원저 ( Original Articles ) ; B . stearothermophilus 의 내열성 α - amylase 의 클로닝과 대장균 , 고초균에서의 발현

The gene coding for thermostable extracellular α-amylase of thermophilic bacteria, Bacillus stearothermophilus was cloned and expressed both in E. coli and B. subtilis. By transforming E. coli HB101 with PBR322 containing chromosomal DNA fragments of B. stearothermophilus which was digested with EcoRI, colonies that showed α-amylase activity was obtained. The plasmids from those colonies contained a 4,200 by insert at the EcoRI site of pBR322. After transformed the 4,200 by fragment to pMK4 which is a shuttle vector between E. coli and B. subtilis, we transformed B. subtilis with these resulting hybrid plasmid. We present evidence that the cloned fragment codes for a B. stearothermophilus α-amylase which is heat stable. The foreign gene was expressed efficiently both in E. coli and B. subtilis and was maintained stably.