Suppression of quorum sensing-mediated cell autolysis for highly efficient lactic acid production by Lactobacillus paracasei LYS2.

Lactic acid (LA) is an important platform chemical with diverse applications and growing market demand. Microbial fermentation using Lactobacillus paracasei is a major route for LA production. However, L. paracasei fermentation often suffers from decreased cell biomass and viability due to cell autolysis, limiting LA production. Quorum sensing (QS) mediates bacterial communication and population behavior, but its role in regulating cell autolysis during LA fermentation remains unclear. In this study, QS inhibition in L. paracasei LYS2 is shown to alleviate cell autolysis, increases biomass, and enhances LA production. The underlying molecular mechanism of QS-mediated regulation was also explored. This fermentation strategy is applicable to the strain using sweet sorghum juice to replace glucose as the carbon source, achieving 206.1 g/L of LA, the highest reported from this substrate to date. This work provides a promising strategy for LA production.