Stable coexistence of syntrophic associations in continuous culture

This paper describes mathematically the growth dynamics of a ‘tight’ syntrophic association of two species of organisms in continuous coculture. Species X utilises substrate S and forms a product P. The substance P both inhibits the growth of X and constitutes the growth limiting substrate of the species Y. It is shown that the resulting dynamical balance in the level of P leads to a stable coexistence of both species over the range of dilution rates consistent with equal values of specific growth rates, provided certain qualitative conditions, characteristic of syntrophic interactions in general, are satisfied.