Regulatory Of Two Quorum Sensingseing Systems On Metabolite Biosynthesis In Lysobacter Enzymogenes

Lysobacter enzymogenes is classfied to the Xanthomonadaceae family, it is a ubiquitous environmental bacterium emerging as a potentially novel biological control agent. It can produce bioactive secondary metabolites of many kinds, such as the Heat-Stable Antifungal Factor (HSAF), gram-positive actinomycetes WAP-8294A2 and photo-protective polyene pigments, but the regulatory mechanism(s) for biosynthesis of these bioactive secondary metabolites remains unknown in L. Enzymogenes.Previous studies have indicated that Xcc wild-type strains could produce two QS (Qurom Sensing) signals:DSF (Diffusible Signal Factor) and DF (Diffusible Factor). Evidences have shown that the DF and DSF have overlapping functions in modulation of bacterial survival, H2O2 resistance, virulence and so on. Just like Xanthomonas campestris pv. Campestris, Lysobacter enzymogenes also belongs to the family of Xanthomonadacaeare. We want to know whether these two QS signals could produced in the Lysobacter enzymogenes, and if so, whether these two signals were involved in the regulation of secondary metabolites HSAF etc.In this study, we identified that the L enzymogenes OH11 could also produce these two QS signals. Both DSF and DF played positive effects in modulating HSAF biosynthesis and WAP-8294A2 biosynthesis. As for in the polyene pigment production, DSF played negative effects, while DF played positive effects, DF is shown to play a more important role in regulating this phenotype. However, DSF regulated colony morphology of L. enzymgenes independently.To further investigate the function of DSF and DF, we conducted microarray testing, where the results show that DSF and DF are global regulators having their own regulons with a few loci regulated by both systems. These findings unveil for the first time novel roles of DSF and DF signaling pathways in these bioactive secondary metabolites.