A mathematical model for the co-existence of incompatible, conjugative plasmids in individual bacteria of a bacterial population.

A model is formulated to examine the possibility of coexistence of two or more plasmids of the same surface exclusion group in a bacterial chemostat culture. It appears that two plasmids are able to coexist. If two plasmids can coexist they will follow different survival strategies, one with a high conjugational transfer rate and a low fitness of its host, and other with a low transfer rate and a high host fitness. Coexistence of three plasmids of the same surface exclusion group is impossible.