Optimization of Production Conditions and Partial Characterization of Extracellular Amylase from Bacillus Subtilis under Submerged Condition

alpha-amylases are one of the most important enzymes used in industries. Bacterial amylases have potential application in food, fermentation, textiles and paper industries. Considering these facts the present study was designed to isolate and screen amylase producing bacteria from soil followed by optimizing physiological conditions for enhanced bacterial growth and amylase production. Garden soil was collected and grown on starch plates and the zone of starch hydrolysis was noted. Among 10 isolates, SS4 isolate showing maximum amylase activity was characterized microscopically and biochemically. Based on these results SS4 isolate was confirmed as Bacillus subtilis. Effect of various factors such as pH (4-10), temperature (20-45 degrees C), incubation period (24-48 hours) and starch concentration (0.2-1.2%) on growth and amylase production was studied. B. subtilis showed maximum growth after 48 hours of incubation, at pH 8 and temperature 37 degrees C in 1% starch containing liquid media. The optimum temperature for amylase production was found to be 37 degrees C. B. subtillis showed maximum amylase activity (1.2 +/- 0.09 U/mg protein) when cultured at pH 8.0. Amylase production occurred in 0.2-1.2% of starch containing media with a maximum at 1% (1.32 +/- 0.09 U/mg protein) after 48 hours of incubation. Amylase was purified and 48 kDa protein was found in SDS polyacrylamide gel electrophoresis.