High-titer lactic acid production by Lactobacillus pentosus FL0421 from corn stover using fed-batch simultaneous saccharification and fermentation

• A LA hetero-fermentative strain was identified as Lb. pentosus FL0421.
• FL0421 produced LA with yields of 0.52–0.82 g/g stover from five agro stovers.
• LA titer and yield reached 92.30 g/L and 0.66 g/g stover in fed-batch SSF.
• FL0421 is a good candidate for genetic engineering for high LA titer and yield.

Because the cost of refined sugar substrate and limit of worldwide food availability, lignocellulosic materials are attractive for use in lactic acid (LA) production. In this study, we found Lactobacillus pentosus strain FL0421 produced LA with high yields (0.52–0.82 g/g stover) from five NaOH-pretreated and washed agro stovers through simultaneous saccharification and fermentation (SSF). We developed a fed-batch SSF process at 37 °C and pH 6.0 using the cellulase of 30 FPU/g stover and 10 g/L yeast extract in a 5-L bioreactor to produce LA from 14% (w/w) NaOH-pretreated and washed corn stover under non-sterile condition. The LA-titer, yield and productivity reached 92.30 g/L, 0.66 g/g stover and 1.92 g/L/h, respectively; and acetic acid titer and yield reached 34.27 g/L and 0.24 g/g stover. This study presented a feasible process for LA production from agro stovers and provided a candidate strain for genetic engineering for high-titer and -yield lignocellulosic LA production.