DEGRADATION OF CHLORINATED DIBENZOFURANS AND DIBENZO-P-DIOXINS BY SPHINGOMONAS SP STRAIN RW1

The ability of the dibenzofuran- and dibenzo-p-dioxin-mineralizing bac terium Sphingomonas sp. strain RW1 (R.-M. Wittich, H. Wilkes, V. Sinnw ell, W. Francke, and P. Fortnagel, Appl. Environ. Microbiol, 58:1005-1 010, 1992) to oxidize chlorinated derivatives of dibenzofuran and dibe nzo-p-dioxin was analyzed. Strain RW1 degraded several mono- and dichl orinated dibenzofurans and dibenzo-p-dioxins, but it did not degrade m ore highly chlorinated congeners. Most mono- and dichlorinated dibenzo furans and dibenzo-p-dioxins investigated in this study were degraded to the corresponding mono- and dichlorinated salicylates and catechols , respectively, together with salicylate and catechol. This indicates an initial dioxygenolytic attack on the substituted as well as on the nonsubstituted aromatic nucleus of most of the target compounds, Strai n RW1 could not grow at the expense of monochlorinated dibenzo-p-dioxi ns and dibenzofurans as carbon sources, with the exception of 4-chloro dibenzofuran, which was stoichiometrically converted to 3-chlorosalicy late.