Malassezia (formerly known as Pityrosporum) is a rather annoying genus of fungi. It’s behind dandruff and most skin diseases in humans. Malassezia species inhabit the skin of about 90% of adult humans without causing any harm. Unfortunately in some people the fungi suppress the body's immune response to it allowing it to proliferate and cause a skin disorder, often without any inflammatory response.
Researchers assumed that the fungi evolved to inhabit mammals, but recent studies have showed that Malassezia has a much wider reach than our skin. In fact, a new study found species of Malassezia widespread in marine environments, e.g. on seals, fish, plankton, corals and lobsters. The authors suspect that over time, the fungi diversified repeatedly into and out of marine environments.
The fungi are very difficult to cultivate in the lab, but the team from the University of Hawaii found that they are easily detected through environmental DNA sequencing techniques, using standard fungal DNA Barcoding protocols. They also found Malassezia species in several water and sediment samples. One of the most remarkable finds was a single strain of the noted human associate, Malassezia restricta, which was found in some of the most extreme and disconnected habitats on the planet, including arctic soils and hydrothermal vents.
Analysis of environmental sequences demonstrates that putative members of the Malassezia lineage likely rank among the most widespread fungi on the planet. They are found in a startling diversity of habitats and locations, from polar regions to deep-sea vents. Malassezia-like species appear to dominate certain marine habitats, which should most certainly be the focus of future research into the diversity and distribution of this enigmatic group. Clearly, considering Malassezia a mere epidermis-commensal is a definition that is only skin deep.