James Tiedje

Date: September 19, 2002

Chlorinated hydrocarbons have desirable properties for many commercial applications often because of their stability and increased toxicity for biocidal applications. As a result synthetic chemists have produced a number of such products for the marketplace, many of which now reside in the environment and some with undesirable consequences. We hold out hope that the microbes in nature have the capacities for removing many of these chemicals.

What do we know about this prospect, what are the potentials, limits and challenges? While most attribute chlorochemicals to the chemists, there are many haloorganics synthesized naturally by organisms and by natural processes. The long-term presence of haloorganics is thought to have resulted in microbes with the capacity to degrade at least some chlorochemicals.

I will describe how the biodegradation capacity is patterned in the extant microbial world and the organismal, enzymatic and genetic diversity that resides in biodegrading microbes. One of the interesting outcomes of studies of new biodegradation processes is the interesting new contributions to biology that are uncovered. For example the energy generating process of halorespiration was uncovered from biodegradation driven studies, and with this the discovery of very different new genera and families of organisms, and a new yet poorly understood family of reductive dehalogenases and dehalogenase-like genes. Finally, I will show some examples of putting dehalogenators to work in the field to cleanup chloro-solvent contaminated groundwaters.