Physiological Characteristics of Bacillus sp. HR6 in the Process of Decomposing Bean Curd Refuse

Abstract

Bacillus sp. HR6 and Bacillus subtilis ATCC6051 were compared in terms of their growth, activity of α -amylase, and pattern of heat evolution. Bacillus sp. HR6 grew faster than B. subtilis ATCC6051 at temperatures higher than 45 °C. The maximum activities of α -amylase were 304 and 280 U/ml for Bacillus sp. HR6 and B. subtilis ATCC6051, respectively. The highest activity of α-amylase from Bacillus sp. HR6 was observed at 70 °C, and more than 60% of that was still seen at 75 °C. In case of B. subtilis ATCC6051, the maximum activity was observed at 65 °C, and 30% of that was seen at 75 °C. A rapid heat evolution was found for Bacillus sp. HR6 in comparison with that for B. subtilis ATCC6051 when cultivation was initiated in bean curd refuse at 50 °C. However, there was no obvious difference in the heat evolution patterns between two strains at the starting temperature of 27 °C. These results suggest that Bacillus sp. HR6 has a higher activity in decomposing bean curd refuse than B. subtilis ATCC6051 at higher temperatures.