ISOLATION AND CHARACTERIZATION OF A DIBENZOFURAN-DEGRADING YEAST - IDENTIFICATION OF OXIDATION AND RING-CLEAVAGE PRODUCTS

We characterized the ability of a yeast to cleave the aromatic structu re of the dioxin-like compound dibenzofuran. The yeast strain was isol ated from a dioxin-contaminated soil sample and identified as Trichosp oron mucoides. During incubation of glucose-pregrown cells with dibenz ofuran, six major metabolites were detected by high-performance liquid chromatography. The formation of four different monohydroxylated dibe nzofurans was proven by comparison of analytical data (gas chromatogra phy-mass spectrometry) with that for authentic standards. Further oxid ation produced 2,3-dihydroxydibenzofuran and its ring cleavage product 2-(1-carboxy methylidene)-2,3-dihydrobenzo[b]furanylidene glycolic ac id, which were characterized by mass spectrometry and H-1 nuclear magn etic resonance spectroscopy, These two metabolites are derived from 2- hydroxydibenzofuran and 3-hydroxydibenzofuran, as shown by incubation experiments using these monohydroxylated dibenzofurans as substrates.