Dandruff and Seborrheic Dermatitis: A Head Scratcher 396 infundibulum. These cells secrete hydrolytic enzymes, including lipase, into the extracellular milieu. The lipase enzymes cleave sebaceous triglycerides into free fatty acids and glycerol. The Malassezia consume the saturated fatty acids necessary for their proliferation and leave behind an increased amount of irritating unsaturated free fatty acids. These unsaturated fatty acids penetrate into the epidermis, and in susceptible individuals (discussed below) induce a breach of the skin’s barrier function, inducing either directly or indirectly irritation and a subsequent hyperproliferation and flaking. Lipases have been shown to play a key role in the lifestyle of Malassezia species on skin.45 In order to better understand this role, we isolated a lipase from M. globosa. One highly expressed lipase was sequenced and the corresponding lipase gene (LIP1) cloned and sequenced. This work was a first step toward a molecular description of lipid metabolism on the scalp and a more complete understanding of the role of microbial metabolism in the etiology of dandruff. Based on the limited activity of LIP1, it was postulated that additional lipases were present in Malassezia, and sequencing of the Malassezia genomes has revealed that to be the case. Figure 7. The role of Malassezia lipid metabolism in dandruff genesis