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
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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
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环境生物技术
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遗传学
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生物化学
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DOI
PubMed
高影响因子
Environmental Technology & Innovation
·
2021
·
IF 5.263
Zhong Lin,Weijian Zhang,Xiaoping Zhu,Weijian Wu,Yijie Chen,Gaoyang Li,Lei Ren,Shuwen Luo,Yucheng Xie,Yongxiang Huang,Xinzi Wang,Zhen Zhen,Dayi Zhang
Di-2-ethylhexylphthalate (DEHP) is a common plasticizer and widely detected in sediments, water and biota. For its strong reproductive toxicity, teratogenicity and poisonousness, many approaches are developed to remediate DEHP-contaminated soils. This study aimed to evaluate the roles of biochar in accelerating DEHP degradation, assess the impacts of biochar pyrolysis temperature on DEHP removal performance, and explore the underlying mechanisms. Biochar had a satisfactory performance in DEHP adsorption and followed a Freundlich isotherm, exhibiting proportional adsorption capabilities to pyrolysis temperature. Biochar amendment significantly accelerated soil DEHP degradation, and the degradation efficiency ranged from 61.4% to 82.2% and increased with biochar pyrolysis temperature. Biochar remarkably changed soil physiochemical properties by increasing soil pH, organic matter and humus. Soil bacterial community was altered with biochar amendment that the relative abundance of Nocardioides , Marinobacter , Rhodococcus and Gramella increased. Our findings suggested that biochar-assisted bioremediation has a huge potential in soil DEHP degradation and pyrolysis temperature is a critical factor affecting the performance. Our work characterize biochar at different pyrolysis temperatures and explored the underlying mechanisms of biochar-assisted DEHP bioremediation, offering both scientific and practical hints for DEHP bioremediation in coastal sediments.
研究领域:
环境科学
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土壤学
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微生物学
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污染控制
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生物修复
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产品关联
DOI
高影响因子
BIODEGRADATION
·
2017
·Vol. 29
·期 1
·1-10
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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
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生物修复
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微生物生态学
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趋化性
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产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2022
·
IF 9.988
Qingyun Ma,Hao Tan,Jinlong Song,Miaomiao Li,Zhiye Wang,Rebecca E. Parales,Lin Li,Zhiyong Ruan
This study aims to investigate the effects of long-term nicosulfuron residue on an herbicide factory ecosystem. High-throughput sequencing was used to investigate the environmental microbial community structure and interactions. The results showed that the main contributor to the differences in the microbial community structure was the sample type, followed by oxygen content, pH and nicosulfuron residue concentration. Regardless of the presence or absence of nicosulfuron, soil, sludge , and sewage were dominated by groups of Bacteroidetes, Actinobacteria, and Proteobacteria. Long-term exposure to nicosulfuron increased alpha diversity of bacteria and archaea but significantly decreased the abundance of Bacteroidetes and Acidobateria compared to soils without nicosulfuron residue. A total of 81 possible nicosulfuron-degrading bacterial genera, e.g., Rhodococcus , Chryseobacterium , Thermomonas , Stenotrophomonas , and Bacillus , were isolated from the nicosulfuron factory environmental samples through culturomics. The co-occurrence network analysis indicated that the keystone taxa were Rhodococcus , Stenotrophomonas , Nitrospira , Terrimonas , and Nitrosomonadaceae_MND1. The strong ecological relationship between microorganisms with the same network module was related to anaerobic respiration, the carbon and nitrogen cycle , and the degradation of environmental contaminants. Synthetic community (SynCom), which provides an effective top-down approach for the critical degradation strains obtained, enhanced the degradation efficiency of nicosulfuron. The results indicated that Rhodococcus sp. was the key genus in the environment of long-term nicosulfuron exposure.
研究领域:
环境科学
·
微生物学
·
生态学
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产品关联
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Lianghe Lv,Lina Sun,Chunli Yuan,Yue Han,Zhaohui Huang
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous persistent organic pollutants in soil, which have carcinogenic, teratogenic and mutagenic hazards. The effects of rhamnolipid (RL), nano zero-valent iron (nZVI), and anthraquinone-2,6-disulfonic acid (AQDS) on the degradation of PAHs in soil were studied. It was found that the treatment of 5 mg·kg −1 RL + 1% nZVI +0.2 mmol·kg −1 AQDS had the highest degradation rate. The degradation rate of total PAHs and HMW-PAHs was 72.81% and 79.47% respectively after 90 days. High-throughput sequencing showed that in RL + nZVI + AQDS enhanced soil, Clostridium , Geobacter , Anaeromyxobacter and Sphingomonas were the dominant species for anaerobic degradation of PAHs. Rhodococcus , Nocardioides , and Microvirga are the dominant species for aerobic degradation of PAHs. The activities of methyltransferase, dehydrogenase and catechol 1,2-dioxygenase in the anaerobic-aerobic degradation process of PAHs were consistent with the degradation process of PAHs, indicating the role of these enzymes in the degradation of PAHs. RL, nZVI, and AQDS combined enhanced microbial anaerobic-aerobic degradation has great application potential in remediation of PAHs-contaminated soil.
研究领域:
环境科学
·
土壤学
·
生物修复
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2023
·
IF 8.3
Haiping Gu,Jie Yan,Yuhao Liu,Xuewei Yu,Yan Feng,Xuanyi Yang,Su Shiung Lam,Mu. Naushad,Cheng Li,Christian Sonne
Bioaugmentation helps to obtain a microbiome capable of remediating polycyclic aromatic hydrocarbons (PAHs). In this study, acclimation of microorganisms to soil supplemented with phenanthrene (PHE) led to enrichment with PAH-degraders, including those in Actinobacteriota and in the genera Streptomyces , Rhodococcus , Nocardioides , Sphingomonas , and Mycobacterium . Aqueous (28 °C, pH 6.5) and soil cultures inoculated with PHE-acclimated soil showed a high PHE (ca. 50 mg L −1 ) degradation efficiency. The PHE degradation kinetics in aqueous and soil incubations fitted to the Gompertz equation and the first-order kinetic equation, respectively. Indigenous microorganisms adapted to PHE in their environment, and this increased their capacity to degrade PHE. The effect of co-contaminants and pathway intermediates on PHE degradation showed that the degradation of PHE improved in the presence of diesel while being hindered by lubricant oil, catechol, salicylic and phthalic acid. Our findings provide theoretical and practical support for bioremediationof PAHs in the environment.
研究领域:
环境微生物学
·
土壤科学
·
生物修复技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）