Production of thermotolerant β-amylase byBacillus circulans.

An isolate from a Hong Kong soil sample which produced β-amylase was identified as a thermotolerant strain ofBacillus circulans with a growth range of 35 to 55δC. The β-amylase was stable at 45°C for 30 min but lost half of its activity after 30 min at 50°C. Maximum specific activity of β-amylase (36.2 units/mg protein) in the culture broth was detected after 36 h of cultivation at 45°C in a medium containing soluble starch, beef extract, coconut water and inorganic salts.