SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Tao Zhang,Shuang-yan Xu,Hui Lin,Jian Yang,Zhuo-qun Zhao,Damià Barceló,Hua-bao Zheng
Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0–10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENGINEERING IN LIFE SCIENCES
·
2015
·Vol. 16
·期 3
·299-305
·
IF 2.485
Naiqiang Li,Howard Chou,Yan Xu
Cadaverine has the potential to become an important platform chemical for the production of nylon. Previously, a system that overexpresses the Klebsiella oxytoca lysine decarboxylase in Escherichia coli was engineered. The system was optimized by codon optimization, and tuning the expression level of the gene by testing various promoters and inducer concentrations. Here, we further improved the system by optimizing the sequence located in the region of the ribosome-binding site in order to enhance translation efficiency. We also identified mutant lysine decarboxylase enzymes that demonstrated enhanced cadaverine-production ability. Together, these modifications increased cadaverine production in the system by 50%, and the system has a yield of 80% from lysine-HCl under the conditions we tested. This is the first time that a system to produce cadaverine using the lysine decarboxylase from K. oxytoca performed at a level that is competitive with the traditional systems using the E. coli lysine decarboxylases in both lab-scale and batch fermentation conditions.
✓ 已验证
产品关联
DOI
高影响因子
BIOTECHNOLOGY AND BIOPROCESS ENGINEERING
·
2015
·Vol. 19
·期 6
·965-972
·
IF 1.113
Li Naiqiang,Chou Howard,Yu Lijun,Xu Yan
Cadaverine, as a biogenic amine, is an important platform chemical for the production of industrial polymers, such as polyamides, polyurethanes, and nylon. Previous efforts focused on the bio-based production of cadaverine using two lysine decarboxylases of Escherichia coli CadA and LdcC. In this study, we report the biotransformation of cadaverine using a lysine decarboxylase from Klebsiella oxytoca . Codon optimization of the gene encoding this enzyme was carried on for the heterologous expression in E. coli , which led to a system that converted more than 24% lysine-HCl to cadaverine compared to the same system expressing CadA. The system was further optimized by using three different inducible promoters to control the expression of lysine decarboxylase gene of K. oxytoca in E. coli . The final optimized system converted lysine-HCl to cadaverine at a conversion rate of 0.133%/min/g. When the optimized system described above is coupled to an industrial process, the combined process has the potential to produce cadaverine with high conversion efficiency (46%) from sugar.
✓ 已验证
DOI
高影响因子
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2014
·Vol. 99
·期 5
·2431-2439
·
IF 3.811
Yu Lei,Zhang Xiao-yu,Xie Tian,Hu Jin-mei,Wang Shi,Li Wen-wei
Reduction of azo dye methyl red coupled with aerobic respiration by growing cultures of Klebsiella oxytoca GS-4-08 was investigated. In liquid media containing dye and 0.6 % glucose in a mineral salts base, 100 mg l −1 of the dye are completely removed in 3 h under shaking conditions. The dye cannot be aerobically decolorized by strain GS-4-08 without extra carbon sources, indicating a co-metabolism process. Higher initial dye concentration prolonged the lag phase of the cell growth, but final cell concentrations of each batches reached a same level with range from 6.3 to 7.6 mg l −1 after the dye adaption period. This strain showed stronger dye tolerance and decolorization ability than many reported strains. Furthermore, a new intracellular oxygen-insensitive azoreductase was isolated from this strain, and the specific activity of enzyme was 0.846 and 0.633 U mg −1 protein in the presence of NADH and NADPH, respectively. N , N dimethyl- p -phenylenediamine and anthranilic acid were stoichiometrically released from MR dye, indicating the breakage of azo bonds accounts for the intracellular decolorization. Combining the characteristics of azoreductase, the stoichiometry of EMP, and TCA cycle, the electron transfer chain theory of aerobic respiration, and the possible mechanism of aerobic respiration coupled with azo reduction by K. oxytoca GS-4-08 are proposed. This study is expected to provide a sound theoretical basis for the development of the K. oxytoca strain in aerobic process for azo dye containing wastewaters.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ARCHIVES OF MICROBIOLOGY
·
2025
·Vol. 207
·期 12
·1-19
·
IF 2.6
Xu Jingjing,Sun Meng,Chang Jiangcheng,Xie Qingchao,Wang Yongjie,Chen Lanming
Klebsiella oxytoca can cause gastrointestinal infections in humans. Within the instestinal tract, the bacterium encounters diverse host-derived signals (most notably bile salts, BS) and secondary metabolites (such as short-chain fatty acid salts, SCFAs) produced by microbial community. However, the mechanism of K. oxytoca response to BS and SCFAs stresses has been rarely reported. Recently, we found K. oxytoca in 14 species of aquatic food animals, of which K. oxytoca 7-7-27 of mussel origin had strong biofilm formation characteristics and many putative virulence-associated genes. Herein, we investigated the impact of normal physiological concentrations of BS (0.2% – 2.2%) and SCFAs (0.4% – 2.0%) in the tract on survival and virulence of K. oxytoca 7-7-27. The results revealed that the major BS (0.2% sodium cholate, or 0.8% sodium glycocholate) and SCFAs (0.4% sodium acetate, or 0.4% sodium butyrate) stimulated the bacterial growth, and significantly increased cell surface hydrophobicity, auto-aggregation rate and biofilm formation, as well as adhesion and invasion rates of K. oxytoca 7-7-27 toward the human colon Caco-2 cell ( p < 0.05). Notably, comparative secretomic and proteomic analyses uncovered a number of differentially secreted (i.e., 53) and produced (i.e., 1,049) proteins, as well as putative virulence-associated proteins (i.e., 69) triggered by the BS and SCFAs. K. oxytoca adopted multiple strategies to cope with the BS and SCFAs stresses. The results of this study highlighted the potential risk of ingestion of K. oxytoca -contaminated aquatic products.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
·
2013
·
IF 4.75
Dong Zhang,Lizhong Zhu,Feng Li
Surfactant-enhanced bioremediation has been proposed as a promising technology for the treatment of organic polluted soils; however its application has been hindered by the controversial influences and mechanisms of surfactants on the biodegradation of hydrophobic organic compounds. To address this problem, effects of five surfactants on the sorption and biodegradation of pyrene by Klebsiella oxytoca PYR-1, as well as their interactions with bacterial cell surface and membrane lipids were investigated. We found that surfactants enhanced or inhibited pyrene biodegradation depending on their effects on the sorption of pyrene onto bacterial cell, which occurred mainly through modifying cell surface hydrophobicity (such as Tween series surfactants) or disrupting bacterial membrane (such as Triton X-100), respectively. A relatively high positive correlation ( P < 0.0001) was observed between biodegradation promotion ( B s ∗ / B 0 ∗ ) and enhancement of sorption coefficients ( K d,s ∗ / K d,0 ∗ ) for pyrene in the presence of surfactant, indicating that surfactant-induced sorption played the dominant role during pyrene biodegradation.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2011
·Vol. 95
·期 1
·255-262
·
IF 3.28
Yu Lei,Li Wen-Wei,Lam Michael Hon-Wah,Yu Han-Qing,Wu Chao
A facultative anaerobic bacteria strain GS-4-08, isolated from an anaerobic sequence batch reactor for synthetic dye wastewater treatment, was investigated for azo-dye decolorization. This bacterium was identified as a member of Klebsiella oxytoca based on Gram staining, morphology characterization and 16S rRNA gene analysis. It exhibited a good capacity of simultaneous decolorization and hydrogen production in the presence of electron donor. The hydrogen production was less affected even at a high Methyl Orange (MO) concentration of 0.5 mM, indicating a superior tolerability of this strain to MO. This efficient bio-hydrogen production from electron donor can not only avoid bacterial inhibition due to accumulation of volatile fatty acids during MO decolorization, but also can recover considerable energy from dye wastewater.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-11
·
IF 5.228
Yu Lei,Tang Qing-wen,Zhang Yu-jia,Chen Rong-ping,Liu Xin,Qiao Wei-chuan,Li Wen-wei,Ruan Hong-hua,Song Xin
In this work, the effect of cultivation factors on the flocculation efficiency (FE) of bioflocculant P-GS408 from Klebsiella oxytoca was optimized by the response surface methodology. The most significant factor, i.e . culture time, was determined by gray relational analysis. A total of 240 mg of purified P-GS408 was prepared from 1 liter of culture solution under the optimal conditions. GC-MS analysis results indicated that the polysaccharide of P-GS408 mainly contains Rhamnose and Galactose, and the existence of abundant hydroxyl, carboxyl and amino groups was evidenced by FTIR and XPS analyses. With the aid of Fe 3+ , the FE of kaolin solution by P-GS408 could achieve 99.48% in ten minutes. Functional groups of polysaccharide were involved in the first adsorption step and the zeta potential of kaolin solution changed from −39.0 mV to 43.4 mV in the presence of Fe 3+ and P-GS408. Three-dimensional excitation-emission (EEM) fluorescence spectra demonstrates that the trivalent Fe 3+ and Al 3+ can bind efficiently with P-GS408, while those univalent and divalent cations cannot. With the help of SEM images, FTIR, zeta potential and EEM spectra, we proposed the P-GS408 flocculation mechanism, which consists of coordination bond combination, charge neutrality, adsorption and bridging, and net catching.
✓ 已验证
DOI
高影响因子
PLANT AND SOIL
·
2026
·
IF 4.8
Chen Ji,Wang Yazhuo,Fan Zhongdi,Wang Conghu,Zhang Zihan,Liu Yuting,He Yanhui,Wu Zhansheng
Introduction Plant growth-promoting rhizobacteria (PGPR) colonize the rhizosphere and enhance plant growth, stress tolerance, and soil properties. To better harness these benefits, this study investigates the synergistic interaction between two PGPR strains— Bacillus subtilis SL-44 and Klebsiella oxytoca RS-5—and evaluates their combined effects on rapeseed growth through integrated direct and indirect mechanisms. Methods The plant growth-promoting traits (e.g., phosphate solubilization, siderophore and indole-3-acetic acid (IAA) production) and biofilm-forming capacity of individual strains and their consortium were characterized in vitro. Subsequently, pot experiments were conducted to evaluate their effects on rapeseed growth parameters and rhizosphere soil quality. Finally, the rhizosphere microbial communities were analyzed via high-throughput sequencing on the Illumina NextSeq platform. Results The co-culture consortium (SR) demonstrated synergistic enhancements in key plant growth-promoting traits and biofilm stability in vitro. Pot experiments confirmed that SR treatment most effectively promoted rapeseed biomass accumulation, improved physiological status, and elevated antioxidant capacity. It also optimally enhanced rhizosphere soil nutrient availability, enzyme activities, and selectively reshaped the microbial community by enriching beneficial taxa and increasing ecological network complexity. Ultimately, plant growth promotion was achieved through an integrated mechanism combining direct stimulation and microbiome-mediated soil improvement. Conclusion In summary, this study demonstrates that functional complementarity between PGPR strains drives synergistic growth promotion through combined direct stimulation and rhizosphere microbiome engineering, offering a framework for developing effective microbial consortia for sustainable agriculture. Graphical
✓ 已验证
DOI
高影响因子
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
·
2017
·Vol. 83
·期 10
·
IF 3.807
Lei Yu,Ming-yue Cao,Peng-tao Wang,Shi Wang,Ying-rong Yue,Wen-duo Yuan,Wei-chuan Qiao,Fei Wang,Xin Song
Biohydrogen production from the pulp and paper effluent containing rich lignocellulosic material could be achieved by the fermentation process. Xylose, an important hemicellulose hydrolysis product, is used less efficiently as a substrate for biohydrogen production. Moreover, azo dyes are usually added to fabricate anticounterfeiting paper, which further increases the complexity of wastewater. This study reports that xylose could serve as the sole carbon source for a pure culture of Klebsiella oxytoca GS-4-08 to achieve simultaneous decolorization and biohydrogen production. With 2 g liter−1 of xylose as the substrate, a maximum xylose utilization rate (URxyl) and a hydrogen molar yield (HMY) of 93.99% and 0.259 mol of H2 mol of xylose−1, respectively, were obtained. Biohydrogen kinetics and electron equivalent (e− equiv) balance calculations indicated that methyl red (MR) penetrates and intracellularly inhibits both the pentose phosphate pathway and pyruvate fermentation pathway, while methyl orange (MO) acted independently of the glycolysis and biohydrogen pathway. The data demonstrate that biohydrogen pathways in the presence of azo dyes with sulfonate and carboxyl groups were different, but the azo dyes could be completely reduced during the biohydrogen production period in the presence of MO or MR. The feasibility of hydrogen production from industrial pulp and paper effluent by the strain if the xylose is sufficient was also proved and was not affected by toxic substances which usually exist in such wastewater, except for chlorophenol. This study offers a promising energy-recycling strategy for treating pulp and paper wastewaters, especially for those containing azo dyes.IMPORTANCE The pulp and paper industry is a major industry in many developing countries, and the global market of pulp and paper wastewater treatment is expected to increase by 60% between 2012 and 2020. Such wastewater contains large amounts of refractory contaminants, such as lignin, whose reclamation is considered economically crucial and environmentally friendly. Furthermore, azo dyes are usually added in order to fabricate anticounterfeiting paper, which further increases the complexity of the pulp and paper wastewater. This work may offer a better understanding of biohydrogen production from xylose in the presence of azo dyes and provide a promising energy-recycling method for treating pulp and paper wastewater, especially for those containing azo dyes.
✓ 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）