Unraveling the Diverse Profile of N-Acyl Homoserine Lactone Signals and Their Role in the Regulation of Biofilm Formation in -Associated .

N-acyl homoserine lactones (AHLs) are small, diffusible chemical signal molecules that serve as social interaction tools for bacteria, enabling them to synchronize their collective actions in a density-dependent manner through quorum sensing (QS). The QS activity from epiphytic bacteria of the red macroalgae , along with its involvement in biofilm formation and regulation, remains unexplored in prior scientific inquiries. Therefore, this study explores the AHL signal molecules produced by epiphytic bacteria. The bacterium isolated from the surface of was identified as by 16s rRNA gene sequencing and screened for AHLs using two AHL reporter strains, A136 and CV026. The crystal violet assay was used for the biofilm-forming phenotype. The inferences revealed that produces four different types of AHL molecules, i.e., C4-HSL, C8-HSL, C18-HSL, and 3-oxo-C16-HSL, and it was observed that its biofilm formation phenotype is regulated by QS molecules. This is the first study providing insights into the QS activity, diverse AHL profile, and regulatory mechanisms that govern the biofilm formation phenotype of . These findings offer valuable insights for future investigations exploring the role of AHL producing epiphytes and biofilms in the life cycle of .