Expression of thermostable ?-amylase gene from Bacillus stearothermophilus in various Bacillus subtilis strains

The recombinant plasmid pC194Amy harbouring 5.25 kbp DNA fragment encoding the thermostable ?-amylase gene of Bacillus stearothermophilus was introduced into Bacillus subtilis YB886 and B. subtilis BR151 strains by electroporation. The expressing of the ?-amylase gene in recombinant strains were confirmed on starch plate, SDS-PAGE and zymogram analysis. In the condition of 100 °C and 15 min, YB886Amy, BR151Amy and ATCC31786 ?-amylases were maintained up to 80, 67 and 52% of their maximum activity respectively. The specific enzyme activities of YB886Amy, BR151Amy and ATCC 31786 were estimated as 2.59, 2.98 and 2.9 µM/mg protein/min respectively