Which factor coordinates gene expression for adhesion, EPS production, metabolism, and virulence promoting maturation and stability of the biofilm?

• A. Neutrophils
• B. Antibiotics
• C. Quorum sensing
• D. Host immune response

Answer: (C)

Quorum sensing is the mechanism by which bacteria coordinate gene expression based on population density, driving biofilm development from initial attachment to a mature, stable community. Each cell releases signaling molecules (autoinducers); as the local cell number grows, these signals accumulate until they reach a threshold that is detected by receptors. This triggers changes in transcription that upregulate adhesion factors to help cells stick together, enhance production of extracellular polymeric substances to build the matrix, shift metabolism to suit the nutrient-limited biofilm environment, and control virulence factor expression to promote maturation and persistence. Some signals enable communication across species, helping a mixed biofilm coordinate as a community.

Host immune responses or antibiotics act on the biofilm from outside and can influence its survival, but they do not coordinate the synchronized gene expression that drives biofilm maturation. Neutrophils and other immune defenses attack the biofilm, while antibiotics apply selective pressure, but the cohesive regulation of adhesion, EPS production, metabolism, and virulence within the bacterial population is governed by quorum sensing.