The Oxidation of Fatty Acids by Spores of Penicillium roqueforti

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Abstract
The ability of washed spores of Penicillium roqueforti to oxidize fatty acids decreased markedly with age but was restored by adding specific sugars and amino acids. Only the C6 to Cl2 fatty acids were oxidized to the corresponding methyl ketone with one less carbon atom. The yield of methyl ketone between pH 5.5 and 7.0 decreased progressively from a maximum of 75% from octanoic acid to zero from myristic acid. The small amounts of metabolic carbon dioxide evolved greatly stimulated the oxidation of C10 and C12 fatty acids. The addition of sodium azide, 2,4-dinitrophenol (DNP) and certain divalent metallic ions, but not chloramphenicol, inhibited the oxidation of fatty acids. Oxidation was preceded by a lag period which was lengthened by increasing the fatty acid concentration or by decreasing the concentration of spores. Since cell-free extracts of spores were able to oxidize fatty acids, the lag phase with whole spores appears to be due to the absence of active transport systems. This is also indicated by the elimination of the lag phase by pre-incubation with octanoic acid but not by pre-incubation with glucose or casamino acids. The possible significance of methyl ketone formation in fatty acid metabolism is discussed.