Lactic acid bacteria in biorefineries

Lactic acid bacteria (LAB) are versatile microorganisms capable of producing a wide range of industrially important chemicals. For decades, they were used for production of fermented foods, as natural preservatives or as probiotics. In recent years, their application in biorefineries, where primary crops as well as agro-industrial wastes are used as substrates for fermentation, has been researched extensively. Currently, the main compound of interest in LAB-based biorefineries is lactic acid (LA), which is a bulk chemical with many applications, e.g., in the production of environmentally friendly bioplastics such as polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA). Moreover, LAB were identified to produce other value-added compounds that have potential to be produced in this type of biorefineries, e.g., polyhydroxyalkanoates, antimicrobial agents, exopolysaccharides, aromas, sweeteners, and nutraceuticals. This chapter includes an extensive overview of the main industrially important chemicals synthesized by LAB, future challenges connected with their production, and recent innovations regarding LAB-based biorefineries.