These jumbo viruses – very large viruses that attack bacteria – appear to live mainly on our hands and feet.

Microbiomes – communities of microorganisms – are really everywhere on Earth. There are also many micro-organisms such as bacteria, viruses and yeasts in and on our body. However, our knowledge of the precise composition of our so-called ‘skin microbiome’ – the cocktail of microbes that live on our skin – is not enough. Time to change that.

Study

In a new study the researchers took 594 skin samples from twelve healthy volunteers. They then decided to sequence the genomes of the microorganisms found in the samples. It leads to the discovery of hundreds of new bacteria, viruses and fungi that live on human skin.

Jumbo viruses

Among other things, the researchers uncovered twenty new jumbo viruses; very large viruses that target and infect bacteria. Jumbo viruses have a genome larger than 200 kilobases and are between three and five times larger than an average virus.

Hands and feet

These newly discovered (jumbo) viruses appear to reside mainly on the surface of the hands and feet of the volunteers studied. Something that the researchers can explain. “These parts of the body have very diverse microbiomes,” explains researcher Sara Kashaf. “This makes sense, by the way, because we constantly use our hands to touch everything in our environment. Our future work will focus on better understanding what the different microbes do within these communities.”

Other discoveries

The research team also found 174 previously unknown bacterial species and four new eukaryotes. “In addition to the bacteria and viruses we normally find, we also found 12 genomes of single-celled eukaryotes — fungi, such as yeast — on human skin,” said study researcher Rob Finn. “Some of these genomes were already known to us, for example Malassezia globosa. In addition, we found four new eukaryotes. One of these turns out to be a common one, which can be found in many of us.”

Skin microbiome

Thanks to the study, we have gained a better picture of the human skin microbiome. With their findings, the researchers expand the catalog of known skin bacteria by no less than 26 percent.

Health and sickness

It is very important that we gain more knowledge. The skin microbiome is thought to play a key role in skin health and disease. For example, certain microorganisms in the skin microbiome have been linked to various skin conditions, including acne and eczema. “Our study is an important step towards a more complete picture of the skin microbiome,” said researcher Julie Sefre. “We hope these data will support future studies that will improve our understanding of skin health and disease.”

The researchers used different and advanced methods to obtain the new insights. An important caveat, however, is that the subjects studied are only from North America. In follow-up studies, the researchers plan to also study the skin microbiome of people from other parts of the world, to gain an even better understanding of the diversity of the skin microbiome.