Starches from different sources hydrolysis using a new thermo-tolerant amylase complex produced by Bacillus subtilis T41a: Characterization and efficiency evaluation

Bacillus subtilis T41a, an amylase-producing bacterium, was isolated from wheat phylosphere. The optimum catalytic activity and affinity toward different starch types hydrolysis were studied. Response surface methodology was applied to investigate the optimum catalytic conditions. The results indicated that the optimum conditions for enzyme activity were 58 degrees C and pH 7.2. The enzyme complex was thermostable, retaining almost 50% of its original activity after being kept at 60 degrees C for 1.5 h. Furthermore, the temperature stability test showed that it was stable at 40 degrees C for 48 h. Moreover, it was quite stable in a wide pH range of 5-9. Also, the enzyme efficiency in hydrolysing different starches was demonstrated more affinity toward potato starch. The hydrolysis rate recorded over 9 h for 10% substrate concentration of potato, corn and wheat starches were 41, 39 and 38% respectively. AFM images of hydrolyzed starches established similar pattern for potato and corn starches while different surficial morphology in case of wheat starch has been observed. Hence, the B. subtilis T41a amylase complex, as a thermo-tolerant amylase with a good ability to hydrolyze starch can be considered as an interesting and economical candidate for industrial application.