Isolation, Purification and Characterization of Thermostable alpha-amylase Enzyme from Bacillus TULH

摘要

This research reported the isolation, purification and characterization of thermostable alpha-amylase enzyme from Bacillus TULH. Studies on the a-amylase production were carried out with a bacterial strain isolated from a hot water spring of gir national forest. The addition of yeast extract, Mgso(4), Vitamins and amino acids to the mineral medium shortened the lag period and improved the growth and a-amylase synthesis. The bacteria showed optimum growth at pH 6.8 and optimum temperature for the growth at 70 degrees C. The optimal pH and temperature of the amylase activity were 6.8 and 68 degrees C, respectively. The enzyme was found to be stable in the pH range of 5 to 8. Maximum a-amylase activity was determined in 2% starch. The enzyme was purified using 60% ammonium sulphate precipitation, dialysis and DEAE cellulose ion exchange chromatography which resulted in 11.1 fold purity with specific activity of 9.40 units/mg protein/ml. SDS-PAGE showed a single band equal to molecular weight of about 67 kDa which is equivalent to microbial amylases. The activity of the purified a-amylase increased with increasing enzyme concentration and incubation time.