Open fermentative production of l-lactic acid by Bacillus sp. strain NL01 using lignocellulosic hydrolyzates as low-cost raw material

Highly efficient l-lactate production by a thermophilic strain Bacillus sp. NL01 was demonstrated in this study. Lignocellulosic hydrolyzates containing a high content of glucose, which was prepared from corn stover, was used as substrate for l-lactic acid production. The fermentation was carried out under open condition without sterilization and used NaOH as alkaline neutralizing reagent. In batch fermentation, 56.37 g l−1 l-lactic acid was obtained from lignocellulosic hydrolyzates which contained the solid residues produced in enzymatic saccharification. In fed-batch fermentation, 75.03 g l−1 l-lactic acid was obtained from lignocellulosic hydrolyzates supernatant. The yield was 74.5% and the average productivity was 1.04 g l−1 h−1.