Lactic Acid Production from Lignocellulose - A Review of Major Challenges and Selected Solutions

The industrial application of lactic acid is very broad; hence, the high demand is forecasted to multiply in the future. This review presented the major problems for the efficient production of lactic acid from lignocellulose biomass using lactic acid bacteria (LAB) and further proposes three promising solutions to solve these problems, exposing their potentials and future research needs. Recombinant cellulolytic strategy in LAB promises a significant reduction of lactic acid production costs, however, extensive research on genetic engineering is still needed. Microwave-assisted deep eutectic solvent pretreatment is extremely fast and produces little to no harmful by-products, but it has not been investigated for lactic acid production yet. Continuous simultaneous saccharification and fermentation with enzyme and cell recycle is newly proposed by the authors as a process set up that can solve the problems of feedback-, substrate- and end-product inhibition while resulting in higher lactic acid productivities, yield, and concentration.