Aerobic and anoxic degradation and detoxification of profenofos insecticide by Pseudomonas plecoglossicida strain PF1

Assessing environmental and human health risks: Insight from the enantioselective metabolism and degradation of fenpropidin

Fenpropidin (FPD), a widely employed chiral fungicide, is frequently detected in diverse environments. In an in vitro rat liver microsomes cultivation (RLMs), the metabolism exhibited the order of R-FPD > S-FPD, with respective half-lives of 10.42 ± 0.11 and 12.06 ± 0.15 min, aligning with kinetic analysis results. CYP3A2 has been demonstrated to be the most significant oxidative enzyme through CYP450 enzyme inhibition experiments. Molecular dynamics simulations unveiled the enantioselective metabolic mechanism, demonstrating that R-FPD forms hydrogen bonds with the CYP3A2 protein, resulting in a higher binding affinity (-6.58 kcal mol-1) than S-FPD. Seven new metabolites were identified by Liquid chromatography time-of-flight high-resolution mass spectrometry, which were mainly generated through oxidation, reduction, hydroxylation, and N-dealkylation reactions. The toxicity of the major metabolites predicted by the TEST procedure was found to be stronger than the predicted toxicity of FPD. Moreover, the enantioselective fate of FPD was studied by examining its degradation in three soils with varying physical and chemical properties under aerobic, anaerobic, and sterile conditions. Enantioselective degradation of FPD occurred in soils without enantiomeric transformation, displaying a preference for R-FPD degradation. R-FPD is a low-risk stereoisomer both in the environment and in mammals. The research presented a systematic and comprehensive method for analyzing the metabolic and degradation system of FPD enantiomers. This approach aids in understanding the behavior of FPD in the environment and provides valuable insights into their potential risks to human health.

Unlocking the interaction of organophosphorus pesticide residues with ecosystem: Toxicity and bioremediation

Organophosphorus adulteration in the environment creates terrestrial and aquatic pollution. It causes acute and subacute toxicity in plants, humans, insects, and animals. Due to the excessive use of organophosphorus pesticides, there is a need to develop environmentally friendly, economical, and bio-based strategies. The microbiomes, that exist in the soil, can reduce the devastating effects of organophosphates. The use of cell-free enzymes and yeast is also an advanced method for the degradation of organophosphates. Plant-friendly bacterial strains, that exist in the soil, can help to degrade these contaminants by oxidation-reduction reactions, enzymatic breakdown, and adsorption. The bacterial strains mostly from the genus Bacillus, Pseudomonas, Acinetobacter, Agrobacterium, and Rhizobium have the ability to hydrolyze the bonds of organophosphate compounds like profenofos, quinalphos, malathion, methyl-parathion, and chlorpyrifos. The native bacterial strains also promote the growth abilities of plants and help in detoxification of organophosphate residues. This bioremediation technique is easy to use, relatively cost-effective, very efficient, and ensures the safety of the environment. This review covers the literature gap by describing the major effects of organophosphates on the ecosystem and their bioremediation by using native bacterial strains.

Significantly enhanced biodegradation of profenofos by Cupriavidus nantongensis X1T mediated by walnut shell biochar

The feasibility of using walnut shell biochar to mediate biodegradation of Cupriavidus nantongensis X1T for profenofos was investigated. The results of scanning electron microscopy, classical DLVO theory and Fourier transform infrared spectroscopy indicated that strain X1T was stably immobilized on biochar by pore filling, van der Waals attraction, and hydrogen bonding. Profenofos degradation experiments showed that strain X1T immobilized on biochar significantly decomposed profenofos (shortened the half-life by 5.2 folds) by promoting the expression of the degradation gene opdB and the proliferation of strain X1T. The immobilized X1T showed stronger degradation ability than the free X1T at higher initial concentration, lower temperature and pH. The immobilized X1T could maintain 83% of removal efficiency for profenofos after 6 reuse cycles in paddy water. Thus, X1T immobilized using walnut shell biochar as a carrier could be practically applied to biodegradation of organophosphorus pesticides present in agricultural water.

The looming threat of profenofos organophosphate and microbes in action for their sustainable degradation

Organophosphates are the most extensively used class of pesticides to deal with increasing pest diversity and produce more on limited terrestrial areas to feed the ever-expanding global population. Profenofos, an organophosphate group of non-systematic insecticides and acaricides, is used to combat aphids, cotton bollworms, tobacco budworms, beet armyworms, spider mites, and lygus bugs. Profenofos was inducted into the system as a replacement for chlorpyrifos due to its lower toxicity and half-life. It has become a significant environmental concern due to its widespread presence. It accumulates in various environmental components, contaminating food, water, and air. As a neurotoxic poison, it inhibits acetylcholinesterase receptor activity, leading to dizziness, paralysis, and pest death. It also affects other eukaryotes, such as pollinators, birds, mammals, and invertebrates, affecting ecosystem functioning. Microbes directly expose themselves to profenofos and adapt to these toxic compounds over time. Microbes use these toxic compounds as carbon and energy sources and it is a sustainable and economical method to eliminate profenofos from the environment. This article explores the studies and developments in the bioremediation of profenofos, its impact on plants, pollinators, and humans, and the policies and laws related to pesticide regulation. The goal is to raise awareness about the global threat of profenofos and the role of policymakers in managing pesticide mismanagement.

Biodegradation of fipronil: molecular characterization, degradation kinetics, and metabolites

Fipronil (C12H4Cl2F6N4OS) is a commonly used insecticide effective against numerous insects and pests. Its immense application poses harmful effects on various non-target organisms as well. Therefore, searching the effective methods for the degradation of fipronil is imperative and logical. In this study, fipronil-degrading bacterial species are isolated and characterized from diverse environments using a culture-dependent method followed by 16S rRNA gene sequencing. Phylogenetic analysis showed the homology of organisms with Acinetobacter sp., Streptomyces sp., Pseudomonas sp., Agrobacterium sp., Rhodococcus sp., Kocuria sp., Priestia sp., Bacillus sp., Aeromonas sp., and Pantoea sp. The bacterial degradation potential for fipronil was analyzed through high-performance liquid chromatography (HPLC). Incubation-based degradation studies revealed that Pseudomonas sp. and Rhodococcus sp. were found to be the most potent isolates that degraded fipronil at 100 mg L-1 concentration, with removal efficiencies of 85.9 and 83.6%, respectively. Kinetic parameter studies, following the Michaelis-Menten model, also revealed the high degradation efficiency of these isolates. Gas chromatography-mass spectrometry (GC-MS) analysis revealed fipronil sulfide, benzaldehyde, (phenyl methylene) hydrazone, isomenthone, etc., as major metabolites of fipronil degradation. Overall investigation suggests that native bacterial species isolated from the contaminated environments could be efficiently utilized for the biodegradation of fipronil. The outcome derived from this study has immense significance in formulating an approach for bioremediation of fipronil-contaminated surroundings.

Biodegradation of di(2-ethylhexyl) phthalate by a new bacterial consortium

Di(2-ethylhexyl) phthalate (DEHP) with continuous high concentration was used as the sole carbon and energy source to isolate a new bacterial consortium (K1) from agricultural soil covered with plastic film for a long time. Unclassified Comamonadaceae, Achromobacter, and Pseudomonas in K1 were identified as major genera of the consortium by high-throughput sequencing, and unclassified Commanadaceae was first reported to be related to DEHP degradation. Response surface method (RSM) showed that the optimum conditions for K1 to degrade DEHP were 31.4 °C, pH 7.3, and a concentration of 420 mg L^-1. K1 maintains normal cell viability and stable DEHP degradation efficiency in the range of 10-3000 mg L^-1 DEHP concentration, which is superior to existing research. The biodegradation of DEHP followed first-order kinetics when the initial concentration of DEHP was between 100 and 3,000 mg L^-1. GC-MS analysis of different treatment groups showed that DEHP was degraded by the consortium group through the de-esterification pathway, and treatment effect was significantly better than that of the single bacteria treatment group. The subsequent substrate utilization experiment further confirmed that K1 could quickly mineralize DEHP. In addition, K1 has high degradation capacity for the most common phthalate acid esters in the environment.

Response of the Pardosa astrigera bacterial community to Cry1B protein

While genetically modified (GM) crops bring economic benefits to human beings, their impact on non-target organisms has become an important part of environmental safety assessments. Symbiotic bacteria play an important role in eukaryotic biological functions and can adjust host communities to adapt to new environments. Therefore, this study examined the effects of Cry1B protein on the growth and development of non-target natural enemies of Pardosa astrigera (L. Koch) from the perspective of symbiotic bacteria. Cry1B protein had no significant effect on the health indicators of P. astrigera (adults and 2nd instar spiderlings). 16S rRNA sequencing results revealed that Cry1B protein did not change the symbiotic bacteria species composition of P. astrigera, but did reduce the number of OTU and species diversity. In 2nd instar spiderlings, neither the dominant phylum (Proteobacteria) nor the dominant genus (Acinetobacter) changed, but the relative abundance of Corynebacterium-1 decreased significantly; in adult spiders, the dominant bacteria genera of females and males were different. The dominant bacterial genera were Brevibacterium in females and Corynebacterium-1 in males, but Corynebacterium-1 was the dominant bacteria in both females and males feeding on Cry1B. The relative abundance of Wolbachia also increased significantly. In addition, bacteria in other genera varied significantly by sex. KEGG results showed that Cry1B protein only altered the significant enrichment of metabolic pathways in female spiders. In conclusion, the effects of Cry1B protein on symbiotic bacteria vary by growth and development stage and sex.

Biodegradation of monocrotophos by Brucella intermedia Msd2 isolated from cotton plant

Widespread and inadequate use of Monocrotophos has led to several environmental issues. Biodegradation is an ecofriendly method used for detoxification of toxic monocrotophos. In the present study, Msd2 bacterial strain was isolated from the cotton plant growing in contaminated sites of Sahiwal, Pakistan. Msd2 is capable of utilizing the monocrotophos (MCP) organophosphate pesticide as its sole carbon source for growth. Msd2 was identified as Brucella intermedia on the basis of morphology, biochemical characterization and 16S rRNA sequencing. B. intermedia showed tolerance of MCP up to 100 ppm. The presence of opd candidate gene for pesticide degradation, gives credence to B. intermedia as an effective bacterium to degrade MCP. Screening of the B. intermedia strain Msd2 for plant growth promoting activities revealed its ability to produce ammonia, exopolysaccharides, catalase, amylase and ACC-deaminase, and phosphorus, zinc and potassium solubilization. The optimization of the growth parameters (temperatures, shaking rpm, and pH level) of the MCP-degrading isolate was carried out in minimal salt broth supplemented with MCP. The optimal pH, temperature, and rpm for Msd2 growth were observed as pH 6, 35 °C, and 120 rpm, respectively. Based on optimization results, batch degradation experiment was performed. Biodegradation of MCP by B. intermedia was monitored using HPLC and recorded 78% degradation of MCP at 100 ppm concentration within 7 days of incubation. Degradation of MCP by Msd2 followed the first order reaction kinetics. Plant growth promoting and multi-stress tolerance ability of Msd2 was confirmed by molecular analysis. It is concluded that Brucella intermedia strain Msd2 could be beneficial as potential biological agent for an effective bioremediation for polluted environments.

Efficient biodegradation characteristics and detoxification pathway of organophosphorus insecticide profenofos via Cupriavidus nantongensis X1T and enzyme OpdB

Profenofos residues in the environment pose a high risk to mammals and non-target organisms. In this study, the biodegradation and detoxification of profenofos in an efficient degrading strain, Cupriavidus nantongensis X1^T, was investigated. Strain X1^T could degrade 88.82 % of 20 mg/L profenofos in 48 h. The optimum temperature and inoculation amount of strain X1^T for the degradation of profenofos were 30-37 °C and 20 % (V/V), respectively. Metabolic pathway analysis showed that strain X1^T could degrade both profenofos and its main metabolite 4-bromo-2-chlorophenol. Metabolite toxicity analysis results showed that dehalogenation was the main detoxification step in profenofos biodegradation. The key gene and enzyme for profenofos degradation in strain X1^T were also explored. RT-qPCR shows that organophosphorus hydrolase (OpdB) was the key enzyme to control the hydrolysis process in strain X1^T. The purified enzyme OpdB in vitro had the same degradation characteristics as strain X1^T. Divalent metal cations could significantly enhance the hydrolysis activity of strain X1^T and enzyme OpdB. Meanwhile, strain X1^T could degrade 60.89 % of 20 mg/L profenofos in actual field soil within 72 h. This study provides an efficient biological resource for the remediation of profenofos residual pollution in the environment.

Biodegradation of organophosphorus pesticide profenofos by the bacterium Bacillus sp. PF1 and elucidation of initial degradation pathway

Among the organophosphate pesticides, the wide and indiscriminate use of profenofos (PFF) in agricultural and horticultural crops has resulted in serious environmental and animal health concerns and therefore demands an urgent need to develop a biological solution for its effective removal from the environment. For the bioremediation of PFF, a strain PF1, capable of utilizing profenofos as the sole source of carbon and energy was isolated from the soil samples of apple orchards of Shimla region of Himachal Pradesh, India. Based on the biochemical, FAME, and 16S rRNA gene analysis the bacterium PF1 was identified as Bacillus altitudinis (GenBank: MH986176). The strain was able to degrade 50μg mL^-1 PFF up to 93% within 30 days of incubation at 28°C, pH 7.0. A linear regression analysis performed on the data-set revealed the statistical significance of the relationship between the growth of the bacterial population and the degradation of pesticides. The compound 4-Bromo-2-chlorophenol (BCP) was detected as one of the pathway metabolites which further were completely degraded to lower pathway metabolites. A probable PFF degradation pathway has been proposed which follows the path from PFF to BCP and ultimately enters into the TCA cycle. To the best of our knowledge, this is the first report of PFF biodegradation by any Bacillus species of western Himalayan origin exhibiting close phylogenetic association with Bacillus altitudinis. This indigenous bacterium can be useful to bio-remediate the PFF contaminated soil as this pesticide is extensively used in the different horticulture fields in Himachal Pradesh, India.

Pesticide contamination in agro-ecosystems: toxicity, impacts, and bio-based management strategies

Continuous rise in application of pesticides in the agro-ecosystems in order to ensure food supply to the ever-growing population is of greater concern to the human health and the environment. Once entered into the agro-ecosystem, the fate and transport of pesticides is determined largely by the nature of pesticides and the soil attributes, in addition to the soil-inhabiting microbes, fauna, and flora. Changes in the soil microbiological actions, soil properties, and enzymatic activities resulting from pesticide applications are the important factors substantially affecting the soil productivity. Disturbances in the microbial community composition may lead to the considerable perturbations in cycling of major nutrients, metals, and subsequent uptake by plants. Indiscriminate applications are linked with the accumulation of pesticides in plant-based foods, feeds, and animal products. Furthermore, rapid increase in the application of pesticides having long half-life has also been reported to contaminate the nearby aquatic environments and accumulation in the plants, animals, and microbes surviving there. To circumvent the negative consequences of pesticide application, multitude of techniques falling in physical, chemical, and biological categories are presented by different investigators. In the present study, important findings pertaining to the pesticide contamination in cultivated agricultural soils; toxicity on soil microbes, plants, invertebrates, and vertebrates; effects on soil characteristics; and alleviation of toxicity by bio-based management approaches have been thoroughly reviewed. With the help of bibliometric analysis, thematic evolution and research trends on the bioremediation of pesticides in the agro-ecosystems have also been highlighted.

Imidacloprid degrading efficiency of Pseudomonas plecoglossicida MBSB-12 isolated from pesticide contaminated tea garden soil of Assam

Long-term use of toxic pesticides in agricultural grounds has led to adverse effects on the environment and human health. Microbe-mediated biodegradation of pollutants is considered an effective strategy for the removal of contaminants in agricultural and environmental sustainability. Imidacloprid, a neonicotinoid class of pesticides, was widely applied insecticide in the control of pests in agricultural fields including the tea gardens of Assam. Here, native bacteria from imidacloprid contaminating tea garden soils were isolated and screened for imidacloprid degradation efficiency under laboratory conditions. Out of the 30 bacterial isolates, 4 were found to tolerate high concentrations of imidacloprid (25,000 ppm), one of which isolate MBSB-12 showed the highest efficiency for imidacloprid tolerance and utilization as the sole carbon source. Morphological, biochemical, and 16 S ribosomal RNA gene sequencing-based characterization revealed the isolate as Pseudomonas plecoglossicida MBSB-12. The isolate reduced 87% of extractable imidacloprid from the treated soil in 90 days compared to the control soil (without bacterial treatment). High-Resolution Mass Spectrometry (HRMS) analysis indicated imidacloprid breakdown to comparatively less harmful products viz., imidacloprid guanidine olefin [m/z = 209.0510 (M + H)⁺], imidacloprid urea [m/z = 212.0502 (M + H)⁺] and a dechlorinated degraded product of imidacloprid with m/z value 175.0900 (M + H)⁺. Further investigation on the molecular machinery of P. plecoglossicida MBSB-12 involved in the degradation of imidacloprid is expected to provide a better understanding of the degradation pathway.

Biodegradation of 4-nitroaniline by novel isolate Bacillus sp. strain AVPP64 in the presence of pesticides

In this study, Bacillus sp. strain AVPP64 was isolated from diuron-contaminated soil. It showed 4-nitroaniline (4-NA) degradation, pesticide tolerance, and self-nutrient integration via nitrogen (N)-fixation and phosphate (P)-solubilization. The rate constant (k) and half-life period (t_1/2) of 4-NA degradation in the aqueous medium inoculated with strain AVPP64 were observed to be 0.445 d^-1 and 1.55 d, respectively. Nevertheless, in the presence of chlorpyrifos, profenofos, atrazine and diuron pesticides, strain AVPP64 degraded 4-NA with t_1/2 values of 2.55 d, 2.26 d, 2.31 d and 3.54 d, respectively. The strain AVPP64 fixed 140 μg mL^-1 of N and solubilized 103 μg mL^-1 of P during the presence of 4-NA. In addition, strain AVPP64 produced significant amounts of plant growth-promoting metabolites like indole 3-acetic acid, siderophores, exo-polysaccharides and ammonia. In the presence of 4-NA and various pesticides, strain AVPP64 greatly increased the growth and biomass of Vigna radiata and Crotalaria juncea plants. These results revealed that Bacillus sp. strain AVPP64 can be used as an inoculum for bioremediation of 4-NA contaminated soil and sustainable crop production even when pesticides are present.

Sublethal Exposure to Deltamethrin Stimulates Reproduction and Alters Symbiotic Bacteria in Aphis gossypii

In aphids, hormesis and symbiotic bacteria are the drivers for the development of pesticide resistance. However, the related mechanism remains unclear. Here, we evaluated the sublethal and transgenerational effects of the extensively used pyrethroid pesticide deltamethrin (DMT) on the population dynamics in Aphis gossypii and tested its influence on symbiotic bacterial communities. The leaf-dip bioassay revealed that DMT was highly toxic to A. gossypii, and at a low lethal concentration of DMT, the intrinsic (r) and finite rates of increase (λ) of the initially exposed aphids (G0) significantly decreased. Intriguingly, the r, λ, and net reproductive rate (R₀) of G1 and G2 significantly increased, but the r and λ decreased in G3. The adult and total preoviposition period increased in G3 but decreased in G4. Additionally, the diversity of the bacterial community decreased, while the abundance values of Buchnera, Pseudomonadaceae, and Burkholderiaceae increased after 24 h of exposure to LC₃₀ DMT in G0 aphids, and the latter two decreased in G1 but increased in G2. In summary, sublethal DMT has intergenerational hormesis effect on cotton aphids in G1-G2 and remarkably altered their symbiotic bacterial community and abundance. These results broaden our understanding of the relationship of hormesis and symbiotic bacteria in aphids under insecticide exposure.

Efficacy of rhizobacteria for degradation of profenofos and improvement in tomato growth

Pesticides are widely used for managing pathogens and pests for sustainable agricultural output to feed around seven billion people worldwide. After their targeted role, residues of these compounds may build up and persist in soils and in the food chain. This study evaluated the efficiency of bacterial strains capable of plant growth promotion and biodegradation of profenofos. To execute this, bacteria were isolated from an agricultural area with a history of repeated application of profenofos. The profenofos degrading bacterial strains with growth-promoting characteristics were identified based on biochemical and molecular approaches through partial 16S ribosomal rRNA gene sequencing. The results revealed that one strain, Enterobacter cloacae MUG75, degraded over 90% profenofos after 9 days of incubation. Similarly, plant growth was significantly increased in plants grown in profenofos (100 mg L^-1) contaminated soil inoculated with the same strain. The study demonstrated that inoculation of profenofos degrading bacterial strains increased plant growth and profenofos degradation. Novelty statementPesticides are extensively applied in the agriculture sector to overcome pest attacks and to increase food production to fulfill the needs of the growing world population. Residues of these pesticides can persist in the environment for long periods, may enter the groundwater reservoirs and cause harmful effects on living systems highlighting the need for bioremediation of pesticide-contaminated environments. Microbes can use pesticides as a source of carbon and energy and convert them into less toxic and non-toxic products. Application of profenofos degrading rhizobacteria in interaction with the plants in the rhizosphere can remediate the pesticide-contaminated soils and minimize their uptake into the food chain. Hence, this approach can improve soil health and food quality without compromising the environment.

Biodegradation pathway of the organophosphate pesticides chlorpyrifos, methyl parathion and profenofos by the marine-derived fungus Aspergillus sydowii CBMAI 935 and its potential for methylation reactions of phenolic compounds

The indiscriminate use of organophosphate pesticides causes serious environmental and human health problems. This study aims the biodegradation of chlorpyrifos, methyl parathion and profenofos with the proposal of new biodegradation pathways employing marine-derived fungi as biocatalysts. Firstly, a growth screening was carried out with seven fungi strains and Aspergillus sydowii CBMAI 935 was selected. For chlorpyrifos, 32% biodegradation was observed and the metabolites tetraethyl dithiodiphosphate, 3,5,6-trichloropyridin-2-ol, 2,3,5-trichloro-6-methoxypyridine, and 3,5,6-trichloro-1-methylpyridin-2(1H)-one were identified. Whereas 80% methyl parathion was biodegraded with the identification of isoparathion, methyl paraoxon, trimethyl phosphate, O,O,O-trimethyl phosphorothioate, O,O,S-trimethyl phosphorothioate, 1-methoxy-4-nitrobenzene, and 4-nitrophenol. For profenofos, 52% biodegradation was determined and the identified metabolites were 4-bromo-2-chlorophenol, 4-bromo-2-chloro-1-methoxybenzene and O,O-diethyl S-propylphosphorothioate. Moreover, A. sydowii CBMAI 935 methylated different phenolic substrates (phenol, 2-chlorophenol, 6-chloropyridin-3-ol, and pentachlorophenol). Therefore, the knowledge about the fate of these compounds in the sea was expanded, and the marine-derived fungus A. sydowii CBMAI 935 showed potential for biotransformation reactions.

Rapid biodegradation and biofilm-mediated bioremoval of organophosphorus pesticides using an indigenous Kosakonia oryzae strain -VITPSCQ3 in a Vertical-flow Packed Bed Biofilm Bioreactor

The widespread use of pesticides has been one of the major anthropogenic sources of environmental pollution. Organophosphorus (OP) pesticides are predominantly used in agriculture due to their broad-spectrum insecticidal activity and chemical stability. The study was focused on the biodegradation of OP pesticides, Profenofos (PF) and Quinalphos (QP) in culture media using bacterium isolated from wetland paddy rhizosphere. The strain VITPSCQ3 showed higher pesticide tolerance, efficient biofilm formation and was capable of synthesizing organophosphate degrading enzymes. Based on the 16S rRNA gene sequencing the isolate exhibited maximum sequence similarity with Kosakinia oryzae (GenBank accession number: KR149275). Biodegradation assay with various concentrations of PF and QP (200, 400, 600 and 800 mg L^-1) showed maximum degradation up to 82% and 92% within 48 h. The kinetic studies revealed the biodegradation rates (k) to be 0.0844 min^-1 and 0.107 min^-1 with half-lives (h) of 18 h and 14.8 h for PF and QP. The degradation products were identified by GCMS and possible degradation pathways were proposed using Insilico techniques. To the best of our knowledge, this is the first report on the biodegradation of PF and QP using Kosakonia oryzae. Bioremoval of PF and QP from aqueous solution was performed using the biofilm of VITPSCQ3 developed on selected substrates in a circulating Vertical-flow packed-bed biofilm (VFPBB) bioreactor. Charcoal, gravel and mushroom (Agaricus bisporus) were used as biofilm carriers. Mushroom showed strong biofilm formation with optimum biodegradation capacity of up to 96% for PF and 92% for QP within 120 min reaction time.