NOVEL DETOXIFICATION OF THE TRICHOTHECENE MYCOTOXIN DEOXYNIVALENOL BYA SOIL BACTERIUM ISOLATED BY ENRICHMENT CULTURE

A mixed microbial culture capable of metabolizing deoxynivalenol was o btained from soil samples by an enrichment culture procedure. A bacter ium (strain E3-39) isolated from the enrichment culture completely rem oved exogenously supplied deoxynivalenol from culture medium after inc ubation for 1 day, On the basis of morphological, physiological, and p hylogenetic studies, strain E3-39 was classified as a bacterium belong ing to the Agrobacterium-Rhizobium group. Thin-layer chromatographic a nalysis indicated the presence of one major and two minor metabolites of deoxynivalenol in ethyl acetate extracts of the E3-39 culture filtr ates, The main metabolite was identified as 3-keto-4-deoxynivalenol by mass spectroscopy and H-1 and C-13 nuclear magnetic resonance analysi s, The immunosuppressive toxicity of 3-keto-4-deoxynivalenol was evalu ated by means of a bioassay based on the mitogen-induced and mitogen-f ree proliferations of mouse spleen lymphocytes, This compound exhibite d a remarkably decreased (to less than one tenth) immunosuppressive to xicity relative to deoxynivalenol, indicating that the 3-OH group in d eoxynivalenol is likely to be involved in exerting its immunosuppressi ve toxicity, Strain E3-39 was also capable of transforming 3-acetyldeo xynivalenol but not nivalenol and fusarenon-X.