Isolation and screening of amylase producing thermophilic spore forming Bacilli from starch rich soil and characterization of their amylase activities using submerged fermentation

Use of thermostable amylases from bacilli for industrial application is significant. The search for such thermostable amylases from bacilli in starch rich soil was the objective of this study. Amylase producing bacilli were isolated and their enzymes were also characterized. Effect of temperature, pH, substrate and salt concentration on amylases activity were determined. All amylases produced by different isolates were hydrolyzed greater than 90% of starch after 60 h of fermentation. There was no significant (P ≥ 0.05) variation in enzyme productivity along with fermentation time. Amylase producing isolates were designated as A1, A2 and A3. Aamylases activities of all isolates were reached their optimum at 60oC. Amylases from isolate A1, A2 and A3 were shown hydrolysis capacity of 96.59%, 97.39% and 97.78% of starch, respectively. The optimum enzyme activity of amylase from A2 isolate was extended from pH 7 to 8 with starch hydrolysis efficiency of 99.25% but other isolates enzyme activity reaches 100% at pH 8. Thermal and pH stability of all amylases were retained above 91%. Amylases of this finding with thermophilic, alkalophilic and halophlic characterstics have wide range of huge potnetial for industrial applications.