Microbiology of Seamounts Common Patt erns Observed in Community Structure

Much interest has been generated by the discoveries of biodiversity associated with seamounts. The volcanically active portion of these undersea mountains hosts a remarkably diverse range of unusual microbial habitats, from black smokers rich in sulfur to cooler, diffuse, iron-rich hydrothermal vents. As such, seamounts potentially represent hotspots of microbial diversity, yet our understanding of the microbiology of seamounts is still in its infancy. Here, we discuss recent work on the detection of seamount microbial communities and the observation that specific community groups may be indicative of specific geochemical scenarios, such as iron and sulfur cycling. These observations are based on the metabolisms predicted by phylogenetic characteristics exhibited by the dominant populations found within these microbial communities as compared to the closest related isolate found in culture. Therefore, these studies combine the use of both cultivation-dependent and -independent analyses. Cultivation-independent studies were primarily completed using cloning and sequencing techniques targeting small subunit ribosomal gene (SSU rDNA) biomarkers along with similar biomolecular tools like terminal-restriction fragment length polymorphism (T-RFLP) and quantitative polymerase chain reaction (Q-PCR), which allow for the determination of phylotypes (analogous to species). We discuss the notion of Zetaproteobacteria and/or Epsilonproteobacteria being the most common members of hydrothermal habitats associated with seamounts exhibiting volcanic activity. Another noneruptive seamount scenario is also examined, for example, South Chamorro Seamount, an active forearc serpentinite mud volcano. iNtroductioN Microbial life is remarkable for its resilience to extremes of temperature, pH, and pressure, as well its ability to persist and thrive using an amazing number of organic or inorganic food sources. Nowhere are these traits more evident than in the deep ocean. Much of the deep seafloor consists of cold, relatively static sedimentary environments where heterotrophic microbes exist in significant numbers, but conditions remain relatively unchanged over long periods of time. Mid-ocean ridges associated with diverging plate boundaries are often sites of high-temperature hydrothermal venting and host many chemoautotrophic microbes; however, these systems are more homogeneous with respect to their physical and chemical properties than vent systems associated with volcanic arcs and backarcs (Takai et al., b y d aV i d e M e r s o N a N d c r a i g l . M o y e r common Patterns observed in community structure Th is aticle as been pulished in O ceagraphy, Vlum e 3, N um er 1, a qurterly jornal of Th e o ceagraphy soiety. © 2010 by Th e o ceagraphy soiety. a ll rhts rerved. Perm ision is gnted to cpy his aticle or se in teching nd rearch. replication, sstem m tic repruction, or coective redirbution of ny prtion of his aticle by phocopy m acine, repsting, or oher m eans is perm ited only w ith he aproval of Th e o ceagraphy soiety. send ll corrondence o: ifo@ tos.org or Th e o ceagraphy soiety, Po ox 131, rokville, M d 208-1931, u sa .