复合诱变法选育谷氨酰胺转胺酶高产菌株

Screening and Characterization of High-Yield Microbial Transglutaminase-Producing Mutants Induced by a Novel Method

为筛选谷氨酰胺转胺酶高产菌株,利用紫外-硫酸二乙酯复合诱变、一次筛选的方法诱变生产菌株茂源链霉菌(Streptoymyces mobaraensis),结合高通量筛选技术筛选高产菌株。结果表明:复合诱变的方式较单独诱变的方式效率高。经过诱变的高产菌株由于酶的成熟加快或者蛋白表达量增加而提高了酶活力,最高可达7.02 U/mL,比野生菌株提高了54%。进一步研究高产菌株发现,高产菌株谷氨酰胺转胺酶的成熟加快,可提前24 h结束发酵;发酵液中酶原含量高,会降低发酵液中酶活性。

Microbial transglutaminase(MTG)-producing strain Streptoymyces mobaraensis(S. mobaraensis) was subjected to mutagenesis using UV irradiation and diethyl sulfate(DES) treatment and the resulting colonies were screened by a high throughput method. Results showed that the combined mutagenesis had better performance than single mutagenesis. The high-yield MTG-producing mutants had either a higher MTG protein expression or a shortened maturation time of MTG. Among these, one mutant had the highest yield of 7.02 U/mL enzymatic activity, which was 54% higher than that of the wild-type strain. Further study found that this strain expressed MTG products 24 hours earlier than the wild-type one did. However, the yield of MTG could be highly inhibited by the zymogen pro-MTG.