Kinetics study of nicosulfuron degradation by a Pseudomonas nitroreducens strain NSA02

Effects of herbicide mixtures on the diversity and composition of microbial community and nitrogen cycling function on agricultural soil: A field experiment in Northeast China

Herbicide mixtures application is a widespread and effective practice in modern agriculture; however, a knowledge gap exists regarding the potential ecotoxicological effects of herbicide mixtures in agricultural systems. Here, the effects of various doses of herbicide mixtures (atrazine, nicosulfuron, and mesotrione) under different varieties of maize cultivation on the structure and function of microbial communities and soil chemical parameters were clarified through field experiments. The results showed that the application of herbicide mixtures increased the bacterial and fungal community alpha diversity at jointing and maturity, indicating a prolonged effect of the herbicide mixtures. Moreover, herbicide mixtures alter the composition of bacterial and fungal communities, with sensitive taxa suppressed and herbicide-tolerant taxa enriched. The herbicide mixtures significantly reduced the abundances of Bacillus even at lower doses, but Penicillum was enriched. FAPROTAX analysis and quantitative PCR (qPCR) results showed that herbicide mixtures inhibited the soil nitrogen-cycle process and related genes AOA-amoA, AOB-amoA, and nifH at maize seedling stage. Moreover, network analysis showed that low concentrations of the herbicide mixtures increased bacterial interactions while high concentrations inhibited them, which indicated that the network complexity may be herbicide concentration dependent. A synthetic community (SynCom) consisting of six bacterial strains was established for the biodegradation of the herbicide mixtures based on the analysis of the bacterial network, which resulted in an increase in the degradation efficiency of nicosulfuron by 15.90%. Moreover, potted maize experiment showed that the addition of the SynCom alleviated the toxic effects of herbicide mixtures on the plants. In summary, this study provides a comprehensive perspective for assessing the ecological risk at taxonomic and functional levels and the biodegradation approach of herbicide mixtures residue on agricultural soils in Northeastern China.

Kinetic study on the degradation of Acid Red 88 azo dye in a constructed wetland-microbial fuel cell inoculated with Shewanella oneidensis MR-1

Removal of Acid Red 88 (AR88) as an azo dye from the synthetic type of wastewater was studied in a laboratory-made constructed wetland microbial fuel cell (CW-MFC) inoculated with Shewanella oneidensis MR-1 (SOMR-1). Plant cultivation was implemented using a typical CW plant known as Cyperus alternifolius. The complexity of the SOMR-1 cell membrane having different carriers of electrons and H+ ions gives the microbe special enzymatic ability to participate in the AR88 oxidation link to the O2 reduction. Nernst equation developed based on analyzing the involved redox potential values in these electron exchanges is describable quantitatively in terms of the spontaneity of the catalyzed reaction. Power density (PD) at 100 mg/L of the AR88 under closed-circuit conditions in the presence of the plant was 11.83 mW/m2. Reduction of internal resistance positively affected the PD value. In determining degradation kinetics, two approaches were undertaken: chemically in terms of first- and second-order reactions and biochemically in terms of the mathematical equations for rate determination developed on the basis of substrate inhibitory concept. The first-order rate constant was 0.263 h-1 without plant cultivation and 0.324 h-1 with plant cultivation. The Haldane kinetic model revealed low ks and ki values indicating effective degradation of the AR88. Moreover, the importance of acclimatization in terms of the crucial role of lactate was discussed. These findings suggest that integrating the SOMR-1 electrochemical role with CW-MFC could be a promising approach for the efficient degradation of azo dyes in wastewater treatment.

Removal of chlorimuron-ethyl from the environment: The significance of microbial degradation and its molecular mechanism

Chlorimuron-ethyl is a selective pre- and post-emergence herbicide, which is widely used to control broad-leaved weeds in soybean fields. However, herbicide residues have also increased as a result of the pervasive use of chlorimuron-ethyl, which has become a significant environmental concern. Consequently, the removal of chlorimuron-ethyl residues from the environment has garnered significant attention in recent decades. A variety of technologies have been developed to address this issue, including adsorption, aqueous chlorination, photodegradation, Fenton, photo-Fenton, ozonation, and biodegradation. After extensive studies, the biodegradation of chlorimuron-ethyl by microorganisms has now been recognized as an efficient and environmentally friendly degradation process. As research has progressed, a number of microbial strains associated with chlorimuron-ethyl degradation have been identified, such as Pseudomonas sp., Klebsiella sp., Rhodococcus sp., Stenotrophomonas sp., Aspergillus sp., Hansschlegelia sp., and Enterobacter sp. In addition, the enzymes and genes responsible for chlorimuron-ethyl biodegradation are also being investigated. These degradation genes include sulE, pnbA, carE, gst, Kj-CysJ, Kj-eitD-2267, Kj-kdpD-226, Kj-dxs-398, Kj-mhpC-2096, and Kj-mhpC-2289, among others. The degradation enzymes associated with chlorimuron-ethyl biodegradation includes esterases (SulE, PnbA, and E3), carboxylesterase (CarE), Cytochrome P450, flavin monooxygenase (FMO), and glutathione-S-transferase (GST). Regrettably, few reviews have focused on the microbial degradation and molecular mechanisms of chlorimuron-ethyl. Therefore, this review covers the microbial degradation of chlorimuron-ethyl and its degradation pathways, the molecular mechanism of the microbial degradation of chlorimuron-ethyl, and the outlook on the practical application of the microbial degradation of sulfonylurea herbicides are all covered in this review's overview of previous studies into the degradation of chlorimuron-ethyl.

Enhanced bioremediation of soils contaminated with nicosulfuron using the bacterial complex A12

AIMS

To construct an efficient bacterial complex to degrade nicosulfuron and clarify its degradative characteristics, promote the growth of maize (Zea mays), and provide a theoretical foundation for the efficient remediation of soil contaminated with nicosulfuron.

METHODS AND RESULTS

Biocompatibility was determined by the filter paper sheet method by mixing Serratia marcescens A1 and Bacillus cereus A2 in a 1:1 ratio, yielding A12. The optimum culture conditions for the bacterial composite were obtained based on a three-factor, three-level analysis using response surface methodology, with 29.25 g l-1 for maltodextrin, 10.04 g l-1 for yeast extract, and 19.93 g l-1 for NaCl, which resulted in 92.42% degradation at 4 d. The degradation characteristics of A12 were clarified as follows: temperature 30°C, pH 7, initial concentration of nicosulfuron 20 mg l-1, and 4% inoculum. The ability to promote growth was determined by measuring the ratio of the lysosphere diameter (D) to the colony diameter (d), and the ability of the complex A12 to promote growth was higher than that of the two single strains.

CONCLUSIONS

Nicosulfuron degradation in sterilized and unsterilized soils reached 85.4% and 91.2% within 28 d, respectively. The ability of the strains to colonize the soil was determined by extraction of total soil DNA, primer design, and gel electrophoresis. The bioremediation effect of A12 was confirmed by the maximum recovery of fresh weight (124.35%) of nicosulfuron-sensitive crop plants and the significant recovery of soil enzyme activities, as measured by the physiological indices in the sensitive plants.

Herbicide Safeners: From Molecular Structure Design to Safener Activity

Herbicide safeners, highly effective antidotes, find widespread application in fields for alleviating the phytotoxicity of herbicides to crops. Designing new herbicide safeners remains a notable issue in pesticide research. This review focuses on discussing and summarizing the structure-activity relationships, molecular structures, physicochemical properties, and molecular docking of herbicide safeners in order to explore how different structures affect the safener activities of target compounds. It also provides insights into the application prospects of computer-aided drug design for designing and synthesizing new safeners in the future.

Occurrence, ecological risk, and advanced removal methods of herbicides in waters: a timely review

Coastal pollution caused by the importation of agricultural herbicides is one of the main environmental problems that directly affect the coastal primary productivity and even the safety of human seafood. It is urgent to evaluate the ecological risk objectively and explore feasible removal strategies. However, existing studies focus on the runoff distribution and risk assessment of specific herbicides in specific areas, and compared with soil environment, there are few studies on remediation methods for water environment. Therefore, we systematically reviewed the current situation of herbicide pollution in global coastal waters and the dose-response relationships of various herbicides on phytoplankton and higher trophic organisms from the perspective of ecological risks. In addition, we believe that compared with the traditional single physical and chemical remediation methods, biological remediation and its combined technology are the most promising methods for herbicide pollution remediation currently. Therefore, we focus on the application prospects, challenges, and management strategies of new bioremediation systems related to biology, such as constructed wetlands, membrane bioreactor processes, and microbial co-metabolism, in order to provide more advanced methods for reducing herbicide pollution in the water environment.

Microbial degradation as a powerful weapon in the removal of sulfonylurea herbicides

Sulfonylurea herbicides have been widely used worldwide and play a significant role in modern agricultural production. However, these herbicides have adverse biological effects that can damage the ecosystems and harm human health. As such, rapid and effective techniques that remove sulfonylurea residues from the environment are urgently required. Attempts have been made to remove sulfonylurea residues from environment using various techniques such as incineration, adsorption, photolysis, ozonation, and microbial degradation. Among them, biodegradation is regarded as a practical and environmentally responsible way to eliminate pesticide residues. Microbial strains such as Talaromyces flavus LZM1, Methylopila sp. SD-1, Ochrobactrum sp. ZWS16, Staphylococcus cohnii ZWS13, Enterobacter ludwigii sp. CE-1, Phlebia sp. 606, and Bacillus subtilis LXL-7 can almost completely degrade sulfonylureas. The degradation mechanism of the strains is such that sulfonylureas can be catalyzed by bridge hydrolysis to produce sulfonamides and heterocyclic compounds, which deactivate sulfonylureas. The molecular mechanisms associated with microbial degradation of sulfonylureas are relatively poorly studied, with hydrolase, oxidase, dehydrogenase and esterase currently known to play a pivotal role in the catabolic pathways of sulfonylureas. Till date, there are no reports specifically on the microbial degrading species and biochemical mechanisms of sulfonylureas. Hence, in this article, the degradation strains, metabolic pathways, and biochemical mechanisms of sulfonylurea biodegradation, along with its toxic effects on aquatic and terrestrial animals, are discussed in depth in order to provide new ideas for remediation of soil and sediments polluted by sulfonylurea herbicides.

Current insights into the microbial degradation of nicosulfuron: Strains, metabolic pathways, and molecular mechanisms

Nicosulfuron is among the sulfonylurea herbicides that are widely used to control annual and perennial grass weeds in cornfields. However, nicosulfuron residues in the environment are likely to cause long-lasting harmful environmental and biological effects. Nicosulfuron degrades via photo-degradation, chemical hydrolysis, and microbial degradation. The latter is crucial for pesticide degradation and has become an essential strategy to remove nicosulfuron residues from the environment. Most previous studies have focused on the screening, degradation characteristics, and degradation pathways of biodegrader microorganisms. The isolated nicosulfuron-degrading strains include Bacillus, Pseudomonas, Klebsiella, Alcaligenes, Rhodopseudomonas, Ochrobactrum, Micrococcus, Serratia, Penicillium, Aspergillus, among others, all of which have good degradation efficiency. Two main intermediates, 2-amino-4,6-dimethoxypyrimidine (ADMP) and 2-aminosulfonyl-N,N-dimethylnicotinamide (ASDM), are produced during microbial degradation and are derived from the C-N, C-S, and S-N bond breaks on the sulfonylurea bridge, covering almost every bacterial degradation pathway. In addition, enzymes related to the degradation of nicosulfuron have been identified successively, including the manganese ABC transporter (hydrolase), Flavin-containing monooxygenase (oxidase), and E3 (esterase). Further in-depth studies based on molecular biology and genetics are needed to elaborate on their role in the evolution of novel catabolic pathways and the microbial degradation of nicosulfuron. To date, few reviews have focused on the microbial degradation and degradation mechanisms of nicosulfuron. This review summarizes recent advances in nicosulfuron degradation and comprehensively discusses the potential of nicosulfuron-degrading microorganisms for bioremediating contaminated environments, providing a reference for further research development on nicosulfuron biodegradation in the future.

Effects of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.)

The sulfonylurea herbicide nicosulfuron is efficient, harmless and selective at low doses and has been widely used in maize cultivation. In this study, a pair of corn sister lines, HK301 (nicosulfuron-tolerence, NT) and HK320 (nicosulfuron-sensitive, NS), was chosen to study the effect of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.) seedlings. All the experimental samples were subjected to treatment with water or 80 mg kg^–1 of nicosulfuron when the sweet maize seedlings grew to the four-leaf stage. Nicosulfuron significantly inhibited the growth of NS line. The content of sucrose and the activities of sucrose phosphate synthase and sucrose synthase in the two inbred lines increased differentially under nicosulfuron stress compared with the respective control treatment. After nicosulfuron treatment, the activities of hexokinase and 6-phosphofructokinase and the contents of pyruvic acid and citric acid in NS line decreased significantly compared with those of NT line, while the content of sucrose and activities of sucrose phosphate synthase and sucrose synthase increased significantly. The disruption of sugar metabolism in NS line led to a lower supply of energy for growth. This study showed that the glycolysis pathway and the tricarboxylic acid cycle were enhanced in nicosulfuron-tolerant line under nicosulfuron stress in enhancing the adaptability of sweet maize.

Transcriptomic response of Pseudomonas nicosulfuronedens LAM1902 to the sulfonylurea herbicide nicosulfuron

The overuse of the herbicide nicosulfuron has become a global environmental concern. As a potential bioremediation technology, the microbial degradation of nicosulfuron shows much promise; however, the mechanism by which microorganisms respond to nicosulfuron exposure requires further study. An isolated soil-borne bacteria Pseudomonas nicosulfuronedens LAM1902 displaying nicosulfuron, chlorimuron-ethyl, and cinosulfuron degradabilities in the presence of glucose, was used to determine the transcriptional responses to nicosulfuron exposure. RNA-Seq results indicated that 1102 differentially expressed genes (DEGs) were up-regulated and 702 down-regulated under nicosulfuron stress. DEGs were significantly enriched in “ABC transporters”, “sulfur metabolism”, and “ribosome” pathways (p ≤ 0.05). Several pathways (glycolysis and pentose phosphate pathways, a two-component regulation system, as well as in bacterial chemotaxis metabolisms) were affected by nicosulfuron exposure. Surprisingly, nicosulfuron exposure showed positive effects on the production of oxalic acid that is synthesized by genes encoding glycolate oxidase through the glyoxylate cycle pathway. The results suggest that P. nicosulfuronedens LAM1902 adopt acid metabolites production strategies in response to nicosulfuron, with concomitant nicosulfuron degradation. Data indicates that glucose metabolism is required during the degradation and adaptation of strain LAM1902 to nicosulfuron stress. The present studies provide a glimpse at the molecular response of microorganisms to sulfonylurea pesticide toxicity and a potential framework for future mechanistic studies.

Exploration of the Quorum-Quenching Mechanism in Pseudomonas nitroreducens W-7 and Its Potential to Attenuate the Virulence of Dickeya zeae EC1

Quorum quenching (QQ) is a novel, promising strategy that opens up a new perspective for controlling quorum-sensing (QS)-mediated bacterial pathogens. QQ is performed by interfering with population-sensing systems, such as by the inhibition of signal synthesis, catalysis of degrading enzymes, and modification of signals. In many Gram-negative pathogenic bacteria, a class of chemically conserved signaling molecules named N-acyl homoserine lactones (AHLs) have been widely studied. AHLs are involved in the modulation of virulence factors in various bacterial pathogens including Dickeya zeae. Dickeya zeae is the causal agent of plant-rot disease of bananas, rice, maize, potatoes, etc., causing enormous economic losses of crops. In this study, a highly efficient AHL-degrading bacterial strain W-7 was isolated from activated-sludge samples and identified as Pseudomonas nitroreducens. Strain W-7 revealed a superior ability to degrade N-(3-oxododecanoyl)-l-homoserine lactone (OdDHL) and completely degraded 0.2 mmol/L of OdDHL within 48 h. Gas chromatography-mass spectrometry (GC-MS) identified N-cyclohexyl-propanamide as the main intermediate metabolite during AHL biodegradation. A metabolic pathway for AHL in strain W-7 was proposed based on the chemical structure of AHL and intermediate products. In addition to the degradation of OdDHL, this strain was also found to be capable of degrading a wide range of AHLs including N-(3-oxohexanoyl)-l-homoserine lactone (OHHL), N-(3-oxooctanoyl)-l-homoserine lactone (OOHL), and N-hexanoyl-l-homoserine lactone (HHL). Moreover, the application of strain W-7 as a biocontrol agent could substantially attenuate the soft rot caused by D. zeae EC1 to suppress tissue maceration in various host plants. Similarly, the application of crude enzymes of strain W-7 significantly reduced the disease incidence and severity in host plants. These original findings unveil the biochemical aspects of a highly efficient AHL-degrading bacterial isolate and provide useful agents that exhibit great potential for the control of infectious diseases caused by AHL-dependent bacterial pathogens.

Protective efficacy of phenoxyacetyl oxazolidine derivatives as safeners against nicosulfuron toxicity in maize

BACKGROUND

Herbicide safeners mitigate crop damage without reducing herbicide efficacy. Here, the protective effects of phenoxyacetyl oxazolidine derivatives as potential safeners were evaluated with a view toward reducing injury caused by sulfonylurea herbicide nicosulfuron to sensitive maize varieties.

RESULTS

Growth indices demonstrated that the bioactivity of compound 9 (N-phenoxyacety-2-methyl-2,4-diethyl-1,3-oxazolidine) was superior to that of R-28725 and all other compounds tested. Compound 9 induced endogenous glutathione and upregulated glutathione-S-transferase (GST) in maize. Thus, it could enhance maize tolerance to nicosulfuron. Compared with the untreated water control group, the maximum reaction rate of GST was increased by 37.62%, while the maximum velocity of GST was decreased by 61.93% after treatment with compound 9. Acetolactate synthase relative activity was significantly enhanced in the case of treatment with compound 9, indicating the excellent protective effects of compound 9 against nicosulfuron in maize.

CONCLUSIONS

The present work demonstrates that phenoxyacetyl oxazolidine derivatives are potentially efficacious as herbicide safeners and merit further investigation.

Biotransformation of the herbicide nicosulfuron residues in soil and seven sulfonylurea herbicides by Bacillus subtilis YB1: A climate chamber study

Bacillus subtilis YB1 is a strain that can efficiently transform nicosulfuron. In order to study its remediation ability and effects on other microorganisms in the soil, indoor biological remediation experiments and rhizosphere microbial diversity analysis were performed. B. subtilis YB1 granules were prepared and applied to the nicosulfuron contaminated soil. The concentration of nicosulfuron was detected by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and changes in the physiological indicators of wheat were measured. At the same time, the changes in the rhizosphere soil microbial diversity were determined by 16S RNA sequencing. Results showed that the YB1 granules made a contribution to the transformation of nicosulfuron (0.05 mg kg^-1) in the soil within 55 days. The physiological indicators of wheat also showed consistent result about nicosulfuron transformation. Rhizosphere soil microbial diversity results indicated the relative abundance of Firmicutes decreased (3.0%-0.35%) and Acidobacteria first decreased (25.82%-22.38%) and then increased (22.3%-26.1%) with nicosulfuron added (N group). The relative abundance of Acidobacteria first decreased (25.8%-15.3%) and then increased (15.3%-21.7%) while Proteobacteria increased (26.5%-38.08%). At the same time, Firmicutes first increased (2.6%-12.3%) and then decreased to original level (12.3%-0.7%) in the N group with YB1 granules (NYB1 group). Members of the genus Bacillus initially increased and then decreased to the original level as the Control group, therefore, they did not become dominant in the rhizosphere soil. Alpha diversity analyses showed no obvious differences in species diversity among the N, NYB1 and Control groups. So YB1 did not have obvious influence on the rhizosphere microbial community structure during nicosulfuron transformation, which only had some effect on species abundance. This study revealed the successful indoor bioremediation of nicosulfuron in the soil, providing a potential strategy for solving the problem of nicosulfuron contamination.

Design, Synthesis, and Biological Activity of Novel Diazabicyclo Derivatives as Safeners

Herbicide safeners selectively protect crops from herbicide damage without reducing the herbicidal efficiency on target weed species. The title compounds were designed by the intermediate derivatization approach and fragment splicing to exploit novel potential safeners. A total of 31 novel diazabicyclo derivatives were synthesized by the microwave-assistant method using isoxazole-4-carbonyl chloride and diazabicyclo derivatives. All synthetic compounds were confirmed by infrared, ¹H and ¹³C nuclear magnetic resonance, and high-resolution mass spectrometry. The bioassay results demonstrated that most of the title compounds could reduce the nicosulfuron phytotoxicity on maize. The glutathione S-transferase (GST) activity in vivo was assayed, and compound 4(S15) revealed an inspiring safener activity comparable to commercialized safeners isoxadifen-ethyl and BAS-145138. The molecular docking model exhibited that the competition at the active sites of target enzymes between compound 4(S15) and nicosulfuron was investigated with respect to herbicide detoxification. The current work not only provided a powerful supplement to the intermediate derivatization approach and fragment splicing in design pesticide bioactive molecules but also assisted safener development and optimization.

Pathway and kinetics of malachite green biodegradation by Pseudomonas veronii

Malachite green is a common environmental pollutant that poses a great threat to non-target organisms, including humans. This study reports the characterization of a bacterial strain, Pseudomonas veronii JW3-6, which was isolated from a malachite green enrichment culture. This strain degraded malachite green efficiently in a wide range of temperature and pH levels. Under optimal degradation conditions (32.4 °C, pH 7.1, and inoculum amount of 2.5 × 10⁷ cfu/mL), P. veronii JW3-6 could degrade 93.5% of 50 mg/L malachite green within seven days. Five intermediate products from the degradation of malachite green were identified: leucomalachite green, 4-(dimethylamino) benzophenone, 4-dimethylaminophenol, benzaldehyde, and hydroquinone. We propose a possible degradation pathway based on these findings. The present study is the first to report the degradation of malachite green by P. veronii and the identification of hydroquinone as a metabolite in the degradation pathway.

Insight into the Characteristics and New Mechanism of Nicosulfuron Biodegradation by a Pseudomonas sp. LAM1902

A total of five strains of nicosulfuron-degrading bacteria were isolated from a continuously cultivated microbial consortium using culturomics. Among them, a novel Pseudomonas strain, LAM1902, with the highest degradation efficiency was investigated in detail. The characteristics of nicosulfuron-degradation by LAM1902 were investigated and optimized by response surface analysis. Furthermore, non-targeted metabolomic analysis of extracellular and intracellular biodegradation of nicosulfuron by LAM1902 was carried out by liquid chromatography/mass spectroscopy (LC-MS) and gas chromatography-time-of-flight/mass spectroscopy (GC-TOF/MS). It was found that nicosulfuron was degraded by LAM1902 mainly via breaking the sulfonylurea bridge, and this degradation might be attributed to oxalate accumulation. The results of GC-TOF/MS also showed that the intracellular degradation of nicosulfuron did not occur. However, nicosulfuron exerted a significant influence on the metabolism of inositol phosphate, pyrimidine, arginine/proline, glyoxylate, and dicarboxylate metabolism and streptomycin biosynthesis. The changes of myo-inositol, trehalose, and 3-aminoisobutanoic acid were proposed as a mechanism of self-protection against nicosulfuron stress.

Temperature and pH sensitive composite for rapid and effective removal of sulfonylurea herbicides in aqueous solution

Excessive pesticide residues in the environment have caused more and more serious social problems. In this article, the polymer materials and graphene oxide were smoothly grafted together through surface-initiated atom-transfer radical polymerization. A temperature and pH dual-sensitive adsorbent was successfully obtained, which was used for the removal of six sulfonylurea herbicides in the aquatic environment. Experiment results showed that the adsorbent could efficiently remove the tested pesticides in aqueous solution rapidly (only 1 min). The adsorption process was in consist with the pseudo-second-order kinetics equation and Freundlich model, and the thermodynamic parameters were also calculated. Furthermore, the mechanism for removal performance was judged as n-π, π-π, hydrogen bonding, hydrophobic and electrostatic interaction verdict. Exhilaratingly, the material showed no significant toxicity to Daphnia magna on risk assessment.

Polymorphism and molecular conformations of nicosulfuron: structure, properties and desolvation process

Nine solid forms of nicosulfuron were found for the first time and their structures and properties were studied in detail.

Nicosulfuron Degradation by an Ascomycete Fungus Isolated From Submerged Alnus Leaf Litter

Nicosulfuron is a selective herbicide belonging to the sulfonylurea family, commonly applied on maize crops. Its worldwide use results in widespread presence as a contaminant in surface streams and ground-waters. In this study, we isolated, for the first time, the Plectosphaerella cucumerina AR1 nicosulfuron-degrading fungal strain, a new record from Alnus leaf litter submerged in freshwater. The degradation of nicosulfuron by P. cucumerina AR1 was achieved by a co-metabolism process and followed a first-order model dissipation. Biodegradation kinetics analysis indicated that, in planktonic lifestyle, nicosulfuron degradation by this strain was glucose concentration dependent, with a maximum specific degradation rate of 1 g/L in glucose. When grown on natural substrata (leaf or wood) as the sole carbon sources, the Plectosphaerella cucumerina AR1 developed as a well-established biofilm in 10 days. After addition of nicosulfuron in the medium, the biofilms became thicker, with rising mycelium, after 10 days for leaves and 21 days for wood. Similar biofilm development was observed in the absence of herbicide. These fungal biofilms still conserve the nicosulfuron degradation capacity, using the same pathway as that observed with planktonic lifestyle as evidenced by LC-MS analyses. This pathway involved first the hydrolysis of the nicosulfuron sulfonylurea bridge, leading to the production of two major metabolites: 2-amino-4,6-dimethoxypyrimidine (ADMP) and 2-(aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide (ASDM). One minor metabolite, identified as 2-(1-(4,6-dimethoxy-pyrimidin-2-yl)-ureido)-N,N-dimethyl-nicotinamide (N3), derived from the cleavage of the C-S bond of the sulfonylurea bridge and contraction by elimination of sulfur dioxide. A last metabolite (N4), detected in trace amount, was assigned to 2-(4,6-dimethoxy-pyrimidin-2-yl)-N,N-dimethyl-nicotinamide (N4), resulting from the hydrolysis of the N3 urea function. Although fungal growth was unaffected by nicosulfuron, its laccase activity was significantly impaired regardless of lifestyle. Leaf and wood surfaces being good substrata for biofilm development in rivers, P. cucumerina AR1 strain could thus have potential as an efficient candidate for the development of methods aiming to reduce contamination by nicosulfuron in aquatic environments.