Culture conditions for the production of thermostable amylase by Bacillus sp

RESUMO

Studies on the alfa-amylase production were carried out with a bacterial strain isolated from a soil sample. The cells were cultivated in a mineral medium containing soluble starch as sole carbon source. The addition of calcium (10 mM) or peptone 1(per cent) and yeast extract 0.5(per cent) to the mineral medium shortened the lag period and improved the growth and alfa-amylase synthesis. The addition of glucose to the culture diminished greatly the synthesis of alfa-amylase, demonstrating that a classical glucose effect is operative in this organism. The optimum temperature and initial medium pH for amylase synthesis by the organism were 50ºC and 7.0 respectively. The optimal pH and temperature for activity were 6.0 and 50ºC respectively. The enzyme extract retained 100 per cent activity when incubated for one hour at 90ºC and 40(per cent) at 60ºC for 24 h. The addition of glucose to the culture diminished greatly the synthesis of alfa-amylase.