American Journal of Agricultural and Biological Sciences

A Thermostable α-Amylase Producing Natural Variant of Bacillus spp. Isolated From Soil in Iran

Iraj Rasooli, Shakiba D. A. Astaneh, Hojjat Borna and Kamal A. Barchini

DOI : 10.3844/ajabssp.2008.591.596

American Journal of Agricultural and Biological Sciences

Volume 3, Issue 3

Pages 591-596


Thermophilic processes appear more stable, rapid and less expensive and facilitate reactant activity and product recovery. Amylases have a quarter of the world enzyme market and thermostable a-amylases possess extensive commercial applications. Since little work has been done on strain isolation, growth and enzyme yield optimization, the level of thermophilic enzyme production remains relatively low. Therefore, large scale exploitation of thermophiles requires further intensive and integrated work. The present study describes isolation of an α-amylase producing bacillus from soil. The isolated bacillus was identified and named as Bacillus licheniformis Shahed-07. The strain was cultured in liquid media to produce α-amylase. The enzyme production conditions of the newly isolated bacillus revealed that the maximum enzyme production after 26 h of cultivation at pH 7.0 and 50°C. 0.5% tryptophan in production medium enhanced the enzyme productivity to two fold whereas peptone and lysin at 0.5% level showed a strong repression. Crude α-amylase characterization revealed that optimum activity was at pH 7.5 and 70°C. The crude enzyme was stable for 24 h at pH range of 6-7 at 70°C. Enzyme activity increased with temperature within the range of 40-70°C. The Bacillus licheniformis Shahed-07 strain produced thermostable α-amylase with characteristics suitable for application in starch processing and food industries.


© 2008 Iraj Rasooli, Shakiba D. A. Astaneh, Hojjat Borna and Kamal A. Barchini. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.