A novel cold-adapted beta-galactosidase from Alteromonas sp. ML117 cleaves milk lactose effectively at low temperature

文献类型： 外文期刊

第一作者： Yao, Congyu

作者： Yao, Congyu;Sun, Jingjing;Wang, Wei;Liu, Junzhong;Hao, Jianhua;Yao, Congyu;Sun, Jingjing;Wang, Wei;Liu, Junzhong;Hao, Jianhua;Zhuang, Zhiwei;Hao, Jianhua

作者机构：

关键词： Alteromonas; Cold-adapted enzyme; beta-galactosidase; Enzyme properties; Lactose hydrolysis

期刊名称：PROCESS BIOCHEMISTRY （ 影响因子：3.757； 五年影响因子：3.665 ）

ISSN： 1359-5113

年卷期： 2019 年 82 卷

页码：

收录情况： SCI

摘要： A novel beta-galactosidase gene (Bgal) was cloned from the marine bacterium Alteromonas sp. ML117. Bgal from Alteromonas sp. ML117 was heterologously expressed in Escherichia coli BL21 (DE3) cells to study the enzymatic properties of the recombinant beta-galactosidase. Using gel-filtration chromatography and SDS-PAGE, the recombinant enzyme was identified to be a tetrameric enzyme that belonged to the glycoside hydrolase family GH2. The purified recombinant Bgal was able to hydrolyze lactose and o-nitrophenyl-beta-D-galactopyranoside (ONPG), and showed maximum activity at pH 8.0 and 30 degrees C to hydrolyze ONPG and at 35 degrees C to hydrolyze lactose. The enzyme's activity level quickly diminished when incubated at 35 degrees C, suggesting that it was a cold-adapted variant. At 10 degrees C, the purified enzyme had K-m values of 1.6 mM for ONPG and 3.8 mM for lactose. The enzyme tolerated NaCl, and retained 80% of its activity in a 30% ethanol reaction system. In addition, the recombinant Bgal hydrolyzed 86% of the lactose from milk over 24 h at 10 degrees C. Taken together, this study identified a recombinant Alteromonas sp. ML117 beta-galactosidase that may be used for industrial applications.

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