除虫链霉菌10个聚酮类抗生素生物合成基因簇的敲除对阿维菌素产量的影响

Effects on productivity of avermectin by knockout of 10 polyketide biosynthetic gene clusters in Streptomyces avermitilis genome

摘要:

【目的】考察除虫链霉菌基因组中其它聚酮合成酶类(Polyketide synthase，PKS)抗生素生物合成基因簇的敲除突变对于阿维菌素产量的影响。【方法】构建了11个PKS基因簇的打靶Cosmid和质粒载体，导入除虫链霉菌中筛选突变株。【结果】在工业菌株MMR630中成功敲除了10个PKS基因簇。发酵结果显示7个PKS基因簇敲除突变株中阿维菌素的产量均有不同程度的提高，而2个突变株不能产生阿维菌素。然而，在3个连续敲除2个PKS基因簇的突变株中阿维菌素产量没有能够超过单个PKS敲除突变株的提升幅度。【结论】除虫链霉菌基因组的一些PKS基因簇的敲除可以提高阿维菌素的产量，同时暗示同一类次生代谢产物的代谢流之间存在复杂的相互作用关系。

Abstract:

[Objective] We studied whether avermectin productivity could be affected by other polyketide biosynthetic gene clusters in Streptomyces avermitilis genome. [Methods] By constructing gene knock-out cosmids or plasmids and introducing into industrial host, 10 mutants were obtained after screening double crossover colonies from conjugants of each polyketide gene clusters knocked-out vectors. [Results] Avermectin productivities of seven polyketide null mutants were higher than that of the starting strain. Two mutants abolished avermectin production. Three mutants with combined knock-out of two of three strong effect clusters had no further increase on avermectin productivity. [Conclusion] Deletions of some polyketide gene clusters can be used to increase avermectin productivities in Streptomyces avermitilis. The results also suggested that there were interweaved networks among these polyketide gene clusters in Streptomyces avermitilis.