Enhancement of transglutaminase production in Streptomyces mobaraensis DSM 40587 by non-nutritional stress conditions: Effects of heat shock, alcohols, and salt treatments

Stress-mediated bioprocess is a strategy designed to enhance biological target productivity. In this study, an attempt was made to enhance transglutaminase (TGase) production by Streptomyces mobaraensis by using different stress conditions including heat shock, alcohols and salt stress. Results showed that the effects of stress on TGase production depended on the type applied. For heat shock, TGase production (1.32 U/ml) was recorded maximum in the culture treated at 48 h post inoculation in water bath at 60 °C for 1 min. For alcohols treatment, the maximum activity of TGase (1.77 and 1.75 U/ml) was obtained when 3% methanol was added into the medium at 0 or 24 h of fermentation. However, a 3.5-fold increased production of TGase (3.8 U/ml) was observed in the medium supplemented with 0.2 mol/l MgCl ₂ compared with the basic medium at the beginning of fermentation. In conclusion, TGase production from S. mobaraensis was improved by heat shock, methanol and salt stress treatments, MgCl ₂ stress was the most effective.