Quorum-sensing biofilm model (per step dt = 0.05):
dAI/dt = 0.8 N (planktonic/100) - 0.5 flow AI - 0.1 AI
QS active when AI > threshold -> attached cells switch to biofilm phenotype
attach rate = (1 - flow) 0.3 N ; division 0.02 N per step in biofilm
EPS grows with N ; kill prob = dose (1 - resistance) 0.02
resistance = 0.9 EPS + 0.1 (biofilm) or 0.05 (planktonic)
Stages: reversible attachment, irreversible attachment, microcolony, maturation and dispersal, set by biofilm cell count (5 / 20 / 50 / 90).