KMID : 0545120150250060828
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Journal of Microbiology and Biotechnology 2015 Volume.25 No. 6 p.828 ~ p.836
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Screening, Gene Cloning, and Characterizations of an Acid-Stable ¥á-Amylase
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Xinyu Liu
Wei Jia Yi An Kun Cheng Mingdao Wang Sen Yang Hongge Chen
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Abstract
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Based on its ¥á-amylase activity at pH 5.0 and optimal pH of the crude enzyme, a strain (named B-5) with acid ¥á-amylase production was screened. The B-5 strain was identified as Bacillus amyloliquefaciens through morphological, physiological, and biochemical characteristics analysis, as well as 16S rDNA phylogenetic analysis. Its ¥á-amylase gene of GenBank Accession No. GU318401 was cloned and expressed in Escherichia coli. The purified recombinant ¥á-amylase AMY-Ba showed the optimal pH of 5.0, and was stable at a pH range of 4.0-6.0. When hydrolyzing soluble starch, amylose, and amylopectin, AMY-Ba released glucose and maltose as major end products. The ¥á-amylase AMY-Ba in this work was a different type from the well-investigated J01542 (GenBank Accession No.)-type ¥á-amylase from the same species. AMY-Ba exhibited notable adsorption and hydrolysis ability towards various raw starches. Structure analysis of AMY-Ba suggested the presence of a new starch-binding domain at its C-terminal region.
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KEYWORD
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¥á-amylase, Bacillus amyloliquefaciens, raw starch, starch-binding domain
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