Genetically Engineered Erwinia carotovora : Survival, Intraspecific Competition, and Effects upon Selected Bacterial Genera

Abstract

Environmental use of genetically engineered microorganisms has raised concerns about potential ecological impact. This research evaluated the survival, competitiveness, and effects upon selected bacterial genera of wild-type and genetically engineered Erwinia carotovora subsp. carotovora to ascertain if differences between the wild-type and genetically engineered strains exist in soil microcosms. The engineered strain contained a chromosomally inserted gene for kanamycin resistance. No significant differences in survival in nonsterile soil over 2 months or in the competitiveness of either strain were observed when the strains were added concurrently to microcosms. For reasons that remain unclear, the engineered strain did survive longer in sterilized soil. The effects of both strains on total bacteria, Pseudomonas and Staphylococcus strains, and actinomycetes were observed. While some apparent differences were observed, they were not statistically significant. A better understanding of the microbial ecology of engineered bacteria, especially pathogens genetically altered for use as biological control agents, is essential before commercial applications can be accomplished.