Purification and characterization of a high-salt-resistant microbial transglutaminase from Streptomyces mobaraensis

A novel microbial transglutaminase (MTG-TX) was obtained from Streptomyces mobaraensis by fermentation and purification. The enzyme was purified by ethanol precipitation via a two-step purification method, with a 44.0% yield and a specific activity of 39.2 U mg⁻¹. The purified enzyme exhibited stable performance over a range of pH 5.0–pH 10.0 and displayed maximal activity at pH 6 and 48 °C. We verified through biochemical analyses that the enzyme is a novel MTG variant possessing the same zymogen characteristics as that of another reported MTG from Streptoverticillium ladakanum B1. Furthermore, the loss of enzyme activity by MTG-TX in the presence of high salt was only 79.8% that observed in a control MTG from S. mobaraensis DSM40847. On the basis of salt resistance, the novel MTG-TX presented here also performed well in food-related applications by successfully crosslinking proteins in high-salt environments, thereby enhancing the cohesiveness of bacon.