Mechanistic Insight for Improving Transglutaminase Production Through Combined HVCP and LiCl Mutagenesis in Streptomyces mobaraensis.

Transglutaminase (TGase) is widely used in food, medicine, textile, and other industries owing to its excellent ability to promote protein cross-linking. The growing demand urgently requires the improvement of TGase production. Streptomyces mobaraensis FETSm1 was subjected to complex mutagenesis by high-voltage atmospheric cold plasma (HVCP) in combination with the chemically assisted mutagen lithium chloride (LiCl), and then a mutant FETSm2 with a 140% increase in TGase activity (12 U/mL) was obtained. FETSm2 had higher intracellular ATP content, which promotes the metabolism of the cells. The expression of TGase in FETSm2 was twofold higher than that of FETSm1, while enhanced activase activity promoted pro-TGase activation, contributing to the eventual increased TGase production. The application of the CCD-RSM and GA-ANN models further enhanced TGase production. FETSm2 could achieve a 17.64 U/mL TGase activity at the optimal ratio of the peptone, MgSO₄, K₂HPO₄, which was 41.12% higher than the original fermentation medium.