Alpha amylase production by a native thermophilic strain Bacillus licheniformis-AZ2 isolated from Qinarje Hot spring in Ardebil Province

Abstract

Thermophilic microorganisms are the main sources of valuable thermostable hydrolytic enzymes hence they have very importance in different industries. In comparison with other amylolytic enzymes, application of alpha amylase in starch processing industries, fermentation and carbohydrate products is a great importance and they could also be substituted with chemical hydrolysis of starch in industries. Determination of optimal conditions for thermostable α-amylase production by native strain Bacillus licheniformis was the aim of this study. Bacillus licheniformis strain has been isolated from Qinarje Hotspring (Ardebil Prov.) recently which have been identified and registered as the name of Bacillus licheniformis-AZ2 in bacterial collection of agricultural biotechnology department of Bu-Ali Sina University. In this article, possibility of the amylolytic activity of this microorganism has been evaluated using Gram’s iodine staining method. Results showed that maximum growth rate and also amylase production in basal medium conditions which was inoculated with 1% (V/V) inoculums achieved at 40˚C and pH=9, 84 hours after inoculation. Amylase assay also showed that the optimum enzyme activity was achieved at 80˚C and pH=7, so this enzyme has been considered to be thermostable. Our results showed that Bacillus licheniformis-AZ2 strain produced thermostable α-amylase with characteristics suitable for application in starch processing and other food industries.

Keywords

• bacillus licheniformis- thermostable α-amylase
• optimization
• production medium