Cell-associated alpha-amylases of butyrate-producing Firmicute bacteria from the human colon.

摘要: Selected butyrate-producing bacteria from the human colon that are related to Roseburia spp. and Butyrivibrio fibrisolvens showed a good ability utilize variety of starches for growth when compared with Gram-negative amylolytic anaerobe Bacteroides thetaiotaomicron. A major cell-associated amylase high molecular mass (140-210 kDa) was detected in each strain by SDS-PAGE zymogram analysis, genes corresponding these enzymes were analysed two representative strains. Amy13B But. 16/4 is multi-domain enzyme 144.6 kDa includes family 13 glycoside hydrolase domain, duplicated 26 carbohydrate-binding modules. Amy13A (182.4 kDa), inulinivorans A2-194, also which preceded repeat units approximately 116 aa rich aromatic residues, an isoamylase N-terminal pullulanase-associated additional unidentified domain. Both have signal peptides C-terminal cell-wall sorting signals, including modified LPXTG motif similar involved interactions cell surface other Gram-positive bacteria, hydrophobic transmembrane segment, basic C terminus. The overexpressed domains absolute requirement Mg2+ or Ca2+ activity, functioned as 1,4-alpha-glucanohydrolases (alpha-amylases; EC 3.2.1.1). These starch-degrading thus appear be anchored wall this important group gut bacteria.