Characterisation and optimisation of microbial production of transglutaminase produced by Streptoverticillium cinnamoneum

Optimal conditions for the production of microbial transglutaminase (MTG) by Streptoverticillium cinnamoneum KKP 1648 under bioreactor conditions were determined using response surface methodology (RSM). The test medium contained soluble starch, Aminobak, waste corn steep liquor, yeast extract, and mineral salts such as KH₂PO₄, Na₂HPO₄∙12H₂O, and MgSO₂∙7H₂O. The culture was conducted at 28 °C, stirring at 200 rpm, using aeration with compressed air at a flow rate of 2.0 vvm. Optimal culture parameters included a pH of 6.5, a nitrogen dose of 2.75%, and an incubation time of 72 h, and yielded MTG activities of 4.29 ± 0.08 and 22 ± 0.05 U/mL after precipitation with ammonium sulfate. The molecular weight of the enzyme was estimated to be 43 kDa by SDS-PAGE. The transglutaminase tested showed optimal activity in the temperature range 20-37 °C, with a significant decrease in activity above 50 °C and complete inactivation at 60 °C. The enzyme was stable in the pH range of 5.0-9.0, reaching maximum activity at pH 7.0. The use of waste corn steep liquor as a nutrient solution revealed a potential management strategy for this type of waste. The results suggest potential applications of transglutaminase in the food industry, particularly in enhancing the structural properties of meat, bakery, and dairy products. KEY POINTS: High MTG activity after 72 h of culture confirms the effectiveness of selected parameters The use of corn waste in MTG production can reduce production costs The use of the RSM method allowed us to determine the best parameters for MTG production. The MTG enzyme was stable at pH 5.0 to 9.0, with maximum activity at pH 7.0.