Structural changes of rice resistant starch and its quorum sensing regulatory effect on Lactobacillus gasseri

Abstract

There are many studies on regulating effect of resistant starch (RS) on intestinal microorganisms, but the specific mechanism is unclear. RS can significantly increase the abundance of Lactobacillus, and Lactobacillus gasseri is an important strain of Lactobacillus with excellent probiotic properties. Quorum sensing (QS) is a communication system between microorganisms. In this paper, rice RS was digested in vitro and fermentation by Lactobacillus gasseri, its structural changes were characterized and its QS regulatory effect on Lactobacillus gasseri was explored. Results showed that structural changes of rice resistant starch during fermentation process were obvious. Different concentration of RS could promote the proliferation of Lactobacillus gasseri and the production of polysaccharides and short-chain fatty acids. 0.1%–0.5% RS promoted biofilm formation, while 1%–2% inhibited biofilm and destroyed bacterial structure. Different concentrations of RS promoted the synthesis of signal molecule autoinducer-2 (AI-2) by regulating the expression of luxS and pfs, thereby regulating biofilm formation. Exogenous addition of AI-2 precursor of 4,5-dihydroxy-2,3-pentanedione could also effectively promote biofilm formation. This study provides a fundamental research on interaction between RS and Lactobacillus gasseri during the fermentation process, which is of important significance for in-depth exploration of intestinal microorganisms to develop functional foods such as RS.