Lü X Y, Jiang R Z, Wang G F
Dept. of Biology, Nankai Univ., Tianjin.
Yi Chuan Xue Bao. 1991;18(2):185-92.
Using Bacteriophage lambda and plasmid pAT153 and pNQ122 as vectors, alpha-Amylase gene from B. megaterium has been cloned into both hosts of E. coli and B. subtilis. Expression level of the gene is 250 times higher than B. megaterium when it resides in B. subtilis. The enzyme produced by B. subtilis harboring the hybrid plasmid can digest amylase into maltose and maltotriose at first, then turn them to maltose and glucose, as incubation time extended. It also can digest maltotriose to maltose and glucose. As a control, the extracts from the broth of recipient strain have no detectable amylase activities. Therefore the enzyme coded by this gene is defined as saccharifying type alpha-amylase. Its molecular weight is about 58,000 daltons.
利用噬菌体λ以及质粒pAT153和pNQ122作为载体，巨大芽孢杆菌的α-淀粉酶基因已被克隆到大肠杆菌和枯草芽孢杆菌这两种宿主中。当该基因存在于枯草芽孢杆菌中时，其表达水平比在巨大芽孢杆菌中高250倍。携带杂交质粒的枯草芽孢杆菌所产生的酶首先能将淀粉酶消化成麦芽糖和麦芽三糖，然后随着培养时间的延长，再将它们转化为麦芽糖和葡萄糖。它还能将麦芽三糖消化成麦芽糖和葡萄糖。作为对照，受体菌株培养液的提取物没有可检测到的淀粉酶活性。因此，该基因编码的酶被定义为糖化型α-淀粉酶。其分子量约为58,000道尔顿。
