In Bacillus subtilis, biofilm dispersal is intricately regulated by quorum sensing, a communication system that enables bacteria to coordinate behavior based on population density. At the core of this process is the regulation of the com operon, which is essential for the development of genetic competence in response to environmental signals. As the bacterial population grows, it secretes signaling molecules like ComX, a key peptide that accumulates and activates the ComP-ComA two-component regulatory system. ComP, a histidine kinase, phosphorylates ComA, which then functions as a transcriptional activator, inducing the expression of the com operon. This operon governs the uptake of extracellular DNA, allowing bacteria to enhance genetic diversity—a critical adaptation in nutrient-limited environments. Additionally, ComA activation leads to the transcription of the srfA operon, which is responsible for producing surfactin, a biosurfactant that plays a crucial role in biofilm dispersal. The synthesis of surfactin is tightly linked to quorum sensing, ensuring that bacteria respond to their environment collectively. Once released, surfactin reduces surface tension and disrupts cell-to-cell adhesion within the biofilm, promoting cell detachment and dispersal. This transition enables bacteria to colonize new niches while also enhancing their ability to uptake extracellular DNA, further increasing genetic adaptability. The coordinated action of the com and srfA operons exemplifies how Bacillus subtilis balances biofilm maintenance, dispersal, and genetic exchange in response to high cell density. By integrating competence development with surfactin production, this system elegantly orchestrates the shift from a sessile biofilm state to a motile and genetically diverse population, optimizing bacterial survival and adaptability.

Quorum Sensing: ComX Pheromone Biosynthesis (com Operon and srfA Operon Activation) References