Comparative transcriptomic analysis of Lactiplantibacillus plantarum RS66CD biofilm in high-salt conditions and planktonic cells

Background Lactiplantibacillus plantarum (L. plantarum), a dominant strain in traditional fermented foods, is widely used in fermentation industry because of its fast acid production. However, L. plantarum is easily inactivated due to acidity, high temperature and other factors. The formation of biofilm by bacteria can effectively increase environmental tolerance. Therefore, it is important to improve the environmental tolerance of L. plantarum by studying its biofilm formation conditions and regulatory mechanisms. Methods After determining a suitable NaCl concentration for promoting biofilm formation, L. plantarum was grown with 48 g L−1 NaCl. Differential gene expressions in L. plantarum biofilm vs. planktonic cells were analyzed using RNA sequencing and validated using qPCR. Result L. plantarum RS66CD biofilm formation formed highest amount of when grown at 48 g L−1 NaCl. Altogether 447 genes were up-regulated and 426 genes were down-regulated in the biofilm. KEGG pathway analysis showed that genes coding for D-Alanine metabolism, peptidoglycan biosynthesis, two-component system, carbon metabolism, bacterial secretion system, lysine biosynthesis and fatty acid metabolism were crucial for biofilm formation. In addition, eight other genes related to biofilm formation were differentially expressed. Our results provide insights into the differential gene expression involved in biofilm formation, which can help to reveal gene regulation during L. plantarum biofilm formation.