Optimization of poly-γ-glutamic acid (PGA) produced by the glutamate-independent Bacillus licheniformis SAB-26 has been earned out using response surface methodology. Predicted maximum PGA yield (57.9 g L -1) was calculated using non-linear optimization algorithm powered by Microsoft Excel, where the optimized medium composition was (g L-1): casein hydrolysate, 12.2; ammonium sulfate, 20; K2HPO4, 27 and KH2PO4, 27 after 72 h. A verification experiment was carried out to compare predicted and experimental results, where experimental yield reached (59.9 g L-1) in a good sign of model validity. Pulsed feeding experiment of citrate at different time intervals revealed increasing the polymer production to 88 g L-1.