Enantioselective Uptake Determines Degradation Selectivity of Chiral Profenofos in Cupriavidus nantongensis X1T

Chiral Separation and Determination of Multiple Organophosphorus Pesticide Enantiomers in Soil Based on Cellulose-Based Chiral Column by LC-MS/MS

The widespread use of organophosphorus pesticides (OPs) has raised significant environmental and health concerns due to their residues in soil and potential entry into the food chain. This study introduced chiral analysis methods for four OPs-methamidophos (METHP), dipterex (DIP), malathion (MALA), and isothiophos-methyl (ISOME)-using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with cellulose-based chiral columns. Three distinct methods were established: one for METHP, another for DIP, and a third for MALA and ISOME. Key chromatographic variables, including organic mobile phases and column temperatures, were systematically optimized, achieving maximum resolutions (Rs) of 1.61 for METHP, 2.40 for DIP, 1.70 for MALA, and 2.02 for ISOME. The QuEChERS method was employed for sample pretreatment, ensuring high recoveries. All three methods demonstrated excellent linearity (R > 0.998), accuracy with recoveries ranging from 79% to 121%, precision with RSD% < 11%, and sensitivity with low limits of enantiomer detection (LODs) as low as 0.17 µg/kg for METHP, 0.087 µg/kg for DIP, 0.062 µg/kg for MALA, and 0.054 µg/kg for ISOME, representing a sensitivity improvement of 16-172 times compared to existing methods. Field soil samples from Yangzizhou District, Nanchang, China, revealed significant contamination by ISOME, with concentrations of a single enantiomer reaching up to 8343 µg/kg, while MALA exhibited varying enantiomeric ratios with depth. This study provides robust analytical tools for monitoring chiral OP residues in soil, contributing to food safety and environmental protection.

Dissipation of the insecticide profenofos in tropical agricultural soils (Berambadi catchment, South India): Insight from compound-specific isotope analysis (CSIA)

Assessing the role of agricultural lands in pesticide contamination of water ecosystems is critical for water management agencies and policymakers when formulating effective mitigation strategies. Current approaches based on concentration measurements are often insufficient to evaluate the contribution of pesticide dissipation processes in complex agroecosystems. This study focuses on the dissipation of profenofos insecticide within plots subject to intensive agriculture in the Berambadi watershed (India). We examined profenofos dissipation kinetics and related carbon isotopic fractionation in laboratory volatilisation, hydrolysis, photolysis and soil biodegradation experiments, and in a field plot experiment. Process-specific isotope fractionation analyses revealed significant carbon isotope fractionation, with εC = - 2.0 ± 0.8 ‰ during UV photolysis, and εC = - 0.9 ± 0.4 ‰ during biodegradation of profenofos in the soil. Accordingly, the formation of 4-bromo-2-chlorophenol and another profenofos transformation product indicated the cleavage of OP and CBr bonds in soil experiments. By integrating dissipation kinetics, compound-specific isotope analysis (CSIA), transformation products analysis and modelling results, biodegradation was identified as the dominant dissipation process in the agricultural plot, accounting for > 90 % of profenofos dissipation. Model predictions were consistent with the observed dissipation kinetics and isotopic data, confirming the fast degradation (T1/2 = 1.1 ± 0.6 day) and low (< 0.02 %) leaching potential of profenofos, which was not detected in the local groundwater monitored by passive samplers (POCIS). Overall, these results highlight the usefulness of profenofos CSIA to identify and unravel dissipation processes in tropical agroecosystems for improving contamination risk assessment.

The interaction and response of gut microbes to exposure to chiral ethiprole in honeybees (Apis mellifera)

Widespread pesticide use is believed to be a major factor contributing to the decline of bee populations. Previous studies have shown that enantiomers of chiral pesticides may have different toxicities on bee, but the effects of pesticide enantiomers on honeybees and their gut microbiota are still unknown. In this study, we assessed the gut microbial and their host toxicities of ethiprole enantiomers at a concentration of 15 μg/L in honeybees. Compared to the sucrose control and R-ethiprole, S-ethiprole exposure significantly reduced bee survival. Notably, bees exposed to ethiprole and its enantiomers affected sucrose consumption and body weight, and developed a small gut with thinning and degeneration. 16S rRNA gene amplicon sequencing of the bee gut revealed that ethiprole and its enantiomers significantly disrupted the microbial communities. In contrast, S-ethiprole exposure markedly reduced community size and diversity and exhibited a lower niche width. In addition, the expression of immune detoxification genes (Defensin1,Defensin2,GST3) was upregulated by R-ethiprole in bees and S-ethiprole downregulated the mRNA levels of CYP6AS14 in bees. The expression of immune response-related genes was negatively correlated with core bacteria.This study offers comprehensive insights the effect of chiral ethiprole on the health of bees, particularly the risk of S-ethiprole in bees. Moreover, it provides a reference for exploring the interactions between host and microbiota systems under exogenous stress.

Efficient and Sensitive Detection of Organophosphate Pesticides in Orange Juice Using Dispersed Solid-Phase Extraction Based on Amorphous UiO-66

Organophosphate pesticides can cause long-term neurological damage to humans. There is an urgent need to develop a more sensitive and efficient method for detecting trace amounts of organophosphorus pesticides in orange juice, particularly in the presence of interfering substances. This study developed a dispersive solid-phase extraction (DSPE) method using amorphous UiO-66 (aUiO-66) as an adsorbent for the detection of four organophosphate pesticides (fenthion, profenofos, fensulfothion, and chlorpyrifos) in orange juice. The aUiO-66 was synthesized in a green, direct method within a deep eutectic solvent composed of diethanolamine hydrochloride and acetamide. Its amorphous nature was confirmed through x-ray diffraction (XRD) and thermogravimetric analysis (TGA). Parameters influencing extraction efficiency, including adsorbent dosage, extraction time, eluent type, and volume, were optimized by genetic neural network (GNN). The method demonstrated good linearity (R2 = 0.9927-0.9981), high recovery (95.35%-110.75%), low limit of detection (0.169-0.214 ng L⁻¹), and precision (intraday RSD = 4.13%-5.44%, interday RSD = 3.28%-4.91%). It was successfully applied to analyze targets in commercially available orange juices, detecting residues within 4.37-36.07 µg L⁻¹. This study's methodological development offers significant guidance for efficient detection of organophosphorus pesticides in food products, potentially facilitating the advancement and application of simpler and more efficient analytical techniques.

Earthworms-enhanced bacterial degradation of the chiral fungicide penflufen R-enantiomer

The widespread application of chiral fungicides as seed-coating agents in agriculture has led to serious residue accumulation in soil, increasingly drawing attention to soil pollution remediation strategies for chiral pesticides. This study explored the role of earthworms and soil microorganisms in selectively accelerating the degradation of penflufen in soil. The results showed that soil microorganisms significantly accelerated penflufen enantiomer degradation, particularly the R-enantiomer. Nocardioides, Variovorax, Arthrobacter, and Pseudomonas were identified as key degrading microorganisms associated with the preferential degradation of the R-enantiomer. The addition of earthworms further significantly enhanced the preferential degradation of the R-enantiomer. Importantly, earthworms markedly promoted the growth and reproduction of the four aforementioned degrading microorganisms in soil treated with enantiomers. Notably, the relative abundance of these degrading microorganisms was significantly higher in R-enantiomer-treated soil with earthworms than in soil treated with the S-enantiomer. Additionally, earthworms significantly increased the relative abundance of degradation genes p450, bphA1, and benA in the soil, especially in the R-enantiomer treated soil. Nocardioides, Variovorax, Arthrobacter, and Pseudomonas were identified as potential hosts for the degradation gene benA. More importantly, twelve strains of penflufen-degrading bacteria were isolated from the treated soil, of which eight belonged to the aforementioned four microorganisms and exhibited a remarkable ability to preferentially degrade the R-enantiomer. This finding highlights the potential of adding earthworms to soil, in conjunction with key degrading microorganisms, which preferentially accelerates penflufen R-enantiomer degradation.

Recent advance in probiotics for the elimination of pesticide residues in food and feed: mechanisms, product toxicity, and reinforcement strategies

The extensive utilization of pesticides in agriculture has resulted in the presence of pesticide residues in food and feed, which poses a significant threat to human health. Various physical and chemical methods have been proposed to remove pesticides, but most of these methods are either costly or susceptible to secondary contamination. Consequently, the utilization of microorganisms, such as probiotics, for eliminating pesticides, has emerged as a promising alternative. Probiotics, including lactic acid bacteria, yeasts, and fungi, have demonstrated remarkable efficiency and convenience in eliminating pesticide residues from food or feed. To promote the application of probiotic decontamination, this review examines the current research status on the utilization of probiotics for pesticide reduction. The mechanisms involved in microbial decontamination are discussed, along with the toxicity and potential health risks of degradation products. Furthermore, the review explores strategies to enhance probiotic detoxification and outlines prospects for future development.

Novel herbicide flusulfinam: absolute configuration, enantioseparation, enantioselective bioactivity, toxicity and degradation in paddy soils

BACKGROUND

Flusulfinam, a novel chiral herbicide, effectively controls Echinochloa crusgalli and Digitaria sanguinalis in paddy fields, indicating significant potential for practical agricultural applications. However, limited information is available on flusulfinam from a chiral perspective. A comprehensive evaluation of the enantiomeric levels of flusulfinam was performed.

RESULTS

Two enantiomers, R-(+)- and S-(-)-flusulfinam, were separately eluted using a Chiralcel OX-RH column. The bioactivity of R-flusulfinam against the two was 1.4-3.1 fold that of Rac-flusulfinam against two weed species. R-flusulfinam toxicity to Danio rerio larvae and Selenastrum capricornutumwere was 0.8- and 3.0-fold higher than Rac-flusulfinam, respectively. Degradation experiments were conducted using soil samples from four Chinese provinces. The findings indicated that S-flusulfinam (half-life T1/2 = 40.8 days) exhibits preferential degradation than R-flusulfinam (T1/2 = 46.2-57.8 days) in the soils of three provinces. Under anaerobic conditions, soil from Anhui exhibited preferential degradation of R-flusulfinam (T1/2 = 46.2 days) over S-flusulfinam (T1/2 = 63 days). Furthermore, two hydrolysis products of flusulfinam (M299 and M100) are proposed for the first time.

CONCLUSION

The enantioselective bioactivity, toxicity and degradation of flusulfinam were investigated. Our findings indicate that R-flusulfinam is an extremely effective and low-toxicity enantiomer for the tested species. The soil degradation test indicated that the degradation of flusulfinam was accelerated by higher organic matter content and lower soil pH. Furthermore, microbial communities may play a crucial role in driving the enantioselective degradation processes. This study lays the groundwork for the systematic evaluation of flusulfinam from an enantiomeric perspective. © 2024 Society of Chemical Industry.

Stereoselective Bioactivity and Action Mechanism of the Fungicide Isopyrazam

Understanding the stereoselective bioactivity of chiral pesticides is crucial for accurately evaluating their effectiveness and optimizing their use. Isopyrazam, a widely used chiral SDHI fungicide, has been studied for its antifungal activity only at the racemic level. Therefore, to clarify the highly bioactive isomers, the stereoselective bioactivity of isopyrazam isomers against four typical phytopathogens was studied for the first time. The bioactivity ranking of the isomers was trans-1S,4R,9R-(+)-isopyrazam > cis-1R,4S,9R-(+)-isopyrazam > trans-1R,4S,9S-(-)-isopyrazam > cis-1S,4R,9S-(-)-isopyrazam. SDH activity was assessed by molecular docking simulation and actual detection to confirm the reasons for stereoselective bioactivity. The results suggest that the stereoselective bioactivity of isopyrazam is largely dependent on the differential binding ability of each isomer to the SDH ubiquitin-binding site, located within a cavity formed by the iron-sulfur subunit, the cytochrome b560 subunit, and the cytochrome b small subunit. Moreover, to reveal the molecular mechanism of isopyrazam stereoselectively affecting mycelial growth, the contents of succinic acid, fumaric acid, and ATP were measured. Furthermore, by measuring exospore polysaccharides and oxalic acid content, it was determined that 1S,4R,9R-(+)- and 1R,4S,9R-(+)-isopyrazam more strongly inhibited the ability of Sclerotinia sclerotiorum to infect plants. The findings provided essential data for the development of high-efficiency isopyrazam fungicides and offered a methodological reference for analyzing the enantioselective activity mechanism of SDHI fungicides.

Combined Transcriptomics and Metabolomics Analysis Reveals Profenofos-Induced Invisible Injury in Pakchoi (Brassica rapa L.) through Inhibition of Carotenoid Accumulation

Profenofos insecticide poses risks to nontarget organisms including mammals and hydrobionts, and its effects on crops are not known. This study examined the invisible toxicity of profenofos on pakchoi (Brassica rapa L.), using transcriptome and metabolome analyses. Profenofos inhibited the photosynthetic efficiency and light energy absorption by leaves and severely damaged the chloroplasts, causing the accumulation of reactive oxygen species (ROS). Metabolomic analysis confirmed that profenofos promoted the conversion of β-carotene into abscisic acid (ABA), as evidenced by the upregulation of the carotenoid biosynthesis pathway genes: zeaxanthin epoxidase (ZEP), 9-cis-epoxycarotenoid dioxygenase (NCED3), and xanthoxin dehydrogenase (XanDH). The inhibitory effects on carotenoid accumulation, photosynthesis, and increased ABA and ROS contents of the leaves led to invisible injury and stunted growth of the pakchoi plants. The findings of this study revealed the toxicological risk of profenofos to nontarget crops and provide guidance for the safe use of insecticides.

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.

Light harvesting enhancement through band structure engineering in graphite carbon nitride / polydopamine nanocomposite photocatalyst: Addressing persistent organophosphorus pesticide pollution in water systems

Organophosphorus pesticides, particularly profenofos (PF), pose a significant threat to the food supply and human health due to their persistence, toxicity, and resistance to natural breakdown processes. An urgent need exists for an environmentally friendly solution, and photocatalysis emerges as a practical, cost-effective option. However, challenges like poor light responsiveness and difficulties in material separation and reusability persist. To address these issues, we developed a nanocomposite consisting of graphite carbon nitride (g-C3N4) doped with polydopamine (pDA) through a hydrothermal synthesis method. This innovative nanocomposite was employed as a photocatalyst to degrade PF. Various analytical techniques, including UV-DRS, FT-IR, XRD, HR-TEM, and EDAX, were utilized to characterize the synthesized nanocomposite. The strategically modulated band gaps of the nanocomposite enable efficient absorption of UV light, facilitating the robust photocatalytic degradation of PF (96.4%). Our study explored photodegradation using different g-C3N4/pDA catalyst dosages, varied PF concentrations, and pH levels (3, 5, 9, and 11) under UV light. Our findings promise applications in wastewater management, offering an efficient catalyst for PF degradation. This marks a significant stride in addressing challenges related to pesticide pollution in the environment.

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.

Enantioselective Behaviors of Chiral Pesticides and Enantiomeric Signatures in Foods and the Environment

Unreasonable application of pesticides may result in residues in the environment and foods. Chiral pesticides consist of two or more enantiomers, which may exhibit different behaviors. This Review intends to provide progress on the enantioselective residues of chiral pesticides in foods. Among the main chiral analytical methods, high performance liquid chromatography (HPLC) is the most frequently utilized. Most chiral pesticides are utilized as racemates; however, due to enantioselective dissipation, bioaccumulation, biodegradation, and chiral conversion, enantiospecific residues have been found in the environment and foods. Some chiral pesticides exhibit strong enantioselectivity, highlighting the importance of evaluation on an enantiomeric level. However, the occurrence characteristics of chiral pesticides in foods and specific enzymes or transport proteins involved in enantioselectivity needs to be further investigated. This Review could help the production of some chiral pesticides to single-enantiomer formulations, thereby reducing pesticide consumption as well as increasing food production and finally reducing human health risks.

Magnetic-assisted exciton-plasmon interactions modulated Bi2S3 nanorods@MoS2 nanosheets heterojunction: towards a split-type photoelectrochemical sensing of profenofos

A split-type photoelectrochemical (PEC) sensor was designed for the detection of profenofos (PFF) depending on the magnetic-assisted exciton-plasmon interactions (EPI) between the semiconductor substrate and Au NPs. The core-shell Bi2S3 nanorods@MoS2 nanosheets (Bi2S3 NRs@MoS2 NSs) heterostructure nanomaterial with fascinating performance was synthesized and used as the photovoltaic conversion substrate and signal molecules absorption platform. The PEC sensor is operated by co-incubating with the released Au NPs-cDNA from the surface of magnetic beads, originating from the target-triggered DNA double-stranded structure opening event. Due to the strong EPI effects, the photocurrent of Bi2S3 NRs@MoS2 NSs decreased and varied with the PFF concentrations. The proposed PEC sensor exhibited outstanding analytical performances, including a wide linear range (1.0 pg mL-1~1.0 μg mL-1), low detection limitation (0.23 pg mL-1, at 3 σ/m), excellent specificity, high stability, and applicability. Overall, this work provides a new signal strategy for PEC biosensors and extends its application in environmental analysis.

Efficient Knocking Out of the Organophosphorus Insecticides Degradation Gene opdB in Cupriavidus nantongensis X1T via CRISPR/Cas9 with Red System

Cupriavidus nantongensis X1^T is a type strain of the genus Cupriavidus, that can degrade eight kinds of organophosphorus insecticides (OPs). Conventional genetic manipulations in Cupriavidus species are time-consuming, difficult, and hard to control. The clustered regularly interspaced short palindromic repeat (CRISPR)/associated protein 9 (Cas9) system has emerged as a powerful tool for genome editing applied in prokaryotes and eukaryotes due to its simplicity, efficiency, and accuracy. Here, we combined CRISPR/Cas9 with the Red system to perform seamless genetic manipulation in the X1^T strain. Two plasmids, pACasN and pDCRH were constructed. The pACasN plasmid contained Cas9 nuclease and Red recombinase, and the pDCRH plasmid contained the dual single-guide RNA (sgRNA) of organophosphorus hydrolase (OpdB) in the X1^T strain. For gene editing, two plasmids were transferred to the X1^T strain and a mutant strain in which genetic recombination had taken place, resulting in the targeted deletion of opdB. The incidence of homologous recombination was over 30%. Biodegradation experiments suggested that the opdB gene was responsible for the catabolism of organophosphorus insecticides. This study was the first to use the CRISPR/Cas9 system for gene targeting in the genus Cupriavidus, and it furthered our understanding of the process of degradation of organophosphorus insecticides in the X1^T strain.

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.

Isolation of Sphingomonas sp. AJ-1 and its enantioselective S-methylation of the triazole fungicide prothioconazole

Prothioconazole is a widely used chiral triazole fungicide, and its residue pollution has attracted wide attention in recent years. However, little is known about microbial metabolic processes of prothioconazole enantiomers. In this study, a prothioconazole-degrading strain, Sphingomonas sp. AJ-1, was isolated from activated sludge. The optimal temperature and pH for prothioconazole degradation by strain AJ-1 were 30 °C and 6.0, respectively, and the degradation rate of prothioconazole by strain AJ-1 was negatively correlated with the initial concentration. When supplemented with additional carbon source, the degradation rates of 10 mg/L (Rac)-/(S)-/(R)-prothioconazole by strain AJ-1 were 76.0 %, 100.0 % and 64.8 % within 6 d, respectively. The CS bond of prothioconazole was methylated to produce (S)-/(R)-prothioconazole-S-methyl by strain AJ-1, but the degradation rate of prothioconazole by strain AJ-1 with (S)-enantiomer was 2.54-fold of that with (R)-enantiomer. Moreover, the toxicity of (Rac)-prothioconazole-S-methyl was 5.57 times lower than that of (Rac)-prothioconazole to Pseudokirchneriella subcapitata. The results showed that strain AJ-1 had obvious enantioselective metabolism for prothioconazole, and this metabolism was a detoxification process. This study provides new insights into the enantioselective metabolism of the chiral fungicide prothioconazole in microorganisms.

The profiles of chiral pesticides in peri-urban areas near Yangtze River: Enantioselective distribution characteristics and correlations with surface sediments

Chiral pesticides account for 30% of pesticides. Pesticides are inevitably leached into the groundwater by runoff. At the watershed level, the distribution characteristics of enantiomers in sediments collected from the river network of an agricultural area near the middle and lower reaches of the Yangtze River were tested, and their potential correlations with the physicochemical properties and microbial communities of the sediments were analyzed. The sediment pollution was serious at sites 8 and 9, with their pollution source possibly being agricultural or industrial sewage. Moreover, there were higher cumulative contents of pesticide residues at sites 4, 8, and 9. Specifically, Cycloxaprid was the most detected chiral pesticide in the study area, followed by Dinotefuran and Diclofop-methyl. Additionally, Ethiprole and Difenoconazole had strong enantioselectivity in the study area. Interestingly, the enantiomers of some chiral pesticides, such as Tebuconazole, had completely different distributions at different sites. Pearson correlation analysis showed that sediment catalase and microbial biomass carbon were important factors for enantioselectivity of chiral pesticides. The effect of sediment physicochemical properties on enantioselective distribution was achieved by influencing the microorganisms in the sediment. Furthermore, the enantioselective distribution of Tebuconazole was closely related to the genus Arenimonas. Overall, the enantioselective distribution of most of the chiral pesticides was positively correlated with the prokaryotic microbial community. This study provides empirical support for agricultural non-point source pollution caused by chiral pesticides, and also lays a research foundation for exploring the factors that affect the fate of chiral pesticides in the environment.

Occurrence and fate of chiral and achiral drugs in estuarine water - a case study of the Clyde Estuary, Scotland

There is currently a lack of enantiospecific studies on chiral drugs in estuarine environments. In this study, the occurrence and fate of 20 prescription and illicit drugs, metabolites and associated contaminants were investigated in the Clyde Estuary, Scotland, over a 6 month period. More than half of the drugs were detected in at least 50% of water samples collected (n = 30), with considerable enantiomer enrichment observed for some of the compounds. Enantiomeric fraction (EF) values of the chiral drugs investigated in this study ranged from <0.03 for amphetamine to 0.70 for bisoprolol. Microcosm studies revealed enantioselective degradation of fluoxetine and citalopram for the first-time in estuarine waters (over 14 days at 8.0 °C in water of 27.8 practical salinity units). Interestingly, fish collected from the inner estuary (Platichthys flesus - European flounder) contained drug enantiomers in muscle and liver tissues. This included propranolol, fluoxetine, citalopram, and venlafaxine. Considerable enantiospecific differences were observed between the two fish tissues, and between fish tissues and water samples. For example, citalopram EF values in muscle and liver were 0.29 ± 0.03 and 0.18 ± 0.01, respectively. In water samples EF values were in the range 0.36-0.49. This suggests enantioselective metabolism of citalopram by P. flesus. The enantioselectivity of drugs observed within the Clyde Estuary highlights the need for enantiospecific effect-driven studies on marine organisms to better understand their impact in estuarine environments, contributing to the likely cumulative impacts of the range of contaminants to which marine coastal wildlife is exposed.

Enantioselective degradation of the organophosphorus insecticide isocarbophos in Cupriavidus nantongensis X1T: Characteristics, enantioselective regulation, degradation pathways, and toxicity assessment

The chiral pesticide enantiomers often show selective efficacy and non-target toxicity. In this study, the enantioselective degradation characteristics of the chiral organophosphorus insecticide isocarbophos (ICP) by Cupriavidus nantongensis X1^T were investigated systematically. Strain X1^T preferentially degraded the ICP R isomer (R-ICP) over the S isomer (S-ICP). The degradation rate constant of R-ICP was 42-fold greater than S-ICP, while the former is less bioactive against pest insects but more toxic to humans than the latter. The concentration ratio of S-ICP to R-ICP determines whether S-ICP can be degraded by strain X1^T. S-ICP started to degrade only when the ratio (C_S-ICP/C_R-ICP) was greater than 62. Divalent metal cations could improve the degradation ability of strain X1^T. The detected metabolites that were identified suggested a novel hydrolysis pathway, while the hydrolytic metabolites were less toxic to fish and green algae than those from P-O bond breakage. The crude enzyme degraded both R-ICP and S-ICP in a similar rate, indicating that enantioselective degradation was due to the transportation of strain X1^T. The strain X1^T also enantioselectively degraded the chiral organophosphorus insecticides isofenphos-methyl and profenofos. The enantioselective degradation characteristics of strain X1^T make it suitable for remediation of chiral organophosphorus insecticide contaminated soil and water.

Selective uptake determines the variation in degradation of organophosphorus pesticides by Lactobacillus plantarum

Organophosphorus pesticides (OPPs) are widely used worldwide, leading to varying degrees of residues in food. Lactic acid bacteria (LAB) can degrade OPPs by producing phosphatase. This study explored the reasons for the variation in the degradation of different OPPs by Lactobacillus plantarum. The results showed that the degradation effects of OPPs by L. plantarum (intact cells) varied greatly, the degradation rate constant of phoxim was 1.65-fold higher than that of dichlorvos. However, the phosphatase extracted from L. plantarum had no degradation selectivity for OPPs in vitro. It was speculated that the selective uptake of cells determines this degradation selectivity. The results of molecular docking supported this hypothesis because there was no difference in the binding energies between phosphatase and OPPs, while the binding energies between phosphate-binding protein and pesticides were different, and they were negatively correlated with the degradation rate constants of the eight OPPs by L. plantarum.