As a result of screening Bacillus sp. strains isolated from different natural substrates, strain BKL20 was identified as a producer of a thermostable alkaline α-amylase. Maximum production of this α-amylase was achieved by optimizing culture conditions. Production of α-amylase seemed to be independent of the presence of starch in the culture medium and was stimulated by the presence of peptone (0.3%, m/v) and yeast extract (0.2%, m/v). The enzyme was thermostable and retained amylolytic activity after 30 min of incubation at 60 and 70 8C. High activity was maintained over a broad pH range, from 6.0 to 11.0, and the enzyme remained active after alkaline incubation for 24 h. Bacillus sp. BKL20 α-amylase was not stimulated by Ca2+ or other bivalent metal cations and was not inhibited by EGTA or EDTA at 1-10 mmol/L, suggesting that this α-amylase is a Ca2+-independent enzyme. It also showed good resistance to both oxidizing (H2O 2) and denaturating (urea) agents.

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Canadian Journal of Microbiology
Department of Biology

Kubrak, O.I. (Olha I.), Storey, J, Storey, K, & Lushchak, V.I. (Volodymyr I.). (2010). Production and properties of α-amylase from Bacillus sp. BKL20. Canadian Journal of Microbiology, 56(4), 279–288. doi:10.1139/W10-014