News

A team of researchers led by Anna-Louise Reysenbach, a microbiologist at Portland State University, has discovered and characterized the first acid-loving microbes living at deep-sea hydrothermal vents. The results of the study, “A ubiquitous obligate thermoacidophilic archaeon from deep-sea hydrothermal vents,” were published in the July 27, 2006 issue of Nature.

Reysenbach worked with researchers from University of Guelph, University of New Hampshire, Woods Hole Oceanographic Institution, U.S. Geological Survey and The Royal Netherlands Institute for Sea Research to conduct exploratory research at newly discovered deep-sea hydrothermal vents in the southwestern Pacific Ocean, along the Eastern Lau Spreading Center between Tonga and Fiji.

Previously, microbes discovered in these hydrothermal vents had existed in pH-neutral environments and were, at best, tolerant of more acidic conditions. The abundance of acid-loving microbes in terrestrial hot springs, such as those found in mudpots in Yellowstone National Park, had created significant speculation in the scientific community as to why these microbes had not been isolated in the underwater vents.

“This finding has confirmed that acid- and heat-loving microbes can thrive in the acidic deep-sea hydrothermal vent conditions, and what’s more, the organism we grew occurs at all deep-sea vent sites thus far studied in the world’s oceans,” said Anna-Louise Reysenbach of Portland State University. Following the identification of this organism from deep-sea vents, Reysenbach was able to culture and characterize the microbe in her laboratory at Portland State.

This newly discovered microbe represents the first example of a line of microbes that thrive in conditions acidic, hot and under significant pressure. Understanding how life evolves and survives in such environments can lead to a better understanding of how life may emerge elsewhere, on other planets. These types of microbes may have applications beyond basic science, in emerging fields such as bio-mining to help remove valuable metals from mine tailings. The discovery also confirms that there remains much to be learned about deep-sea life.

The microbe grows at acidic pHs between 3.3 and 5.8 (neutral is 7) and at temperatures of 55–75°C (131–167°F). It belongs to a special group of microbes called Archaea and was named “Aciduliprofundum boonei” in honor of the late David Boone, a professor of environmental microbiology at PSU who was best known for his research on microbial production of methane by another member of the Archaea, the methanogens. Boone created and directed the Oregon Collection of Methanogens, a global repository for more than 841 different strains and one of only two such repositories in existence. Boone passed away in May 2005 (http://www.pdx.edu/profile/In-memory-of-david-boone).

The National Science Foundation provided funding for sampling and initial characterization of hydrothermal fluids, deposits, microfauna and megafauna at vent fields along the Eastern Lau Spreading Center.

Reysenbach is one of several researchers at Portland State researching life in extreme environments, from volcanoes to glaciers, and fields from physics and biology to chemistry and geology. For more information on the research of Anna-Louise Reysenbach, visit http://www.alrlab.pdx.edu.

Additional resources:
Nature podcast: http://www.nature.com/nature/podcast/v442/n7101/nature-2006-07-27.mp3
Article online: http://www.nature.com/nature/journal/v442/n7101/edsumm/e060727-09.html

Source: Anna Louise Reysenbach, PSU Department of Biology (503-725-3864)

For Immediate Release (#06-095)