BIODEGRADATION
·
2017
·Vol. 29
·期 1
·1-10
·
IF 2.018
Wang Hui,Hu Jinxing,Xu Kai,Tang Xianjin,Xu Xinhua,Shen Chaofeng
Two biphenyl-degrading bacterial strains, SS1 and SS2, were isolated from polychlorinated biphenyl (PCB)-contaminated soil. They were identified as Rhodococcus ruber and Rhodococcus pyridinivorans based on the 16S rRNA gene sequence, as well as morphological, physiological and biochemical characteristics. SS1 and SS2 exhibited tolerance to 2000 and 3000 mg/L of biphenyl. And they could degrade 83.2 and 71.5% of 1300 mg/L biphenyl within 84 h, respectively. In the case of low-chlorinated PCB congeners, benzoate and 3-chlorobenzoate, the degradation activities of SS1 and SS2 were also significant. In addition, these two strains exhibited chemotactic response toward TCA-cycle intermediates, benzoate, biphenyl and 2-chlorobenzoate. This study indicated that, like the flagellated bacteria, non-flagellated Rhodococcus spp. might actively seek substrates through the process of chemotaxis once the substrates are depleted in their surroundings. Together, these data provide supporting evidence that SS1 and SS2 might be good candidates for restoring biphenyl/PCB-polluted environments.
研究领域:
环境微生物学
·
生物修复
·
微生物生态学
·
趋化性
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2023
·
IF 8.3
Ni-Hong Yao,Ya-Nan Du,Jia-Xi Xiong,Ying Xiao,Hang-Hang He,Ze-Feng Xie,Duo Huang,Qi Song,Jing Chen,Dazhong Yan,Hong-Jun Chao
The compound 3,5-xylenol is an essential precursor used in pesticides and industrial intermediate in the disinfectants and preservatives industry. Its widespread application makes it an important source of pollution. Microbial bioremediation is more environmentally friendly than the physicochemical treatment process for removing alkylphenols from a polluted environment. However, the 3,5-xylenol-degrading bacteria is unavailable, and its degradation mechanism remains unclear. Here, a 3,5-xylenol-metabolizing bacterial strain, designated Rhodococcus sp. CHJ602, was isolated using 3,5-xylenol as the sole source of carbon and energy from a wastewater treatment factory. Results showed that strain CHJ602 maintained a high 3,5-xylenol-degrading performance under the conditions of 30.15 °C and pH 7.37. The pathway involved in 3,5-xylenol degradation by strain CHJ602 must be induced by 3,5-xylenol. Based on the identification of intermediate metabolites and enzyme activities , this bacterium could oxidize 3,5-xylenol by a novel metabolic pathway. One methyl oxidation converted 3,5-xylenol to 3-hydroxymethyl-5-methylphenol, 3-hydroxy-5-methyl benzaldehyde, and 3-hydroxy-5-methylbenzoate. After that, another methyl oxidation is converted to 5-hydroxyisophthalicate, which is metabolized by the protocatechuate pathway. It is catalyzed by a series of enzymes in strain CHJ602. In addition, toxicity bioassay result indicates that 3,5-xylenol is toxic to zebrafish and Rhodococcus sp. CHJ602 could eliminate 3,5-xylenol in water to protect zebrafish from its toxicity. The results provide insights into the bioremediation of wastewater contaminated 3,5-xylenol.
研究领域:
环境科学
·
微生物学
✓ 已验证
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2023
·
IF 8.8
Xiaoyuan Guo,Lan Qiu,Zhiwei Liang,Qihong Lu,Shanquan Wang,Hojae Shim
The coronavirus disease 2019 (COVID-19) pandemic has significantly increased the demand of disinfectant use. Chloroxylenol ( para -chloro- meta -xylenol, PCMX) as the major antimicrobial ingredient of disinfectant has been widely detected in water environments, with identified toxicity and potential risk. The assessment of PCMX in domestic wastewater of Macau Special Administrative Region (SAR) showed a positive correlation between PCMX concentration and population density. An indigenous PCMX degrader, identified as Rhodococcus sp. GG1, was isolated and found capable of completely degrading PCMX (50 mg L −1 ) within 36 h. The growth kinetics followed Haldane's inhibition model, with maximum specific growth rate, half-saturation constant, and inhibition constant of 0.38 h −1 , 7.64 mg L −1 , and 68.08 mg L −1 , respectively. The degradation performance was enhanced by optimizing culture conditions, while the presence of additional carbon source stimulated strain GG1 to alleviate inhibition from high concentrations of PCMX. In addition, strain GG1 showed good environmental adaptability, degrading PCMX efficiently in different environmental aqueous matrices. A potential degradation pathway was identified, with 2,6-dimethylhydroquinone as a major intermediate metabolite. Cytochrome P450 (CYP450) was found to play a key role in dechlorinating PCMX via hydroxylation and also catalyzed the hydroxylated dechlorination of other halo-phenolic contaminants through co-metabolism. This study characterizes an aerobic bacterial pure culture capable of degrading PCMX metabolically, which could be promising in effective bioremediation of PCMX-contaminated sites and in treatment of PCMX-containing waste streams.
研究领域:
环境科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
·
2015
·
IF 4.494
Shumei Fang,Xuejiao An,Hongyuan Liu,Yi Cheng,Ning Hou,Lu Feng,Xinning Huang,Chunyan Li
Nitriles are common environmental pollutants, and their removal has attracted increasing attention. Microbial degradation is considered to be the most acceptable method for removal. In this work, we investigated the biodegradation of three aliphatic nitriles (acetonitrile, acrylonitrile and crotononitrile) by Rhodococcus rhodochrous BX2 and the expression of their corresponding metabolic enzymes. This organism can utilize all three aliphatic nitriles as sole carbon and nitrogen sources, resulting in the complete degradation of these compounds. The degradation kinetics were described using a first-order model. The degradation efficiency was ranked according to t 1/2 as follows: acetonitrile > trans-crotononitrile > acrylonitrile > cis-crotononitrile. Only ammonia accumulated following the three nitriles degradation, while amides and carboxylic acids were transient and disappeared by the end of the assay. mRNA expression and enzyme activity indicated that the tested aliphatic nitriles were degraded via both the inducible NHase/amidase and the constitutive nitrilase pathways, with the former most likely preferred.
研究领域:
环境微生物学
·
生物修复
·
酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Chunyan Li,Yueling Sun,Guanjun Sun,Hailian Zang,Shanshan Sun,Xinyue Zhao,Ning Hou,Dapeng Li
Triclocarban (TCC) is an emerging and intractable environmental contaminant due to its hydrophobicity and chemical stability. However, the antibacterial property of TCC limits its biodegradation, and only the functional enzyme TccA involved in TCC degradation has been characterized to date. In this study, we report a highly efficient TCC-degrading bacterium, Rhodococcus rhodochrous BX2, that could degrade and mineralize TCC (10 mg/L) by 76.8% and 56.5%, respectively, within 5 days. Subsequently, the TCC biodegradation pathway was predicted based on the detection of metabolites using modern mass spectrometry techniques. Furthermore, an amidase (TccS) and a novel phenol hydroxylase (PH IND ) encoded by the tccS and PH IND genes, respectively, were identified by genomic and transcriptomic analyses of strain BX2, and these enzymes were further unequivocally proven to be the key enzymes responsible for the metabolism of TCC and its intermediate 4-chloroaniline (4-CA) by using a combination of heterologous expression and gene knockout. Our results shed new light on the mechanism of TCC biodegradation and better utilization of microbes to remediate TCC contamination.
研究领域:
环境微生物学
·
生物修复
·
酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2020
·
IF 2.87
Li Wang,Shengxian Liu,Wenjing Du,Tongyi Dou,Changhai Liang
5-Cyanovaleramide (5-CVAM) is an important intermediate of a herbicide and chemical raw material. Herein, we found a novel nitrile hydratase from the strain Rhodococcus erythropolis CCM2595, exhibiting high regioselectivity with higher substrate specificity toward dinitriles than mononitriles. In the past, the strain was shown to degrade only phenol, hydroxybenzoate, p-chlorophenol, aniline, and other aromatic compounds. In our study, 20 mM adiponitrile was completely consumed within 10 min with 95% selectivity to 5-CVAM and 5% selectivity to adipamide. In addition to its high regioselectivity, our recombinant Escherichia coli showed a higher substrate tolerance of up to 200 mM adiponitrile even after 3 h when compared with two reported strains with their cyano-tolerance concentrations of up to 100 mM, which is considered to be the highest cyano-tolerance. Such a robust biocatalyst is a desirable attribute of a biocatalyst intended for use in commercial applications of 5-CVAM.
研究领域:
生物催化
·
生物化学
·
化学工程
·
酶技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Frontiers in Microbiology
·
2018
·
IF 4.019
Zhang Hui,Yu Ting,Wang Yiran,Li Jie,Wang Guangli,Ma Yingqun,Liu Yu
4-Chlorophenol (4-CP) oxidation plays an essential role in the detoxification of 4-CP. However, oxidative regulation of 4-CP at the genetic and biochemical levels has not yet been studied. To explore the regulation mechanism of 4-CP oxidation, a novel gene cluster, cphRA2A1, involved in biodegradation of 4-CP was identified and cloned from Rhodococcus sp. strain YH-5B by genome walking. The sequence analysis showed that the cphRA2A1 gene cluster encoded an AraC-type transcriptional regulator and a two-component monooxygenase enzyme, while quantitative real-time PCR analysis further revealed that cphR was constitutively expressed and positively regulated the transcription of cphA2A1 genes in response to 4-CP or phenol, as evidenced by gene knockout and complementation experiments. Through the transcriptional fusion of the mutated cphA2A1 promoter with the lacZ gene, it was found that the CphR regulator binding sites had two 15-bp imperfect direct repeats (TGCA-N6-GGNTA) at −35 to −69 upstream of the cphA2A1 transcriptional start site. Notably, the sub-motifs at the −46 to −49 positions played a critical role in the appropriate interaction with the CphR dimer. In addition, it was confirmed that the monooxygenase subunits CphA1 and CphA2, which were purified by His-tag affinity chromatography, were able to catalyze the conversion of 4-CP to 4-chlorocatechol, suggesting that strain YH-5B could degrade 4-CP via the 4-chlorocatechol pathway. This study enhances our understanding of the genetic and biochemical diversity in the transcriptional regulation of 4-CP oxidation in Gram-positive bacteria.
研究领域:
微生物学
·
环境生物技术
·
遗传学
·
生物化学
✓ 已验证
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2024
·Vol. 31
·期 14
·21659-21667
·
IF 0
Pan Hanqing,Ma Qiao,Zhang Jiaxin,Hu Haodong,Dai Huiyu,Shi Yuyan,Lu Shuxian,Wang Jingwei
Chloroxylenol is a commonly used antimicrobial agent in antibacterial and disinfection products, which has been detected in various environments, such as wastewater treatment plants, rivers, seawater, and even drinking water, with concentrations ranging from ng/L to mg/L. However, the biodegradation of chloroxylenol received limited attention with only sporadic reports available so far. In this study, an efficient chloroxylenol-degrading consortium, which could degrade 20 mg/L chloroxylenol within two days, was obtained after five months of enrichment. Amplicon sequencing analysis revealed a decrease in the α-diversity (e.g., Shannon index and Inv_Simpson index) of the community during the domestication process. Microbial community dynamics were uncovered, with sequences affiliated to Achromobacter , Pseudomonas , and Rhodococcus identified as the most abundant taxonomic groups. From the consortium, five pure isolates were obtained; however, it was found that only one strain of Rhodococcus could degrade chloroxylenol. Strain Rhodococcus sp. DMU2021 could degrade chloroxylenol efficiently under the conditions of temperature 30–40 °C, and neutral/alkaline conditions. Chloroxylenol was toxic to strain DMU2021 and triggered both enzymatic and non-enzymatic antioxidant systems in response. This study provides novel insights into the biodegradation process of chloroxylenol, as well as valuable bioresources for bioremediation.
研究领域:
环境科学
·
微生物学
·
生物技术
·
生态毒理学
✓ 已验证
DOI
JACS Au
·
2024
·
IF 8.5
Yaoyun Wu,Yaozhong Cui,Wei Song,Wanqing Wei,Zhizhen He,Jinyang Tao,Dejing Yin,Xiulai Chen,Cong Gao,Jia Liu,Liming Liu,Jing Wu
l-Amino acid oxidase (LAAO) is an important biocatalyst used for synthesizing α-keto acids. LAAO from Rhodococcus opacus (RoLAAO) has a broad substrate spectrum; however, its low total turnover number limits its industrial use. To overcome this, we aimed to employ crystal structure-guided density functional theory calculations and molecular dynamic simulations to investigate the catalytic mechanism. Two key steps were identified: S → [TS1] in step 1 and Int1 → [TS2] in step 2. We reprogrammed the transition states [TS1] and [TS2] to reduce the identified energy barrier and obtain a RoLAAO variant capable of catalyzing 19 kinds of l-amino acids to the corresponding high-value α-keto acids with a high total turnover number, yield (≥95.1 g/L), conversion rate (≥95%), and space-time yields ≥142.7 g/L/d in 12–24 h, in a 5 L reactor. Our results indicated the promising potential of the developed RoLAAO variant for use in the industrial production of α-keto acids while providing a potential catalytic-mechanism-guided protein design strategy to achieve the desired physical and catalytic properties of enzymes.
研究领域:
生物催化
·
酶工程
·
计算化学
·
蛋白质工程
✓ 已验证
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2016
·
IF 3.698
Chunyan Li,Zhenlei Yue,Fengzhao Feng,Chuanwu Xi,Hailian Zang,Xuejiao An,Keran Liu
There is a great need for efficient acetonitrile removal technology in wastewater treatment to reduce the discharge of this pollutant in untreated wastewater. In this study, a nitrilase gene ( nit ) isolated from a nitrile-degrading bacterium ( Rhodococcus rhodochrous BX2) was cloned and transformed into a biofilm-forming bacterium ( Bacillus subtilis N4) that expressed the recombinant protein upon isopropylthio-β-galactoside (IPTG) induction. The recombinant bacterium ( B. subtilis N4-pHT01- nit ) formed strong biofilms and had nitrile-degrading capability. Further testing demonstrated that biofilms formed by B. subtilis N4-pHT01- nit were highly resistant to loading shock from acetonitrile and almost completely degraded the initial concentration of acetonitrile (800 mg L −1 ) within 24 h in a moving bed biofilm reactor (MBBR) after operation for 35 d. The bacterial composition of the biofilm, identified by high-throughput sequencing, in a reactor in which the B. subtilis N4-pHT01- nit bacterium was introduced indicated that the engineered bacterium was successfully immobilized in the reactor and became dominant genus. This work demonstrates that an engineered bacterium with nitrile-degrading and biofilm-forming capacity can improve the degradation of contaminants in wastewater. This approach offers a novel strategy for enhancing the biological oxidation of toxic pollutants in wastewater.
研究领域:
环境工程
·
微生物学
·
生物技术
·
污水处理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Waste and Biomass Valorization
·
2023
·Vol. 15
·期 5
·2625-2635
·
IF 3.2
Luo Xiaoliang,Zhao Bincheng,Yao Junwen,Peng Mingguo,Mao Linqiang,Zhang Wenyi,Shen Rongyan
A large amount of estrogen is introduced into the feed to improve livestock growth, excessive residual estrogen would exist in the excrements. The accumulation of estrogen can cause the water and soil pollution around the farm, further inhibit growth and induce caner for organisms and human. Anaerobic digestion (AD) could effectively remove estrogen in livestock manure while the mechanism is still unclear. In this study, the mechanism of estrogen removal by AD was explored during AD process of pig manure. Estrone (E1), estradiol (E2) estriol (E3) and ethinylestradiol (EE2) were selected as research subjects. The removal rates of E1, E2, E3 and EE2 were 19.14, 28.62, 25.83 and 11.81%. Dissolved organic matters (DOM), especially humic acid, play an important role in reducing bioavailability of estrogen. Estrogen will be absorbed by DOM through structures such as aromatic ring and amides. Estrogen may also promote the growth of microorganisms which could degrade estrogen, such as Rhodococcus , Sphingomonas and Pseudomonas . The amount of these microorganisms and dissolved microbial metabolites did not change obviously. This study would give a new explanation for the removal of estrogen and can provide theoretical support for harmless treatment of pig manure. Graphical
研究领域:
环境科学
·
微生物学
·
生物技术
·
生态毒理学
·
废弃物管理
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2018
·
IF 1.712
Xiaoqiang Jia,Yun He,Lei Huang,Dawei Jiang,Wenyu Lu
The high-molecular weight polycyclic aromatic hydrocarbons (PAHs) pyrene and typical long chain alkane n -hexadecane are both difficult to degrade. In this study, n -hexadecane and pyrene degrading strain Rhodococcus sp. T1 was isolated from oil contaminated soil. Strain T1 could remove 90.81% n -hexadecane (2 vol%) and 42.79% pyrene (200 mg·L − 1 ) as a single carbon within 5 days, respectively. Comparatively, the degradation of pyrene increased to 60.63%, but the degradation of n -hexadecane decreased to 87.55% when these compounds were mixed. Additionally, identification and analysis of degradation metabolites of Rhodococcus sp. T1 in the above experiments showed that there were significant changes in alanine, methylamine, citric acid and heptadecanoic acid between sole and dual substrate degradation. The optimal conditions for degradation were then determined based on analysis of the pH, salinity, additional nutrient sources and liquid surface activity. Under the optimal conditions of pH 7.0, 35 °C, 0.5% NaCl, 5 mg·L − 1 of yeast extract and 90 mg·L − 1 of surfactant, the degradation increased in single or dual carbon sources. To our knowledge, this is the first study to discuss metabolite changes in Rhodococcus sp. T1 using sole substrate and dual substrate to enhance the long-chain alkanes and PAHs degradation potential.
研究领域:
环境微生物学
·
生物修复
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）