The Oxidation of Fatty Acids by Spores of Penicillium roqueforti

Abstract

SUMlMARYThe 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 C, to C,, 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 yo from octanoic acid to zero from myristic acid. The small amounts of metabolic carbon dioxide evolved greatly stimulated the oxidation of C,, and C,, 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.

The Metabolism of Triglycerides by Spores of Penicillium roqueforti

“…Distilled water that had been Seitz-filtered was also stimulatory after an extended lag period but only in the presence of a nitrogen source. This confirmed the results of earlier work that Seitz-filtered solutions may contain a factor which is stimulatory to the germination of fungal spores (Farkas & Ledingham, 1959 ;Lawrence, 1966) and which may be identical with a partially characterized factor extracted from R. C. LAWRENCE cotton which permits the rapid germination of rust uredospores (Atkinson & Allen, 1966). Since, however, the effect of Seitz-filtered solutions on the oxidation of triglycerides varied, autoclaved solutions were used in the experiments reported in this paper even although the rate of oxidation was considerably lower.…”

“…The time of harvesting the spores had no significant effect upon the rate of oxidation of triglycerides, in marked contrast to the oxidation of fatty acids (Lawrence, 1966). The hydrolytic step appeared to be a function of spore germination and might therefore be expected to be independent of the age of the spore.…”

“…A source of nitrogen was essential for triglyceride oxidation by spores and for their germination, but not for the oxidation of fatty acids (Lawrence, 1966). Since cell-free extracts of spores possessed esterase activity it seems likely that the utilization of certain nitrogen compounds resulted in the transport of hydrolytic enzymes across the spore wall.…”

“…Penicilhm roqueforti ATCC 6989 (American Type Culture Collection, Washington, D.C.) used in previous work on the oxidation of fatty acids (Lawrence, 1965a(Lawrence, , 1966, was grown on slopes of Czapek-Dox agar or malt agar (Oxoid) at 22". After incubation for 7-10 days the spores were gently dislodged with an inoculation needle and quickly washed in sterile water by centrifugation.…”

Les activités biochimiques des Penicillium utilisés en fromagerie

“…FRANK et HEINEN, 1958). Cette voie se greffe sur la voie normale de la ,B-oxydation des acides gras et les cétones résultantes possèdent un atome de carbone de moins que l'acide originel par perte du carbone du groupe carboxylique (LAWRENCE, 1966 Dans les fromages de types bleu, de vache ou de brebis, les taux de méthyl-cétones apparaissent très variables, de80à 650 ,uM pour 100 g de matière grasse; la 2-heptanone est dominante puis la 2-nonanone et parfois la 2-pentanone (tabl. IV) (SCHWARTZ et PARKS, 1963 a;SCHWARTZet al, 1963).…”