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Genome sequence of the psychrophilic Cryobacterium sp. LW097 and characterization of its four novel cold-adapted beta-galactosidases

文献类型: 外文期刊

作者: Wang, Lijun 1 ; Mou, Yuanzhen 1 ; Guan, Bo 1 ; Hu, Youzhen 1 ; Zhang, Yan 1 ; Zeng, Jun 2 ; Ni, Yongqin 1 ;

作者机构: 1.Shihezi Univ, Sch Food Sci & Technol, Shihezi, Peoples R China

2.Xinjiang Acad Agr Sci, Inst Microbiol, Urumqi, Peoples R China

关键词: Cold-adapted beta-galactosidases; Cryobacterium sp.; Psychrophilic bacterium; Cold-adaption; Lactose hydrolysis; Glacier

期刊名称:INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES ( 影响因子:6.953; 五年影响因子:6.737 )

ISSN: 0141-8130

年卷期: 2020 年 163 卷

页码:

收录情况: SCI

摘要: A psychrophilic strain Cryobacterium sp. LW097 was isolated from the subglacial sediments and discovered to show considerable beta-galactosidases activity at low temperatures. To provide access to genes predicted to encode cold-adapted glycoside hydrolases with biotechnological relevance, we have sequenced the genome of Cryobacterium sp. LW097. Annotation with CAZy database revealed four beta-galactosidase genes, bgal322, bgal435, bgal436, and bgal2567 belonging to the GH-42 family and GH-35 family. All the four beta-galactosidases recombinantly expressed retained a high level of relative activity at 5 degrees C and showed different optimum temperatures ranging from 25 degrees C to 40 degrees C. The enzyme kinetics proved that Bgal322, Bgal436, and Bgal2567 had lower K-m to both oNPG and lactose at 5 degrees C, further proving their adaption to low temperature. Substrate specificity analysis showed that these four beta-galactosidases owned different preferences. The novel GH-42 beta-galactosidases Bgal435 showed beta-D-glucosidase activity (33.67 +/- 0.28%) in addition to beta-D-galactosidase activity. Bgal322 preferred beta-D-(1,4)-galactobiose, whereas the other three preferred lactulose. Bgal435 showed the highest k(cat) value of 68.2 +/- 1.7 s(-1) at 5 degrees C toward lactose among these four enzymes. The exquisite substrate specificity of Bgal436 in milk made it a potential candidate for applications in milk lactulose quantification. (C) 2018 Elsevier B.V. All rights reserved.

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