Quorum Sensing & Biofilm Switch

Quorum Sensing

Bacteria continuously secrete autoinducer (AI) molecules. When population density reaches a threshold, AI concentration triggers a cooperative switch from free-swimming planktonic state to biofilm formation.

dA/dt = α·N - δ·A
Switch: A > A_c → biofilm

Controls

Growth rate 0.3

AI secretion rate 0.5

Quorum threshold 120

AI degradation 0.1

State

Planktonic Phase

Bacteria

0.0

AI Level

Biofilm cells

Time (s)

Green dots = planktonic bacteria (free-swimming). Yellow-green clusters = biofilm formation. Blue halos show autoinducer field intensity.