[Coexistence of transgenic Escherichia coli strains and natural microorganisms in experimental aquatic microcosms]

In experimental aquatic microcosms (AMCs), the population of the Escherichia coli strain Z905 harboring the recombinant plasmid pPHL7 (AprLux+) was found to gradually accumulate AMC-adapted cells, which retained the plasmid but differed from the original cells in some biochemical and physiological characteristics. Both the original and the AMC-adapted E. coli cells could coexist with the native AMC microflora for a year or longer. When introduced into AMCs together with native pseudomonads, the AMC-adapted E. coli Z905-33 (pPHL7) cells were more competitive than nonadapted cells.