The Statistic Optimization for Lactic Acid Production by Lactobacillus Plantarum using Ethanol Stillage as Sole Carbon Source

摘要

Optimization of medium composition and pH for lactic acid production byLactobacillus plantarum ATCC21028 were evaluated using statistical methods. Ethanol stillage, a liquid waste from refinery, was utilized as the sole carbon source. Complex interactions among concentrations of stillage (50-100%), yeast extract as a nitrogen source (0-5 g/L) and pH (4-9) were studied using central composite design (CCD) experiments. Using 50% of stillage in the presence of 2.5 g/L of yeast extract at pH6.5 yield the highest lactic acid (94.68±0.006 mg/L), productivity (1.97 mg/L/h) and yield (0.128 mg/mg initial sugar). The optimum cultivation for the lactic acid production consisted of 50.003% of stillage and2.433 g/L of yeast extract at pH 6.537 (R~2=0.999). The model was confirmed by culturing L. plantarumunder predicted conditions in a 5-L fermenter. The amount of lactic acid (94.24±0.018 mg/L) was not significantly different from the predicted value.