InSituSurvival ofPlasmid-Bearing andPlasmidless Pseudomonas aeruginosa inPristine Tropical Waters

ratios ranged from0.5to1.3; transfer percentages ranged from13to70%. [3H]thymidine uptake indicated DNA synthesis inbothstrains aswellasintransconjugants. Thesestudies indicate that rarewild-type bacterial strains withlarge plasmid loads cansurvive aswellascanbacteria with lowplasmid loads whenexposed totheinsitu conditions ofatropical freshwater habitat. Theseresults also suggest thatgenetic modification ofindigenous microbiota through conjugation ortransformation isfeasible whenrarewild-type strains orgenetically engineered microorganisms arereleased inlarge numbersintropical aquatic ecosystems. Toproperly assess therisks ofreleasing genetically engineeredmicroorganisms intotheenvironment, research needstobeperformed on thesurvival, establishment, growth, andtransfer ofgenetic information ofmodelbacteria. Plasmid-containing wild-type bacterial strains havebeen