(569a) Production of Lactic Acid by Recombinant Bacillus Subtilis in Fed-Batch and Continuous Cultures

Interest in the production of lactic acid has significantly increased recently. Besides the increasing demand, it is also due to the prospects of using environmental friendly, renewable resources instead of petrochemicals as feedstocks. In this study, an UV-induced mutant strain of recombinant Bacillus subtilis 1A304 (Ô105MU331) was used for the production of lactic acid. In fed-batch cultures, the concentration of lactic acid produced was 133.3 g/L and 188.4 g/L in 24h and 52h respectively. The maximum productivity of 16.1 g/L h was obtained at 5 hour. Production of lactic acid in continuous cultures in a wide range of dilution rates (D= 0.03 to 0.4) was also studied. The maximal lactic acid concentration (61.9 g/L) was obtained at D =0.03 with a productivity of 1.9 g/L/h. The maximal lactic acid productivity (17.6 g/L/h) was obtained at D=0.4 with a lactic acid concentration of 44.1 g/L. The lactic acid productivity from fed-batch and continuous cultures in this study are higher than the productivity of current microbial industrial processes which use Lactobacillus to produce lactic acid.