Effect of cultivation conditions on growth and α-amylase production by a thermophilic Bacillus sp.

Growth and amylase production by Bacillus sp. WN11 was studied under different cultivation conditions. Maximum growth was observed at 65 degrees C while the highest amylase production was recorded at 55 degrees C. Good amylase production and growth was observed at an initial medium pH of 5 and 6. No detectable growth was observed at pH 4 and 9. The organism grew better and produced higher levels of amylase activity using proteose peptone and tryptone as nitrogen sources. No growth was observed when NO3+, NH4+ and urea were used as nitrogen sources. Among defined carbohydrates, tested starch and maltose supported good growth and amylase production, with the highest productivity recorded in the presence of starch (24 U/ml). Compared to starch, barley and corn flour resulted in maximum amylase production.