Biological control of the chemostat with nonmonotonic response and different removal rates.

We show the global stabilization of the chemostat with nonmonotonic growth, adding a new species as a "biological" control, in presence of different removal rates for each species. This result is obtained by an extension of the Competitive Exclusion Principle in the chemostat, for the case of two species with different removal rates and at least one nonmonotonic response.