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.
Ruppe
Steffen
S
Department of Food Chemistry, Friedrich-Schiller-University Jena, Dornburger Strasse 25, D-07743 Jena, Germany.
Neumann
Anke
A
Braekevelt
Eric
E
Tomy
Gregg T
GT
Stern
Gary A
GA
Maruya
Keith A
KA
Vetter
Walter
W
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