pH control strategy of batch microbial transglutaminase production with Streptoverticillium mobaraense

pH is one of the most important environmental factors for cell growth and product formation. Batch microbial transglutaminase (MTG) fermentation by Streptoverticillium mobaraense WSH-Z2 at various pH values ranging from 5.0 to 8.5 was studied. A pH-shift strategy was developed to maximize MTG production in batch MTG fermentation. Based on time courses of the specific cell growth rate and specific MTG formation rate, a two-stage pH-shift strategy in which pH 7.0 was controlled at first 13 h, and then switched to 6.5 after 13 h was developed. By applying this pH-shift strategy in MTG fermentation, the maximal MTG activity and productivity had a significant improvement and reached 3.40 u/ml and 81.4 u/l/h, respectively, compared to those of constant pH operation (2.90 u/ml and 61.4 u/l/h).