DIFFERENT UTILIZATION OF NEUTRAL LIPIDS BY MALASSEZIA-FURFUR AND MALASSEZIA-SYMPODIALIS

In recent years, the genus Malassezia has been expanded based on molec ular data; in addition to M. furfur and M. pachydermatis, five new spe cies (M. sympodialis, M globosa, M. obtusa, ill. restricta, M. slooffi ae) have been described. Apart from their lipid dependence, little is known about the metabolism and nutritional requirements of these new s pecies. Defined inocula of Malassezia reference strains were cultured on selective agar for pathogenic fungi which was overlaid with olive o il. Samples of the olive oil overlay were taken at regular intervals a nd the lipid fractions were analysed by high performance thin layer ch romatography. Depending on the time of incubation and the number of ce lls, nil. sympodialis and the other recently described species produce d a significant increase in free fatty acids. In addition, a band of a n apolar substance was identified as a mixture of fatty acid ethyl est ers. While showing growth, strains of M furfur produced only small amo unts of ethyl esters and free fatty acids. The growth kinetics of M. f urfur and M. sympodialis were also different: for M. sympodialis, a cl ear lag phase was observed, possibly indicating the necessity of extra cellular hydrolysis of the triglycerides. The significance of the synt hesis of ethyl esters could not be clarified. For routine differentiat ion, this metabolic difference is only of limited usefulness because s light contamination of M. furfur strains with other lipophilic Malasse zia species may lead to misinterpretation due to the high metabolic ac tivity. These metabolic differences might be important in the pathogen esis of Malassezia infections.