Production and properties of the raw starch-digesting alpha-amylase of Bacillus sp IMD 435

Bacillus sp. IMD 435 produced a raw starch-digesting but non-raw starch-ads orbing alpha-amylase. Maximum amylase yield was achieved in a medium contai ning lactose (4%, w/v) as the carbon source and yeast extract (2%, w/v) as the nitrogen source. Although highest amylase yields were achieved with lac tose, the biomass levels were notably less than those with starch or beta-c yclodextrin. The enzyme was purified in a single step using an alpha-cyclod extrin (CD) Sepharose 6B column, it had an M-r of 63 000 and displayed maxi mum activity at pH 6.0 and 65 degrees C. Glucose and maltose were released as the main end-products on hydrolysis of both soluble starch and raw corn starch. (C) 1999 Elsevier Science Ltd. All rights reserved.