Lactic Acid for Green Chemical Industry: Recent Advances in and Future Prospects for Production Technology, Recovery, and Applications

Lactic acid, an organic acid produced by numerous microorganisms, has many applications in the food, chemical, pharmaceutical, and polymer industries, with novel applications being developed particularly in the chemical industry. The lactic acid market has steadily grown with the introduction of novel and environmentally friendly products. Therefore, developing novel technologies for lactic acid production, with improved yield and reduced production costs, has become a major research goal. Utilization of inexpensive and renewable biomass is a major strategy for economically producing lactic acid. However, most lactic acid bacteria cannot directly utilize lignocellulosic biomass and require hydrolysis, which is costly. Immobilization techniques for large-scale production can enhance fermentation yield. Moreover, novel techniques, such as cell recycling systems and simultaneous saccharification, will enable microorganisms to produce lactic acid with increased concentration, yield, and productivity. Recently, genetic and metabolic engineering methods have been used for key solving problems, such as product inhibition, by-product formation, and suboptimal culture conditions, and for the effective use of cheap substrates. This review presents comprehensive insights into the most recent advances in the biological production of lactic acid from different substrates, bioprocess techniques for yield improvement, lactic acid purification, and applications of lactic acid for human welfare.