L-lactic acid is the preferred isomer in food
preservation and pharmaceutical industries as humans have only L lactate
dehydrogenase whereas D-lactic acid is often harmful to
human metabolism (3).
Industrial production of lactic acid is achieved via chemical
synthesis or microbial fermentation. Optically pure isomers of lactic
acid can be produced only by fermentation process. Currently, lactic
acid production by fermentation uses food feedstock such as
starches and sugars (1), which could cause food shortages and price
increases. Therefore, use of a non-food feedstock such as lignocellulosic
biomass offers a non-competitive, cost-attractive, and environmentally
friendly substrate for the production of lactic acid (4).