Enhanced production of poly (gamma-glutamic acid) from Bacillus licheniformis NCIM 2324 in solid state fermentation.

This work reports on the optimization of PGA production by Bacillus licheniformis NCIM 2324 in solid state fermentation (SSF). In the first step, the one factor-at-a-time method was used to investigate the effect of solid substrates, initial moisture content, pH, and additional carbon and nitrogen source on PGA production; subsequently, response surface methodology (RSM) was used to establish the optimum concentrations of the key nutrients for higher PGA production. In the second step, the effects of amino acids and TCA cycle intermediates on the production of PGA were studied. The final optimized medium gave a maximum yield of 98.64 +/- 1.61 mg gds(-1) of PGA, which is significantly higher than that reported in the literature.