White Paper Title: 
Emerging patterns of global biogeography of Epsilonproteobacteria at deep-sea hydrothermal vents

Julie L Smith1 and Julie A Huber1

1Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 (,

Epsilonproteobacteria dominate the microbial community at many hydrothermal vent systems around the world. Over the last 15 years, a variety of molecular techniques have found Epsiloproteobacteria in almost all vent niches including microbial mats, diffuse fluids, and sulfide chimneys. Epsilonproteobacteria are also associated with Alvinella, Paralvinella, and Riftia tubeworms, various snails, and Kiwa crabs. These ubiquitous chemolithoautotrophs are involved in carbon, sulfur, and nitrogen cycling and play a potentially large role in the biogeochemical processes at hydrothermal vents.

The diverse Epsilonproteobacteria are comprised of both anaerobic hydrogen-oxidizing thermophiles and microaerobic sulfur-oxidizing mesophiles, which effectively straddle the redox gradient present at hydrothermal systems. At higher taxonomic levels, Epsilonproteobacteria are widely distributed at vent sites, however, individual species or strains show variable distribution within single vent chimneys (for example, Nakagawa et al. 2004, 2005, 2006) as well as among different diffuse fluids and chimneys within a hydrothermal field (for example, Huber et al. 2003, 2007, 2010, Opatkiewicz et al. 2009, Takai et al. 2008).

Several recent studies have begun to elucidate the relationships between the geochemical environment and the distribution of Epsilonproteobacteria. At Axial Seamount, the diversity of Epsilonproteobacteria was shown to be an important component in the structuring of the microbial communities and is linked to changes in the amount of sulfur, iron, and hydrogen in hydrothermal fluids (Opatkiewicz et al. 2009). At NW Rota Seamount, the dominant genera of Epsilonproteobacteria shifted from the thermophilic, anaerobic Caminibacter to a mix of Caminibacter and the mesophilic, microaerobic Sulfurimonas and Sulfurovum with a concordant decrease in the temperature of hydrothermal vent fluid (Davis & Moyer 2008). A comparison of 14 vents from 5 active seamounts in the Mariana Arc showed significant structuring of Epsilonproteobacteria among different vents and seamounts, but these differences were not correlated with either distance or chemical parameters, suggesting that further integrative studies are required to determine the underlying mechanisms affecting the biogeography of Epsilonproteobacteria.

We are currently working on a comparison of the NW Rota and West Mata Seamounts in the Western Pacific to Axial Seamount in the Eastern Pacific and look forward to integrating these studies with others from the Eastern Lau Spreading Center, the East Pacific Rise, and the Juan de Fuca Ridge.