RAPID DECHLORINATION OF CARBON-TETRACHLORIDE AND CHLOROFORM BY EXTRACELLULAR AGENTS IN CULTURES OF METHANOSARCINA-THERMOPHILA

Previous experiments in our laboratory suggested the existence of an e xcreted biomolecule from Methanosarcina thermophila, capable of rapid carbon tetrachloride (CT) and chloroform (CF) transformation. Batch ex periments with filtered supernatants from M. thermophila cultured in t he presence and absence of elemental iron (Fe-0) were performed to det ermine if such a molecule existed. Filtering the supernatant with a 0. 22 mu m filter did not alter the CT or CF transformation rate or patte rn. Supernatants from cultures grown in medium without Fe-0 were able to facilitate rapid CT transformation, but could not catalyze subseque nt CF transformation. However, when the organisms were cultured in the presence of high concentrations of Fe-0 (10 g/L), the filtered supern atant catalyzed rapid CT and CF transformation. Autoclaving the supern atant did not significantly alter the CT transformation rate or patter n; however, heat treatment decreased CF transformation. The extracellu lar factor appeared to have a high transformation capacity for CT; upo n dechlorinating 82 mu m CT, the rate of transformation did not decrea se.