ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2019
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IF 4.527
Jinghao Wang,Sijing Bi,Yuancai Chen,Yongyou Hu
Gram-negative Citrobacter freundii with high Pd (II) reduction capacity was isolated from electroplating wastewater, and the electron transfer involved in Pd (II) bio-reduction by C. freundii JH was investigated in phosphate buffer saline solution with sodium formate as sole electron donor under anaerobic condition . FTIR spectra indicated that hydroxyl and amine groups on cell wall participated Pd (II) bio-sorption. TEM , XRD, XPS results confirmed that Pd (0) nanoparticles (NPs) could be bio-synthesized intra/extracellularly. Meanwhile, pH turn-over were observed owing to the reduction of cytochrome c (c-Cyt) in bio-reduction process. EPR spectra indicated that free radicals ( OH) was generated from high concentration Pd (II), which would cause seriously damage to cell. Despite of the lower tolerance to Pd (II), the cells at logarithmic phase exhibited higher Pd (II) reduction capacity (72.21%) than that at stationary phase (56.21%), which might be related to the relatively stronger proton motive force (PMF) created by the substrate oxidation and the electron transfer, as evidenced by electrochemical experiments (CV, DPV, amperometric I-t curves) and protein denaturalization experiments. Additionally, c-Cyt and riboflavin were confirmed to be important participants in electron transfer. Finally, a putative synthesis mechanism of Pd (0)-NPs was deduced. This study contributed to further understanding the electron transfer in Pd (II) reduction, and provided more information for the bio-synthetic of metal nanoparticles.
研究领域:
环境微生物学
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生物技术
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纳米技术
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微生物生物化学
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PubMed
高影响因子
Environmental Technology & Innovation
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2025
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IF 7.1
Xueping Jiang,Hao Li,Jia Kong,Yongjun Zang,Yuqi Li,Jianglong He,Ran Zhang,Bangxing Han,Kwang Sik Lee,Byung Rae Jin,Zhongzheng Gui
Chloramphenicol (CAP), a widely used antibiotic, persists in the environment and poses ecological risks. Despite the growing understanding of these degradation pathways of CAP, the secondary metabolic routes and their impacts on the environment remain poorly understood. Here, we aimed to characterize the CAP-biodegradation capability of a novel bacterial strain, evaluate the biodegradation kinetics of CAP under different nutritional and environmental conditions, and assess the toxicity of CAP and its degradation products. Citrobacter freundii CT2 isolated from fermented silkworm excrement was found to degrade CAP with an efficiency of 96.29 % within 24 h. CAP is the sole source of carbon, nitrogen, and energy for this bacterium. The degradation process fitted well with the first-order kinetics model. Ten potential biotransformation products were identified using ultraperformance liquid chromatography–high-resolution mass spectrometry (UPLC-HRMS) and high-performance liquid chromatography (HPLC), and five distinct metabolic pathways (acetylation, propionylation, butyrylation, dehydration, and oxidation) were predicted. A toxicity assessment of the biotransformation products, conducted using biological indicators, showed that the final metabolites were non-toxic to the environment, confirming that the biodegradation process resulted in detoxification. Bio-enhancement studies further demonstrated that strain CT2 effectively degraded CAP in wastewater. Genomic analysis showed that genes related to acetylation, propionylation, nitro reductase, and dehydrogenation in strain CT2 might be involved in the biodegradation of CAP. These results offer new insights into the diversity of CAP-degrading pathways and highlight the utility of strain CT2 as a potential bioremediation agent for CAP-contaminated environments.
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高影响因子
BIORESOURCE TECHNOLOGY
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2025
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IF 9
Jian Gao,Jingyu Wu,Yuancai Chen
This study found that bio-Pd 0 nanoparticles could launch proton motive force (PMF)-mediated antibiotics efflux pump (AEP) to confer the detoxification capability on Citrobacter freundii , as evidenced by the highest sulfamethoxazole (SMX) specific degradation rate (81.7 μg L −1 mg −1 protein d −1 ) at high PMF (pH 6). The batch experiment and RT-qPCR results indicated that bio-Pd 0 activated the AcrB efflux pump through upregulating the AEP transcriptional regulation factor ramA (2.7–3.1 times), which benefited the intra/extracellular respiration and ATP production/utilization. Path analysis revealed that the prosperity of metabolic activity and extracellular electron output capacity enabled SMX biodegradation, mainly through the electron redistribution and energy optimization with the formate dehydrogenase/hydrogenase based Short-chain (FDH/Hase-S-chain). The upregulation of hypE (2.7–8.6 times) and atpD (1.9–2.3 times) genes encoding the Hase respiratory chain and the F-type ATP synthase, respectively, further supports this mechanism. These novel findings provided a new strategy to improve the biodegradation efficiency of antibiotics wastewater.
研究领域:
微生物学
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环境科学
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DOI
PubMed
高影响因子
Cell Reports
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2025
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IF 6.9
Weiben Xu,Ying Zhou,Haiying Ding,Mengqian Ye,Shujing Li,Linwei Xu,Xiangyu Jin,Zhajun Zhan,Lulu Song,Yuhua Zhang,Canming Wang,Zhengqin Zhu,Liefeng Ma,Libin Pan,Luo Fang
Pancreatic cancer is highly malignant, and while fluoropyrimidines (5-fluorouracil [5-FU] and capecitabine) are critical first-line treatments for metastatic cases, drug resistance remains a major challenge. In this study, we identified an association between Citrobacter enrichment in pancreatic tumors and poor overall survival in patients with pancreatic cancer, particularly in patients receiving fluoropyrimidine-based treatment. Co-culture of 5-FU with the Citrobacter freundii strain isolated from pancreatic cancer and intratumoral injection of this strain in xenograft models significantly reduce the antitumor efficacy of 5-FU. Subsequent analyses using mass spectrometry, bioinformatics, and gene knockout experiments revealed that C. freundii strain inactivates 5-FU via the PreTA, which is homologous to human dihydropyrimidine dehydrogenase (DPD). Gimeracil, a DPD inhibitor, preserves the efficacy of 5-FU by blocking PreTA activity. Other preTA -harboring bacteria also metabolized 5-FU, indicating broader bacteria-mediated 5-FU resistance. These findings reveal a potential microbiome-driven mechanism of chemotherapy failure and identify PreTA as a druggable target.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2026
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IF 12.5
Shuyan Chi,Hanbang Ding,Miao Cai,Yuze Xu,Wenjie Xia,Xuejiao Zhang,Liwei Liu
In situ biomineralized C. freundii -CdS biohybrid enabled light-driven fermentation. • Photoelectrons increased intracellular NADH/NAD + by 59%. • Succinate production increased by 26.2% in a 5 L bioreactor. • rTCA and electron transport pathways were coordinately activated. • Light-driven redox balancing enhanced reductive succinate biosynthesis. Microbial fermentation provides a sustainable route to succinic acid production, yet the reductive tricarboxylic acid (rTCA) pathway demands more NADH than anaerobic glucose catabolism can supply, thereby limiting the yield. Here, we constructed a Citrobacter freundii -CdS biohybrid in which CdS nanoparticles, biomineralized on the cell surface, harvest visible light and are proposed to supply photoelectrons to the host cell, augmenting intracellular NADH availability. Under optimized conditions, the illuminated biohybrid elevated the intracellular NADH/NAD + ratio by 59% relative to controls. In a 5 L bioreactor, the illuminated biohybrid achieved a succinate titer of 42.8 g L −1 (yield: 0.49 g g −1 glucose), a 26.2% increase over the dark control, with concurrent reductions in formate, acetate, and lactate. Transcriptomic analysis identified coordinated upregulation of electron transport, NADH synthesis, and rTCA pathway genes alongside downregulation of competing branch-point enzymes. These findings support a model in which light-driven electron supply can serve as a non-genetic approach for redirecting intracellular reducing power and carbon partitioning toward succinate biosynthesis in facultative anaerobes, although the precise electron-transfer route remains to be established. Download: Download high-res image (170KB) Download: Download full-size image
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高影响因子
WATER RESEARCH
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2023
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IF 12.8
Huimin Liu,Dejin Liu,Yuancai Chen
Considering the negligent degradation of sulfamethoxazole (SMX) by Citrobacter freundii JH , the incorporation of bio-FeS could initiate the SMX biodegradation to 0.0444 (S-FeS), and further to 0.0564 mg L −1 mg −1 protein d −1 (SN-FeS) when coexisted with nitrate. Electrochemical (LSV, I-t , DPV, EIS and EDC) and respiratory inhibition experiments clarified that the bio-FeS could greatly switch/redistribute electron transmembrane-transfer from intracellular to extracellular mainly via FDH/Hases-S-chain, as revealed by the significant increase of ipa- FDH/Hases / ipa- FC-Cyts and ipc- FDH/Hases / ipc- FC-Cyts (from 1.09 and 1.07 (SN-native) to 1.50 and 3.58 (SN-FeS)), while nitrate (linear fitting with NADH ( R 2 = 0.9903)) mainly intensified CoQ-L-chain related INET from Complex I to CoQ to compensate for the electronic competition with SMX. SN-FeS system detoxified the SMX on microbial metabolism (such as membrane rupture and oxidative stress induction) with high SOD activity (737.93 U g FW −1 ). Structural equation modeling indicated that bio-FeS up-regulated PMF-mediated ATP synthesis ( P PMF-ATPs from 0.12 (SN-native) to 0.74 (SN-FeS)) and PMF-mediated NADH ( P PMF-NADH from -0.72 (SN-native) to 0.63 (SN-FeS)), and the nitrate addition intensified this positive feedback. Overall, this study provides a new perspective for bionanoparticles via electron transfer/redistribution to detoxify and launch the antibiotics biodegradation in ecological environment.
研究领域:
环境生物学
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微生物学
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PubMed
高影响因子
ENVIRONMENTAL POLLUTION
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2024
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IF 7.6
Xinxin Jiang,Jingfei Long,Yanzhen Song,Xiaoyu Qi,Ping Li,Kuiquan Pan,Chenyang Yan,Hongzhou Xu,Haixia Liu
The transmission of antibiotic resistance genes (ARGs) in pathogenic bacteria affects culture animal health, endangers food safety, and thus gravely threatens public health. However, information about the effect of disinfectants - triclosan (TCS) on ARGs dissemination of bacterial pathogens in aquatic animals is still limited. One Citrobacter freundii ( C. freundii ) strain harboring tet (X4)-resistant plasmid was isolated from farmed grass carp guts, and subsequently conjugative transfer frequency from C. freundii to Escherichia coli C600 ( E. coli C600) was analyzed under different mating time, temperature, and ratio. The effect of different concentrations of TCS (0.02, 0.2, 2, 20, 200 and 2000 μg/L) on the conjugative transfer was detected. The optimum conditions for conjugative transfer were at 37 °C for 8h with mating ratio of 2:1 or 1:1 ( C. freundii : E. coli C600). The conjugative transfer frequency was significantly promoted under TCS treatment and reached the maximum value under 2.00 μg/L TCS with 18.39 times that of the control group. Reactive oxygen species (ROS), superoxide dismutase (SOD) and catalase (CAT) activities, cell membrane permeability of C. freundii and E. coli C600 were obviously increased under TCS stress. Scanning electron microscope showed that the cell membrane surface of the conjugative strains was wrinkled and pitted, even broken at 2.00 μg/L TCS, while lysed or even ruptured at 200.00 μg/L TCS. In addition, TCS up-regulated expression levels of oxidative stress genes ( kat E, hem F, bcp , hem A, kat G, ahp F, and ahp C) and cell membrane-related genes ( fim C, bam E and omp A) of donor and recipient bacteria. Gene Ontology (GO) enrichment demonstrated significant changes in categories relevant to pilus, porin activity, transmembrane transporter activity, transferase activity, hydrolase activity, material transport and metabolism. Taken together, a tet (X4)-resistant plasmid could horizontal transmission among different pathogens, while TCS can promote the propagation of the resistant plasmid.
研究领域:
微生物学
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分子生物学
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环境科学
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水产养殖
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公共卫生
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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）