Biofilm formation and chemostat dynamics: Pure and mixed culture considerations

Time-dependent biofilm formation effects on continuous fermenter operation are modelled here in general for a mixed culture of N different microorganisms growing on a single substrate. Dynamic computer solutions are detailed for two versions of the general model: a pure culture and a simple two-cell mixed culture. Pure culture model predictions compare favorably with two pure culture experiments in the literature where significant biofilm formation was noted. A mixed culture of one microbe (C(1)) having a higher growth rate than a second microbe (C(2)) is simulated for two hypothetical scenarios of microbe C(2) having different magnitudes of cell deposition rate. Biofilm effects on the estimation of kinetic and stoichiometric parameters in both model versions, plus the impact of biofilms on mixed culture dynamics, are discussed.