一株产常温葡甘聚糖酶的芽孢杆菌的分离、鉴定及产酶发酵条件的研究

Study on Isolation and Identification of a Bacillus Strain Producing Normal Temperature Glucomannase and Fermentation Conditions for Enzyme Production

以魔芋生粉为唯一碳源的筛选培养基,从魔芋废渣中分离筛选出一株可以降解魔芋生粉的细菌菌株,编号为LS-6。根据16SrDNA序列和生理生化特性,将该菌株鉴定为枯草芽孢杆菌Bacillus subtilis。胞内外葡甘露聚糖酶酶活分析结果表明,LS-6产生的葡甘聚糖酶为胞外酶。LS-6产生葡甘聚糖酶的最佳培养基组分和条件是:1%魔芋生粉,0.5%酵母粉,0.5%NaCl,培养基初始pH为6.0,最佳发酵条件是25℃,摇床转速200r/min,培养48h。酶解产物的高效液相色谱分析结果表明,LS-6粗酶液的酶解产物主要为葡萄糖和甘露糖。LS-6的分离为进一步克隆常温葡甘聚糖酶基因和产酶工程菌的构建奠定了基础。

A bacterial strain degrading raw konjac flour, numbered LS-6, was isolated from waste konjac residues on the isolation media plate with raw konjac flour as a single carbon source. By analyses of 16S rDNA sequence, and physiological and biochemical characteristics, LS-6 was identified as Bacillus subtilis. As a result of analyses of extra and intra cellular glucomannanase, the glucomannase produced by LS-6 belongs to the extracellular enzyme. The optimum components for production of the glucomannase by this strain were 1% raw konjac flour as carbon source, 0.5% Yeast extract as nitrogen source, 0.5% NaCl, initial pH 6.0 for the medium, and that the optimum fermentation conditions was for 48 h at 25℃ at 200 r/min. Analysis from high performance liquid chromatography indicated that major enzymatic products of raw konjac flour by crude glucomannanase produced by fermentation with LS-6 included glucose and mannose. The isolation of LS-6 lays a foundation for further cloning of room-temperature glucomannanase as well as construction of engineering bacteria producing the enzyme.