Isolation and identification of a strain producing cold-adapted beta-galactosidase, and purification and characterisation of the enzyme

文献类型： 外文期刊

第一作者： Liu, Wen-yu

作者： Liu, Wen-yu;Shi, Ying-wu;Wang, Xin-qin;Wang, Yun;Lou, Kai;Liu, Wen-yu;Wei, Chang-qing;Wang, Xin-qin

作者机构：

关键词： psychrotrophic microorganism;cold-adapted beta-galactosidase;lactose hydrolysis

期刊名称：CZECH JOURNAL OF FOOD SCIENCES （ 影响因子：1.279； 五年影响因子：1.829 ）

ISSN： 1212-1800

年卷期： 2008 年 26 卷 4 期

页码：

收录情况： SCI

摘要： Enzymes with high specific activities at low temperatures have potential uses in the food industry. Cold-adapted microorganisms are potentially useful sources of cold-active enzyme. To find cold-adapted P-galactosidase, we isolated several cold-adapted microorganisms from glacier zone soil. One cold-adapted P-galactosidase producing strain was obtained. The biochemical characteristics and the results of 16S rDNA sequencing identified the strain as Rahnella aquatilis. The enzyme was purified by column chromatography after which a single protein band migrating near 60 kDa was observed by means of SDS-PAGE. The beta-galactosidase was optimally active at 35 degrees C and at pH 6.5 when assayed with o-nitrophenyl-beta-D-galactopyrano-side as substrate. The enzyme activity was sensitive to temperatures above 40 degrees C and was undetectable at 45 degrees C. Metal ions Mn2+ and K+ activated the enzyme while Cu2+, Zn2+, Fe3+, and Al3+ inhibited the activity. The enzyme was also assayed for lactose hydrolysis. When milk is treated with the enzyme at 30 degrees C for 2 h, the degree of lactose hydrolysis can reach 80%. It has, thus, potential applications in the food industry.

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