To date, there are several studies on production of L-lactic acid; however, the information on biosynthesis of D-lactic acid is limited. Two strains: Lactobacillus delbrueckii ATCC 9649 and Sporolactobacillus inulinus ATCC 15538 were screened for D (-) lactic acid production. L. delbrueckii was selected based on its high D (-) lactic acid productivity and purity. The Saccharification of pulp and mechanically modified pulp was performed by using CTec2 and NS50010 enzymes (Novozymes. Inc). D (-) lactic acid production using the sugars generated from pulp and mechanically modified pulp was performed at flask level and a yield of 0.77 g/g glucose and a productivity of 0.31 g/l/h were obtained. The optical purity of D (-) lactic acid from the feedstocks was 99.8%. Batch and Fed-Batch experiments were carried out at pH 6.5 and at 37°C in a 5-L fermentor, and a product concentration of 37.9 % (w/v) and 68.9% (w/v), and a productivity of 1.05 g/l.h and 0.86 g/l.h were attained, respectively.
Further, L. delbrueckii will be genetically engineered to utilize multiple sugars, such as xylose and glucose for D (-) lactic acid synthesis. These results will be discussed at the presentation.