title: Screening, Gene Cloning, and Characterizations of an Acid-Stable α-Amylase.
abstract: Based on its α-amylase activity at pH 5.0 and optimal pH of the crude enzyme, a strain (named B-5) with acid α-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 α-amylase gene of GenBank Accession No. GU318401 was cloned and expressed in Escherichia coli. The purified recombinant α-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 α-amylase AMY-Ba in this work was a different type from the well-investigated J01542 (GenBank Accession No.)-type α-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.
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai 201403, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jia
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: An
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Kun
authors.initials: K
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Mingdao
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Sen
authors.initials: S
authors.lastname: Yang
authors.affiliation: Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture, College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, P.R. China.
authors.forename: Hongge
authors.initials: H
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D015373:Bacterial Typing Techniques; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005820:Genetic Testing; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008320:Maltose / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013213:Starch / Q000378:metabolism; D000516:alpha-Amylases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D011994:Recombinant Proteins; D008320:Maltose; D013213:Starch; D000516:alpha-Amylases; D005947:Glucose