초록
E. coli-Yeast shuttle vector YEp 13에 B. amyloliquefaciens의 $\alpha$-amylase gene을 cloning하여 얻은 hybrid plasnidlasmid를 E. coli를 숙주세포로 하여 형질을 발현시켰다. 형질전환주의 $\alpha$-amylase 활성 측정 결과, B. amyloliquefaciens에 대해 20-30%의 상대 활성도를 나타내었다. 형질전환주의 경우 생성된 $\alpha$-amylase의 60-65%가 periplasm에 축적되었으며 세포 외부로의 분비는 없었다. Hybrid DNA를 agarose-gel 전기영동으로 조사한 결과 그 크기가 다른 다수의 hybrid DNA가 확인되었으며 pHA28의 plasmid (a)(Fig.3)에서만 $\alpha$-amylase 활성을 나타내는 것으로 밝혀졌다 pHA28의 plasmid(a)의 크기가 YEp 13 plasmid DNA보다 작은 것은 YEp13 plasmid에서 yeast gene부분이 deletion된 결과로 추측되었다.
$\alpha$-Amylase gene of B. amyloliquefaciens was cloned to E. coli-yeast shuttle vector YEp-13 and expressed in E. coli. Chromosomal DNA of B. amyloliquefaciens was partially digested with Sau3Al and YEp13 plasmid was cleaved with BamH1. The hybrid plasmid, pHA28, was constructed by shotgun method and transformed to E. coli C600 and HB101. The amount of $\alpha$-amylase produced by transformants of E. coli was about 20% to 30% of that produced by B. amyloli-quefaciens. About 65% of $\alpha$-amylase produced by transformant was secreted into periplasm and the others were located in cytoplasm. $\alpha$-Amylase production was maximal when transformants were cultivated for 15hr to 20hr. As the result of agarose gel electrophoresis, pHA28 plasmid was found to be various in its size. This result suggested that pHA28 plasmid was segregated.