A COMMUNITY MODEL OF CILIATE TETRAHYMENA AND BACTERIA ESCHERICHIA-COLI .2. INTERACTIONS IN A BATCH SYSTEM

Premised on relatively simple assumptions, mathematical models like th ose of Monod, Pirt or Droop inadequately explain the complex transient behavior of microbial populations. In particular, these models fail t o explain many aspects of the dynamics of a Tetrahymena pyriformis-Esc herichia coli community. In this study an alternative approach, an ind ividual-based model, is employed to investigate the growth and interac tions of Tetrahymena pyriformis and E. coli in a batch culture. Due to improved representation of physiological processes, the model provide s a better agreement with experimental data of bacterial density and c iliate biomass than previous modeling studies. It predicts a much larg er coexistence domain than rudimentary models, dependence of biomass d ynamics on initial conditions (bacteria to ciliate biomasses ratio) an d appropriate timing of minimal bacteria density. Moreover, it is foun d that accumulation of E. coli sized particles and E. coli toxic metab olites has a stabilizing effect on the system.