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Ge Z.,Key Laboratory of Industrial Fermentation Microbiology | Mao S.,Tianjin Key Laboratory of Industrial Microbiology | Li Y.,Tianjin University of Science and Technology | Liu X.,Tianjin Key Laboratory of Industrial Microbiology | Lu F.,Tianjin Key Laboratory of Industrial Microbiology
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2014

In order to discover the steroid biotransformation ability of filamentous fungus Aspergillus niger TCCC41650, we studied the fermentation of 4-androstene-3,17-dione with A. niger TCCC41650. The transformation product was purified, crystallized and determined as 16β-hydroxy-androst-4-ene-3,17-dione by X-ray single crystal diffraction method. The best fermentation condition was found to be pH 6.0, ethanol amount 2% with a substrate concentration of 1‰, the transformation rate is 85.81% after 72 h. Based on the best of our knowledge, 16β-hydroxylation rarely occurs in microbial transformations of steroid. This study laid the foundation for the research of 16β-hydroxylation steroids. © 2014 by the Institute of Microbiology, the Chinese Academy of Sciences and the Chinese Society for Microbiology Source

Liu Y.H.,Key Laboratory of Industrial Fermentation Microbiology | Liu Y.H.,National Engineering Laboratory for Industrial Enzymes | Liu Y.H.,Tianjin University of Science and Technology | Hu B.,Key Laboratory of Industrial Fermentation Microbiology | And 11 more authors.
Journal of Applied Microbiology | Year: 2012

Aims: The purpose of this research was to obtain the mutant of Bacillus licheniformis alpha amylase (BLA) with an improved acid stability and elucidate the difference in catalytic mechanism under acidic conditions between wild-type and mutant BLAs. Methods and Results: The stability of BLA under acid condition was enhanced through direct evolution using error-prone polymerase chain reaction. Two mutation sites, T353I and H400R, were obtained in BLA. To identify the mutation of amino acids in Thr353Ile/His400Arg related to its acid stability, single mutants Thr353Ile and His400Arg were obtained via site-directed mutagenesis. Among the resulting mutant enzymes, the kcat/Km values of the mutants Thr353Ile, His400Arg and Thr353Ile/His400Arg under pH 4·5 were 3·5-, 6·0- and 11·3-fold higher, respectively, than that of the wild-type. Thr353Ile/His400Arg exhibited stronger tolerance towards a lower pH without obvious difference in thermostability when compared with wild-type. Conclusions: The results combined with three-dimensional structure analysis of mutant BLAs demonstrated that Thr353Ile/His400Arg showed an improved acid stability under low pH condition as a result of the interactions of hydrogen bonding, hydrophobicity, helix propensity and electrostatic fields. Significance and Impact of Study: It provides theoretical basis and background data for the improvement of acid stability in BLA by protein engineering. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology. Source

Zheng H.,Key Laboratory of Industrial Fermentation Microbiology | Zheng H.,Tianjin University of Science and Technology | Liu Y.,Key Laboratory of Industrial Fermentation Microbiology | Liu Y.,Tianjin Key Laboratory of Industrial Microbiology | And 9 more authors.
Journal of Microbiology and Biotechnology | Year: 2012

High levels of xylanase activity (143.98 IU/ml) produced by the newly isolated Paenibacillus campinasensis G1-1 were detected when it was cultivated in a synthetic medium. A thermostable xylanase, designated XynG1-1, from P. campinasensis G1-1 was purified to homogeneity by Octyl-Sepharose hydrophobic-interaction chromatography, Sephadex G75 gel-filter chromatography, and Q-Sepharose ion-exchange chromatography, consecutively. By multistep purification, the specific activity of XynG1-1 was up to 1,865.5 IU/mg with a 9.1-fold purification. The molecular mass of purified XynG1-1 was about 41.3 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Sequence analysis revealed that XynG1-1 containing 377 amino acids encoded by 1,134 bp genomic sequences of P. campinasensis G1-1 shared 96% homology with XylX from Paenibacillus campinasensis BL11 and 77%~78% homology with xylanases from Bacillus sp. YA- 335 and Bacillus sp. 41M-1, respectively. The activity of XynG1-1 was stimulated by Ca 2+, Ba 2+, DTT, and β- mercaptoethanol, but was inhibited by Ni 2+, Fe 2+, Fe 3+, Zn 2+, SDS, and EDTA. The purified XynG1-1 displayed a greater affinity for birchwood xylan, with an optimal temperature of 60°C and an optimal pH of 7.5. The fact that XynG1-1 is cellulose-free, thermostable (stability at high temperature of 70°C~80°C), and active over a wide pH range (pH 5.0~9.0) suggests that the enzyme is potentially valuable for various industrial applications, especially for pulp bleaching pretreatment. © The Korean Society for Microbiology and Biotechnology. Source

Chen K.,Tianjin University of Science and Technology | Liang N.,Medical Institute | Luo X.,Tianjin University of Science and Technology | Luo X.,Tianjin Key Laboratory of Industrial Microbiology | And 2 more authors.
Journal of Microbiology and Biotechnology | Year: 2013

Previous studies have shown that lactic acid bacteria can inhibit inflammatory responses, but the mechanisms are very little known. In this study, transaction and expression of three proinflammatory factors, iNOS, PTGS-2, and IL8, which are closely related to the inflammatory response, were investigated by luciferase reporter assay and RT-PCR in HT-29 cells treated by Lactobacillus acidophilus. The results showed that the live L. acidophilus sharply down-regulated the transcription of these three genes. Because there was a NF-κB binding site located at-265 bp,-225 bp, and-95 bp upstream of the iNOS, PTGS-2, and IL8 promoters, respectively, we further addressed the effects of NF-κB on transaction of the three promoters by cotransfection. As was expected, NF-κBs remarkably up-regulated the activity of the reporter gene and, no effect of NF-κBs on IL-8 promoter transaction was found after NF-κB binding site mutation of the IL8 promoter in HT-29 cells. In conclusion, the live L. acidophilus decreased the transcriptional activity of NF-κB and, in turn, inhibited the transaction of NF-κB on the three proinflammatory factors mentioned above.© the Korean Society for Microbiology and Biotechnology. Source

Wei Q.,Tianjin University of Science and Technology | Wei Q.,Laboratory of Industrial Fermentation Microbiology | Wang H.,Tianjin University of Science and Technology | Wang H.,Laboratory of Industrial Fermentation Microbiology | And 12 more authors.
Applied Microbiology and Biotechnology | Year: 2013

Soy sauce is a traditional condiment manufactured by natural inoculation and mixed culture fermentation. As is well known, it is the microbial community that plays an important role in the formation of its flavors. However, to date, its dynamic changes during the long period of fermentation process are still unclear, intensively constraining the improvement and control of the soy sauce quality. In this work, we revealed the dynamic changes of the microbial community by combining a cultured dependent method and a cultured independent method of polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis. Results indicated that the two methods verified and complemented each other in profiling microbial community, and that significant dynamics of the microbial community existed during the fermentation process, especially the strong inhibition of the growth of most of the microbes when entering into the mash stage from the koji stage. In the analysis of bacterial community, Staphylococcus and Bacillus were found to be the dominant bacteria and detected in the whole fermentation process. Kurthia and Klebsiella began to appear in the koji stage and then fade away in the early stage of the mash fermentation. In the analysis of fungal community, Aspergillus sojae and Zygosaccharomyces rouxii were found to be the dominant fungi in the koji and mash fermentation, respectively. It was clearly shown that when A. sojae decreased and disappeared in the middle stage of the mash fermentation, Z. rouxii appeared and increased at the meantime. Aspergillus parasiticus, Trichosporon ovoides and Trichosporon asahii also appeared in the koji and the early period of the mash fermentation and disappeared thereafter. Similar to Z. rouxii, Millerozyma farinosa and Peronospora farinosa were also found spontaneously which appeared in the mid-late period of the mash fermentation. The principal component analysis suggested that the microbial community underwent significant changes in the early period of the fermentation and, thereafter, tended to the stabilization in the mid-late periods. This study gave us important clues to understand the fermentation process and can serve as a foundation for improving the quality of soy sauce in the future. © 2013 Springer-Verlag Berlin Heidelberg. Source

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