Polymicrobial biofilms: quorum-sensing mechanisms and therapeutic strategies

In nature, all microbial populations form biofilms. Aggregated microbial communities attached to surfaces form a biofilm, surrounded by biosynthesised polymeric substances. In polymicrobial biofilm formation, the interspecific interactions within microbial communities remain unclear. Individual microbial populations maintain their phenotypes and genotypes in response to their competitive environment. In recent studies, numerous mechanisms underlying supportive communication within polymicrobial biofilm communities have been identified, including social interactions, interspecies exchange of antibiotic resistance genes, fundamental ecological factors, and antibiotic inactivation. Quorum-sensing mechanisms coordinate the expression of specific metabolic pathways across bacterial populations in different environmental conditions. Quorum sensing in bacterial species is vital for microbial physiology, community behaviour, and the control of the spread of antibiotic resistance. In this review, we discuss the molecular mechanisms of quorum sensing in polymicrobial biofilms and highlight its role in polymicrobial interactions, antibiotic resistance, and infections. Understanding quorum-sensing mechanisms can provide insights into polymicrobial pathogenesis, biofilm formation, and antibiotic resistance, informing the development of therapeutic strategies and emerging directions in drug discovery.