Nature offers remarkable biodegradative capabilities in certain organisms. Modern genetics can be done with some of these organisms, and the rates of biodégradation can be enhanced to what should be useful levels. The ability to dechlorinate highly persistant chlorinated pesticides would be especially desirable.
Ecosystems present severe challenges for survival and effectiveness of genetically engineered or selected organisms, due to low concentrations of substrate, toxins, predators, physical barriers, and seasonal or other fluctuations in environmental conditions.
Potential ecological hazards should be minimal so long as genes are transferred within bacteria or within fungi, as opposed to moving mammalian genes into plants or bacteria.
The best strategy for efficacy and safety is to isolate organisms from environments of interest—sediments, sludges, dumps, soils, introduce the plasmid or gene coding for the biodegradative enzyme(s), and then return the organism to its habitat.