A new study by researchers at Portland State University and the University of Wisconsin finds that a rich diversity of microorganisms live in interdependent communities in high-temperature geothermal environments in the deep sea. The study, which was published in the journal Microbiome, was led by Anna-Louise Reysenbach, professor of biology at PSU. Emily St. John, who earned a master's degree in microbial ecology from PSU, also contributed significantly to the study, along with researchers from the University of Wisconsin.

When the 350-400 degree Celsius fluid exiting the Earth's crust through deep-sea hydrothermal vents mixes with sea water it creates large porous rocks often referred to as 'chimneys' or hydrothermal deposits. These chimneys are colonized by microbes that thrive in high-temperature environments. For decades, Reysenbach has collected chimneys from deep-sea hydrothermal vents across the world's oceans, and her lab uses genetic fingerprinting and cultivation techniques to study the microbial diversity of the communities associated with these rocks.

In this new study, Reysenbach and the team were able to take advantage of advances in molecular biology techniques to sequence the entire genomes of the microbes in these communities to learn more about their diversity and interconnected ecosystems.

The team constructed genomes of 3,635 Bacteria and Archaea from 40 different rock communities. The amount of diversity was staggering and greatly expands what is known about how many different types of Bacteria and Archaea exist. The researchers discovered at least 500 new genera (the level of taxonomic organization above species) and have evidence for two new phyla (five levels up from species). "Phyla is way up on the taxonomic rank, so that's really cool," says Reysenbach.