Transcriptome Analysis Reveals the Role of Sucrose in the Production of L3 Exopolysaccharide.

() is a species of lactic acid bacteria (LAB) mostly studied according to its application in food fermentation. Previously, L3 was isolated by our laboratory and possessed the capability of high exopolysaccharide (EPS) yield during sucrose-added fermentation. However, the understanding of sucrose promoting EPS production is still limited. Here, we analyzed the growth characteristics of L3 and alterations of its transcriptional profiles during sucrose-added fermentation. The results showed that L3 could survive between pH 4.0 and pH 9.0, tolerant to NaCl (<10%, /) and urea (<6%, /). Meanwhile, transcriptomic analysis showed that a total of 426 differentially expressed genes and eight non-coding RNAs were identified. Genes associated with sucrose metabolism were significantly induced, so L3 increased the utilization of sucrose to produce EPS, while genes related to uridine monophosphate (UMP), fatty acids and folate synthetic pathways were significantly inhibited, indicating that L3 decreased self-growth, substance and energy metabolism to satisfy EPS production. Overall, transcriptome analysis provided valuable insights into the mechanisms by which L3 utilizes sucrose for EPS biosynthesis. The study provided a theoretical foundation for the further application of functional EPS in the food industry.