Biological and Photolytic Transformations Fast and Effective Transformation of Toxaphne by Superreduced Vitamin B12 and Dicyanocobalamin

The chloropesticide toxaphene (Camphechlor, Melipax) has been used in high quantities since 1945 . Toxaphene has been classified as a persistent organohalogen pollutant (POP) and belongs to the “dirty dozen” . Due to its heavy use in the 1960s and 1970s, several environmental compartments were significantly contaminated with toxaphene. For instance, concentrations in polluted areas could exceed 1 mg/kg sediment . Recently, it was shown that cultures of the isolated bacterium Dehalospirillum multivorans transformed toxaphene in a similar way as anaerobic sediment and soil samples . The potential of D. multivorans for the anaerobic transformation of organohalogens was previously demonstrated for chloroethenes (PCE and TCE) . The reactive dehalogenase of D. multivorans contains a corrinoide co-factor . In this study two corrinoids cyanocobalamin (vitamin B12, CCA) and dicyanocobinamide (DCC) were used in their superreduced forms (i. e. those having the central atom Co in the oxidation state +I) . Interestingly, a very fast transformation of toxaphene was observed with superreduced DCC. Unfortunately, the transformation occurred so fast that no transformation products could be identified. For this reason, we performed further experiments with the less reactive superreduced vitamin B12 (CCAs). CCAs has previously been used for the transformation of PCBs, hexachlorobenzene, chloroform, and chloroethanes .