Journal of Environmental Chemical Engineering
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2026
·Vol. 14
·期 3
·122943
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IF 7.5
Qiannan Li,Hanyu Pan,Yunna Jia,Zhenhua Ma,Ye Wang,Xiaojun Liang,Xiuzhen Yu,Yunhang Gao
The molecular mechanism by which microorganisms degrade the endocrine-disrupting contaminant 17β-estradiol (E2) at low temperatures remains largely unclear, with only limited studies available. Here, we investigated the adaptive strategy of the cryotolerant bacterium Rhodococcus sp . RCBS9 for sustaining E2 degradation at 10 °C, a temperature at which efficient estrogen degradation has rarely been reported. Using time-resolved multi-omics and phenotypic assays, we characterized a dynamic, staged adaptation process involving changes in oxidative stress defense, membrane composition, transcription factors, signaling factors, and stress proteins. We uncovered three major novelties. First, RCBS9 employs a distinct degradation pathway that first cleaves the saturated sterol rings, in contrast to the canonical 4,5-seco pathway that initiates with aromatic ring A cleavage. Second, we identified and functionally validated a cold-tolerant short-chain dehydrogenase/reductase (SDR) encoded by gene RQCS_RS03565 that converts E2 to estrone (E1), as confirmed by heterologous expression and site-directed mutagenesis. Third, subsequent sterol ring cleavage proceeds via a suite of oxidoreductases and hydrolases. The resulting aromatic intermediates are then mineralized through the β-ketoadipate pathway, as suggested by the coordinated upregulation of intradiol dioxygenase and carboxymuconolactone decarboxylase. Additionally, trace iron (50 μM) promoted E2 degradation and reduced E1 accumulation, partly attributable to enhanced metabolic activity and upregulation of iron-requiring enzyme genes. Overall, this work provides fundamental insights into a novel estrogen biodegradation logic under cold stress and proposes a practical iron-mediated strategy for low-temperature bioremediation.
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DOI
高影响因子
INTERNATIONAL BIODETERIORATION & BIODEGRADATION
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2022
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IF 4.907
Xiaoyong Song,Zihan Zhang,Yanran Dai,Deshou Cun,Baihui Cui,Yuewei Wang,Yaocheng Fan,Haibin Tang,Liang Qiu,Feihua Wang,Dongru Qiu,Wei Liang
Di-(2-ethylhexyl) phthalate (DEHP), the most extensively used phthalate acid esters (PAEs), poses a potential risk to human and environment. A novel bacterial strain , Rhodococcus sp. LW-XY12, with efficient PAE-degrading capability, was isolated from activated sludge. Strain LW-XY12 could degrade 96.91 ± 0.68% of DEHP (500 mg L −1 ) within 32 h. The degradation curves of DEHP (50–1500 mg L −1 ) and PAE mixture (500 mg L −1 each) fitted well with the modified Gomperz kinetics model. DEHP metabolic pathway was reconstructed by using genome annotation and metabolic intermediate analyses. The DEHP metabolic pathway might comprise de-esterification and β-oxidation. Homologous modeling and molecular docking analysis revealed that DEHP and MEHP (mono-(2-ethylhexyl) phthalate) could be bound to putative carboxylesterase (KXC42_04905) via hydrogen bonding and hydrophobic interaction. A conserved catalytic triad (Ser195-Glu319-His412) might act as an active protein pocket and catalyze the hydrolysis of DEHP. Carboxylesterase (KXC42_04905) could hydrolyze ester bond and a possible mechanism underlying ester bond hydrolysis catalyzed by the carboxylesterase was proposed. Protocatechuate 3,4-dioxygenase, 3-oxoadipate CoA-transferase, benzoate 1,2-dioxygenase, catechol 1,2-dioxygenase, and catechol 2,3-dioxygenase transcripts were detected and significantly up-regulated under DEHP induction. This study sheds light on the functional genes associated with DEHP degradation and metabolic mechanism in this versatile bacterium for degradation of PAEs.
研究领域:
环境微生物学
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基因组学
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生物降解
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生物化学
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产品关联
DOI
高影响因子
Frontiers in Microbiology
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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
CHEMOSPHERE
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2015
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IF 3.34
Jing-Nan Jin,Jun Yao,Qing-Ye Zhang,Chan Yu,Peng Chen,Wen-Juan Liu,Dan-Ning Peng,Martin M.F. Choi
Naphthalene dioxygenase (NDO) is the initial enzyme catalyzing the biodegradation of aromatic compounds, and it plays a key role in microbial remediation of polluting sites. In this study, Rhodococcus sp. ustb-1 derived from crude oil was selected to investigate the biodegradation characters and dihydroxylation mechanism of pyrene by an integrated approach of bioassay and molecular docking. The biodegradation experiment proved that the strain ustb-1 shows high effective biodegradability to pyrene with a 70.8% degradation on the 28th day and the metabolite pyrene cis-4,5-dihydrodiol was found. The results of molecular docking indicated that the regions surrounding pyrene are defined by hydrophobic amino acids which are favorable for the binding of dioxygen molecule at C4 and C5 positions of pyrene in a side-on mode. The binding positions of dioxygen are in agreement with the mass spectral analysis of the metabolite pyrene cis-4,5-dihydrodiol. In summary, this study provides a promising explanation for the possible binding behavior between pyrene and active site of NDO.
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高影响因子
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