Isolation, Identification and Production of Amylases from Thermophilic Spore Forming Bacilli Using Starch Raw Materials Under Submerged Culture

Abstract

Out of 133 amylase producing bacterial isolates, two isolates were selected, which gave the highest values of starch hydrolysis ratio (SHR) on agar plates ranged from 2.80 to 3.06 and α-amylase activity in broth medium ranged from 73.5 to 77.0 Uml-1 after 48 h at 50°C were recorded by B85 and B87. These isolates were identified based on phenotypic characteristics and confirmed by 16S rRNA gene analysis (genotypic characterizes), the isolates B85 and B87 were identified as Bacillus megaterium and B. licheniformis, respectively. The results also showed both strains achieved the highest growth and amylases activity during 10 – 24 h and 18 - 24 h incubation periods, respectively. Corn starch and broken rice proved to be the best carbon sources for the production of the highest enzymes by B. megaterium and B. licheniformis at 2% concentration, respectively. 0.44 gL-1 ammonium sulphate and 3.65 gL-1 corn steep liquor were the best nitrogen concentration for amylases activity by B. megaterium and B. licheniformis, respectively. The increase of enzymes activity for α-amylase about 2.9-fold, β-amylase about 18.5 &15.6-fold and γ-amylase about 3.8 & 23.9-fold on modified medium, as compared with basal medium for B. megaterium and B. licheniformis, respectively.