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

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.