Toxicological Screen to Determine In vitro Survival and Competition of Environmentally Applied Pseudomonads with Mouse Fecal Microbiota

摘要

Engineered bacterial strains have been developed for a number of environmental uses including bioremediation and application as biopesticides. An in vitro system was developed to screen environmentally relevant microorganisms for their ability to colonize the mammalian intestinal tract and compete with the normal intestinal tract flora. Previous in vivo work examined the colonization and competition potential of Pseudomonas spp. isolated from a commercial product for PCB degradation with the intestinal flora of CD-1 mice. The study evaluated the same pseudomonads and additional Escherichia coli 'control' strains by an in vitro tier testing approach. Initially, the competitor strains were tested for their ability to survive in anaerobic pure culture. All strains tested survived for 48 hours in pure culture, and all survived for 24 hours in culture with the mouse fecal microbiota. The only consistent effect on the microbiota attributed to the addition of a competitor strain was the reduction of the obligately anaerobic Gram-negative bacilli by the mouse intestinal homogenate P. aeruginosa strain PAMG.