A highly thermostable and alkaline amylase from a Bacillus sp. PN5

A highly thermostable alkaline amylase producing Bacillus sp. PN5 was isolated from soil, which yielded 65.23 U mL−1 of amylase in medium containing (%) 0.6 starch, 0.5 peptone and 0.3 yeast extract at 60 °C, pH 7.0 after 60 h of incubation. Maximum amylase activity was at pH 10.0 and 90 °C. The enzyme retained 80% activity after 1 h at pH 10.0. It exhibited 65% activity at 105 °C and had 100% stability in the temperature range between 80 and 100 °C for 1 h. In addition, there was 86.36% stability after 1-h incubation with sodium dodecylsulphate. These properties indicated possible use of this amylase in starch saccharification and detergent formulation.