title: A novel beta-mannanase with high specific activity from Bacillus circulans CGMCC1554: gene cloning, expression and enzymatic characterization.
abstract: A DNA fragment of 2,042 bp containing a novel beta-mannanase gene, man5A, was identified from the genome of the mannan-degrading bacterium Bacillus circulans CGMCC1554. The open reading frame of man5A comprised 978 bp encoding a protein of 326 amino acids with a predicted molecular weight of 32 kDa. The amino acid sequence of the encoded mannanase, MAN5A, showed the highest identity (78.5%) to beta-mannanases belonging to glycosyl hydrolases family 5. The gene man5A was efficiently expressed in Escherichia coli and Pichia pastoris with the highest activity of 541 U/ml in a 3-L fermenter. Recombinant MAN5A purified from E. coli had a high specific activity of 4,839 U/mg, which is much higher than that of enzymes that showed high sequence identity. The enzyme showed maximum activity at pH 7.6 and 60 degrees C and resistance to trypsin. After hydrolysis of LBG, oligomannosides accounted for 76% of the hydrolysis products. All these properties collectively make MAN5A a better candidate than current mannanases for use in the food and feed industry.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Yanan
authors.initials: Y
authors.lastname: Li
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Yuan
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Bai
authors.forename: Zhichun
authors.initials: Z
authors.lastname: Zhan
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D001407:Bacillus / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004795:Enzyme Stability; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D044902:beta-Mannosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D044902:beta-Mannosidase