Temperature is one of the most important environmental factors for cell growth and product formation. Batch microbial transglutaminase (MTG) fermentations by Streptoverticillium mobaraense WSH-Z2 at various temperatures, ranging from 25 to 35 degreesC, were studied. MTG activity and dry cell weight (DCW) reached 2.94 u/ml and 25.1 g/l, respectively at 30 degreesC, which were higher than those at other temperatures. The lag time was shorter and the specific cell growth rate (mu (cell)) and specific MTG production rate (mu (MTG)) in the early stages of growth were higher at 32 degreesC or higher temperature. At the mid- and later stages of growth, mu (cell) and mu (MTG) were higher at 28 degreesC. Based on these results, a two-stage temperature control strategy was developed in which 32 degreesC was used for fermentation for the first 18 h and the temperature was switched to 28 degreesC after 18 h. Using this temperature-shift strategy, the maximal MTG activity and productivity reached 3.37 u/ml and 80.2 u/l/h, respectively. The average specific cell growth rate and average specific MTC production rate were 3.02 u/h/g DCW and 0.028 g/h/g DCW, respectively. The MTG fermentation level obtained by the strategy was higher than those in single temperature-control experiments. (C) 2001 Elsevier Science Ltd. All rights reserved.