Biodegradation of chlorimuron-ethyl and the associated degradation pathway by Rhodococcus sp. D310-1

Abstract

Chlorimuron-ethyl is a typical long-term residual sulfonylurea herbicide, and strategies for its removal have attracted increasing attention. Microbial degradation is considered the most acceptable dissipation method. In this study, we optimized the cultivation conditions (substrate concentration, pH, inoculum concentration, and temperature) of the chlorimuron-ethyl-degrading bacterium Rhodococcus sp. D310-1 using response surface methodology (RSM) to improve the biodegradation efficiency. A maximum biodegradation rate of 88.95 % was obtained. The Andrews model was used to describe the changes in the specific degradation rate as the substrate concentration increased. Chlorimuron-ethyl could be transformed with a maximum specific degradation rate (q max), half-saturation constant (K S), and inhibition constant (K i) of 0.4327 day(-1), 63.50045 mg L(-1), and 156.76666 mg L(-1), respectively. Eight biodegradation products (2-amino-4-chloro-6-methoxypyrimidine, ethyl 2-sulfamoyl benzoate, 2-sulfamoyl benzoic acid, o-benzoic sulfimide, 2-[[(4-chloro-6-methoxy-2-pyrimidinyl) carbamoyl] sulfamoyl] benzoic acid, ethyl 2-carbonyl sulfamoyl benzoate, ethyl 2-benzenesulfonyl isocyanate benzoate, and N,N-2(ethyl formate)benzene sulfonylurea) were identified, and three possible degradation pathways were proposed based on the results of high performance liquid chromatography HPLC, liquid chromatography tandem mass spectroscopy (LC-MS/MS), and Fourier transform infrared spectroscopy (FTIR) analyses and the relevant literature. This systematic study is the first to examine the chlorimuron-ethyl degradation pathways of the genus Rhodococcus.

Characterizing the Microbial Consortium L1 Capable of Efficiently Degrading Chlorimuron-Ethyl via Metagenome Combining 16S rDNA Sequencing

“…The six pathways mentioned above involve degradation of the benzene ring structure and chloride, which agrees with previous studies on the degradation of CE via urea bridge cleavage, de-esterification, oxidation, cyclization, and cleavage of the N–C bond of the sulfonylurea bridge and pyrimidine ring (Li et al, 2016 ). In addition, “toluene degradation,” “chlorocyclohexane degradation, ” and “chlorobenzene degradation” were reported to respond to CE in Rhodococcus erythropolis D310-1 (Cheng et al, 2018 ).…”

Bioremediation of Historically Chlorimuron-Ethyl-Contaminated Soil by Co-Culture Chlorimuron-Ethyl-Degrading Bacteria Combined with the Spent Mushroom Substrate

“…D310-5 were isolated from activated sludge samples obtained from a factory producing sulfonylurea herbicides in China and then stored in our laboratory: Rhodococcus sp. D310-1 (GenBank accession number, GU138102.1; the maximum biodegradation efficiency of 88.95% was obtained with a substrate concentration of 100 mg•L −1 , a pH value of 6.0, an inoculum size of 1.94% and a temperature of 28 • C) [17] and Enterobacter sp. D310-5 (GenBank accession number: KU204704; the maximum biodegradation efficiency of 87.6% was obtained with a substrate concentration of 100 mg•L −1 , a pH value of 6.6, an inoculum size of 2.01% and a temperature of 30 • C) [18].…”

“…The chlorimuron-ethyl extraction assay was performed according to Li et al [17], and the detailed information is described in the supplementary material. The samples were filtered through a 0.22-µm millex-gp pes filter for hplc analysis [8].…”

A Novel Pathway of Chlorimuron-Ethyl Biodegradation by Chenggangzhangella methanolivorans Strain CHL1 and Its Molecular Mechanisms

“…Several microorganisms that can degrade chlorimuron-ethyl have been enriched and isolated, and some conceivable pathways for chlorimuron-ethyl degradation have been identified [ 11 , 12 ]. For example, Rhodococcus erythropolis D310-1 has been found to degrade chlorimuron-ethyl through three pathways, the cleavage of the sulfonylurea bridge, the ester bond, and the methoxy group [ 13 ]. Aspergillus flavus , Aspergillus niger , and Saccharomyces cerevisiae F8 can degrade chlorimuron-ethyl by cleaving the sulfonylurea bridge and the ester bond [ 14 ].…”