[Phenotypic variability of a recombinant luminescent strain of Escherichia coli in water microcosms]

The behavior of Escherichia coli Z905, carrying a recombinant plasmid pPHL7 with genes determining ampicillin resistance and bacterial luminescence, and the efficiency of expression of cloned genes were studied after introduction of the strain into model aqueous ecosystems with different trophic chain lengths. The E. coli Z905 variants isolated from ecosystems after different periods of time were found to vary in their resistance to ampicillin (from 50 to 0.05 micrograms/ml) and in the intensity of bioluminescence. An increase in the concentration of the selective factor (ampicillin) or in the extent of the aqueous microcosm blooming restored the expression of the recombinant plasmid genes in some clones.