耐热链霉菌的分子育种改造

BIB0830是一株可将泰乐菌素转化为乙酰异戊酰泰乐菌素（AIV）的耐热链霉菌工业菌株。以pIJ8600为载体分别构建了acyB1-B2基因整合型表达载体pBIB425和带红霉素突变启动子ermEp*的红霉素抗性ermE基因整合型表达载体pBIB304。通过大肠杆菌-链霉菌属间接合转移分别将pBIB425、pBIB304和pBIB308（耐热链霉菌的nsdA基因中断载体，本实验室保存）导入工业菌株BIB0830，抗性筛选分别得到接合子BIB425、BIB304和BIB308。PCR验证均为阳性克隆。摇瓶发酵结果表明：与出发菌株BIB0830相比，BIB425和BIB308泰乐菌素转化率分别提高了14%和22%，BIB304无明显影响。

Molecular Breeding manipulation of Streptomyces thermotolerans

The industrial strain BIB0830 of Streptomyces thermotolerans can produce acetyl-isovaleryl tylosin(AIV) by bioconversion using tylosin as a processor. Recombinant plasmid pBIB425 containing structural gene of acyB1-B2, pBIB304 containing up-mutant promoter of ermE（ermEp* ）and structural gene of ermE, were derived from pIJ8600. The recombinant strain BIB425, BIB304 and BIB308 were obtained by introducing pBIB425, pBIB304 and pBIB308 containing disruption cassette of nsdA gene (stored by lab) respectively into the industrial strain BIB0830 through intergeneric conjugal transfer. After PCR analysis, they were confirmed to be the positive clones. Compared with the start strain BIB0830, in the level of flask, the bioconversion abilities of tylosin to acetyl-isovaleryl tylosin (AIV) of recombiant BIB425 and BIB308 increased 14% and 22%, respectively .The BIB304 was not affected.