FUNGAL STRATEGIES FOR DETOXIFICATION OF MEDIUM-CHAIN FATTY-ACIDS

Fungi can degrade free fatty acids and triacylglycerols to provide a c arbon and energy source. Medium chain fatty acids (those with a carbon length between six and 12 carbon atoms) are relatively uncommon. They are found in three oils of commercial importance-coconut, palm kernel and butter. The ability of fungi to convert medium chain fatty acids or triacylglycerols containing these acids to methyl ketones one carbo n atom less has been known for a long time. Five genera can undertake these bioconversions-Aspergillus and Penicillium, and their correspond ing teleomorphic genera Trichoderma, Cladosporium and Fusarium. Medium chain fatty acids inhibit fungal growth. The degree of inhibition dep ends on the concentration of the un-ionised acids. A number of fungal bioconversions of medium chain fatty acids can occur leading to the pr oduction of volatile metabolites. These include a partial beta-oxidati on to give the methyl ketone one carbon atom less than the parent fatt y acid, reduction of the ketone to give the secondary alcohol, hydroxy lation of the ketone to give a mono-hydroxy ketone, esterification and decarboxylation. It is suggested that the production of these volatil e metabolites is a fungal strategy to eliminate metabolites which woul d otherwise be toxic.