INFLUENCE OF NITRATE CONCENTRATION ON CARBON-TETRACHLORIDE TRANSFORMATION BY A DENITRIFYING MICROBIAL CONSORTIUM

A denitrifying consortium capable of transforming carbon tetrachloride (CCl4) was cultured from an aquifer soil isolated sample from the DOE Hanford Site in southeastern Washington State. Experiments were perfo rmed to determine the effects of nitrate concentration on CCl4 transfo rmation by these microbes. The microorganisms were cultured under two different experimental conditions, both of which gave similar cell gro wth. Under conditions where both the electron donor (acetate) and elec tron acceptor (nitrate) were present at all times, little CCl4 transfo rmation was observed. However, transformation was observed if the nitr ate concentration was reduced to a level where it was periodically dep leted. These results are discussed in relation to the design of an in situ bioremediation system.