A comprehensive profiling of quorum quenching by bacterial pigments identifies quorum sensing inhibition and anti-biofilm action of prodigiosin against Acinetobacter baumannii

Abstract

Bacterial pigments represent a diverse group of secondary metabolites offering advantages to the producers in terms of survival and replication in communities. The bioactive potential of such metabolites including antimicrobial, anticancer and immune-suppressive properties are being explored. Reckoning that several of such pigments are produced in response to quorum sensing mediated expression of biosynthetic gene clusters and do influence cell-cell communication while residing in communities, systemic profiling of the pigments for possible impact on quorum sensing appears crucial; particularly in the quest of novel alternatives to confront drug nonresponsive pathogens. In this context, a series of bacterial pigments are clustered based on their physicochemical properties and representatives of the clusters are screened for quorum sensing inhibition. The screen highlighted prodigiosin as a potent quorum quencher although its production from Serratia marcescens apparently is QS-independent. In silico analysis indicated potential interaction with AbaI and AbaR, two major QS regulator in Acinetobacter baumannii. While developing multi-bacterial biofilm, prodigiosin producer S. marcescens significantly impaired fitness of A. baumannii and accentuated responsiveness against colistin under co-culture. Prodigiosin impaired a major QS dependent process, biofilm formation, in A. baumannii and also enhanced antibiotic action against A. baumannii biofilms. Collectively, the results underpin the prospect of prodigiosin-based therapeutic strategy in combating A. baumanii infection.