Biotransformation of 2,7-Dichloro- and 1,2,3,4-Tetrachlorodibenzo- p -Dioxin by Sphingomonas wittichii RW1

Abstract

Aerobic biotransformation of the diaryl ethers 2,7-dichlorodibenzo- p -dioxin and 1,2,3,4-tetrachlorodibenzo- p -dioxin by the dibenzo- p -dioxin-utilizing strain Sphingomonas wittichii RW1, producing corresponding metabolites, was demonstrated for the first time. Our strain transformed 2,7-dichlorodibenzo- p -dioxin, yielding 4-chlorocatechol, and 1,2,3,4-tetrachlorodibenzo- p -dioxin, producing 3,4,5,6-tetrachlorocatechol and 2-methoxy-3,4,5,6-tetrachlorophenol; all of these compounds were unequivocally identified by mass spectrometry both before and after N , O -bis(trimethylsilyl)-trifluoroacetamide derivatization by comparison with authentic standards. Additional experiments showed that strain RW1 formed a second metabolite, 2-methoxy-3,4,5,6-tetrachlorophenol, from the original degradation product, 3,4,5,6-tetrachlorocatechol, by methylation of one of the two hydroxy substituents.