Optically pure lactic acid production from softwood-derived mannose by Pediococcus acidilactici.

Softwood is of interest as a renewable carbon source for production of lactic acid. Softwood hydrolysate contains a high content of mannose. Lactic acid production from mannose by two modified strains, L-lactic acid producing Pediococcus acidilactici TY112 and D-lactic acid producing ZP26, was investigated in the current work. The two strains efficiently converted mannose to L- and D-lactate isomers with an optical purity exceeding 99 %, although the mannose utilization rates were lower than the glucose utilization rates. The mannose conversion to L- and D-lactic acids by P. acidilactici was also confirmed in dilute spruce hemicellulose hydrolysate. The present study provides important knowledge on utilization of the spectrum of fermentable sugars in softwood for future production of chiral lactic acid from lignocellulose feedstocks.