@article {Jungbluth2016,
	title = {{Novel microbial assemblages inhabiting crustal fluids within mid-ocean ridge flank subsurface basalt}},
	journal = {ISME Journal},
	volume = {10},
	year = {2016},
	pages = {2033{\textendash}2047},
	abstract = {Although little is known regarding microbial life within our planet{\textquoteright}s rock-hosted deep subseafloor biosphere, boreholes drilled through deep ocean sediment and into the underlying basaltic crust provide invaluable windows of access that have been used previously to document the presence of microorganisms within fluids percolating through the deep ocean crust. In this study, the analysis of 1.7 million small subunit ribosomal RNA genes amplified and sequenced from marine sediment, bottom seawater and basalt-hosted deep subseafloor fluids that span multiple years and locations on the Juan de Fuca Ridge flank was used to quantitatively delineate a subseafloor microbiome comprised of distinct bacteria and archaea. Hot, anoxic crustal fluids tapped by newly installed seafloor sampling observatories at boreholes U1362A and U1362B contained abundant bacterial lineages of phylogenetically unique Nitrospirae, Aminicenantes, Calescamantes and Chloroflexi. Although less abundant, the domain Archaea was dominated by unique, uncultivated lineages of marine benthic group E, the Terrestrial Hot Spring Crenarchaeotic Group, the Bathyarchaeota and relatives of cultivated, sulfate-reducing Archaeoglobi. Consistent with recent geochemical measurements and bioenergetic predictions, the potential importance of methane cycling and sulfate reduction were imprinted within the basalt-hosted deep subseafloor crustal fluid microbial community. This unique window of access to the deep ocean subsurface basement reveals a microbial landscape that exhibits previously undetected spatial heterogeneity.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1038/ismej.2015.248},
	author = {Jungbluth, S P and Bowers, R M and Lin, H-T and Cowen, J P and Rappe, M S}
}
@article {Lin2015,
	title = {{Dissolved amino acids in oceanic basaltic basement fluids}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {164},
	year = {2015},
	pages = {175{\textendash}190},
	abstract = {The oceanic basaltic basement contains the largest aquifer on Earth and potentially plays an important role in the global carbon cycle as a net sink for dissolved organic carbon (DOC). However, few details of the organic matter cycling in the subsurface are known because great water depths and thick sediments typically hinder direct access to this environment. In an effort to examine the role of water{\textendash}rock{\textendash}microorganism interaction on organic matter cycling in the oceanic basaltic crust, basement fluid samples collected from three borehole observatories installed on the eastern flank of the Juan de Fuca Ridge were analyzed for dissolved amino acids. Our data show that dissolved free amino acids (1{\textendash}13 nM) and dissolved hydrolyzable amino acids (43{\textendash}89 nM) are present in the basement. The amino acid concentrations in the ridge-flank basement fluids are at the low end of all submarine hydrothermal fluids reported in the literature and are similar to those in deep seawater. Amino acids in recharging deep seawater, in situ amino acid production, and diffusional input from overlying sediments are potential sources of amino acids in the basement fluids. Thermodynamic modeling shows that amino acid synthesis in the basement can be sustained by energy supplied from inorganic substrates via chemolithotrophic metabolisms. Furthermore, an analysis of amino acid concentrations and compositions in basement fluids support the notion that heterotrophic activity is ongoing. Similarly, the enrichment of acidic amino acids and depletion of hydrophobic ones relative to sedimentary particulate organic matter suggests that surface sorption and desorption also alters amino acids in the basaltic basement. In summary, although the oceanic basement aquifer is a net sink for deep seawater DOC, similar amino acid concentrations in basement aquifer and deep seawater suggest that DOC is preferentially removed in the basement over dissolved amino acids. Our data also suggest that organic carbon cycling occurs in the oceanic basaltic basement, where an active subsurface biosphere is likely responsible for amino acid synthesis and degradation.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.gca.2015.04.044},
	author = {Lin, H-T and Amend, J P and LaRowe, D E and Bingham, J-P and Cowen, J P}
}
