Discovered where mushrooms have the greatest diversity in human skin

(While humans have used the power of yeast to ferment bread and beer, the function of yeast and of other fungi living in and on the human body is not well understood.

In the first study of fungal diversity on human skin , scientists from the National Institute of Health Research decoded the DNA sequence of a parasitic fungus on human skin to identify populations. Pine mushrooms usually reside on human skin and provide information to help research conditions that cause fungal skin diseases.

Human skin surface is a complex ecosystem of microorganisms, including fungi, bacteria and viruses, collectively referred to as skin microbiome (skin microbiome is understood to be the entire genome of living microorganisms. in and on the skin). Although fungal infections affect about 29 million people in the United States, mushrooms are slow and difficult to cultivate in the laboratory, complex diagnosis and treatment even the most common cases of skin fungi, for example like nail infections.

The research team from the National Institute of Human Genetics, and the National Cancer Research Institute, both under NIH, have expanded the study of the sequence of their recent skin bacteria, using DNA sequencing techniques are optimized to identify fungi. The study was published May 22, 2013 online in the journal Nature.

Researchers found that a single fungus, belonging to the Malassezia genus , is common on the head and body. The human hand is home to a large variety of bacteria, which is home to a small number of fungi. In contrast, feet, including toenails, heels and insteps, have a huge diversity of fungi.

'Using DNA sequences to study dermatosis is a natural development to learn about the symbiotic microbial life on our bodies' , scientific director of NHGRI, medical doctor, Dr. Daniel Kastner said. 'Along with the recent gene sequence to identify microbial diversity, this analysis of fungal diversity provides a more comprehensive picture of human microbiome'.

'Mushroom populations reside in complex niches, even on the human body' . Heidi Kong, a medical doctor, a senior co-author and a dermatologist in NCI's Center for Cancer Research, said. 'By being more fully aware of bacterial and fungal ecosystems, we can treat skin diseases that are associated with better fungi and bacteria, including skin conditions that can be linked. related to cancer therapies' .

The researchers sampled in 14 different aerosols of 10 healthy adults. The mushroom DNA sequence in the DNA samples was identified, called phylogenetic marker (phylogenetic marker). ), can be calculated and used to distinguish a fungus from other fungi. Arrangement efforts have created more than 5 million standard scales, from samples, representing more than 80 species of mushrooms, or genera. In contrast, traditional culture methods produced 130 colonies of fungi representing only 18 fungal genera.

Marker - is a standard scale, this is a set of predetermined and predetermined pieces of DNA and used as a standard scale to estimate the size of a certain segment of nucleic acid in the electrophoresis technique.

In 20% of the study participants, the researchers observed problems such as changes in the heel, toe and toenails that could be infected with the fungus. From genetic sequence analysis, the team found differences in heel infections between individuals with common fungal populations at those sites, while those with nail infections for The mushroom population is very different.

'DNA sequences show a huge diversity of fungi, although they are difficult to grow in culture,' said Julie Segre, Ph.D., senior co-author and senior investigator of the Genetic Branch and NHGRI's molecular biology said. 'The DNA sequence allows us to learn more about areas where fungi predominate as part of human skin microbiome'.

The researchers identified fungi from the two sexes, Ascomycetes and Basidiomycetes, as part of a survey of common fungal numbers at 14 skin sites. The most common genus Malassezia has been present in 11 of the 14 sampling sites on the body. The researchers found Malassezia fungi on all skin surfaces of healthy volunteers, whether behind the head, behind the ears, in the nostrils or on the heels. The heel is also home to many other fungi, including Aspergillus, Cryptococcus, Rhodotorula and Epicoccum.

'Sequence-based identification of DNA sequences allows us to distinguish between different fungal species and conclude that the diversity of fungi is highly dependent on body positions, not on the body. sampler ' , Dr Kong said. As a dermatologist, Dr. Kong explains why these positions were chosen for research: 'Our research focuses on skin areas where we often see related skin diseases. to mushrooms'.

The most complex position, the heel, is home to about 80 genera of mushrooms. Researchers found 60 types of toenail swab samples and 40 types of interstitial skin swabs. Other positions with high fungal diversity are inside the elbow, inside the arms and palms , with each position having 18 to 32 genera of mushrooms. Surprisingly, positions such as head and body - including the back, back of the neck, inside the ears, behind the ears and between the eyebrows - have much fewer fungi, with only about 10 genera.

The team compared fungal diversity data with upper skin bacteria and healthy adults. They found that while the arms rich in bacteria had low fungal diversity. They found the opposite to be true for foot positions. The central locations of the body do not have high bacterial and fungal diversity. Researchers have shown that the diversity of bacteria on the human body can be predicted by both the skin's properties, moisture, dryness or oily skin. Instead, fungal diversity seems to depend on the location on the human body.

They observed, in addition, that there was a greater similarity in fungal population structure on the left and right side of the same person compared to different body parts on any two different people. Mushroom populations also appear to be quite stable over time, with little change between two separate trials 3 months apart.
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"The data from our research gives us a basis for normal individuals that we have never had before," Dr. Segre said. "The bottom line is that your feet are full of mushrooms, so tiptoe in the locker room if you don't want to mix your foot fungus with someone's foot fungus."