Optimization of the culture conditions for production of glutamate decarboxylase by Streptococcus salivarius ssp. thermophilus

The culture conditions for glutamate decarboxylase (GAD) production under submerged fermentation by Streptococcus salivarius ssp. thermophilus were investigated. The results indicated the optimum culture medium was composed as follows: 15.0 g L −1 of peptone, 12.5 g L −1 of beef extract, 12.5 g L −1 of sucrose, 1.03 g L −1 of dipotassium hydrogen phosphate, 5 g L −1 of sodium acetate, 2 g L −1 of ammonium dibasic citrate, 2.12 g L −1 of calcium chloride, 1 g L −1 of Tween 80, and initial pH 6.79. The optimum culture temperature and time were 37 °C and 12 h, respectively. Under these conditions, GAD production was 257.46 ± 5.12 U, which was about 1.45‐fold that of Man–Rogosa–Sharpe broth.