Significantly improved production of Welan gum by Sphingomonas sp. WG through a novel quorum-sensing-interfering dipeptide cyclo(L-Pro-L-Phe)

A variety of physiological functions such as exopolysaccharide synthesis, antibiotic production, and primary metabolism are tightly controlled by quorum sensing in microorganisms. In this study, a marine-derived bacterium Sphingomonas sp. WG was found to possess a cyclo(L-Pro-L-Phe)-mediated quorum sensing mechanism. The cyclo(L-Pro-L-Phe) produced by Sphingomonas sp. WG functions as a signalling molecule in this quorum sensing system. It is the first attempt to characterize cyclic dipeptides as quorum sensing signalling molecules in Sphingomonas sp. and the results effectively make the classical quorum sensing theory more perfect. Furthermore, the supplementation with isolated cyclo(L-Pro-L-Phe) resulted in a 15% increase in the production of welan gum secreted by Sphingomonas sp. WG in the submerged fermentation. The data presented in this study will provide evidences for exploring the role of cyclic dipeptides in regulating the production of welan gum.