Species: Malassezia globosa
Description and Significance
M. globosa is a unicellular fungus species. It has the typical spherical shape associated with yeast spores. The spores are typically around 2 micrometers in diameter. The species naturally exhibits a cream/yellow color and a venose and furrowed appearance. A colony of M. globosa typically has a butyrous texture. In addition, this microbial species exhibits monopolar and sympodial budding. It is most known for causing dandruff in humans.
M. globosa’s genome contains 4,286 genes. Its total genome size is 8.9 Mb, which is relatively small for a free-living fungus. It has 6,377 exons and 2,092 introns. There are approximately 6.2 Mbp of nucleotides in the exons. This genome also includes mating genes, indicating the possibility of sexual reproduction for the species. Interestingly, the genome does not encode the enzyme fatty acid synthase, even though the organisms is dependent upon lipids for growth and survival. However, it does encode secreted lipase to break down external lipids. It also encodes the necessary enzymes for glycolysis, the Krebs cycle, the pentose phosphate pathway, and the synthesis of the typical amino acid and nucleic acid “building blocks.”
Cell Structure, Metabolism and Life Cycle
Ecology and Known Roles in Symbiosis
M. globosa is most known for causing dandruff, which affects approximately 50% of the population at some point in their lifetime. Interestingly, much of the research on this species has been funded by Proctor & Gamble, makers of Head & Shoulders anti-dandruff shampoo.The symptoms of dandruff include dry, flaky skin on the scalp, along with redness and irritation. These symptoms are most likely the result of the non-metabolized oleic acid byproduct of the M. globosa lipase breaking down lipids from the skin surface. Human skin can react to the oleic acid by producing more skin cells, causing dead cells to “flake” off. Interestingly, it does not appear that people with dandruff have higher levels of the pathogen, but instead have different sensitivities to its metabolic byproducts. This condition is treated efficiently with antifungal shampoos and creams. M. globosa has also been implicated in other skin conditions, such as sweat allergy. It releases MGL_1304, a 17-kDa protein that acts as an antigen for the release of high levels of histamine. It also plays a role, along with other species of Malassezia, in pityriasis versicolor and atopic eczema.