Enzymatic properties of TGase from Streptomyces mobaraensis XM4 and construction of a high-yield strain of Tgase

Abstract:

[Objective]To systematically analyze the enzymatic properties of transglutaminase (TGase) from Streptomyces mobaraensis CGMCC 4.1851(strain XM4) and subsequently develop a high-yielding strain by engineering for achieving efficient expression of TGase in Streptomyces with reduced fermentation duration and enhanced production efficiency.[Methods]The pH of the fermentation broth and TGase activity were measured to assess the fermentation characteristics of strain XM4.TGase from XM4 was purified by alcohol precipitation combined with ion-exchange chromatography.The reaction conditions (pH,temperature,metal ions) were optimized for the enzyme,and the enzymatic kinetics were tested.The catalytic efficiency was evaluated by casein cross-linking experiments.Subsequently,genetic engineering was employed to enhance the modified strain through heterologous expression and replacement of the ribosome-binding site (RBS),followed by measurement of TGase production.[Results]TGase from strain XM4 exhibited good activity and stability within the range of pH 4.0–11.0,with the highest activity at 50℃ and pH 10.0.The modification realized efficient expression of TGase in S.mobaraensis,inceasing the production by 103.3% compared with the original strain and reducing the fermentation time to 24 h.[Conclusion]TGase from strain XM4 demonstrates excellent acid-base tolerance and thermal stability,demonstrating broad application prospects in the food industry,especially dairy processing.Additionally,the engineered strain enables efficient production of TGase,providing new options for the industrial production and application of TGase.

Key words:Streptomyces mobaraensis;transglutaminase;casein cross-linking;enzymatic properties;food industry