HR: 0800h
AN: V51C-1503    [Abstracts]
TI: Endolithic Mn-oxidizing bacteria commonly associated with basalts at active Seamounts
AU: * Templeton, A
EM: alexis.templeton@colorado.edu
AF: University of Colorado, Geological Sciences Campus Box 399, Boulder, CO 80309 United States
AU: Haucke, L
EM: lhaucke@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Bailey, B
EM: bebailey@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Staudigel, H
EM: hstaudig@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Tebo, B
EM: btebo@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093 United States
AB: Mn is a trace component of volcanic rocks that is commonly enriched by 1-2 orders of magnitude within the secondary mineral assemblages associated with submarine basalts. Our analysis of relatively young basalts recovered from active seamounts such as Loihi Seamount (Hawaii) and Vailulu'u Seamount (American Samoa) shows that Mn(IV)-oxides readily form during short time-periods (10 years) of low-temperature (~2C) alteration, although the abiotic kinetics of Mn(II)-oxidation are slow at this temperatures and pH. We suggest that the formation of these secondary minerals are likely due to the common presence of heterotrophic bacteria with the functional capability of Mn(II)-oxidation, which accelerate the rates of oxidation several orders of magnitude faster than predicted for water-rock interaction alone. To identify and isolate endolithic Mn(II)-oxidizing microorganisms from naturally-weathered basalt surfaces, samples were recovered from the cold outer-flanks of Loihi and Vailulu'u Seamount via submersible with a sealable biobox. Using a variety of oligotrophic to organic-rich seawater-based media, we have isolated over 40 strains of Mn(II)-oxidizing bacteria. These isolates are primarily alpha- and gamma-Proteobacteria that can grow on low concentrations of simple to complex organics, but not Mn(II) as a sole energy source. None of the isolates, nor their closest relatively, were previously recognized as Mn(II)-oxidizing bacteria. In particular, we have found that there are several strains that are common to the basalts recovered from Loihi & Vailulu'u Seamount, as well as from basalts collected at the East Pacific Rise, particularly Pseudoalteromonas and Sulfitobacter sp. The 16S rRNA gene sequences of the Pseudoalteromonas isolates are also observed in T-RFLP data and 16S clone libraries for microbial mats at Loihi, indicating that these isolates are environmentally-relevant and abundant in-situ. The ubiquitous distribution of these isolates also suggests that they may play an important role in the submarine alteration of volcanic rocks and the formation of ferromanganese crusts, and thereby affect the net chemical fluxes associated with water-rock exchange.
DE: 0448 Geomicrobiology
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
DE: 0471 Oxidation/reduction reactions (4851)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005