Diphenyl Ether Herbicides Research Articles

The effects of long-term application of fomesafen on weed seedbank and resistance levels of Amaranthus retroflexus L.

Amaranthus retroflexus L. is one of the invasive malignant weeds in soybean fields. Diphenyl ether herbicides are commonly used to control weeds in soybean fields currently, among which fomesafen is the most widely used. With the long-term use of fomesafen, the weed species in soybean fields in multiple areas declined, and the control effect of fomesafen against Amaranthus retroflexus decreased significantly. This study aims to confirm the effects of long-term use of fomesafen on weed community richness and the current resistance level of Amaranthus retroflexus. In this paper, the result of seed germination indicated that the weed community richness decreased significantly due to the long-term application of fomesafen, and the primary dominant weed was Amaranthus retroflexus. The result of the whole-plant bioassay showed that Amaranthus retroflexus has developed resistance to fomesafen, and the resistance index was 50~59 g a.i. ha-1. The resistance level and mechanism of Amaranthus retroflexus were clarified by target gene detection, enzyme activity determination, and gene expression analysis. The results showed that there were both target resistance with Arg128Gly mutation in the PPX2 gene and non-target resistance (NTSR), with increased activity of metabolic enzymes (cytochromes P450 (P450s) and glutathione S-transferase (GSTs)) and protective enzymes (peroxidase (POD) and catalase (CAT)) in Amaranthus retroflexus.

Maize Root Exudates Promote Bacillus sp. Za Detoxification of Diphenyl Ether Herbicides by Enhancing Colonization and Biofilm Formation.

Diphenyl ether herbicides are extensively utilized in agricultural systems, but their residues threaten the health of sensitive rotation crops. Functional microbial strains can degrade diphenyl ether herbicides in the rhizosphere of crops, facilitating the restoration of a healthy agricultural environment. However, the interplay between microorganisms and plants in diphenyl ether herbicides degradation remains unclear. Thus, the herbicide-degrading strain Bacillus sp. Za and the sensitive crop, maize, were employed to uncover the interaction mechanism. The degradation of diphenyl ether herbicides by strain Bacillus sp. Za was promoted by root exudates. The strain induced root exudate re-secretion in diphenyl ether herbicide-polluted maize. We further showed that root exudates enhanced the rhizosphere colonization and the biofilm biomass of strain Za, augmenting its capacity to degrade diphenyl ether herbicide. Root exudates regulated gene fliZ, which is pivotal in biofilm formation. Wild-type strain Za significantly reduced herbicide toxicity to maize compared to the ZaΔfliZ mutant. Moreover, root exudates promoted strain Za growth and chemotaxis, which was related to biofilm formation. This mutualistic relationship between the microorganisms and the plants demonstrates the significance of plant-microbe interactions in shaping diphenyl ether herbicide degradation in rhizosphere soils. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

A Review of Remediation Strategies for Diphenyl Ether Herbicide Contamination.

In agriculture, diphenyl ether herbicides are a broad-spectrum family of pesticides mainly used to control annual weeds in agriculture. Although diphenyl ether herbicides have a long-lasting effect in weed control, they can also be harmful to succeeding crops, as well as to the water and soil environment. Residual herbicides can also harm a large number of non-target organisms, leading to the death of pest predators and other beneficial organisms. Therefore, it is of great significance to control and remediate the contamination caused by diphenyl ether herbicide residues for the sake of environmental, nutritional, and biological safety. This review provides an overview of the techniques used for remediating diphenyl ether herbicide contamination, including biological, physical, and chemical remediation. Among these techniques, bioremediation, particularly microbial biodegradation technology, is extensively employed. The mechanisms and influencing factors of different remediation techniques in eliminating diphenyl ether herbicide contamination are discussed, together with a prospect for future development directions. This review serves as a scientific reference for the efficient remediation of residual contamination from diphenyl ether herbicides.

Enhancing the efficiency of polypyrrole-dodecylbenzene sulfonic acid in-tube solid-phase microextraction coating for analysis of nitrogen-containing pesticides in water environments

Background: With the growing use of nitrogen-containing pesticides in agriculture, their residues in the environment have raised significant public health concerns.Objective: This study aimed to develop a novel PPy-DBSA/IT-SPME coating to enhance the detection efficiency of polar nitrogen-containing pesticides in water matrices.Methods: The preparation conditions were optimized, including pyrrole concentration at 7.0 mol/L, DBSA concentration at 0.014 mol/L, oxidant concentration at 0.35 mol/L, and a coating cycle repeated 10 times. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was employed for detection.Results: The novel coating effectively adsorbed 19 different categories of polar nitrogen-containing pesticides, including sulfonylureas, triazolopyrimidines, diphenyl ether herbicides, benzoylurea insecticides, and phenylurea herbicides, with unadsorbed rates below 10%. The analytical method achieved an average recovery rate of 61.92% to 115.21%, with an RSD below 5.0%. Detection and quantification limits ranged from 0.012 to 0.524 μg/L and 0.127 to 5.243 μg/L, respectively.Conclusion: The developed method is green, efficient, simple, and cost-effective. It offers an environmentally friendly and user-friendly approach for the detection of polar nitrogen-containing pesticide residues, demonstrating good recovery and precision. This method holds potential for wide application in environmental monitoring and food safety.

Bifenox induces hepatotoxicity and vascular toxicity in zebrafish embryos via ROS production and alterations in signaling pathways

Existing evidence shows that currently used pesticides pose toxicological risks to exposed wildlife. Chemically, bifenox belongs to diphenyl ethers, a well-known group of herbicides. Its mechanism of action primarily involves inducing lipid peroxidation and blocking protoporphyrinogen oxidases. Toxicity of diphenyl ether herbicides has been elucidated in animal cells; however, in vivo toxicological evaluations of bifenox are required to determine its unexpected effects. This study aimed to determine the negative effects of bifenox, and its effects on higher eukaryotes. We found that early stages of zebrafish embryo exposed to bifenox demonstrated increased mortality and physiological defects, based on the LC50 value. Bifenox severely inhibited blood vessel growth by reducing key elements of complex connectivity; fluorescently tagged transgenic lines (fli1a:EGFP) showed morphological changes. Additionally, transgenic lines that selectively identified hepatocytes (fabp10a:DsRed) showed reduced fluorescence, indicating that bifenox may inhibit liver development. To evaluate the level of oxidative stress, we used 2′,7′-dichlorofluorescein diacetate (DCFH-DA) probes in zebrafish embryos to identify the underlying mechanisms causing developmental damage. Our findings demonstrate that exposure to bifenox causes abnormalities in the hepatic and cardiovascular systems during zebrafish embryogenesis. Therefore, this study provides new information for the evaluation of toxicological risks of bifenox in vertebrates.

Development of an immunoassay based on a specific antibody for the detection of diphenyl ether herbicide fomesafen

Fomesafen belongs to the diphenyl ether herbicide, and is widely used in the control of broadleaf weeds in crop fields due to its high efficiency and good selectivity. The residual of fomesafen in soil has a toxic effect on subsequent sensitive crops and the microbial community structure because of its long residual period. Therefore, an efficient method for detecting fomesafen is critical to guide the correct and reasonable use of this herbicide. Rapid and sensitive immunoassay methods for fomesafen is unavailable due to the lack of specific antibody. In this study, a specific antibody for fomesafen was generated based on rational design of haptens and a sensitive immunoassay method was established. The half maximal inhibitory concentration (IC50) of the immunoassay was 39 ng/mL with a linear range (IC10–90) of 1.92–779.8 ng/mL. In addition, the developed assay had a good correlation with the standard UPLC-MS/MS both in the spike-recovery studies and in the detection of real soil samples. Overall, the developed indirect competitive enzyme immunoassay reported here is important for detecting and quantifying fomesafen contamination in soil and other environmental samples with good sensitivity and high reproducibility.

Evaluation of the diphenyl herbicide, oxyfluorfen, for effects on thyroid hormones in the juvenile rat

Recently, oxyfluorfen, a pre- and post-emergent diphenyl ether herbicide, was identified in our laboratory as an inhibitor of iodide uptake by the sodium iodide symporter (NIS), the first key step in the synthesis of thyroid hormones (THs). This inhibition was observed in vitro, using both a human NIS engineered cell line (hNIS-HEK293T-EPA) and a rat thyroid follicular cell line (FRTL-5). Oxyfluorfen was found to be a potent inhibitor of NIS activity with an EC50 of approximately 2 µM in both cell lines with no observed cytotoxicity at any concentration tested up to 100 μM. The current research tested the hypothesis that oxyfluorfen alters circulating concentrations of THs. This hypothesis was first tested in a pilot study with both juvenile male and female rats exposed to oxyfluorfen for 4 days at 0, 125, 250 and 500 mg/kg/day. Once we identified that this short-term 4-day oxyfluorfen exposure suppressed both total serum thyroxine (T4) and triiodothyronine (T3) at all doses, we tested seven lower concentrations of oxyfluorfen (0.8125 to 62.5 mg/kg day) in an 8-day exposure paradigm to more closely evaluate the dose–response. We found that oxyfluorfen suppressed serum T4 with a LOEL of 3.25 mg/kg/day and T3 with a LOEL 62.5 mg/kg/day. Analytical chemistry of the serum showed an accumulation over time following oral exposure to oxyfluorfen in both the 4- and 8-day groups. Analytical chemistry of the thyroid glands in the 8-day study revealed higher accumulation in the thyroid as compared to the serum (2 to 3- fold at 62.5 mg/kg). No changes in thyroid weight or serum TSH were observed following the 8-day exposure. This study is the first to demonstrate an effect of oxyfluorfen on serum thyroid hormones in the rat. Additional studies are needed to further evaluate the effects on thyroid homeostasis with extended exposures and the potential implications of the observed effects.

COF-300-AR@CRL as a two-in-one nanocatalyst for one-step chemiluminescent detection of diphenyl ether herbicide residues in vegetable and fruit samples.

A sensitive and accurate chemiluminescence (CL) method wasdevelopedfor one-step determination of diphenyl ether herbicides at trace level with nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) as a model analyte. Candida rugosa lipase (CRL) was immobilized on a nanocarrier of amine-linked covalent organic framework (named as COF-300-AR) through a self-assembly strategy. The formed nanocomposite of COF-300-AR@CRL owns dual enzymatic catalytic activities. It can directly catalyze luminol-dissolved oxygen reaction to produce an intense CL emission by virtue of oxidase mimic activity of COF-300-AR but also effectively decompose nitrofen to release phenolic compounds by the immobilized CRL. The released phenolic compounds own strong reducing capacity and in turn decrease the CL signal sharply. Under the optimal conditions, the decreased CL intensity presents a good linear response to nitrofen concentration in the 0.02-50.0 μM range. The limit of detection (LOD, 3sb/S) is 11 nM and the precision is 2.0% for replicate measurements of 50.0 nM nitrofen solution (n = 11). This method has the advantages of rapid analytical efficiency, good selectivity, satisfactory stability, and recyclability. Recovery experiments were conducted on spiked vegetable and fruit samples with the recoveries falling in the range 90.0-107.0%.

Remediation of fomesafen contaminated soil by Bacillus sp. Za: Degradation pathway, community structure and bioenhanced remediation

Fomesafen is a diphenyl ether herbicide used to control the growth of broadleaf weeds in bean fields. The persistence, phytotoxicity, and negative impact on crop rotation associated with this herbicide have led to an increasing concern about the buildup of fomesafen residues in agricultural soils. The exigent matter of treatment and remediation of soils contaminated with fomesafen has surfaced. Nevertheless, the degradation pathway of fomesafen in soil remains nebulous. In this study, Bacillus sp. Za was utilized to degrade fomesafen residues in black and yellow brown soils. Fomesafen's degradation rate by strain Za in black soil reached 74.4%, and in yellow brown soil was 69.2% within 30 days. Twelve intermediate metabolites of fomesafen were identified in different soils, with nine metabolites present in black soil and eight found in yellow brown soil. Subsequently, the degradation pathway of fomesafen within these two soils was inferred. The dynamic change process of soil bacterial community structure in the degradation of fomesafen by strain Za was analyzed. The results showed that strain Za potentially facilitate the restoration of bacterial community diversity and richness in soil samples treated with fomesafen, and there were significant differences in species composition at phylum and genus levels between these two soils. However, both soils shared a dominant phylum and genus, Actinobacteriota, Proteoobacteria, Firmicutes and Chloroflexi dominated in two soils, with a high relative abundance of Sphingomonas and Bacillus. Moreover, an intermediate metabolite acetaminophen degrading bacterium, designated as Pseudomonas sp. YXA-1, was isolated from yellow brown soil. When strain YXA-1 was employed in tandem with strain Za to remediate fomesafen contaminated soil, the degradation rate of fomesafen markedly increased. Overall, this study furnishes crucial insights into the degradation pathway of fomesafen in soil, and presents bacterial strain resources potentially beneficial for soil remediation in circumstances of fomesafen contamination.

A novel doped metal–organic skeleton MnDUT-52 as a sorbent for dispersive solid phase extraction of diphenyl ether herbicides in the water environment

A manganese doped metal–organic framework composite (MnDUT-52) was fabricated by a facile solvothermal method and applied as an adsorbent for dispersive solid phase extraction (DSPE) of trace diphenyl ether herbicides (Des) in water samples. The doped material exhibited large surface area (527.3 m2/g) and a higher zeta potential (43.2 mV) compared with its precursor (8.57 mV). And the quantitative parameters affecting the DSPE process (i.e., adsorbent amount, adsorption time, pH, ionic strength, desorption solvent and desorption volume) were optimized in detail. Under the optimal conditions, MnDUT-52 exhibited good reusability (6 times reuse, RSDs ≤ 5.8 %). Notably, the conjugation, hydrophobic and electrostatic interactions contributed to the good adsorption of Des by MnDUT-52. Finally, a method coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed. It provided wide linear range (0.2–300 ng/mL), low detection limits (0.06–0.10 ng/mL) and extraction recovery (82.4–102.5 %). The developed method was successfully applied for the fast and sensitive determination of Des in water samples.

Selectivity of diphenyl-ether herbicides with postemergence applications in chickpea

Selectivity of diphenyl-ether herbicides with postemergence applications in chickpea

A nitroreductase DnrA catalyzes the biotransformation of several diphenyl ether herbicides in Bacillus sp. Za

A nitroreductase DnrA catalyzes the biotransformation of several diphenyl ether herbicides in Bacillus sp. Za

Study of the degradation of diphenyl-ether herbicides aclonifen and bifenox in different environmental waters

The degradation of the diphenyl-ether herbicides aclonifen (ACL) and bifenox (BF) in water samples has been studied under different laboratory conditions, using in-tube solid-phase microextraction (IT-SPME) coupled to capillary liquid chromatography (capLC). The working conditions were selected in order to detect also bifenox acid (BFA), a compound formed as a result of the hydroxylation of BF. Samples (4 mL) were processed without any previous treatment, which allowed the detection of the herbicides at low ppt levels. The effects of temperature, light and pH on the degradation of ACL and BF have been tested using standard solutions prepared in nanopure water. The effect of the sample matrix has been evaluated by analysing different environmental waters spiked with the herbicides, namely ditch water, river water and seawater. The kinetics of the degradation have been studied and the half-life times (t1/2) have been calculated. The results obtained have demonstrated that the sample matrix is the most important parameter affecting the degradation of the tested herbicides. The degradation of both ACL and BF was much faster in ditch and river water samples, where t1/2 values of only a few days were observed. However, both compounds showed a better stability in seawater samples, where they can persist for several months. In all matrices ACL was found to be more stable than BF. In samples where BF had been substantially degraded, BFA was also detected, although the stability of this compound was also limited. Other degradation products have been detected along the study.

Contrasting Toxicity of a Fomesafen-Based Herbicide on Three Freshwater Phytoplanktonic Species

Pesticides leaching and run-off to nearby freshwater sources are a major ecological concern. The emergence of herbicide-resistant weeds led to the increased usage of fomesafen, a diphenyl ether herbicide inhibiting protoporphyrinogen oxidase (PPO). This recent rise in demand and use for this molecule invariably increases the chance of this herbicide entering freshwater environments and affecting non-target organisms. However, there is still a lack of information in the literature regarding the impact of this herbicide on the physiology of freshwater phytoplankton. This study aimed to determine the impact of five concentrations (0, 5, 10, 40, 320 µg · L−1) of a fomesafen-based herbicide (Reflex®) on the physiology of two species of green microalgae (Raphidocelis subcapitata FACHB-271; Chlamydomonas snowii) and one cyanobacterial species (Microcystis aeruginosa CPCC 632). While physiological biomarkers (growth, photosynthesis, pigment content, oxidative stress and morphology) of R. subcapitata were significantly affected by the fomesafen treatments, no significant effects were observed in the physiology of C. snowii and M. aeruginosa. We hypothesize that this difference in fomesafen resistance is most likely due to intracellular morphological and genetic differences between species. Modeling of fomesafen uptake in R. subcapitata showed that alteration of cell biovolume is unlikely to be an efficient mechanism modulating fomesafen toxicity and that potential fomesafen efflux or breakdown would need to be very fast (and operate at a high energy cost) in order to protect against uptake and toxicity. This study provides new insights into the sensitivity of different algae species toward fomesafen as well as the associated cellular toxicity mechanisms.

Cross species extrapolation of the disruption of thyroid hormone synthesis by oxyfluorfen using in vitro data, physiologically based pharmacokinetic (PBPK), and thyroid hormone kinetics models

The thyroid hormones play key roles in physiological processes such as regulation of the metabolic and cardiac systems as well as the development of the brain and surrounding sympathetic nervous system. Recent efforts to screen environmental chemicals for their ability to alter thyroid hormone synthesis, transport, metabolism and/or function have identified novel chemicals that target key processes in the thyroid pathway. One newly identified chemical, oxyfluorfen, is a diphenyl-ether herbicide used for control of annual broadleaf and grassy weeds in a variety of tree fruit, nut, vine, and field crops. Using in vitro high-throughput screening (HTS) assays, oxyfluorofen was identified to be a potent inhibitor of the thyroidal sodium-iodide symporter (NIS). To quantitatively assess this inhibition mechanism in vivo, we extrapolated in vitro NIS inhibition data to in vivo disruption of thyroid hormones synthesis in rats using physiologically based pharmacokinetic (PBPK) and thyroid hormone kinetics models. The overall computational model (chemical PBPK and THs kinetic sub-models) was calibrated against in vivo data for the levels of oxyfluorfen in thyroid tissue and serum and against serum levels of thyroid hormones triiodothyronine (T3) and thyroxine (T4) in rats. The rat thyroid model was then extrapolated to humans using human in vitro HTS data for NIS inhibition and the chemical specific hepatic clearance rate in humans. The overall species extrapolated PBPK-thyroid kinetics model can be used to predict dose–response (% drop in thyroid serum levels compared to homeostasis) relationships in humans. These relationships can be used to estimate points of departure for health risks related to a drop in serum levels of TH hormones based on HTS assays in vitro to in vivo extrapolation (IVIVE), toxicokinetics, and physiological principles.

Development of solid agents of the diphenyl ether herbicide degrading bacterium Bacillus sp. Za based on a mixed organic fertilizer carrier.

The long-term and widespread use of diphenyl ether herbicides has caused serious soil residue problems and threatens the agricultural ecological environment. The development of biodegrading agents using high-efficiency degrading strains as pesticide residue remediation materials has been widely recognized. In this study, the strain Bacillus sp. Za was used to prepare solid agents for the remediation of diphenyl ether herbicides-contaminated soil. The ratio of organic fertilizer was 1:3 (pig manure: cow dung), the inoculum amount of Za was 10%, the application amount of solid agents was 7%, and the application mode was mixed application, all of which were the most suitable conditions for solid agents. After the solid agents were stored for 120 days, the amount of Za remained above 108 CFU/g. The degradation rates of the solid agents for lactofen, bifenox, fluoroglycofen, and fomesafen in soil reached 87.40, 82.40, 78.20, and 65.20%, respectively, on the 7th day. The application of solid agents alleviated the toxic effect of lactofen residues on maize seedlings. A confocal laser scanning microscope (CLSM) was used to observe the colonization of Za-gfp on the surface of maize roots treated in the solid agents, and Za-gfp mainly colonized the elongation zone and the mature area of maize root tips, and the colonization time exceeded 21 days. High-throughput sequencing analysis of soil community structural changes in CK, J (solid agents), Y (lactofen), and JY (solid agents + lactofen) groups showed that the addition of solid agents could restore the bacterial community structure in the rhizosphere soil of maize seedlings. The development of solid agents can facilitate the remediation of soil contaminated with diphenyl ether herbicide residues and improve the technical level of the microbial degradation of pesticide residues.

Aclonifen could induce implantation failure during early embryonic development through apoptosis of porcine trophectoderm and uterine luminal epithelial cells

Aclonifen is a diphenyl-ether herbicide that is used to control the growth of weeds while growing crops such as corn and wheat. Although the biochemical effects of aclonifen are well characterized, including its ability to inhibit protoporphyrinogen oxidase and carotenoid synthesis, the toxicity of aclonifen in embryonic implantation and development during early pregnancy, has not been reported. Thus, in this study, we investigated the potential interference of aclonifen in embryonic implantation using porcine trophectoderm (pTr) and uterine luminal epithelial (pLE) cells isolated during implantation period of early pregnancy. Cell viability in both pTr and pLE cells significantly decreased in a dose-dependent manner following aclonifen treatment. Moreover, the proportion of cells in the sub-G1 phase of the cell cycle gradually increased upon treatment with increasing concentrations of aclonifen, which in turn led to an increase in the number of apoptotic cells, as determined by annexin V and propidium iodide staining. Aclonifen treatment caused mitochondrial dysfunction by increasing the depolarization of the mitochondrial membrane potential and the mitochondrial calcium concentration. Aclonifen inhibited cell mobility by suppressing the expression of implantation-related genes in pTr and pLE cells. To explore the underlying mechanism, we evaluated the phosphorylation of PI3K and MAPK signaling molecules. The phosphorylation of AKT, S6, JNK, and ERK1/2 were significantly increased by aclonifen. Collectively, our results suggest that aclonifen may interrupt implantation during early pregnancy by disrupting maternal–fetal interaction.

Aclonifen induces bovine mammary gland epithelial cell death by disrupting calcium homeostasis and inducing ROS production

Herbicides play key roles in agriculture. Aclonifen is a diphenyl ether herbicide that is widely used for sunflower, potato, corn, and wheat crops. Since it has a long half-life, it is considered persistent and can easily accumulate in the environment. Therefore, livestock and humans are at risk of exposure to aclonifen. Importantly, aclonifen is toxic to several mammals such as rats, mice, and dogs. However, the toxicity of aclonifen in cattle remains unclear. Therefore, we sought to investigate its toxicity in cattle using bovine mammary gland epithelial cells (MAC-T). We found that aclonifen induces sub-G1 phase arrest and represses MAC-T proliferation. In addition, aclonifen caused mitochondrial dysfunction, as evidenced by excessive ROS production and loss of mitochondrial membrane potential. Furthermore, cytosolic and mitochondrial calcium homeostases were disrupted after aclonifen treatment. Moreover, aclonifen treatment caused alterations in the PI3K/AKT and MAPK signaling pathways, which are involved in the regulation of cell survival and death. In conclusion, aclonifen causes MAC-T cell death through mitochondrial dysfunction and the collapse of calcium homeostasis.

Biodegradation of diphenyl ether herbicide lactofen by Bacillus sp. YS-1 and characterization of two initial degrading esterases

The extensive use of the diphenyl ether herbicide lactofen in recent years has caused serious environmental problems. Therefore, detoxification and elimination of lactofen from the environment are urgently required. In this study, the lactofen-degrading strain Bacillus sp. YS-1 was isolated, which achieved a 97.6% degradation rate of 50 mg/L lactofen within 15 h. The ester bond of lactofen was hydrolyzed, which generated acifluorfen, and then, the nitro group was reduced to the amino group, which generated aminoacifluorfen. Finally, the amino group was acetylated, which formed acetylated aminoacifluorfen, a novel end product in the degradation of lactofen. The toxicity of acetylated aminoacifluorfen to the root and seedling growth of cucumber and sorghum was significantly decreased compared with that of lactofen. The two esterase genes rhoE and rapE, encoding two esterases responsible for lactofen hydrolysis to acifluorfen, were cloned and expressed. The amino acid sequences encoded by rhoE and rapE were 27.78% and 88.21% identical with known esterases, respectively. The optimum temperatures for RhoE and RapE degradation of lactofen were 35 °C and 25 °C, respectively, and both esterases displayed maximal activity at pH 8.0. Both RhoE and RapE prioritized the degradation of (S)-(+)-lactofen, (S)-(−)-quizalofop-ethyl, and (S)-(−)-diclofop-methyl. This study provided the resources of bacterial strain and hydrolyzing enzyme for the removal of lactofen from the environment and the bioremediation of herbicide-contaminated soil.

Determination of three diphenyl ether herbicides in rice by magnetic solid phase extraction using Fe<sub>3</sub>O<sub>4</sub>@MOF-808 coupled with high performance liquid chromatography

利用溶剂热法构筑了Fe3O4@MOF-808吸附剂,将其用于大米中除草醚(NIT)、乙氧氟草醚(OXY)和甲羧除草醚(BIF)3种二苯醚类除草剂的富集,结合高效液相色谱法,建立了大米中该类除草剂的分析方法。研究通过傅里叶变换红外光谱、X射线衍射仪、扫描电子显微镜以及振动样品磁强计对构筑的磁性吸附剂的结构、表面形貌及磁强度进行表征。表征结果显示,球形的Fe3O4纳米颗粒与八面体形貌的MOF-808成功复合,Fe3O4@MOF-808饱和磁化强度可达40.35 emu/g,可以满足磁性固相萃取的需求;对吸附剂用于大米中3种二苯醚类除草剂富集的磁性固相萃取条件(吸附剂用量、吸附时间、洗脱溶剂种类以及洗脱体积)进行了优化。优化结果显示,25 mg吸附剂在6 min内即可达到对目标物的完全吸附,洗脱溶剂采用0.5 mL×2的甲醇。在最优的磁性固相萃取条件下,结合高效液相色谱-紫外检测法,建立了大米中3种二苯醚类除草剂的分析方法。方法在2~300 μg/L范围内线性关系良好(r > 0.998), NIT、OXY、BIF的检出限和定量限依次为0.6、0.6、0.4 μg/kg和2.0、2.0、1.5 μg/kg,在5、10和20 μg/kg 3个加标水平下的回收率为87.3%~96.7%,相对标准偏差不超过10.8%,且富集因子在25~29之间。将所建方法用于大米中NIT、OXY、BIF的分析,各样品均未检出这3种二苯醚类除草剂。该方法具有操作简单、快速、准确的特点,适用于大米样品中除草剂的残留分析。