EXTRACELLULAR ENZYME PRODUCTION BY INDIGENOUS THERMOPHILIC BACTERIA: PARTIAL PURIFICATION AND CHARACTERIZATION OF α-AMYLASE BY BACILLUS SP WA21

Thermostability is a characteristic of most of the enzymes available for bulk industrial usage. Thermophilic microorganisms are of special interest as a source of novel thermostable enzymes. A total of 50 bacterial strains, isolated from local hot springs and ash samples were screened for the extracellular enzyme production including amylase, lipase, esterase, cellulase and beta-galactosidase. As a follow up, studies on alpha-amylase were carried out with a bacterial strain identified as Bacillus sp. WA21 (from hot spring) on the basis of maximum zone of starch hydrolysis in agar plate medium. Bacillus WA21 showed growth over a wide range of temperature (35-55 degrees C) and pH (3-11) with optimum being 45 degrees C and pH 6. Maximum enzyme production was observed after 144 hours. The enzyme was found optimally active at 55 degrees C and pH 6. Temperature stability profile revealed that enzyme alpha-amylase retained more than half of its activity at 85 degrees C and between pH 5-9. Thus, Bacillus WA21 may be regarded as a promising source of a- amylase for biotechnological and industrial applications.