Batch and fed-batch strategies of lactic acid production by Lactobacillus plantarum BL011 using soybean hull hydrolysates as substrate

We optimized the production of lactic acid by Lactobacillus plantarum BL011, using acid and enzymatic soybean hull hydrolysates as cultivation media. Selection of cultivation conditions was performed in Erlenmeyer flasks, in orbital shaker at 37 degrees C and 120 rpm, pH 6.0. Plackett-Burman experimental design was performed as tool to identify the best cultivation temperature and whether medium supplementation should be necessary for further experiments. Crude yeast extract and magnesium sulfate supplementation, temperature of 30 degrees C, 48 h of cultivation, were the ideal conditions defined in batch cultivations (anaerobiosis and controlled pH), allowing for the production of 39.34 g.L-1 of lactic acid, and a productivity of 0.82 g.(L.h)(-1) at 48 h of cultivation. Fed-batch bioreactor cultivations were performed, applying 12-h linear ascending feeding strategy, using enzymatic hydrolysate containing either 90 g.L-1 or 130 g.L-1 of total sugars, resulting in a productivity above 1.5 g.(L.h)(-1) and acid lactic concentration of 58.6 g.(L.h)(-1), after 48 h of cultivation. Our results demonstrate the possibility of using this abundant waste lignocellulosic biomass hydrolysates to cultivate Lactobacillus and to obtain high concentrations of lactic acid.