ABSTRACT
Acetochlor is a selective pre-emergent herbicide that is widely used to control annual grass and broadleaf weeds. However, due to its stable chemical structure, only a small portion of acetochlor exerts herbicidal activity in agricultural applications, while most of the excess remains on the surfaces of plants or enters ecosystems, such as soil and water bodies, causing harm to the environment and human health. In recent years, researchers have become increasingly focused on the repair of acetochlor residues. Compared with traditional physical and chemical remediation methods, microorganisms are the most effective way to remediate chemical pesticide pollution, such as acetochlor, because of their rich species, wide distribution, and diverse metabolic pathways. To date, researchers have isolated and identified many high-efficiency acetochlor-degrading strains, such as Pseudomonas oleovorans, Klebsiella variicola, Bacillus subtilus, Rhodococcus, and Methylobacillus, among others. The microbial degradation pathways of acetochlor include dechlorination, hydroxylation, N-dealkylation, C-dealkylation, and dehydrogenation. In addition, the microbial enzymes, including hydrolase (ChlH), debutoxylase (Dbo), and monooxygenase (MeaXY), responsible for acetochlor biodegradation are also being investigated. In this paper, we review the migration law of acetochlor in the environment, its toxicity to nontarget organisms, and the main metabolic methods. Moreover, we summarize the latest progress in the research on the microbial catabolism of acetochlor, including the efficient degradation of microbial resources, biodegradation metabolic pathways, and key enzymes for acetochlor degradation. At the end of the article, we highlight the existing problems in the current research on acetochlor biodegradation, provide new ideas for the remediation of acetochlor pollution in the environment, and propose future research directions.
Subject(s)
Biodegradation, Environmental , Herbicides , Toluidines , Toluidines/toxicity , Toluidines/metabolism , Herbicides/metabolism , Herbicides/toxicity , Herbicides/chemistry , Bacteria/metabolism , Environmental Pollutants/toxicity , Environmental Pollutants/metabolism , Environmental Restoration and Remediation/methodsABSTRACT
Propanil residues can contaminate habitats where microbial degradation is predominant. In this study, an efficient propanil-degrading strain C-1 was isolated from paddy and identified as Rhodococcus sp. It can completely degrade 10 µg/L-150 mg/L propanil within 0.33-10 h via the hydrolysis of the amide bond, forming 3,4-dichloroaniline. A novel bifunctional amidase, PamC, was identified in strain C-1. PamC can catalyze the hydrolysis of the amide bond of propanil to produce 3,4-dichloroaniline as well as the hydrolysis of the ester bonds of aryloxyphenoxypropionate herbicides (APPHs, clodinafop-propargyl, cyhalofop-butyl, fenoxaprop-p-ethyl, fluazifop-p-butyl, haloxyfop-p-methyl, and quizalofop-p-ethyl) to form aryloxyphenoxypropionic acids. Molecular docking and site-directed mutagenesis confirmed that the catalytic triad Lys82-Ser157-Ser181 was the active center for PamC to hydrolyze propanil and cyhalofop-butyl. This study presents a novel bifunctional amidase with capabilities for both amide and ester bond hydrolysis and enhances our understanding of the molecular mechanisms underlying the degradation of propanil and APPHs.
Subject(s)
Amidohydrolases , Bacterial Proteins , Biodegradation, Environmental , Herbicides , Propanil , Rhodococcus , Rhodococcus/enzymology , Rhodococcus/genetics , Rhodococcus/metabolism , Herbicides/metabolism , Herbicides/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/chemistry , Propanil/metabolism , Propanil/chemistry , Amidohydrolases/metabolism , Amidohydrolases/chemistry , Amidohydrolases/genetics , Molecular Docking Simulation , Hydrolysis , BiocatalysisABSTRACT
The extensive use of chemical pesticides, such as herbicides, has resulted in significant environmental pollution. Microbial degradation represents a crucial approach for managing this pesticide-associated pollution, with enrichment culturing serving as a method for isolating pesticide-degrading microorganisms. However, the efficiency of this strategy is limited, often yielding only a few isolated strains. In this study, a new mineral salt medium (MSM) was developed, and a high-throughput method was used for screening pendimethalin-degrading bacteria by measuring the bacterial growth in the MSM. The utilization of this method resulted in the isolation of 56 pendimethalin-degrading bacteria from approximately 2000 bacterial strains, including 37 Bacillus spp., 10 Alcaligenes spp., 5 Pseudomonas spp., and other 4 strains identified for the first time as pendimethalin-degrading strains. This method may hold promise not only for isolating bacterial strains capable of degrading other pesticides but also for facilitating the utilization of the substantial bacterial strains stored in bacterial banks.
Subject(s)
Aniline Compounds , Bacteria , Herbicides , High-Throughput Screening Assays , Aniline Compounds/metabolism , Bacteria/metabolism , Bacteria/isolation & purification , Bacteria/classification , Bacteria/genetics , Bacteria/growth & development , Herbicides/metabolism , High-Throughput Screening Assays/methods , Biodegradation, Environmental , Culture Media/chemistryABSTRACT
Esterases are crucial for aryloxyphenoxypropionate herbicide (AOPP) biodegradation. However, the underlying molecular mechanisms of AOPP biodegradation by esterases are poorly understood. In the current work, Corynebacterium sp. Z-1 was isolated and found to degrade multiple AOPPs, including quizalofop-p-ethyl (QPE), haloxyfop-p-methyl (HPM), fenoxaprop-p-ethyl (FPE), cyhalofop-butyl (CYB), and clodinafop-propargyl (CFP). A novel esterase, QfeH, which catalyzes the cleavage of ester bonds in AOPPs to form AOPP acids, was identified from strain Z-1. The catalytic activities of QfeH toward AOPPs decreased in the following order: CFP > FPE > CYB > QPE > HPM. Molecular docking, computational analyses, and site-directed mutagenesis indicated the catalytic mechanisms of QfeH-mediated degradation of different AOPPs. Notably, the key residue S159 is essential for the activity of QfeH. Moreover, V222Y, T227M, T227A, A271R, and M275K mutants, exhibiting 2.9-5.0 times greater activity than QfeH, were constructed. This study facilitates the mechanistic understanding of AOPPs bioremediation by esterases.
Subject(s)
Biodegradation, Environmental , Corynebacterium , Esterases , Herbicides , Herbicides/metabolism , Herbicides/chemistry , Esterases/metabolism , Esterases/genetics , Esterases/chemistry , Corynebacterium/metabolism , Corynebacterium/genetics , Corynebacterium/enzymology , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/chemistry , Molecular Docking Simulation , Propionates/metabolismABSTRACT
This study represents the initial examination of the herbicidal efficacy, crop safety, and degradation patterns of 2,4-D ethylhexyl ester (2,4-D EHE) at the enantiomeric level. Baseline separation of 2,4-D EHE enantiomers was achieved using a superchiral R-AD column, with their absolute configurations determined through chemical reaction techniques. Evaluation of weed control efficacy against sensitive species such as sun spurge and flixweed demonstrated significantly higher inhibition rates for S-2,4-D EHE compared to R-2,4-D EHE. Conversely, no stereoselectivity was observed in the fresh-weight inhibition rates of both enantiomers on crops or nonsensitive weeds. A sensitive HPLC-MS/MS method was developed to simultaneously detect two enantiomers and the metabolite 2,4-D in plants. Investigation into degradation kinetics revealed no substantial difference in the half-lives of R- and S-2,4-D EHE in maize and flixweed. Notably, the metabolite 2,4-D exhibited prolonged persistence at elevated levels on flixweed, while it degraded rapidly on maize.
Subject(s)
Herbicides , Tandem Mass Spectrometry , Zea mays , Zea mays/chemistry , Zea mays/metabolism , Herbicides/chemistry , Herbicides/pharmacology , Herbicides/metabolism , Stereoisomerism , 2,4-Dichlorophenoxyacetic Acid/chemistry , 2,4-Dichlorophenoxyacetic Acid/metabolism , Chromatography, High Pressure Liquid , Plant Weeds/drug effects , Plant Weeds/growth & development , Plant Weeds/metabolism , Plant Weeds/chemistry , Kinetics , Esters/chemistry , Esters/pharmacology , Esters/metabolism , Araceae/chemistry , Araceae/drug effects , Araceae/metabolismABSTRACT
This study confirmed a field population of American sloughgrass (Beckmannia syzigachne (Steud.) Fernald) that developed simultaneously high levels of resistance (resistance index >10) to three divergent modes of action herbicides: fenoxaprop-P-ethyl, mesosulfuron-methyl, and isoproturon. The resistance phenotype observed in this population was not attributed to target-site alterations; rather, the resistant plants exhibited a significant increase in the activity of cytochrome P450s (P450s) and enhanced metabolism rates for all three herbicides. RNA sequencing revealed significant upregulation of two P450s, CYP709B1 and CYP704C1, in the resistant plants both before and after herbicide treatments. Molecular docking predicted that the homology models of these P450s should exhibit a binding affinity for a range of herbicides. The heterologous expression of the identified P450s in yeast cells indicated improved growth in the presence of all three of the aforementioned herbicides. Collectively, the increased expression of CYP709B1 and CYP704C1 likely contributed to the P450s-mediated enhanced metabolism, thereby conferring multiple herbicide resistance in B. syzigachne.
Subject(s)
Cytochrome P-450 Enzyme System , Herbicide Resistance , Herbicides , Plant Proteins , Herbicide Resistance/genetics , Cytochrome P-450 Enzyme System/metabolism , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/chemistry , Herbicides/pharmacology , Herbicides/metabolism , Herbicides/chemistry , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Proteins/chemistry , Molecular Docking Simulation , Poaceae/genetics , Poaceae/metabolism , Poaceae/enzymology , Poaceae/drug effects , Poaceae/chemistryABSTRACT
Tripyrasulfone is currently the only HPPD-inhibiting herbicide that possesses outstanding selectivity even for direct-seeded rice (Oryza sativa) when applied POST to control grass weeds; however, the underlying mechanisms remain unclear. In this study, the inhibitory effects of the real active HDT of tripyrasulfone on recombinant 4-hydroxyphenylpyruvate dioxygenase (HPPDs) from rice and barnyard grass (Echinochloa crus-galli) were similar, with consistent structural interactions and similar binding energies predicted by molecular docking. However, the HPPD expression level in rice was significantly greater than that in barnyard grass after tripyrasulfone treatment. Tripyrasulfone was rapidly taken up and hydrolyzed into HDT, which was similarly distributed within the whole plants of rice and barnyard grass at 24 h after treatment. Compared with barnyard grass, rice has more uniform epicuticular wax in the cuticle of its leaves, absorbing less tripyrasulfone and metabolizing much more tripyrasulfone. Overall, to a greater extent, the different sensitivities to tripyrasulfone between barnyard grass and rice resulted from metabolic variations.
Subject(s)
4-Hydroxyphenylpyruvate Dioxygenase , Echinochloa , Herbicides , Molecular Docking Simulation , Oryza , Plant Proteins , Oryza/metabolism , Oryza/chemistry , Echinochloa/drug effects , Echinochloa/genetics , Echinochloa/metabolism , Echinochloa/growth & development , Echinochloa/chemistry , Herbicides/pharmacology , Herbicides/chemistry , Herbicides/metabolism , Plant Proteins/metabolism , Plant Proteins/genetics , Plant Proteins/chemistry , 4-Hydroxyphenylpyruvate Dioxygenase/metabolism , 4-Hydroxyphenylpyruvate Dioxygenase/antagonists & inhibitors , 4-Hydroxyphenylpyruvate Dioxygenase/genetics , 4-Hydroxyphenylpyruvate Dioxygenase/chemistry , Plant Weeds/drug effects , Plant Weeds/metabolism , Enzyme Inhibitors/pharmacology , Enzyme Inhibitors/chemistryABSTRACT
Engineering natural microbiomes for biotechnological applications remains challenging, as metabolic interactions within microbiomes are largely unknown, and practical principles and tools for microbiome engineering are still lacking. Here, we present a combinatory top-down and bottom-up framework to engineer natural microbiomes for the construction of function-enhanced synthetic microbiomes. We show that application of herbicide and herbicide-degrader inoculation drives a convergent succession of different natural microbiomes toward functional microbiomes (e.g., enhanced bioremediation of herbicide-contaminated soils). We develop a metabolic modeling pipeline, SuperCC, that can be used to document metabolic interactions within microbiomes and to simulate the performances of different microbiomes. Using SuperCC, we construct bioremediation-enhanced synthetic microbiomes based on 18 keystone species identified from natural microbiomes. Our results highlight the importance of metabolic interactions in shaping microbiome functions and provide practical guidance for engineering natural microbiomes.
Subject(s)
Biodegradation, Environmental , Herbicides , Microbiota , Microbiota/genetics , Herbicides/metabolism , Soil Microbiology , Soil Pollutants/metabolism , Models, Biological , Bacteria/metabolism , Bacteria/genetics , Bacteria/classificationABSTRACT
Mesotrione is a herbicide used in agricultural production; however, its stability and long-term residues pose ecological risks to soil health and subsequent crops. In this research, the strain Amycolatopsis nivea La24 was identified as capable of completely degrading 50 mgâL-1 mesotrione within 48 h. It exhibited a broad adaptability to various environment and could degrade three sulfonylurea herbicides (nicosulfuron, chlorimuron-methyl, and cinosulfuron). Non-target metabonomic and mass spectrometry demonstrated that La24 strain broke down the mesotrione parent molecule by targeting the ß-diketone bond and nitro group, resulting in the production of five possible degradation products. The differentially expressed genes were significantly enriched in fatty acid degradation, amino acid metabolism, and other pathways, and the differentially metabolites in glutathione metabolism, arginine/proline metabolism, cysteine/methionine metabolism, and other pathways. Additionally, it was confirmed by heterologous expression that nitroreductase was directly involved in the mesotrione degradation, and NDMA-dependent methanol dehydrogenase would increase the resistance to mesotrione. Finally, the intracellular response of La24 during mesotrione degradation was proposed. This work provides insight for a comprehensive understanding of the mesotrione biodegradation mechanism, significantly expands the resources for pollutant degradation, and offers the potential for a more sustainable solution to address herbicide pollution in soil.
Subject(s)
Amycolatopsis , Biodegradation, Environmental , Cyclohexanones , Herbicides , Herbicides/metabolism , Herbicides/chemistry , Cyclohexanones/metabolism , Amycolatopsis/metabolism , Amycolatopsis/genetics , Metabolomics , Sulfonylurea Compounds/metabolism , Soil Pollutants/metabolism , MultiomicsABSTRACT
The widely used phenylurea herbicide isoproturon (IPU) and its residues can inhibit the growth of subsequently planted crops. However, reports on bioremediation of IPU-contaminated soil are scarce. In this study, Sphingobium sp. strain YBL2-gfp (a derivative of the IPU-degrading Sphingobium sp. strain YBL2 isolated by our lab) was constructed to bioremediate IPU-contaminated soil. In pot experiments, strain YBL2-gfp colonized the roots of wheat and eliminated IPU residues in the soil within 21 d, effectively alleviating its toxicity and restoring wheat growth. IPU treatment reduced the richness and diversity of soil bacteria, while inoculation YBL2-gfp mainly affected richness with less impact on diversity. The high concentrations of IPU and inoculation of YBL2-gfp alone reduced the soil microbial community connections, while bioaugmentation treatment enhanced the soil microbial community connections. Additionally, strain YBL2-gfp stimulated the metabolic capacity of the indigenous microbes, promoting the degradation of IPU and reducing the negative impact of high concentrations of IPU on microbial community. Taken together, this study offers relatively comprehensive insights into the practical application of bioaugmentation, demonstrating that strain YBL2 has the potential to remediate IPU-contaminated soils.
Subject(s)
Biodegradation, Environmental , Herbicides , Phenylurea Compounds , Soil Microbiology , Soil Pollutants , Sphingomonadaceae , Soil Pollutants/metabolism , Sphingomonadaceae/metabolism , Sphingomonadaceae/genetics , Sphingomonadaceae/growth & development , Herbicides/metabolism , Phenylurea Compounds/metabolism , Triticum/metabolism , Triticum/growth & development , Plant Roots/metabolism , Plant Roots/growth & developmentABSTRACT
Sulfonylurea (SU) herbicides are widely used and often detected in environmental matrices and have toxic effects on ecosystems and plant development. However, the interaction between SU and soil-plant metabolism during the whole wheat growth cycle remains poorly investigated. Field trials demonstrated that bensulfuron methyl exposure reduced wheat height and a thousand grains' weight, disrupting the critical metabolic pathways, including linoleic acid and amino acid metabolism in the maturity stage. During different growth processes, bensulfuron methyl exposure decreases wheat soil and plants' defense-related indole alkaloid compounds, such as benzoxazinoids and melatonin. Microbial sequencing results showed that bensulfuron methyl treated decreased the abundance of beneficial microorganisms (Gammaproteobacteria, Bacteroidia, and Blastocatella) in the rhizosphere soil, which positively correlated with the inhibition of soil enzyme activity and the secretion of allelopathic substances (benzoxazinoids and melatonin). Molecular docking further confirmed that bensulfuron methyl affects protein molecular structure by establishing hydrogen bonds, which disequilibrate wheat benzoxazinoids and melatonin metabolism. Therefore, bensulfuron methyl exposure disrupted the interaction between soil microorganisms and indole alkaloid metabolism, hindering plant development. This study provides constructive insights into the environmental risks of herbicides and agricultural product safety throughout wheat development.
Subject(s)
Herbicides , Soil Microbiology , Sulfonylurea Compounds , Triticum , Triticum/drug effects , Triticum/metabolism , Triticum/growth & development , Sulfonylurea Compounds/toxicity , Sulfonylurea Compounds/metabolism , Herbicides/toxicity , Herbicides/metabolism , Microbiota/drug effects , Soil Pollutants/toxicity , Soil Pollutants/metabolism , Stress, Physiological/drug effects , Metabolic Networks and Pathways/drug effects , Molecular Docking Simulation , RhizosphereABSTRACT
Chlortoluron (CTU) is an herbicide extensively used in agricultural settings for crop cultivation. Its presence in water has been identified as a pollutant detrimental to aquatic species. The objective of the present study was to explore the metabolic activation and hepatotoxicity of CTU. Through human and rat liver microsomal incubations supplemented with CTU, nicotinamide adenine dinucleotide phosphate (NADPH), and either glutathione or N-acetyl cysteine, a benzylic alcohol metabolite (M1) was discerned, alongside a phenol metabolite (M2), a glutathione conjugate (M3), and an N-acetyl cysteine conjugate (M4). In rats exposed to CTU, biliary M3 and urinary M4 were detected in their bile and urine, respectively. The generation of M1 was detected in the presence of NADPH. The observation of M3 and M4 suggests the formation of an iminoquinone methide intermediate arising from the oxidation of M1. CYP3A4 was found to be the principal enzyme catalyzing the metabolic activation of CTU. Furthermore, CTU exhibited cytotoxic properties in cultured rat primary hepatocytes in a concentration-dependent pattern. Concomitant treatment of hepatocytes with ketoconazole mitigated their susceptibility to the cytotoxic effects of CTU.
Subject(s)
Cytochrome P-450 CYP3A , Hepatocytes , Microsomes, Liver , Animals , Rats , Cytochrome P-450 CYP3A/metabolism , Humans , Hepatocytes/drug effects , Hepatocytes/metabolism , Male , Microsomes, Liver/metabolism , Rats, Sprague-Dawley , Activation, Metabolic , Cell Survival/drug effects , Cells, Cultured , Molecular Structure , Herbicides/toxicity , Herbicides/metabolism , Dose-Response Relationship, DrugABSTRACT
Phytoremediation is an environmental safety strategy that might serve as a viable preventative approach to reduce soil contamination in a cost-effective manner. Using plants to remediate pollution from the environment is referred to as phytoremediation. In the past few decades, plants have undergone genetic manipulation to overcome inherent limitations by using genetically modified plants. This review illustrates the eco-friendly process of cleaning the environment using transgenic strategies combined with omics technologies. Herbicides tolerance and phytoremediation abilities have been established in genetically modified plants. Transgenic plants have eliminated the pesticides atrazine and metolachlor from the soil. To expand the application of genetically engineered plants for phytoremediation process, it is essential to test strategies in the field and have contingency planning. Omics techniques were used for understanding various genetic, hormonal, and metabolic pathways responsible for phytoremediation in soil. Transcriptomics and metabolomics provide useful information as resources to understand the mechanisms behind phytoremediation. This review aims to highlight the integration of transgenic strategies and omics technologies to enhance phytoremediation efficiency, emphasizing the need for field testing and comprehensive planning for successful implementation.
Subject(s)
Biodegradation, Environmental , Metabolomics , Plants, Genetically Modified , Plants, Genetically Modified/genetics , Plants, Genetically Modified/growth & development , Plants, Genetically Modified/metabolism , Metabolomics/methods , Soil Pollutants/metabolism , Herbicides/metabolism , Genomics/methodsABSTRACT
This study investigated the multiple herbicide resistance (MHR) mechanism of one Echinochloa crus-galli population that was resistant to florpyrauxifen-benzyl (FPB), cyhalofop-butyl (CHB), and penoxsulam (PEX). This population carried an Ala-122-Asn mutation in the acetolactate synthase (ALS) gene but no mutation in acetyl-CoA carboxylase (ACCase) and transport inhibitor response1 (TIR1) genes. The metabolism rate of PEX was 2-fold higher, and the production of florpyrauxifen-acid and cyhalofop-acid was lower in the resistant population. Malathion and 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) could reverse the resistance, suggesting that cytochrome P450 (CYP450) and glutathione S-transferase (GST) contribute to the enhanced metabolism. According to RNA-seq and qRT-PCR validation, two CYP450 genes (CYP71C42 and CYP71D55), one GST gene (GSTT2), two glycosyltransferase genes (rhamnosyltransferase 1 and IAAGLU), and two ABC transporter genes (ABCG1 and ABCG25) were induced by CHB, FPB, and PEX in the resistant population. This study revealed that the target mutant and enhanced metabolism were involved in the MHR mechanism in E. crus-galli.
Subject(s)
Cytochrome P-450 Enzyme System , Echinochloa , Herbicide Resistance , Herbicides , Mutation , Plant Proteins , Herbicide Resistance/genetics , Herbicides/pharmacology , Herbicides/metabolism , Echinochloa/genetics , Echinochloa/drug effects , Echinochloa/metabolism , Echinochloa/growth & development , Plant Proteins/genetics , Plant Proteins/metabolism , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/metabolism , Acetyl-CoA Carboxylase/genetics , Acetyl-CoA Carboxylase/metabolism , Plant Weeds/drug effects , Plant Weeds/genetics , Plant Weeds/metabolism , Acetolactate Synthase/genetics , Acetolactate Synthase/metabolism , Butanes , Nitriles , Sulfonamides , Uridine/analogs & derivativesABSTRACT
Development of a biotechnological system for rapid degradation of pesticides is important to mitigate the environmental, food security, and health risks that they pose. Degradation of atrazine (ATZ) and isoproturon (IPU) in rice crops promoted by the brassinosteroid (BR) signaling component BRASSINAZOLE RESISTANT4 (OsBZR4) is explored. OsBZR4 is localized in the plasma membrane and nucleus, and is strongly induced by ATZ and IPU exposure. Transgenic rice OsBZR4-overexpression (OE) significantly enhances resistance to ATZ and IPU toxicity, improving growth, and reducing ATZ and IPU accumulation (particularly in grains) in rice crops. Genetic destruction of OsBZR4 (CRISPR/Cas9) increases rice sensitivity and leads to increased accumulation of ATZ and IPU. OE plants promote phase I, II, and III metabolic reactions, and expression of corresponding pesticide degradation genes under ATZ and IPU stress. UPLC-Q-TOF-MS/MS analysis reveals increased relative contents of ATZ and IPU metabolites and conjugates in OE plants, suggesting an increased OsBZR4 expression and consequent detoxification of ATZ and IPU in rice and the environment. The role of OsBZR4 in pesticide degradation is revealed, and its potential application in enhancing plant resistance to pesticides, and facilitating the breakdown of pesticides in rice and the environment, is discussed.
Subject(s)
Atrazine , Brassinosteroids , Oryza , Phenylurea Compounds , Plants, Genetically Modified , Oryza/metabolism , Oryza/genetics , Oryza/drug effects , Oryza/growth & development , Phenylurea Compounds/pharmacology , Phenylurea Compounds/metabolism , Brassinosteroids/metabolism , Atrazine/toxicity , Atrazine/metabolism , Plant Proteins/metabolism , Plant Proteins/genetics , Herbicides/metabolism , Herbicides/toxicity , Biodegradation, Environmental , Signal Transduction/drug effects , Gene Expression Regulation, Plant/drug effectsABSTRACT
Glyphosate is a broad spectrum and non-selective herbicide employed to control different weeds in agricultural and urban zones and to facilitate the harvest of various crops. Currently, glyphosate-based formulations are the most employed herbicides in agriculture worldwide. Extensive use of glyphosate has been related to environmental pollution events and adverse effects on non-target organisms, including humans. Reducing the presence of glyphosate in the environment and its potential adverse effects requires the development of remediation and treatment alternatives. Bioremediation with microorganisms has been proposed as a feasible alternative for treating glyphosate pollution. The present study reports the glyphosate resistance profile and degradation capacity of the bacterial strain Burkholderia cenocepacia CEIB S5-2, isolated from an agricultural field in Morelos-México. According to the agar plates and the liquid media inhibition assays, the bacterial strain can resist glyphosate exposure at high concentrations, 2000 mg·L-1. In the degradation assays, the bacterial strain was capable of fast degrading glyphosate (50 mg·L-1) and the primary degradation metabolite aminomethylphosphonic acid (AMPA) in just eight hours. The analysis of the genomic data of B. cenocepacia CEIB S5-2 revealed the presence of genes that encode enzymes implicated in glyphosate biodegradation through the two metabolic pathways reported, sarcosine and AMPA. This investigation provides novel information about the potential of species of the genus Burkholderia in the degradation of the herbicide glyphosate and its main degradation metabolite (AMPA). Furthermore, the analysis of genomic information allowed us to propose for the first time a metabolic route related to the degradation of glyphosate in this bacterial group. According to the findings of this study, B. cenocepacia CEIB S5-2 displays a great glyphosate biodegradation capability and has the potential to be implemented in glyphosate bioremediation approaches.
Subject(s)
Biodegradation, Environmental , Burkholderia cenocepacia , Glycine , Glyphosate , Herbicides , Glycine/analogs & derivatives , Burkholderia cenocepacia/metabolism , Herbicides/metabolismABSTRACT
Alopecurus aequalis Sobol. is a predominant grass weed in Chinese winter wheat fields, posing a substantial threat to crop production owing to its escalating herbicide resistance. This study documented the initial instance of an A. aequalis population (AHFT-3) manifesting resistance to multiple herbicides targeting four distinct sites: acetyl-CoA carboxylase (ACCase), acetolactate synthase, photosystem II, and 1-deoxy-d-xylulose-5-phosphate synthase. AHFT-3 carried an Asp-to-Gly mutation at codon 2078 of ACCase, with no mutations in the remaining three herbicide target genes, and exhibited no overexpression of any target gene. Compared with the susceptible population AHFY-3, AHFT-3 metabolized mesosulfuron-methyl, isoproturon, and bixlozone faster. The inhibition and comparison of herbicide-detoxifying enzyme activities indicated the participation of cytochrome P450s in the resistance to all four herbicides, with glutathione S-transferases specifically linked to mesosulfuron-methyl. Three CYP72As and a Tau class glutathione S-transferase, markedly upregulated in resistant plants, potentially played pivotal roles in the multiple-herbicide-resistance phenotype.
Subject(s)
Acetyl-CoA Carboxylase , Herbicide Resistance , Herbicides , Plant Proteins , Poaceae , Herbicide Resistance/genetics , Herbicides/pharmacology , Herbicides/metabolism , Plant Proteins/genetics , Plant Proteins/metabolism , Acetyl-CoA Carboxylase/genetics , Acetyl-CoA Carboxylase/metabolism , Poaceae/genetics , Poaceae/metabolism , Poaceae/drug effects , Acetolactate Synthase/genetics , Acetolactate Synthase/metabolism , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/metabolism , Mutation , Plant Weeds/drug effects , Plant Weeds/genetics , Plant Weeds/metabolismABSTRACT
The efficiency of the Fenton reaction is markedly contingent upon the operational pH related to iron solubility. Therefore, a heterogeneous Fenton reaction has been developed to function at neutral pH. In the present study, the Bio-Fenton reaction was carried out using magnetite (Fe(II)Fe(III)2O4) and H2O2 generated by a newly isolated H2O2-producing bacterium, Desemzia sp. strain C1 at pH 6.8 to degrade chloroacetanilide herbicides. The optimal conditions for an efficient Bio-Fenton reaction were 10 mM of lactate, 0.5% (w/v) of magnetite, and resting-cells (O.D.600 = 1) of strain C1. During the Bio-Fenton reaction, 1.8-2.0 mM of H2O2 was generated by strain C1 and promptly consumed by the Fenton reaction with magnetite, maintaining stable pH conditions. Approximately, 40-50% of the herbicides underwent oxidation through non-specific reactions of â¢OH, leading to dealkylation, dechlorination, and hydroxylation via hydrogen atom abstraction. These findings will contribute to advancing the Bio-Fenton system for non-specific oxidative degradation of diverse organic pollutants under in-situ environmental conditions with bacteria producing high amount of H2O2 and magnetite under a neutral pH condition.
Subject(s)
Acetamides , Biodegradation, Environmental , Ferrosoferric Oxide , Herbicides , Hydrogen Peroxide , Iron , Herbicides/metabolism , Herbicides/chemistry , Hydrogen Peroxide/metabolism , Ferrosoferric Oxide/metabolism , Ferrosoferric Oxide/chemistry , Iron/metabolism , Iron/chemistry , Acetamides/metabolism , Acetamides/chemistry , Oxidation-Reduction , Hydrogen-Ion ConcentrationABSTRACT
Quinone analogue molecules, functioning as herbicides, bind to the secondary quinone site, QB, in type-II photosynthetic reaction centers, including those from purple bacteria (PbRC). Here, we investigated the impact of herbicide binding on electron transfer branches, using herbicide-bound PbRC crystal structures and employing the linear Poisson-Boltzmann equation. In contrast to urea and phenolic herbicides [Fufezan, C. Biochemistry 2005, 44, 12780-12789], binding of atrazine and triazine did not cause significant changes in the redox-potential (Em) values of the primary quinone (QA) in these crystal structures. However, a slight Em difference at the bacteriopheophytin in the electron transfer inactive branch (HM) was observed between the S(-)- and R(+)-triazine-bound PbRC structures. This discrepancy is linked to variations in the protonation pattern of the tightly coupled Glu-L212 and Glu-H177 pairs, crucial components of the proton uptake pathway in native PbRC. These findings suggest the existence of a QB-mediated link between the electron transfer inactive HM and the proton uptake pathway in PbRCs.
Subject(s)
Atrazine , Herbicides , Photosynthetic Reaction Center Complex Proteins , Triazines , Herbicides/chemistry , Herbicides/metabolism , Atrazine/chemistry , Atrazine/metabolism , Electron Transport , Triazines/chemistry , Triazines/metabolism , Photosynthetic Reaction Center Complex Proteins/metabolism , Photosynthetic Reaction Center Complex Proteins/chemistry , Oxidation-Reduction , Models, Molecular , Rhodobacter sphaeroides/metabolism , Crystallography, X-RayABSTRACT
Microbial herbicide degradation is an efficient bioremediation method. In this study, a strain of Streptomyces nigra, LM01, which efficiently degrades atrazine and nicosulfuron, was isolated from a corn field using a direct isolation method. The degradation effects of the identified strain on two herbicides were investigated and optimized using an artificial neural network. The maximum degradation rates of S. nigra LM01 were 58.09 % and 42.97 % for atrazine and nicosulfuron, respectively. The degradation rate of atrazine in the soil reached 67.94 % when the concentration was 108 CFU/g after 5 d and was less effective than that of nicosulfuron. Whole genome sequencing of strain LM01 helped elucidate the possible degradation pathways of atrazine and nicosulfuron. The protein sequences of strain LM01 were aligned with the sequences of the degraded proteins of the two herbicides by using the National Center for Biotechnology Information platform. The sequence (GE005358, GE001556, GE004212, GE005218, GE004846, GE002487) with the highest query cover was retained and docked with the small-molecule ligands of the herbicides. The results revealed a binding energy of - 6.23 kcal/mol between GE005358 and the atrazine ligand and - 6.66 kcal/mol between GE002487 and the nicosulfuron ligand.