About Hydrothermal Vents

Krista Longnecker, former webmaster and technology manager for the Gulf of Maine Aquarium, is pursuing her PhD in oceanography from Oregon State University. As part of her studies, she is participating in a month-long cruise on the research vessel Atlantis,which will include up to 12 dives on the research submersible Alvin.

The object of the study is to look at life forms that can survive an unimaginable environment: very high temperature, high pressure, underwater areas surrounding deep-sea vents, or "hot springs." Similar research is being conducted on land-based hot springs such as those at Yellowstone National Park.

There are several reasons these microbes are so interesting.

• First: how do they survive temperatures of 700 degrees F (375 Celsius) or more?
• How do they survive under 8300 feet (2500 meters) of water?
• Third: How do they appear so quickly whenever a new vent is formed, when the nearest similar environment with similar organisms is hundreds or even thousands of kilometers away?

It is thought that the answers to these questions may help us understand principles of evolution, because early life on this planet also had to survive extreme conditions.

Because the scientific method requires the posing of an hypothesis, the researchers here are asking a basic question: what role does the element pyrite play in the survival of these organisms? It is thought that pyrite can support primitive forms of life.

Krista tells us, "The vents that we will diving on are 2500 meters underwater. The microbes we're studying can survive temperatures of 375 celsius. However thus far the highest temperature that anyone has been able to culture them is slightly greater than 105 celsius." Read Krista's Latest Dispatch.

The full project description follows:

LEXEN: Pyrite, a Crucial Mineral and Surface for Microbial Life in Extreme Hydrothermal Environments.

Abstract - Luther, Proposal #9714302

Organisms that thrive in high temperature (hyperthermophiles) ecosystems such as at terrestrial and deep-sea hydrothermal vents, have challenged our understanding of the physical and biochemical constraints on the upper temperature limits for life and stimulated new theories on how life originated (e.g., Baross and Hoffman, 1985; Pace, 1991). These hyperthermophiles are the most closely related to the universal ancestor for all life (from small subunit rRNA and gene duplication data) which supports the theory that life arose in highly reduced, high temperature environments such as those encountered at hydrothermal vent systems. Recently scientists proposed a mechanism for the synthesis of the first molecules for life in which pyrite can be synthesized abiotically with hydrogen as a product, laying the framework for the evolution of the first metabolic cycles. The central hypothesis of this study maintains that the abiotic synthesis of pyrite provides the essential properties for sequestering the energy sources for chemoautotrophic metabolism of the deepest lineages of life. Drs. Luther and Reysenbach believe that under an extreme chemical and physical environment microorganisms can utilize the resources provided on the pyrite surfaces for sustained metabolism. They also believe that these organisms will closely represent early life forms that may have occupied similar extreme habitats. Furthermore, since molecular phylogenetic evidence exists that the deepest of these thermophilic lineages inhabit iron and sulfidic-rich environments at deep-sea hydrothermal vents, they are well-positioned to test these assertions.

The objectives of this research are:
1. To establish whether pyrite and the associated adsorbed trace metals and simple inorganic molecules will mediate the microbial community structure in high temperature aquatic environments.

2. To determine whether pyrite synthesis can be predicted, through the simultaneous measurement of FeS and hydrogen sulfide.

This project clearly addresses most of the primary mandates of the LExEn research program. In this interdisciplinary study these collaborators will integrate molecular genetic approaches with in situ geochemistry to study the diversity, ecology, and evolutionary history of the microorganisms thriving in extreme habitats where intense redox and temperature gradients exist. This project is cooperatively supported by the Divisions of Ocean Science and Chemistry, and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate.