MUTANOFACTIN PRODUCTION, BIOFILM FORMATION AND FITNESS OF STREPTOCOCCI: UNRAVELING THE CONNECTION

Bacteria exhibit diverse biochemical capabilities, including secondary metabolite production critical for survival. Among these metabolites, mutanofactins (Mufs)—cyclic lipopeptides—have garnered attention for their role in bacterial biofilm formation, particularly in Streptococcus mutans (Smu), a primary contributor to dental caries. Synthesized via the muf gene cluster, Mufs enhance biofilm robustness, as confirmed in high biofilm-forming Smu strains. This study explores Mufs' roles in biofilm dynamics across Smu, Streptococcus mitis, and Streptococcus agalactiae. Interestingly, S. mitis, with a zinc-responsive motif in its muf promoter, shows enhanced biofilm formation in zinc-rich conditions, while S. agalactiae exhibits minimal biofilm formation despite possessing the muf cluster, underscoring the influence of additional genetic or environmental factors. Preliminary data show growth-phase-dependent muf expression: Smu upregulates Muf production in early log phase, whereas S. mitis peaks in the stationary phase. We hypothesize that Muf biosynthesis is tightly regulated by growth-phase-specific pathways varying among species. This research investigates the genetic diversity of the muf cluster and its effects on biofilm formation in single- and multi-species contexts. Environmental factors like zinc, which enhances S. mitis biofilms, will also be studied. Additionally, we will assess the antimicrobial activity of MFs and their role in interspecies communication within biofilms. Genetic manipulations, including muf promoter fusions and deletion mutants, will elucidate transcriptional regulation. We aim to explore the molecular mechanisms behind MF production, its impact on bacterial adhesion, and interspecies interactions. This work has implications for understanding microbial ecology and developing innovative strategies to combat biofilm-associated infections, including dental caries.