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( Chengbo Zhang ),( Bo Xu ),( Zunxi Huang ),( Tao Lu ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.8
To investigate the diversity of gastrointestinal microflora and lignocellulose-degrading enzymes in wild Asian elephants, three of these animals living in the same group were selected for study from the Wild Elephant Valley in the Xishuangbanna Nature Reserve of Yunnan Province, China. Fresh fecal samples from the three wild Asian elephants were analyzed by metagenomic sequencing to study the diversity of their gastrointestinal microbes and cellulolytic enzymes. There were a high abundance of Firmicutes and a higher abundance of hemicellulose-degrading hydrolases than cellulose-degrading hydrolases in the wild Asian elephants. Furthermore, there were a high abundance and a rich diversity of carbohydrate active enzymes (CAZymes) obtained from the gene set annotation of the three samples, with the majority of them showing low identity with the CAZy database entry. About half of the CAZymes had no species source at the phylum or genus level. These indicated that the wild Asian elephants might possess greater ability to digest hemicellulose than cellulose to provide energy, and moreover, the gastrointestinal tracts of these pachyderms might be a potential source of novel efficient lignocellulose-degrading enzymes. Therefore, the exploitation and utilization of these enzyme resources could help us to alleviate the current energy crisis and ensure food security.
JunPei Zhou,Yanyan Dong,Yajie Gao,Xianghua Tang,Junjun Li,YUN-JUAN YANG,Bo Xu,Zhenrong Xie,Zunxi Huang 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4
The 774-bp pectate lyase gene plyAI4 from Bacillus sp. I4 was cloned and expressed in E. coli. The gene encodes a 257-residue polypeptide (PlyAI4, 28.3 kDa)with the highest identities of 97.3% with a putative pectate lyase from Bacillus subtilis BSn5 (ADV94306) and 60.3%with an identified pectate lyase of the polysaccharide lyase family (PL) 3 from Paenibacillus amylolyticus 27C64(ADB78774). The purified recombinant PlyAI4 (rPlyAI4)exhibited apparently optimal activity at pH 10.5 ~ 11.0 and 50oC. Compared with the majority of reported alkaline pectate lyases, rPlyAI4 exhibited more residual enzyme activity at 20oC (~45%) or at 70oC (~50%) and better thermostability at 70oC (~60 min half-life at 70oC). In the presence of 20% (v/v) ethanol, pectate lyase activity was enhanced by 0.2 fold. After incubation in 40% (v/v)ethanol at 37oC and pH 8.5 for 1 h, the purified rPelAI4retained more than 75% of the initial activity. Sequence analysis proposed a new signature block, A-D-G-[V/I]-H,for PL 3 pectate lyases. These properties may prove to be important with regards to PlyAI4 for basic research and industrial application.
( Tingting Yu ),( Junmei Ding ),( Qingxia Zheng ),( Nanyu Han ),( Jialin Yu ),( Yunjuan Yang ),( Junjun Li ),( Yuelin Mu ),( Qian Wu ),( Zunxi Huang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.4
est19 is a gene from Bacillus sp. K91 that encodes a new esterase. A comparison of the amino acid sequence showed that Est19 has typical Ser-Gly-Asn-His (SGNH) family motifs and could be grouped into the SGNH hydrolase family. The Est19 protein was functionally cloned, and expressed and purified from Escherichia coli BL21(DE3). The enzyme activity was optimal at 60°C and pH 9.0, and displayed esterase activity towards esters with short-chain acyl esters (C2-C6). A structural model of Est19 was constructed using phospholipase A1 from Streptomyces albidoflavus NA297 as a template. The structure showed an α/β-hydrolase fold and indicated the presence of the typical catalytic triad Ser49-Asp227-His230, which were further investigated by site-directed mutagenesis. To the best of our knowledge, Est19 is a new member of the SGNH hydrolase family identified from thermophiles, which may be applicable in the industrial production of semisynthetic β-lactam antibiotics after modification.
( Xianghua Tang ),( Tianbao Luo ),( Xue Li ),( Huanhuan Yang ),( Yunjuan Yang ),( Junjun Li ),( Bo Xu ),( Zunxi Huang ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.11
Enhanced application of solid-state fermentation (SSF) in industrial production and the influence of SSF of Rhizopus K1 on glucoamylase productivity were analyzed using the flat band method. A growth model was implemented through SSF of Rhizopus K1 in this experiment, and spectrophotometric method was used to determine glucoamylase activity. Results showed that in bran and potato culture medium with 70% moisture in a loose state, μ of mycelium reached to 0.15 h<sup>-1</sup> after 45 h of culture in a thermostatic water bath incubator at 30°C. Under a low-magnification microscope, mycelial cells appeared uniform, bulky with numerous branches, and were not easily ruptured. The generated glucoamylase activity reached to 55 U/g (dry basis). This study has good utilization value for glucoamylase production by Rhizopus in SSF.