MOBILIZATION OF A RECOMBINANT NONCONJUGATIVE PLASMID AT THE INTERFACEBETWEEN WASTE-WATER AND THE MARINE COASTAL ENVIRONMENT

The ability of aquatic bacteria isolated from habitats around the outl et of treated wastewater in a coastal marine ecosystem to mobilize the nonconjugative recombinant plasmid pCE328 was studied. A total of 208 strains were screened for their large plasmid content; 51 strains car ried at least one large plasmid. Of these, 6 strains from wastewater a nd 8 from the marine environment were able to mobilize pCE328. Mobiliz ing strains were isolated from all habitats, and the majority belonged to the genus Aeromonas. The frequencies of mobilization in plate mati ng experiments ranged from 2 x 10(-7) to 4.4 x 10(-5) per donor at 15 degrees C and 20 degrees C. Mobilization occurred al lower frequencies in microcosm experiments. The results suggest that recombinant DNA re leased at such interfaces may be transferrred rapidly to the autochton ous populations through several bacterial species.