal, leading to enhanced biodegradation of TCS. The independent variables, such as initial TCS concentration, pH, removal duration, and temperature, were optimized using the response surface method (RSM). As a result, the maximum TCS removal (97%) was detected at a pH value of 7 and a temperature of 32 °C after 9 days and 12 h of treatment. Gas chromatography-mass spectrometry (GC/MS) analysis showed five intermediate products and a newly proposed pathway for TCS degradation. Finally, the phytotoxicity experiment conducted on Cucumis sativus and Lens culinaris seeds demonstrated an increase in germination power and growth of stems and roots in comparison to untreated water. These results indicate that the final treated water was less toxic.

Microbial detoxification of bifenthrin insecticide by selected fungal strains and optimizing conditions using response surface methodology for agricultural sustainability

Bifenthrin is a type I broad spectrum pyrethroid insecticide widely employed in urban and agricultural settings with little knowledge about its biodegradation. Bifenthrin was subjected to a 35 days incubation period in which it was degraded by five fungal strains named as Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Penicillium chrysogenum, and Lasiodiplodia theobromae. Penicillium chrysogenum was found to be extremely effective in degrading bifenthrin up to 85%. Furthermore, response surface methodology (RSM) with Box-Behnken design is applied to optimize the degradation conditions with varying pH, temperature (°C), and incubation time (days). The p value < 0.05 in the response surface design and analysis of variance showed the significance of the reaction parameters. The ideal conditions for Penicillium chrysogenum to break down bifenthrin (10 mgL-1) were found to be 30 °C, pH 7, and a 24 days incubation period. In eutrophic conditions and a glucose-rich media, this fungus co-metabolized bifenthrin. By hydrolytically cleaving the carboxyl ester bond, the Penicillium chrysogenum breaks down bifenthrin, as shown by the chromatogram of four metabolites from GCMS. The biodegradation of bifenthrin by strain Penicillium chrysogenum and its use in agronomic situations are now well understood as per the findings of this study.

Pesticide pestilence: Global scenario and recent advances in detection and degradation methods

Increased anthropogenic activities are confronted as the main cause for rising environmental and health concerns globally, presenting an indisputable threat to both environment and human well-being. Modern-day industrialization has given rise to a cascade of concurrent environmental and health challenges. The global human population is growing at an alarming rate, posing tremendous pressure on future food security, and healthy and environmentally sustainable diets for all. To feed all, the global food production needs to increase by 50% by 2050, but this increase has to occur from the limited arable land, and under the present-day climate variabilities. Pesticides have become an integral component of contemporary agricultural system, safeguarding crops from pests and diseases and their use must be reduce to fulfill the SDG (Sustainable Development Goals) agenda . However, their indiscriminate use, lengthy half-lives, and high persistence in soil and aquatic ecosystems have impacted global sustainability, overshot the planetary boundaries and damaged the pure sources of life with severe and negative impacts on environmental and human health. Here in this review, we have provided an overview of the background of pesticide use and pollution status and action strategies of top pesticide-using nations. Additionally, we have summarized biosensor-based methodologies for the rapid detection of pesticide residue. Finally, omics-based approaches and their role in pesticide mitigation and sustainable development have been discussed qualitatively. The main aim of this review is to provide the scientific facts for pesticide management and application and to provide a clean, green, and sustainable environment for future generations.

Microbial Diversity and Enzyme Activity as Indicators of Permethrin-Exposed Soil Health

Owing to their wide range of applications in the control of ticks and insects in horticulture, forestry, agriculture and food production, pyrethroids pose a significant threat to the environment, including a risk to human health. Hence, it is extremely important to gain a sound understanding of the response of plants and changes in the soil microbiome induced by permethrin. The purpose of this study has been to show the diversity of microorganisms, activity of soil enzymes and growth of Zea mays following the application of permethrin. This article presents the results of the identification of microorganisms with the NGS sequencing method, and of isolated colonies of microorganisms on selective microbiological substrates. Furthermore, the activity of several soil enzymes, such as dehydrogenases (Deh), urease (Ure), catalase (Cat), acid phosphatase (Pac), alkaline phosphatase (Pal), β-glucosidase (Glu) and arylsulfatase (Aryl), as well as the growth of Zea mays and its greenness indicators (SPAD), after 60 days of growth following the application of permethrin, were presented. The research results indicate that permethrin does not have a negative effect on the growth of plants. The metagenomic studies showed that the application of permethrin increases the abundance of Proteobacteria, but decreases the counts of Actinobacteria and Ascomycota. The application of permethrin raised to the highest degree the abundance of bacteria of the genera Cellulomonas, Kaistobacter, Pseudomonas, Rhodanobacter and fungi of the genera Penicillium, Humicola, Iodophanus, Meyerozyma. It has been determined that permethrin stimulates the multiplication of organotrophic bacteria and actinomycetes, decreases the counts of fungi and depresses the activity of all soil enzymes in unseeded soil. Zea mays is able to mitigate the effect of permethrin and can therefore be used as an effective phytoremediation plant.

Esterase and ALDH dehydrogenase-based pesticide degradation by Bacillus brevis 1B from a contaminated environment

The isolated bacterial strain (Bacillus brevis strain 1 B) showed a maximum tolerated level of 450 mg L^-1 of the selected pesticides namely: imidacloprid, fipronil, cypermethrin, and sulfosulfuron. Within 15 days of the experiment, strain 1 B was able to reduce up to 95% of a pesticide mixture (20 mg L^-1) in a carbon-deficient medium (minimal medium). The optimal conditions obtained using Response Surface Methodology (RSM) were: inoculums; 2.0 × 10⁷ CFU mL^-1, shaking speed; 120 rpm, and pesticide concentration; 80 mg L^-1. After 15 days of soil-based bioremediation using strain 1 B, the degradation pattern for imidacloprid, fipronil, cypermethrin, sulfosulfuron, and control was 99, 98.5, 94, 91.67, and 7%, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was used to determine the intermediate metabolites of cypermethrin with bacterial 1 B as 2-cyclopenten-1-one, 2-methylpyrrolidine, 2-oxonanone, 2-pentenoic acid, 2-penten-1-ol, hexadecanoic acid or palmitic acid, pentadecanoic acid, 3-cyclopentylpropionic acid, and 2-dimethyl. Furthermore, genes encoding aldehyde dehydrogenase (ALDH) and esterase were expressed under stress conditions and connected to pesticide bioremediation. Hence the efficacy of Bacillus brevis (1 B) could be employed for the bioremediation of pesticide mixtures and other toxic substances (dye, polyaromatic hydrocarbon, etc.) from contaminated sites.

Imidacloprid biodegradation using novel bacteria Tepidibacillus decaturensis strain ST1 in batch and in situ microcosm study

Imidacloprid is one of the frequently used insecticides. Indiscriminate use of imidacloprid makes it perilous to non-target organisms as well as the environment, including soil and water sources, thus, making its elimination from the environment an irresistible concern. Bioremediation is a technique that uses the degrading capabilities of bacteria to create an economical and reliable method of pesticide abatement. In an attempt to solve the problem arising due to imidacloprid contamination, bacterial strains possessing the ability to degrade imidacloprid were isolated from contaminated agricultural soil samples in the present study. Imidacloprid-degrading isolate, identified as Tepidibacillus decaturensis strain ST1, could effectively degrade imidacloprid in liquid media, slurry, and soil microcosms. The microcosm studies using the isolate resulted in the degradation of around 77.5% and 85% of imidacloprid (200 ppm) in sterile and unsterile soils within 45 days. In addition to biodegradation, sorption of insecticide by the plants and natural reduction of insecticide over time has also been reported. The degradation in soil follows first-order kinetics. Hydrazinecarboxamide and hydroxyurea were identified as metabolites on conducting GC-MS analysis of the degraded samples.

A novel binary pesticidal protein from Chryseobacterium arthrosphaerae controls western corn rootworm by a different mode of action to existing commercial pesticidal proteins

The western corn rootworm (WCR) Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) remains one of the economically most important pests of maize (Zea mays) due to its adaptive capabilities to pest management options. This includes the ability to develop resistance to some of the commercial pesticidal proteins originating from different strains of Bacillus thuringiensis. Although urgently needed, the discovery of new, environmentally safe agents with new modes of action is a challenge. In this study we report the discovery of a new family of binary pesticidal proteins isolated from several Chryseobacterium species. These novel binary proteins, referred to as GDI0005A and GDI0006A, produced as recombinant proteins, prevent growth and increase mortality of WCR larvae, as does the bacteria. These effects were found both in susceptible and resistant WCR colonies to Cry3Bb1 and Cry34Ab1/Cry35Ab1 (reassigned Gpp34Ab1/Tpp35Ab1). This suggests GDI0005A and GDI0006A may not share the same binding sites as those commercially deployed proteins and thereby possess a new mode of action. This paves the way towards the development of novel biological or biotechnological management solutions urgently needed against rootworms.

The Impact of Permethrin and Cypermethrin on Plants, Soil Enzyme Activity, and Microbial Communities

Pyrethroids are insecticides most commonly used for insect control to boost agricultural production. The aim of the present research was to determine the effect of permethrin and cypermethrin on cultured and non-cultivated bacteria and fungi and on the activity of soil enzymes, as well as to determine the usefulness of Zea mays in mitigating the adverse effects of the tested pyrethroids on the soil microbiome. The analyses were carried out in the samples of both soil not sown with any plant and soil sown with Zea mays. Permethrin and cypermethrin were found to stimulate the multiplication of cultured organotrophic bacteria (on average by 38.3%) and actinomycetes (on average by 80.2%), and to inhibit fungi growth (on average by 31.7%) and the enzymatic activity of the soil, reducing the soil biochemical fertility index (BA) by 27.7%. They also modified the number of operational taxonomic units (OTUs) of the Actinobacteria and Proteobacteria phyla and the Ascomycota and Basidiomycota phyla. The pressure of permethrin and cypermethrin was tolerated well by the bacteria Sphingomonas (clone 3214512, 1052559, 237613, 1048605) and Bacillus (clone New.ReferenceOTU111, 593219, 578257), and by the fungi Penicillium (SH1533734.08FU, SH1692798.08FU) and Trichocladium (SH1615601.08FU). Both insecticides disturbed the growth and yielding of Zea mays, as a result of which its yield and leaf greenness index decreased. The cultivation of Zea mays had a positive effect on both soil enzymes and soil microorganisms and mitigated the anomalies caused by the tested insecticides in the microbiome and activity of soil enzymes. Permethrin decreased the yield of its aerial parts by 37.9% and its roots by 33.9%, whereas respective decreases caused by cypermethrin reached 16.8% and 4.3%.

Evaluation of three novel soil bacterial strains for efficient biodegradation of persistent boscalid fungicide: Kinetics and identification of microbial biodegradation intermediates

Boscalid, a new fungicide of anilide group, is intended to prevent and treat grey mould (Botrytis cinerea), primarily in vines and other fruit plants. In many regions, its long half-life in soil and water poses a serious environmental threat. Boscalid is reported to be toxic to a variety of aquatic organisms. One of the best ways to lessen the amount of boscalid that gets into surface and ground waters is to reduce its concentration in soil. Soil microbes are crucial for the degradation of organic pollutants including pesticides. The present study reports the assessment of three novel soil bacterial strains isolated from pesticide-contaminated soil of Crop research centre, Pantnagar, Uttarakhand, India, which possess boscalid degradation ability. Two of these bacterial isolates could degrade boscalid up to 85-95% within 36 h of incubation period under shaking conditions in the minimal medium. The growth pattern of degrading bacterial isolates was monitored by recording the optical density (OD) of bacterial suspension using an ultra violet (UV)-visible spectrophotometer, whereas the concentration of primary boscalid was recorded by High-Performance Liquid Chromatography (HPLC-UV). A linear relationship was observed between the bacterial growth and the decrease in the residual concentration of boscalid. The concentration of boscalid during incubation with different bacterial strains could be best predicted by a second-order polynomial relationship with time and OD of the suspension as independent variables. Three degradation intermediates of boscalid namely, N-(1,1'-biphenyl-2-yl)pyridine-3-carboxamide (C₁₈H₁₄N₂O, N-{[1,1'-biphenyl]-2-yl}-2-chloropyridine-3-carboxamide (C₁₈H₁₃N₂OCl), and N-{[4'-chloro-1,1'-biphenyl]-2-yl}-2-chloropyridine ({C₁₇H₁₁NCl₂}OH) were identified by the liquid chromatography-mass spectrometry (LC-MS) analysis of biodegraded samples. The biodegradation of boscalid through bacterial isolates seemed to be an economical and eco-friendly method for degrading a highly persistent boscalid fungicide.

Biodegradation of the pyrethroid cypermethrin by bacterial consortia collected from orange crops

Pyrethroids, such as cypermethrin (CYP), are widely employed in agriculture, promoting environmental pollution and the need for efficient decontamination methods. In this study, bacteria from orange crops were explored for CYP biodegradation. Among 40 tested bacterial strains, 20 grew in the presence of CYP and 19 performed statistically significant CYP biodegradation in 5 days (20.5%-97.8%). In addition, 3-phenoxybenzoic acid, the main metabolite from CYP, was quantified ranging from 1.1 mg.L^-1 to 32.1 mg.L^-1. The five most efficient strains, and consortia composed of 5, 10 and 20 bacteria biodegraded the CYP formulation as sole carbon source in phosphate buffer and in minimum mineral medium. Under optimized conditions determined employing Response Surface Methodology, Bacillus sp. CSA-1 and the consortium composed of 10 strains biodegraded 71.0% and 71.6% CYP in 24 h, respectively. Moreover, metabolite identification enabled the proposal of an extended biodegradation pathway with 29 identified compounds, including different new amide and amine derivatives that expanded the knowledge about the fate of this compound in the environment. Experiments of bioaugmentation in soil using Bacillus sp. CSA-1 and the consortium of 10 bacterial strains resulted in faster CYP biodegradation than natural attenuation, showing that the selection of efficient strains for composing a consortium is an interesting approach for bioremediation of pyrethroids.

Kinetics investigation of phenolic pollutant degradation via Serratia marcescens ABHI 001 and its application in wastewater treatment

In the present work, kinetic study has been conducted in order to effectively eliminate the p-cresol from wastewater employing isolated bacterial strain Serratia marcescens ABHI001 under batch shake flasks in the concentration varying from 50 to 500 mg/L. Further, effects of various parameters including p-cresol concentration, inoculum dosage, temperature, pH and agitation have been investigated. It was found that 10% v/v inoculum of 24 h age, was effective in degrading p-cresol. Beside this, it was noticed that the concentration of P-cresol above 100 mg/L exhibited an inhibitory effect. The maximum specific growth rate (μmax) was obtained to be 0.360 h-1 for 100 mgL-1 concentration. Further, the experimental results were well fitted with Halden's and Andrew's models and kinetic parameters μmax, KS and Ki in case of Haldane model were calculated to be 0.9697 h-1, 88.07 mgL-1 and 219.9 mgL-1, respectively whereas the corresponding values in case of Andrews's constants were 0.6917 h-1, 62.83 mgL-1 and 307.4 mgL-1, respectively. The yield coefficient for the growth on p-cresol was found to be 0.82.

Process optimization of cypermethrin biodegradation by regression analysis and parametric modeling along with biochemical degradation pathway

Pyrethroid pesticides are of great environmental and health concern with regard to neurotoxicity and ubiquitous occurrence. Here, we reported a new bacterial strain identified as Bacillus cereus AKAD 3-1 that degraded 88.1% of 50 mg/l of cypermethrin in an aqueous medium. The biodegradation of cypermethrin was optimized by CCD (central composite design) and validated by ANN-GA (artificial neural network-genetic algorithm). Both the approaches proved to possess good performance in modeling and optimizing the growth conditions. Results indicated that the process variables have a significant (< 0.0001) impact on cypermethrin biodegradation. Moreover, the predicted CCD model had a "lack of fit p-value" of "0.9975." The optimum CCD and ANN model had an R² value of 0.9703 and 0.9907, indicating that the two models' experimental and predicted values are closely fitted. The isolate successfully converted cypermethrin to CO₂ and phenol without producing any toxic metabolite. Finally, a degradation pathway was proposed with the intermediate compounds identified by GC-MS. The present study highlights an important potential application of strain AKAD 3-1 for the in situ bioremediation of cypermethrin-contaminated environments.

Role of plant growth-promoting rhizobacteria in boosting the phytoremediation of stressed soils: Opportunities, challenges, and prospects

Soil is considered as a vital natural resource equivalent to air and water which supports growth of the plants and provides habitats to microorganisms. Changes in soil properties, productivity, and, inevitably contamination/stress are the result of urbanisation, industrialization, and long-term use of synthetic fertiliser. Therefore, in the recent scenario, reclamation of contaminated/stressed soils has become a potential challenge. Several customized, such as, physical, chemical, and biological technologies have been deployed so far to restore contaminated land. Among them, microbial-assisted phytoremediation is considered as an economical and greener approach. In recent decades, soil microbes have successfully been used to improve plants' ability to tolerate biotic and abiotic stress and strengthen their phytoremediation capacity. Therefore, in this context, the current review work critically explored the microbial assisted phytoremediation mechanisms to restore different types of stressed soil. The role of plant growth-promoting rhizobacteria (PGPR) and their potential mechanisms that foster plants' growth and also enhance phytoremediation capacity are focussed. Finally, this review has emphasized on the application of advanced tools and techniques to effectively characterize potent soil microbial communities and their significance in boosting the phytoremediation process of stressed soils along with prospects for future research.

Indigenous bacterial consortium-mediated cypermethrin degradation in the presence of organic amendments and Zea mays plants

Cypermethrin is a toxic pyrethroid insecticide that is widely used in agricultural and household activities. One of the most serious issues is its persistence in the environment, because it is easily transported to the soil and aquatic ecosystem. The biodegradation of cypermethrin is emerging as an environmentally friendly method for large-scale treatment. This study examined the application of a novel binary bacterial combination-based (Bacillus thuringiensis strain SG4 and Bacillus sp. strain SG2) approach used for the enhanced degradation of cypermethrin from the environment. The bacterial strains degraded cypermethrin (80% and 85%) in the presence of external nitrogen sources (KNO₃ and NaNO₃). Furthermore, when immobilized in agar disc beads, the co-culture degraded cypermethrin (91.3%) with a half-life (t_1/2) of 4.3 days compared to 4.9 days using sodium alginate beads. Cereal straw, farmyard manure, press mud compost, fresh cow dung, and gypsum were used as organic amendments in the soil to stimulate cypermethrin degradation. Cereal straw promoted the fastest cypermethrin degradation among the different organic amendments tested, with a t_1/2 of 4.4 days. The impact of cypermethrin-degrading bacterial consortium on cypermethrin rhizoremediation was also investigated. Bacterial inoculums exhibited beneficial effects on plant biomass. Moreover, Zea mays and the bacterial partnership substantially enhanced cypermethrin degradation in soil. Six intermediate metabolites were detected during the degradation of cypermethrin, indicating that cypermethrin could be degraded first by the hydrolysis of its carboxyl ester bond, followed by the cleavage of the diaryl linkage and subsequent metabolism. Our findings highlight the promising potential and advantages of the bacterial consortium for the bioremediation of a cypermethrin-contaminated environment.

Current status of pesticide effects on environment, human health and it's eco-friendly management as bioremediation: A comprehensive review

Pesticides are either natural or chemically synthesized compounds that are used to control a variety of pests. These chemical compounds are used in a variety of sectors like food, forestry, agriculture and aquaculture. Pesticides shows their toxicity into the living systems. The World Health Organization (WHO) categorizes them based on their detrimental effects, emphasizing the relevance of public health. The usage can be minimized to a least level by using them sparingly with a complete grasp of their categorization, which is beneficial to both human health and the environment. In this review, we have discussed pesticides with respect to their global scenarios, such as worldwide distribution and environmental impacts. Major literature focused on potential uses of pesticides, classification according to their properties and toxicity and their adverse effect on natural system (soil and aquatic), water, plants (growth, metabolism, genotypic and phenotypic changes and impact on plants defense system), human health (genetic alteration, cancer, allergies, and asthma), and preserve food products. We have also described eco-friendly management strategies for pesticides as a green solution, including bacterial degradation, myco-remediation, phytoremediation, and microalgae-based bioremediation. The microbes, using catabolic enzymes for degradation of pesticides and clean-up from the environment. This review shows the importance of finding potent microbes, novel genes, and biotechnological applications for pesticide waste management to create a sustainable environment.

Advances and future prospects of pyrethroids: Toxicity and microbial degradation

Pyrethroids are a class of insecticides structurally similar to that of natural pyrethrins. The application of pyrethrins in agriculture and pest control lead to many kinds of environmental pollution affecting human health and loss of soil microbial population that affect soil fertility and health. Natural pyrethrins have been used since ancient times as insect repellers, and their synthetic versions especially type 2 pyrethroids could be highly toxic to humans. PBO (Piperonyl butoxide) is known to enhance the toxicity of prallethrin in humans due to the resistance in its metabolic degradation. Pyrethroids are also known to cause plasma biochemical profile changes in humans and they also lead to the production of high levels of reactive oxygen species. Further they are also known to increase SGPT activity in humans. Due to the toxicity of pyrethrins in water bodies, soils, and food products, there is an urgent need to develop sustainable approaches to reduce their levels in the respective fields, which are eco-friendly, economically viable, and socially acceptable for on-site remediation. Keeping this in view, an attempt has been made to analyse the advances and prospects in using pyrethrins and possible technologies to control their harmful effects. The pyrethroid types, composition and biochemistry of necessary pyrethroid insecticides have been discussed in detail, in the research paper, along with their effect on insects and humans. It also covers the impact of pyrethroids on different plants and soil microbial flora. The second part deals with the microbial degradation of the pyrethroids through different modes, i.e., bioaugmentation and biostimulation. Many microbes such as Acremonium, Aspergillus, Microsphaeropsis, Westerdykella, Pseudomonas, Staphylococcus have been used in the individual form for the degradation of pyrethroids, while some of them such as Bacillus are even used in the form of consortia.

Genetic diversity of enterotoxigenic Bacillus cereus strains in coriander in southwestern Mexico

Background

Coriander, like other leafy green vegetables, is available all year round and is commonly consumed raw in Mexico as in other countries in the preparation of street or homemade food. Bacillus cereus (B. cereus) is a microorganism that can reach coriander because it is usually found in the soil and in some regions the vegetables are irrigated with polluted water. Therefore, the aim of this study was to determinate the presence of B. cereus in coriander used for human consumption in southwestern Mexico and determine the toxigenic profile, biofilm production, genes associated with the production of biofilms, sporulation rates, enzymatic profile, psychotropic properties, and genetic diversity of B. cereus.

Methods

Fresh coriander samples were collected from several vegetable retailers in different markets, microbiological analysis was performed. Molecular identification, genes related to the production of biofilm, and toxin gene profiling of B. cereus isolates were determined by PCR. The biofilm formation was measured by performing a crystal violet assay. The genetic diversity of B. cereus strains was determined by PCR of repetitive elements using oligonucleotide (GTG) 5.

Results

We found a frequency of B. cereus in vegetables was 20% (13/65). In this study, no strains with genes for the HBL toxin were found. In the case of genes related to biofilms, the frequency was low for sipW [5.8%, (1/17)] and tasA [11.7%, (2/17)]. B. cereus strains produce a low amount of biofilm with sporulation rates around 80%. As for genetic diversity, we observed that strains isolated from the same market, but different vegetable retailers are grouped into clusters. In the coriander marketed in southwestern Mexico, were found B. cereus strains with genes associated with the production of diarrheal toxins. Together, these results show actual information about the state of art of B. cereus strains circulating in the southwestern of Mexico.

Biodegradation Pathway and Detoxification of β-cyfluthrin by the Bacterial Consortium and Its Bacterial Community Structure

In the process of microbial degradation of pyrethroid pesticides, the synergistic effect of the microbial community is more conducive to the complete degradation of toxic compounds than a single strain. At present, the degradation pathway of pyrethroids in a single strain has been well revealed, but the synergistic metabolism at the community level has not been well explained. This study elucidated the bacterial community succession, metabolic pathway, and phytotoxicity assessment during β-cyfluthrin biodegradation by a novel bacterial consortium enriched from contaminated soil. The results showed that the half-life of β-cyfluthrin at different initial concentrations of 0.25, 0.5, 0.75, and 1.0 mg mL^-1 were 4.16, 7.34, 12.81, and 22.73 days, respectively. Enterobacter was involved in β-cyfluthrin degradation metabolism in the initial stage, and other bacterial genera (Microbacterium, Ochrobactrum, Pseudomonas, Hyphomicrobiaceae, Achromobacter, etc.) significantly contribute to the degradation of intermediate metabolites in the later stages. Functional gene prediction and metabolite analysis showed that xenobiotic biodegradation and metabolism, especially benzoate degradation and metabolism by cytochrome P450 were the major means of β-cyfluthrin degradation. Further, two degradation pathways of β-cyfluthrin were proposed, which were mainly ester hydrolysis and oxidation to degrade β-cyfluthrin through the production of carboxylesterase and oxidoreductase. In addition, the inoculated bacterial consortium could degrade β-cyfluthrin residues in water and soil and reduce its phytotoxicity in Medicago sativa. Hence, this novel bacterial consortium has important application in the remediation environments polluted by β-cyfluthrin.

Microbial Interventions in Bioremediation of Heavy Metal Contaminants in Agroecosystem

Soil naturally comprises heavy metals but due to the rapid industrialization and anthropogenic events such as uncontrolled use of agrochemicals their concentration is heightened up to a large extent across the world. Heavy metals are non-biodegradable and persistent in nature thereby disrupting the environment and causing huge health threats to humans. Exploiting microorganisms for the removal of heavy metal is a promising approach to combat these adverse consequences. The microbial remediation is very crucial to prevent the leaching of heavy metal or mobilization into the ecosystem, as well as to make heavy metal extraction simpler. In this scenario, technological breakthroughs in microbes-based heavy metals have pushed bioremediation as a promising alternative to standard approaches. So, to counteract the deleterious effects of these toxic metals, some microorganisms have evolved different mechanisms of detoxification. This review aims to scrutinize the routes that are responsible for the heavy metal(loid)s contamination of agricultural land, provides a vital assessment of microorganism bioremediation capability. We have summarized various processes of heavy metal bioremediation, such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, as well as the use of genetically modified microbes and immobilized microbial cells for heavy metal removal.

Actinobacteria isolated from wastewater treatment plants located in the east-north of Algeria able to degrade pesticides

The pollution of water resources by pesticides poses serious problems for public health and the environment. In this study, Actinobacteria strains were isolated from three wastewater treatment plants (WWTPs) and were screened for their ability to degrade 17 pesticide compounds. Preliminary screening of 13 of the isolates of Actinobacteria allowed the selection of 12 strains with potential for the degradation of nine different pesticides as sole carbon source, including aliette, for which there are no previous reports of biodegradation. Evaluation of the bacterial growth and degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam (tiam) by selected Actinobacteria strains was performed in liquid media. Strains Streptomyces sp. ML and Streptomyces sp. OV were able to degrade 45% of 2,4-DCP (50 mg/l) as the sole carbon source in 30 days and 84% of thiamethoxam (35 mg/l) in the presence of 10 mM of glucose in 18 days. The biodegradation of thiamethoxam by Actinobacteria strains was reported for the first time in this study. These strains are promising for use in bioremediation of ecosystems polluted by this type of pesticides.

Ecological performance of multifunctional pesticide tolerant strains of Mesorhizobium sp. in chickpea with recommended pendimethalin, ready-mix of pendimethalin and imazethpyr, carbendazim and chlorpyrifos application

The present study was designed to screen the Mesorhizobium strains (50) for tolerance with four recommended pesticides in chickpea. In-vitro, robust pesticide tolerant strains were developed in pesticides amended media over several generations. Further, verification of the multifunctional traits of pesticide tolerant mesorhizobia under pesticide stress was conducted in-vitro. Among different pesticides, significantly high tolerance in Mesorhizobium strains was observed with recommended doses of pendimethalin (37%) and ready-mix (36%) followed by chlorpyrifos (31%) and carbendazim (30%), on an overall basis. Based on multifunctional traits, Mesorhizobium strains viz. MR2, MR17 and recommended MR33 were the most promising. Ecological performance of the potential Mesorhizobium strains alone and in dual-inoculation with recommended PGP rhizobacterium strain RB-1 (Pseudomonas argenttinensis JX239745.1) was subsequently analyzed in field following standard pesticide application in PBG-7 and GPF-2 chickpea varieties for two consecutive rabi seasons (2015 and 2016). Dual-inoculant treatments; recommended RB-1 + MR33 (4.1%) and RB-1 + MR2 (3.8%) significantly increased the grain yield over Mesorhizobium alone treatments viz MR33 and MR2, respectively. Grain yield in PBG7 variety was significantly affected (7.3%) by the microbial inoculant treatments over GPF2 variety. Therefore, the potential pesticide tolerant strains MR2 and MR33 can be further explored as compatible dual-inoculants with recommended RB-1 for chickpea under environmentally stressed conditions (pesticide application) at multiple locations. Our approach using robust multifunctional pesticide tolerant Mesorhizobium for bio-augmentation of chickpea might be helpful in the formulation of effective bio-inoculants consortia in establishing successful chickpea-Mesorhizobium symbiosis.

Evaluate the Toxicity of Pyrethroid Insecticide Cypermethrin before and after Biodegradation by Lysinibacillus cresolivuorans Strain HIS7

Herein, bacterial isolate HIS7 was obtained from contaminated soil and exhibited high efficacy to degrade pyrethroid insecticide cypermethrin. The HIS7 isolate was identified as Lysinibacillus cresolivuorans based on its morphology and physiology characteristics as well as sequencing of 16S rRNA. The biodegradation percentages of 2500 ppm cypermethrin increased from 57.7% to 86.9% after optimizing the environmental factors at incubation condition (static), incubation period (8-days), temperature (35 °C), pH (7), inoculum volume (3%), and the addition of extra-carbon (glucose) and nitrogen source (NH₄Cl₂). In soil, L. cresolivuorans HIS7 exhibited a high potential to degrade cypermethrin, where the degradation percentage increased from 54.7 to 93.1% after 7 to 42 days, respectively. The qualitative analysis showed that the bacterial degradation of cypermethrin in the soil was time-dependent. The High-Performance Liquid Chromatography (HPLC) analysis of the soil extract showed one peak for control at retention time (R.T.) of 3.460 min and appeared three peaks after bacterial degradation at retention time (R.T.) of 2.510, 2.878, and 3.230 min. The Gas chromatography-mass spectrometry (GC-MS) analysis confirmed the successful degradation of cypermethrin by L. cresolivuorans in the soil. The toxicity of biodegraded products was assessed on the growth performance of Zea mays using seed germination and greenhouse experiment and in vitro cytotoxic effect against normal Vero cells. Data showed the toxicity of biodegraded products was noticeably decreased as compared with that of cypermethrin before degradation.

Current insights into the microbial degradation for pyrethroids: strain safety, biochemical pathway, and genetic engineering

As a biologically inspired insecticide, pyrethroids (PYRs) exert evident toxic side effects on non-target organisms. PYRs and their general toxic intermediate 3-phenoxybenzoic acid (3-PBA) have shown high detection rates/levels in human beings recently, for which diet was identified as the major exposure route. Microbial mineralization has emerged as a versatile strategy in addressing such escalating concern. Herein, PYRs and 3-PBA biodegradation with regards to strain safety, application and surfactant were summarized. Numerous PYRs-degrading microbes have been reported yet with a minority focused on 3-PBA. Most isolates were from contaminated sites while several microbial food cultures (MFCs) have been investigated. MFCs such as Bacillus spp. and Aspergillus spp. that dominate in PYRs-degrading microbial pools are applicable candidates for agricultural by-products detoxification during the postharvest process. Subsequently, we discussed committed degradation steps, wherein hydrolase responsible for PYRs ester linkage cleavage and oxygenase for 3-PBA diphenyl ether bond rupture play vital roles. Finally, comprehensive information of the key enzyme genes is outlined along with methodologies concerning gene cloning. Cytochrome P450 monooxygenases (CYP) is competent for diphenyl ether scission. Newly-developed omics has become a feasible gene and enzyme mining technology. To achieve PYRs mineralization in feed and food commodities, the screening of MFCs rich in related enzymes and the construction of MFCs-derived genetically modified microbes (GMMs) exhibit great potential considering the safety issues.

Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L⁻¹ of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20–40 °C, pH 5–9, and initial tetramethrin 25–800 mg·L⁻¹. The maximum specific degradation rate (q_max), half-saturation constant (K_s), and inhibition constant (K_i) were determined to be 0.4561 day⁻¹, 7.3 mg·L⁻¹, and 75.2 mg·L⁻¹, respectively. The Box–Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography–mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg⁻¹) with strain A16 (1.0 × 10⁷ cells g⁻¹ of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.

Occurrence, potential ecological risks, and degradation of endocrine disrupter, nonylphenol, from the aqueous environment

Nonylphenol (NP) is considered a potential endocrine-disrupting chemical affecting humans and the environment. Due to widespread occurrence in the aquatic environment and neuro-, immuno, reproductive, and estrogenic effects, nonylphenol calls for considerable attention from the scientific community, researchers, government officials, and the public. It can persist in the environment, especially soil, for a long duration because of its high hydrophobic nature. Nonylphenol is incorporated into the water matrices via agricultural run-off, wastewater effluents, agricultural sources, and groundwater leakage from the soil. In this regard, assessment of the source, fate, toxic effect, and removal of nonylphenol seems a high-priority concern. Remediation of nonylphenol is possible through physicochemical and microbial methods. Microbial methods are widely used due to ecofriendly in nature. The microbial strains of the genera, Sphingomonas, Sphingobium, Pseudomonas, Pseudoxanthomonas, Thauera, Novosphingonium, Bacillus, Stenotrophomonas, Clostridium, Arthrobacter, Acidovorax, Maricurvus, Rhizobium, Corynebacterium, Rhodococcus, Burkholderia, Acinetobacter, Aspergillus, Pleurotus, Trametes, Clavariopsis, Candida, Phanerochaete, Bjerkandera, Mucor, Fusarium and Metarhizium have been reported for their potential role in the degradation of NP via its metabolic pathway. This study outlines the recent information on the occurrence, origin, and potential ecological and human-related risks of nonylphenol. The current development in the removal of nonylphenol from the environment using different methods is discussed. Despite the significant importance of nonylphenol and its effects on the environment, the number of studies in this area is limited. This review gives an in-depth understanding of NP occurrence, fate, toxicity, and remediation from the environments.

Eggshell as a biomaterial can have a sorption capability on its surface: A spectroscopic research

In this study, eggshell as a biomaterial was used as an adsorbent. This natural waste material is easy to access and cost-free. The surface of the eggshell with its porous structure showed affinity to adsorb damaging chemicals. In particular insecticides cause serious environmental pollution in agriculture, and this is a general problem all over the world. The aim was to remove insecticides from the environment and monitor the pesticides on the surface of eggshells by atomic force microscopy (AFM) images, Fourier transform infrared (FTIR) and UV/Vis spectroscopic techniques. Five types of eggshells, Denizli Hen, Coturnix Coturnix Japonica, Light Brahma Chicken, Alectoris Chukar and ISA Tinted -White, were used. Since they are commonly used, Cypermethrin, Deltamethrin and Indoxacarb were chosen as insecticide samples. The interaction effect of insecticides on the surface of eggshells was determined by AFM images; it was seen that the semispherical surface structures of the eggshells were flattened after adsorption. FTIR spectroscopy was used both to detect structural analysis and to determine the adsorption influence. In addition, UV-Vis spectroscopy was performed to evaluate the adsorption and desorption process. Porous media of different types of eggshells with an aqueous solution of insecticides had an electronegativity attractive surface which makes it an ideal adsorbent via hydroxyl groups.

Characterization of the role of esterases in the biodegradation of organophosphate, carbamate, and pyrethroid pesticides

Ester-containing organophosphate, carbamate, and pyrethroid (OCP) pesticides are used worldwide to minimize the impact of pests and increase agricultural production. The toxicity of these chemicals to humans and other organisms has been widely reported. Chemically, these pesticides share an ester bond in their parent structures. A particular group of hydrolases, known as esterases, can catalyze the first step in ester-bond hydrolysis, and this initial regulatory metabolic reaction accelerates the degradation of OCP pesticides. Esterases can be naturally found in plants, animals, and microorganisms. Previous research on the esterase enzyme mechanisms revealed that the active sites of esterases contain serine residues that catalyze reactions via a nucleophilic attack on the substrates. In this review, we have compiled the previous research on esterases from different sources to determine and summarize the current knowledge of their properties, classifications, structures, mechanisms, and their applications in the removal of pesticides from the environment. This review will enhance the understanding of the scientific community when studying esterases and their applications for the degradation of broad-spectrum ester-containing pesticides.

New Role for a Commercially Available Bioinsecticide: Bacillus thuringiensis Berliner Biodegrades the Pyrethroid Cypermethrin

The microbial diversity of several environments has been explored by researchers for the biodegradation of pyrethroids. In this study, a new approach was employed aiming at the use of Bacillus thuringiensis Berliner, a strain commercially available as bioinsecticide, for Cypermethrin (Cyp) biodegradation. This bacterial strain grew in the presence of Cyp and biodegraded this xenobiotic in a liquid medium. A central composite design for surface response methodology was employed for biodegradation. Under optimized conditions (50 mg·L^-1 of Cyp, pH 8.5, 37 °C), 83.5% biodegradation was determined with the production of 12.0 ± 0.6 mg·L^-1 3-phenoxybenzoic acid after 5 days. Moreover, a biodegradation pathway with the 18 compounds identified by GC-MS and LC-MS/MS was proposed. Experiments in soil for 28 days at 30 °C were performed, and 16.7% Cyp degradation was determined under abiotic conditions, whereas 36.6 ± 1.9% biodegradation was observed for B. thuringiensis Berliner with the native microbiome, indicating that bioaugmentation with this strain promoted a significant increase in the Cyp decontamination. Therefore, B. thuringiensis Berliner can act as biodegrader agent and insecticide at the same time, promoting decontamination of chemicals as Cyp while maintaining the protection of crops against insects. Moreover, B. thuringiensis species can produce bacteriocins with antifungal activity, which may increase agricultural productivity.

Plant Growth and Drought Tolerance-Promoting Bacterium for Bioremediation of Paraquat Pesticide Residues in Agriculture Soils

Thailand is an agricultural country. However, agricultural productivity relies on the heavy use of herbicides, especially paraquat. Paraquat accumulation is emerging as a problem in an ever-growing portion of agricultural land. Paraquat residues are toxic to plants, animals, and aquatic organisms in the environment. Biological remediation is a process that can mitigate agricultural chemical contaminants. One of the interesting bioremediators is bacteria. Not only do certain soil bacteria remediate paraquat, but some of them also possess plant growth-promoting properties, which provide advantages in field application. Thus, this study aimed to screen soil bacteria that could degrade paraquat and, at the same time, promote plant growth. Bacteria were isolated from paraquat-treated agricultural soil in Mueang Kaen Pattana municipality, Chiang Mai province, Thailand. On the basis of morphological and 16S rDNA sequence analyses, the selected bacterium was identified as Bacillus aryabhattai strain MoB09. It is capable of growing in nitrogen-free media. B. aryabhattai growth and paraquat degradation were found to be optimum at pH 7 and 30°C. This selected strain also possessed plant growth-promoting abilities, including indole production, siderophore production, phosphate solubilization, and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Paraquat degradation was also evaluated in pot experiments of cowpea (Vigna unguiculata). It was found that this strain could remediate the paraquat residue in both sterilized and non-sterilized soils. The cowpea plants grown in paraquat-contaminated soil with B. aryabhattai showed longer root and shoot lengths than those grown in soil without bacterial inoculation. In addition, B. aryabhattai also promoted the growth of cowpea under induced drought stress. These results suggested that B. aryabhattai could be applied to mitigate paraquat residue in soil and also to promote plant productivity for the organic crop production.

New insights into the degradation of synthetic pollutants in contaminated environments

The environment is contaminated by synthetic contaminants owing to their extensive applications globally. Hence, the removal of synthetic pollutants (SPs) from the environment has received widespread attention. Different remediation technologies have been investigated for their abilities to eliminate SPs from the ecosystem; these include photocatalysis, sonochemical techniques, nanoremediation, and bioremediation. SPs, which can be organic or inorganic, can be degraded by microbial metabolism at contaminated sites. Owing to their diverse metabolisms, microbes can adapt to a wide variety of environments. Several microbial strains have been reported for their bioremediation potential concerning synthetic chemical compounds. The selection of potential strains for large-scale removal of organic pollutants is an important research priority. Additionally, novel microbial consortia have been found to be capable of efficient degradation owing to their combined and co-metabolic activities. Microbial engineering is one of the most prominent and promising techniques for providing new opportunities to develop proficient microorganisms for various biological processes; here, we have targeted the SP-degrading mechanisms of microorganisms. This review provides an in-depth discussion of microbial engineering techniques that are used to enhance the removal of both organic and inorganic pollutants from different contaminated environments and under different conditions. The degradation of these pollutants is investigated using abiotic and biotic approaches; interestingly, biotic approaches based on microbial methods are preferable owing to their high potential for pollutant removal and cost-effectiveness.

Purification and characterization of a novel cypermethrin-hydrolyzing esterase from Bacillus licheniformis B-1

Cypermethrin (CY) is a synthetic pyrethroid widely used to control insect pests and it elicits a toxic effect on the human body. In this study, Bacillus licheniformis B-1 isolated from tea garden soil was used to degrade CY effectively. A specific enzyme was mainly localized in the extracellular compartments of B-1. This enzyme was identified as an esterase that could be produced without CY. The enzyme was purified 23.03-fold to apparent homogeneity with 8.38% overall recovery by ammonium sulfate precipitation, anion exchange chromatography, and gel filtration chromatography. The molecular mass of the CY-degrading enzyme was 66.4 kDa, and its optimal pH and temperature were 8.5 and 40 °C, respectively. Appropriate Zn²⁺ , Mn²⁺ , Mg²⁺ , Tween 80, SDS, Triton X-100, and BSA concentrations could greatly increase the activity of this enzyme. By contrast, EDTA, 1,10-phenanthroline, NaF, and PMSF strongly inhibited its activity. The purified enzyme showed K_m and V_max values were 5.532 nmol/mL and 33.445 nmol/min. The CY residue in lettuce and cherry tomatoes could be removed more than 50% under the conditions of the treatment concentration for 500 mg/L and the enzyme preparation dilution of 100 times. These results suggested that the CY-degrading enzyme, a constitutive enzyme that mainly exists in the extracellular space, was a novel esterase that might be used to detoxify CY, and could remove CY in vegetables effectively. PRACTICAL APPLICATION: Our research found a novel cypermethrin-hydrolyzing esterase from Bacillus licheniformis B-1 and proved that the enzyme could remove cypermethrin in vegetables effectively.

The endangered African Great Ape: Pesticide residues in soil and plants consumed by Mountain Gorillas (Gorilla beringei) in Bwindi Impenetrable National Park, East Africa

Bwindi Impenetrable National Park situated southwest of Uganda is a biodiversity hotspot that is home to about half of the world's endangered mountain gorilla (Gorilla beringei). Given its ecological significance and mounting pressures from agricultural activities such as tea growing, continuous monitoring of the levels of chemical toxins like pesticides in the park and surrounding areas is needed for effective conservation strategies. Furthermore, persistent organochlorine pesticides (OCPs) like DDT were used in agricultural gardens and indoor spraying in Kanungu district between the 1950s and 80s. The focus of this study was to explore the possible exposure of mountain gorillas to OCPs and cypermethrin used by the farmers in the areas near the park. Data from our interviews revealed that glyphosate is the most widely used pesticide by the farmers in areas surrounding the park, followed by cypermethrin, and mancozeb. Samples of leaves from plants consumed by mountain gorillas along the forest edges of the park and surficial soils (15-20 cm depths) were collected from three sites (Ruhija, Nkuringo and Buhoma) and analysed for the presence of cypermethrin and OCPs residues. Concentrations of total (∑) DDTs and ∑endosulfans were up to 0.34 and 9.89 mg/kg dry weight (d.w), respectively in soil samples. Concentrations of ∑DDTs and ∑endosulfans in samples of leaves ranged from 0.67 to 1.38 mg/kg d.w (mean = 1.07 mg/kg d.w) and 0.9 to 2.71 mg/kg d.w (mean = 1.68 mg/kg d.w), respectively. Mean concentration of ∑DDTs in leaves exceeded the European pharmacopeia and United States pharmacopeia recommended maximum residue limit values for DDTs in medicinal plants (1.0 mg/kg). In addition, calculated hazard indices for silverbacks (36.35), females (57.54) and juveniles (77.04) suggested potential health risks to the mountain gorillas. o,p'-DDT/p,p'-DDT ratios (0.5-0.63) in samples of leaves confirmed recent input of dicofol-DDT type in Bwindi rainforest.

Biodegradation of hydrophobic pesticides by microalgae: Transformation products and impact on algae biochemical methane potential

Intensive and extensive use of pesticides has contributed to their wide distribution in soil, air, and water. Due to their detrimental effects on non-target organisms, different technologies have been considered for their removal. In this work, three hydrophobic pesticide active compounds, namely, chlorpyrifos, cypermethrin, and oxadiazon, were selected to study the potential for their removal from aqueous media by a microalgae consortium. An abiotic and a killed control (thermally inactivated dead microalgae biomass) were employed to clarify their removal pathways, and pesticide content was quantified in liquid and biomass phases for 7 days. At the final time, total degradation (biodegradation plus photodegradation) contributed to the removal of 55% of oxadiazon, 35% of chlorpyrifos, and 14% of cypermethrin. Furthermore, more than 60% of chlorpyrifos and cypermethrin were removed by sorption onto microalgae biomass. Overall, the three pesticides showed high removal from the liquid phase. O,O-diethyl thiophosphate was identified in the liquid phase as a transformation product of chlorpyrifos formed by microalgae degradation. Phycoremediation was coupled with anaerobic degradation of the microalgae biomass containing the retained pesticides by sorption through biochemical methane potential tests. Anaerobic digestion was not inhibited by the pesticides as verified by methane production yields. The removal efficiency of the pesticides in the digestate was as follows: chlorpyrifos > cypermethrin > oxadiazon. These results highlight the potential of low-cost algal-based systems for the treatment of wastewater or effluents from agrochemical industries. The integration of wastewater treatment with biogas production through anaerobic digestion is a biorefinery approach that facilitates the economic feasibility of the process.

Mechanism and application of Sesbania root-nodulating bacteria: an alternative for chemical fertilizers and sustainable development

Chemical fertilizers are used in large-scale throughout the globe to satisfy the food and feed requirement of the world. Demanding cropping with the enhanced application of chemical fertilizers, linked with a decline in the recycling of natural or other waste materials, has led to a decrease in the organic carbon levels in soils, impaired soil physical properties and shrinking soil microbial biodiversity. Sustenance and improvement of soil fertility are fundamental for comprehensive food security and ecological sustainability. To feed the large-scale growing population, the role of biofertilizers and their study tends to be an essential aspect globally. In this review, we have emphasized the nitrogen-fixing plants of Sesbania species. It is a plant that is able to accumulate nitrogen-rich biomass and used as a green manure, which help in soil amelioration. Problems of soil infertility due to salinity, alkalinity and waterlogging could be alleviated through the use of biologically fixed nitrogen by Sesbania plants leading to the conversion of futile land into a fertile one. A group of plant growth-promoting rhizobacteria termed as "rhizobia" are able to nodulate a variety of legumes including Sesbania. The host-specific rhizobial strains can be used as potential alternative for nitrogenous fertilizers as they help the host plant in growth and development and enhance their endurance under stressed conditions. The review gives the depth understanding of how the agriculturally important microorganisms can be used for the reduction of broad-scale application of chemical fertilizers with special attention to Sesbania-nodulating rhizobia.

Modeling and simulation of atrazine biodegradation in bacteria and its effect in other living systems

Atrazine is the most commonly used herbicide worldwide in the agricultural system. The increased environmental concentration of the atrazine showed the toxic effects on the non-target living species. Biodegradation of the atrazine is possible with the bacterial systems. The present study investigated biodegradation potential of atrazine degrading bacteria and the impact of atrazine on environmental systems. Model of atrazine fate in ecological systems constructed using the cell designer. The used model further analyzed and simulated to know the biochemistry and physiology of the atrazine in different cellular networks. Topological analysis of the atrazine degradation confirmed the 289 nodes and 300 edges. Our results showed that the overall biomagnification of the atrazine in the different environmental systems. Atrazine is showing toxic effects on humans and plants, whereas degraded by the bacterial systems. To date, no one has analyzed the complete degradation and poisonous effects of the atrazine in the environment. Therefore, this study is useful for overall system biology based modeling and simulation analysis of atrazine in living systems.Communicated by Ramaswamy H. Sarma.

Carbofuran toxicity and its microbial degradation in contaminated environments

Carbofuran is one of the most toxic broad-spectrum and systemic N-methyl carbamate pesticide, which is extensively applied as insecticide, nematicide and acaricide for agricultural, domestic and industrial purposes. It is extremely lethal to mammals, birds, fish and wildlife due to its anticholinesterase activity, which inhibits acetyl-cholinesterase and butyrylcholinesterse activity. In humans, carbofuran is associated with endocrine disrupting activity, reproductive disorders, cytotoxic and genotoxic abnormalities. Therefore, cleanup of carbofuran-contaminated environments is of utmost concern and urgently needs an adequate, advanced and effective remedial technology. Microbial technology (bacterial, fugal and algal species) is a very potent, pragmatic and ecofriendly approach for the removal of carbofuran. Microbial enzymes and their catabolic genes exhibit an exceptional potential for bioremediation strategies. To understand the specific mechanism of carbofuran degradation and involvement of carbofuran hydrolase enzymes and genes, highly efficient genomic approaches are required to provide reliable information and unfold metabolic pathways. This review briefly discusses the carbofuran toxicity and its toxicological impact into the environment, in-depth understanding of carbofuran degradation mechanism with microbial strains, metabolic pathways, molecular mechanisms and genetic basis involved in degradation.