APPLIED AND ENVIRONMENTAL MICROBIOLOGY
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2017
·Vol. 83
·期 23
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IF 3.807
Cui-Wei Chu,Bin Liu,Na Li,Shi-Gang Yao,Dan Cheng,Jia-Dong Zhao,Ji-Guo Qiu,Xin Yan,Qin He,Jian He
Thiobencarb is a thiocarbamate herbicide used in rice paddies worldwide. Microbial degradation plays a crucial role in the dissipation of thiobencarb in the environment. However, the physiological and genetic mechanisms underlying thiobencarb degradation remain unknown. In this study, a novel thiobencarb degradation pathway was proposed in Acidovorax sp. strain T1. Thiobencarb was oxidized and cleaved at the C—S bond, generating diethylcarbamothioic S-acid and 4-chlorobenzaldehyde (4CDA). 4CDA was then oxidized to 4-chlorobenzoic acid (4CBA) and hydrolytically dechlorinated to 4-hydroxybenzoic acid (4HBA). The identification of catabolic genes suggested further hydroxylation to protocatechuic acid (PCA) and finally degradation through the protocatechuate 4,5-dioxygenase pathway. A novel two-component monooxygenase system identified in the strain, TmoAB, was responsible for the initial catabolic reaction. TmoA shared 28 to 32% identity with the oxygenase components of pyrimidine monooxygenase from Agrobacterium fabrum, alkanesulfonate monooxygenase from Pseudomonas savastanoi, and dibenzothiophene monooxygenase from Rhodococcus sp. TmoB shared 25 to 37% identity with reported flavin reductases and oxidized NADH but not NADPH. TmoAB is a flavin mononucleotide (FMN)-dependent monooxygenase and catalyzed the C—S bond cleavage of thiobencarb. Introduction of tmoAB into cells of the thiobencarb degradation-deficient mutant T1m restored its ability to degrade and utilize thiobencarb. A dehydrogenase gene, tmoC, was located 7,129 bp downstream of tmoAB, and its transcription was clearly induced by thiobencarb. The purified TmoC catalyzed the dehydrogenation of 4CDA to 4CBA using NAD+ as a cofactor. A gene cluster responsible for the complete 4CBA metabolic pathway was also cloned, and its involvement in thiobencarb degradation was preliminarily verified by transcriptional analysis.IMPORTANCE Microbial degradation is the main factor in thiobencarb dissipation in soil. In previous studies, thiobencarb was degraded initially via N-deethylation, sulfoxidation, hydroxylation, and dechlorination. However, enzymes and genes involved in the microbial degradation of thiobencarb have not been studied. This study revealed a new thiobencarb degradation pathway in Acidovorax sp. strain T1 and identified a novel two-component FMN-dependent monooxygenase system, TmoAB. Under TmoAB-mediated catalysis, thiobencarb was cleaved at the C—S bond, producing diethylcarbamothioic S-acid and 4CDA. Furthermore, the downstream degradation pathway of thiobencarb was proposed. Our study provides the physiological, biochemical, and genetic foundation of thiobencarb degradation in this microorganism.
研究领域:
环境微生物学
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分子生物学
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生物化学
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DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2025
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IF 11.3
Minmin Zhang,Chenyan Liao,Zhonghuai Zhang,Lichao Lu,Jianmeng Chen,Dongzhi Chen
Chlorobenzene (CB) biodegradation is challenging due to its hydrophobic characteristics. Addition of silicone oil and surfactants are commonly used methods to enhance biodegradation efficiency by improve CB gas-liquid mass transfer efficiency. However, both approaches introduced new chemicals into the reactor, either as carbon sources for microorganisms or requiring regeneration. This study established a synergistic reactor by applying micro-nano bubbles (MNBs) with biodegradation process in a stirred tank bioreactor (STB) to purify CB waste gas. Experimental results demonstrate a reduction in start-up time by 2 days and a 13.5 % increase in overall degradation rate in synergistic reactor. The mass transfer fraction of CB ( β * s ) was increased by 13.33 %. Additionally, the synergistic reactor showed improved system stability and microbial activity, evidenced by the increased Zeta potential, extracellular polymer substances (EPS) secretion, and protein content. Notably, MNBs upregulate genes involved in aromatic ring hydroxylation and dehalogenation processes and promoted the enzyme SCACT (EC2.8.3.18) within the genus Acidovorax , which enhanced intracellular coenzyme A activity and facilitated chlorobenzene degradation in this genus, thereby enhancing CB degradation efficiency. These results indicate that MNBs can significantly improve the biodegradation performance of CB waste gas, offering a promising strategy for industrial applications.
研究领域:
环境科学
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微生物学
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DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
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2025
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IF 7.2
Kuo Liu,Yulin Wu,Lining Zheng,Xian Wu,Hao Zhang
Microbial remediation is an eco-friendly and cost-effective approach to mitigate the environmental risks caused by fomesafen (FSA) and lead (Pb). In this study, a novel strain, Acidovorax temporans LK1, was isolated and demonstrated the ability to degrade 97.5 % of FSA within 2 d. Strain LK1 achieved simultaneous removal rates of 68.6 % for FSA and 38.4 % for Pb within 48 h. The effectiveness of strain LK1 in addressing FSA and Pb co-contamination was further validated by flow cytometry and energy-dispersive spectroscopy (EDS). Analysis of the degradation products revealed potential FSA degradation pathways, including nitro reduction, S-N bond cleavage, C-N bond cleavage, and ether bond cleavage. Over 21 d, strain LK1 removed more than 70 % of FSA and 40 % of Pb from the soil, significantly reducing the combined pollution stress on sweet corn and demonstrating its high efficacy under real-world conditions. Metabolomic analysis revealed that strain LK1 employed a series of metabolic reactions to maintain the intracellular metabolic balance, enabling efficient FSA degradation. These findings highlight the significant potential of strain LK1 for bioremediation, offering a novel solution for addressing the agricultural challenges associated with FSA and Pb co-contamination.
研究领域:
环境微生物学
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污染生态学
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生物修复
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环境毒理学
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分子生态学
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产品关联
DOI
高影响因子
MICROCHEMICAL JOURNAL
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2024
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IF 4.9
Chentao Li,Yafang Wu,Haijuan Zeng,Yinglin Wang,Ying Yu,Jinlong Jiao,Dezhi Li,Qing Liu
The presence of Acidovorax citrulli (Ac), the etiological agent responsible for bacterial fruit blotch (BFB), exerts a profound impact on the growth and development of cucurbit plants. Therefore, it is imperative to promptly detect Ac to effectively mitigate the widespread dissemination of this disease among cucurbit crops. The present study describes the development of a novel label-free immunochromatographic strip (ICTS) sensor for the detection of Ac in cucurbit samples. This was achieved by utilizing 4’,4’’’,4’’’’’,4’’’’’’’-(ethene-1,1,2,2-tetrayl) tetrabiphenyl-4-carboxylic acid (TCBPE) carboxyl activation product (CA-TCBPE) as a fluorescent probe. The CA-TCBPE@Ac complex is captured at the detection site through the immobilization of a monoclonal antibody monoclonal antibody (mAb) targeting Ac in this sensor. Under the excitation of 365 nm ultraviolet (UV) light, the detection of Ac in the concentration range of 10 5 -10 8 CFU/mL was successfully achieved, with a visual detection limit of 10 5 CFU/mL. The accuracy of the sensor was further validated through experimentation with real samples, including watermelon, cantaloupe, cucumber, and zucchini. This study presents the pioneering development of a label-free ICTS sensor, utilizing TCBPE material markers, for rapid and sensitive detection of Ac. This innovative approach offers a robust solution for the swift detecting of Ac in cucurbits and other samples, thereby holding great promise for future applications.
研究领域:
植物病理学
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农业生物技术
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分析化学
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分子生物学
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产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2021
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IF 9.028
Mengyuan Qi,Bin Liang,Long Zhang,Xiaodan Ma,Lei Yan,Wenchen Dong,Deyong Kong,Liying Zhang,Haizhen Zhu,Shu-Hong Gao,Jiandong Jiang,Shuang-Jiang Liu,Philippe F.-X. Corvini,Aijie Wang
Microbial communities are believed to outperform monocultures in the complete catabolism of organic pollutants via reduced metabolic burden and increased robustness to environmental challenges; however, the interaction mechanism in functional microbiomes remains poorly understood. Here, three functionally differentiated activated sludge microbiomes (S1: complete catabolism of sulfamethoxazole (SMX); S2: complete catabolism of the phenyl part of SMX ([phenyl]-SMX) with stable accumulation of its heterocyclic product 3-amino-5-methylisoxazole (3A5MI); A: complete catabolism of 3A5MI rather than [phenyl]-SMX) were enriched. Combining time-series cultivation-independent microbial community analysis, DNA-stable isotope probing, molecular ecological network analysis, and cultivation-dependent function verification, we identified key players involved in the SMX degradation process. Paenarthrobacter and Nocardioides were primary degraders for the initial cleavage of the sulfonamide functional group (−C–S–N– bond) and 3A5MI degradation, respectively. Complete catabolism of SMX was achieved by their cross-feeding. The co-culture of Nocardioides, Acidovorax, and Sphingobium demonstrated that the nondegraders Acidovorax and Sphingobium were involved in the enhancement of 3A5MI degradation. Moreover, we unraveled the internal labor division patterns and connections among the active members centered on the two primary degraders. Overall, the proposed methodology is promisingly applicable and would help generate mechanistic, predictive, and operational understanding of the collaborative biodegradation of various contaminants. This study provides useful information for synthetic activated sludge microbiomes with optimized environmental functions.
研究领域:
环境微生物学
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生物修复
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生态学
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微生物生态学
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产品关联
DOI
PubMed
高影响因子
BIOTECHNOLOGY LETTERS
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2021
·Vol. 43
·期 8
·1617-1624
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IF 2.461
Wang Liuzhu,Jiang Shuiqin,Sun Yangyang,Yang Zeyu,Chen Zhi,Wang Hualei,Wei Dongzhi
Objectives Catalytic promiscuity, or the ability to catalyze a secondary reaction, provides new opportunities for industrial biocatalysis by expanding the range of biocatalytic reactions. Some nitrilases converting nitriles to amides, referred to as the secondary activity, show great potential for amides production. And our goal was exploiting the amide-forming potential of nitrilases. Results In this study, we characterized and altered the secondary activity of nitrilase from Acidovorax facilis 72 W (Nit72W) towards different substrates. We increased the secondary activity of Nit72W towards 2-cyanopyridine by 196-fold and created activity toward benzonitrile and p-nitrophenylacetonitrile by modifying the active pocket. Surprisingly, the best mutant, W188M, completely converted 250 mM 2-cyanopyridine to more than 98% 2-picolinamide in 12 h with a specific activity of 90 U/mg and showed potential for industrial applications. Conclusions Nit72W was modified to increase its secondary activity for the amides production, especially 2-picolinamide.
研究领域:
生物化学
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工业生物技术
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DOI
PubMed
高影响因子
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