Engineering wild-type robust Pediococcus acidilactici strain for high titer l- and d-lactic acid production from corn stover feedstock

Pediococcus acidilactici TY112 producing l -lactic acid and P. acidilactici ZP26 producing d -lactic acid, were engineered from the wild-type P. acidilactici DQ2 by ldhD or ldh gene disruption , and the robustness of the wild-type strain to the inhibitors derived from lignocellulose pretreatment was maintained well. In simultaneous saccharification and fermentation (SSF), 77.66   g   L −1 of l -lactic acid and 76.76   g   L −1 of d -lactic acid were obtained at 25% (w/w) solids content of dry dilute acid pretreated and biodetoxified corn stover feedstock. l - and d -Lactic acid yield and productivity were highly dependent on the inhibitor removal extent due to the significant down-regulation on the expressions of ldh and ldhD encoding lactate dehydrogenase by inhibitor, especially syringaldehyde and vanillin at the low concentrations. This study provided a prototype of industrial process for high titer l - and d -lactic acid production from lignocellulose feedstock.