Biorefinery-Based Lactic Acid Fermentation: Microbial Production of Pure Monomer Product

Demand for lactic acid has increased considerably because of its wide application, especially as monomer feedstock for the production of biodegradable and biocompatible poly(lactic acid) materials. Therefore, improvement in fermentative production of optically pure lactic acid has attracted considerable attention. However, the high costs of the process and of raw materials are two serious obstacles to effective lactic acid production. Investigation of biorefinery-based lactic acid fermentation using residual biomass from agriculture and agro-industries has intensified because of environmental and economic factors. This chapter reviews recent advances, prospects, and limitations of lactic acid production from cellulosic biomass by lactic acid bacteria. The main obstacles to production are discussed and appropriate strategies are suggested for improving biomass hydrolysis and the efficiency of lactic acid fermentation. This chapter also introduces a cost-effective and environmentally friendly fermentation that utilizes "designed biomass." Separation and purification techniques for obtaining purified lactic acid monomers are also summarized.