SCREENING FOR DEOXYNIVALENOL-DETOXIFYING ANAEROBIC RUMEN MICROORGANISMS

Different enrichment methods were used to isolate an active, DON-trans forming microorganism from bovine rumen content. A microorganism capab le of detoxifying DON was enriched by omitting various compounds of a semidefined cultur medium, using CO2 gasatmosphere and treatment with different antibiotics. After several dilution series in optimized medi um under anaerobic conditions the culture consisted of two microorgani sms. Transformation rates were 8,4 mg.l(-1).h(-1), without reaching th e maximum rates. The active biotransforming bacterium in this cocultur e is a Gram-positiv, nonspore-forming, strictly anaerobic irregular ro d (0,2 by 1-1.5 mu m) occuring singly and in long chains up to 150 mu m. No growth occured on solid media. Yeast extract and hemin are essen tial. Growth and detoxification is not inhibited by 2-Bromoethanesulfo nate, a specific inhibitor of methanogenic bacteria. Different electro n transport inhibitors of the anaerobic respiratory chain partly affec ted cell growth and detoxification of DON, indicating a detoxification mechanism coupled with electron transfer, by using DON as electron ac ceptor.