title: Halotolerant, acid-alkali stable, chelator resistant and raw starch digesting α-amylase from a marine bacterium Bacillus subtilis S8-18.
abstract: A halotolerant α-amylase having the ability of digesting the insoluble raw starches was characterized from Bacillus subtilis S8-18, a marine sediment isolate from Palk Bay region. The electrophoresis techniques unveiled that the α-amylase was indeed a monomer with a molecular weight of 57 kDa. The optimum temperature and pH for the enzyme activity were 60 °C and 6.0 respectively. The enzyme was highly stable for 24 h over a wide range of pH from 4.0 to 12.0 by showing 84-94% activity. Interestingly, by retaining 72% activity even after 24 h, the enzyme also showed tolerance towards 28% NaCl. The α-amylase retained a minimum of 93% residual activity in 1 mM concentration for the selected divalent metal ions. The enzyme was found to be chelator resistant as it remained unaffected by 1 mM of EDTA and exhibited 96% activity even at 5 mM concentration. Furthermore, though 1% SDS caused remarkable reduction (68%) in amylase activity, the enzyme showed tolerance towards other detergents (1% of Triton-X and Tween 80) with 85% activity. Additionally, the α-amylase enzyme is capable of hydrolyzing the insoluble raw starch substrates which was evident from the scanning electron microscopic (SEM) and spectrophotometric analyses.
authors.affiliation: Department of Biotechnology, Alagappa University, Karaikudi 630 003, Tamil Nadu, India.
authors.forename: Balu Jancy
authors.initials: BJ
authors.lastname: Kalpana
authors.forename: Shunmugiah Karutha
authors.initials: SK
authors.lastname: Pandian
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013213:Starch; D000516:alpha-Amylases
keywords: Alpha-amylase; Bacillus subtilis; Characterization; Halotolerant; Raw starch