Anaerobic transformation of compounds of technical toxaphene. 2. Fate of compounds lacking geminal chlorine atoms.
The major toxaphene metabolites in sediment and soils (2-exo,3-endo,6-exo,8,9,10-hexachlorobornane [B6-923] and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane [B7-1001]) were incubated with the isolated gram-negative bacterium Dehalospirillum multivorans. Within 14 d, biotransformation of B7-1001 was nearly quantitative, resulting in two penta- and six hexachlorobornanes, as well as one unsaturated hexachloro compound of technical toxaphene. The major transformation product (approximately 50% of all metabolites) was identified as 2-exo,3-endo,5-exo,8,9,10-hexachlorobornane (B6-903). Abiotic dehydrochlorination of B7-1001 with methanolic KOH resulted in the formation and subsequent identification of the lone unsaturated compound as 2,5-endo,6-exo,8,9,10-hexachloroborn-2-ene. Thus, dehydrochlorination was found to be a minor process of the anaerobic transformation of toxaphene. Biotransformation of 70% of amended B6-923 within 14 d demonstrated that reductive dechlorination was not exclusively associated with geminal Cl atoms, as previously suggested. Three pentachlorobornanes were identified as transformation products, one of which was identical with a transformation product of B7-1001. This commonality unequivocally proves this metabolite to be 2-exo,3-endo,8,9,10-pentachlorobornane. Fifteen previously unknown metabolites of B6-923, B7-1001, and other toxaphene compounds identified in this study were detected in sediment from Lake Ontario (Canada), underscoring the importance of microbial toxaphene transformation in natural, aquatic environments.
Department of Food Chemistry, Friedrich-Schiller-University Jena, Dornburger Strasse 25, D-07743 Jena, Germany.
Steffen
S
Ruppe
Anke
A
Neumann
Eric
E
Braekevelt
Gregg T
GT
Tomy
Gary A
GA
Stern
Keith A
KA
Maruya
Walter
W
Vetter
D000693:Anaerobiosis; D001711:Biotransformation; D002713:Chlorine / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D020565:Epsilonproteobacteria / Q000378:metabolism*; D005618:Fresh Water / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D019015:Geologic Sediments / Q000032:analysis*; D009864:Ontario; D012988:Soil Microbiology; D013997:Time Factors; D014112:Toxaphene / Q000737:chemistry / Q000378:metabolism*
D002713:Chlorine; D014112:Toxaphene