@article {ISI:000400818400021,
	title = {{Telepresence is a potentially transformative tool for field science}},
	journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
	volume = {114},
	number = {19},
	year = {2017},
	month = {may},
	pages = {4841{\textendash}4844},
	publisher = {NATL ACAD SCIENCES},
	address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA},
	keywords = {AUV Sentry (Autonomous Underwater Vehicle), HOV Alvin (Human Occupied Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1703514114},
	author = {Marlow, Jeffrey and Borrelli, Chiara and Jungbluth, Sean P and Hoffman, Colleen and Marlow, Jennifer and Girguis, Peter R and Team, AT-36}
}
@article {ISI:000360888000001,
	title = {{Carbon fixation by basalt-hosted microbial communities}},
	journal = {FRONTIERS IN MICROBIOLOGY},
	volume = {6},
	year = {2015},
	month = {sep},
	type = {Article},
	abstract = {Oceanic crust is a massive potential habitat for microbial life on Earth, yet our understanding of this ecosystem is limited due to difficulty in access. In particular, measurements of rates of microbial activity are sparse. We used stable carbon isotope incubations of crustal samples, coupled with functional gene analyses, to examine the potential for carbon fixation on oceanic crust. Both seafloor-exposed and subseafloor basalts were recovered from different mid-ocean ridge and hot spot environments (i.e., the Juan de Fuca Ridge, the Mid-Atlantic Ridge, and the Loihi Seamount) and incubated with C-13-labeled bicarbonate. Seafloor-exposed basalts revealed incorporation of C-13-label into organic matter over time, though the degree of incorporation was heterogeneous. The incorporation of C-13 into biomass was inconclusive in subseafloor basalts. Translating these measurements into potential rates of carbon fixation indicated that 0.1-10 nmol C g(-1) rock d(-1) could be fixed by seafloor-exposed rocks. When scaled to the global production of oceanic crust, this suggests carbon fixation rates of 10(9)-10(12) g C year(-1), which matches earlier predictions based on thermodynamic calculations. Functional gene analyses indicate that the Calvin cycle is likely the dominant biochemical mechanism for carbon fixation in basalt-hosted biofilms, although the reductive acetyl-CoA pathway and reverse TCA cycle likely play some role in net carbon fixation. These results provide empirical evidence for autotrophy in oceanic crust, suggesting that basalt-hosted autotrophy could be a significant contributor of organic matter in this remote and vast environment.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2015.90400904},
	author = {Orcutt, Beth N and Sylvan, Jason B and Rogers, Daniel R and Delaney, Jennifer and Lee, Raymond W and Girguis, Peter R}
}
@article {ISI:000331111400001,
	title = {{Anaerobic oxidation of short-chain alkanes in hydrothermal sediments: potential influences on sulfur cycling and microbial diversity}},
	journal = {FRONTIERS IN MICROBIOLOGY},
	volume = {4},
	year = {2013},
	month = {may},
	type = {Article},
	abstract = {Short-chain alkanes play a substantial role in carbon and sulfur cycling at hydrocarbon-rich environments globally, yet few studies have examined the metabolism of ethane (C-2), propane (C-3), and butane (C-4) in anoxic sediments in contrast to methane (C-1). In hydrothermal vent systems, short-chain alkanes are formed over relatively short geological time scales via thermogenic processes and often exist at high concentrations. The sediment-covered hydrothermal vent systems at Middle Valley (MV Juan de Fuca Ridge) are an ideal site for investigating the anaerobic oxidation of C-1-C-4 alkanes, given the elevated temperatures and dissolved hydrocarbon species characteristic of these metalliferous sediments. We examined whether MV microbial communities oxidized C-1-C-4 alkanes under mesophilic to thermophilic sulfate-reducing conditions. Here we present data from discrete temperature (25, 55, and 75 degrees C) anaerobic batch reactor incubations of MV sediments supplemented with individual alkanes. Co-registered alkane consumption and sulfate reduction (SR) measurements provide clear evidence for C-1-C-4 alkane oxidation linked to SR over time and across temperatures. In these anaerobic batch reactor sediments, 16S ribosomal RNA pyrosequencing revealed that Deltaproteobacteria, particularly a novel sulfate-reducing lineage, were the likely phylotypes mediating the oxidation of C-2-C-4 alkanes. Maximum C-1-C-4 alkane oxidation rates occurred at 55 degrees C, which reflects the mid-core sediment temperature profile and corroborates previous studies of rate maxima for the anaerobic oxidation of methane (AOM). Of the alkanes investigated, C-3 was oxidized at the highest rate over time, then C-4, C-2, and C-1, respectively. The implications of these results are discussed with respect to the potential competition between the anaerobic oxidation of C-2-C(4)alkanes with AOM for available oxidants and the influence on the fate of C-1 derived from these hydrothermal systems.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2013.00110},
	author = {Adams, Melissa M and Hoarfrost, Adrienne L and Bose, Arpita and Joye, Samantha B and Girguis, Peter R}
}
@article {ISI:000320852100014,
	title = {{Characterizing the distribution and rates of microbial sulfate reduction at Middle Valley hydrothermal vents}},
	journal = {ISME JOURNAL},
	volume = {7},
	number = {7},
	year = {2013},
	month = {jul},
	pages = {1391{\textendash}1401},
	type = {Article},
	abstract = {Few studies have directly measured sulfate reduction at hydrothermal vents, and relatively little is known about how environmental or ecological factors influence rates of sulfate reduction in vent environments. A better understanding of microbially mediated sulfate reduction in hydrothermal vent ecosystems may be achieved by integrating ecological and geochemical data with metabolic rate measurements. Here we present rates of microbially mediated sulfate reduction from three distinct hydrothermal vents in the Middle Valley vent field along the Juan de Fuca Ridge, as well as assessments of bacterial and archaeal diversity, estimates of total biomass and the abundance of functional genes related to sulfate reduction, and in situ geochemistry. Maximum rates of sulfate reduction occurred at 90 degrees C in all three deposits. Pyrosequencing and functional gene abundance data revealed differences in both biomass and community composition among sites, including differences in the abundance of known sulfate-reducing bacteria. The abundance of sequences for Thermodesulfovibro-like organisms and higher sulfate reduction rates at elevated temperatures suggests that Thermodesulfovibro-like organisms may have a role in sulfate reduction in warmer environments. The rates of sulfate reduction presented here suggest that-within anaerobic niches of hydrothermal deposits-heterotrophic sulfate reduction may be quite common and might contribute substantially to secondary productivity, underscoring the potential role of this process in both sulfur and carbon cycling at vents.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1751-7362},
	doi = {10.1038/ismej.2013.17},
	author = {Frank, Kiana L and Rogers, Daniel R and Olins, Heather C and Vidoudez, Charles and Girguis, Peter R}
}
@article {ISI:000331550900001,
	title = {{Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments}},
	journal = {FRONTIERS IN MICROBIOLOGY},
	volume = {4},
	year = {2013},
	month = {dec},
	type = {Article},
	abstract = {Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C-2-C-5) and longer alkanes. C-2-C-4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C-1-C-4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the delta C-13 of all the alkanes in the reactors show enrichment over the course of the incubation, with the C-3 and C-4 incubations showing the greatest enrichment (4.4 and 4.5 parts per thousand, respectively). The concurrent depletion in the delta C-13 of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (-3.5 and -6.7 parts per thousand for C-3 and C-4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C-1-C-4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C-3-C-4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial community composition and density.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2013.00386},
	author = {Bose, Arpita and Rogers, Daniel R and Adams, Melissa M and Joye, Samantha B and Girguis, Peter R}
}
@article {ISI:000309446000009,
	title = {{Anaerobic methane oxidation in metalliferous hydrothermal sediments: influence on carbon flux and decoupling from sulfate reduction}},
	journal = {ENVIRONMENTAL MICROBIOLOGY},
	volume = {14},
	number = {10, SI},
	year = {2012},
	month = {oct},
	pages = {2726{\textendash}2740},
	type = {Article},
	abstract = {The anaerobic oxidation of methane (AOM) is a globally significant sink that regulates methane flux from sediments into the oceans and atmosphere. Here we examine mesophilic to thermophilic AOM in hydrothermal sediments recovered from the Middle Valley vent field, on the Juan de Fuca Ridge. Using continuous-flow sediment bioreactors and batch incubations, we characterized (i) the degree to which AOM contributes to net dissolved inorganic carbon flux, (ii) AOM and sulfate reduction (SR) rates as a function of temperature and (iii) the distribution and density of known anaerobic methanotrophs (ANMEs). In sediment bioreactors, inorganic carbon stable isotope mass balances results indicated that AOM accounted for between 16{\%} and 86{\%} of the inorganic carbon produced, underscoring the role of AOM in governing inorganic carbon flux from these sediments. At 90 degrees C, AOM occurred in the absence of SR, demonstrating a striking decoupling of AOM from SR. An abundance of Fe(III)-bearing minerals resembling mixed valent Fe oxides, such as green rust, suggests the potential for a coupling of AOM to Fe(III) reduction in these metalliferous sediments. While SR bacteria were only observed in cooler temperature sediments, ANMEs allied to ANME-1 ribotypes, including a putative ANME-1c group, were found across all temperature regimes and represented a substantial proportion of the archaeal community. In concert, these results extend and reshape our understanding of the nature of high temperature methane biogeochemistry, providing insight into the physiology and ecology of thermophilic anaerobic methanotrophy and suggesting that AOM may play a central role in regulating biological dissolved inorganic carbon fluxes to the deep ocean from the organic-poor, metalliferous sediments of the global mid-ocean ridge hydrothermal vent system.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1462-2912},
	doi = {10.1111/j.1462-2920.2012.02825.x},
	author = {Wankel, Scott D and Adams, Melissa M and Johnston, David T and Hansel, Colleen M and Joye, Samantha B and Girguis, Peter R}
}
@article {ISI:000301095200023,
	title = {{On the Potential for Bioenergy and Biofuels from Hydrothermal Vent Microbes}},
	journal = {OCEANOGRAPHY},
	volume = {25},
	number = {1, SI},
	year = {2012},
	month = {mar},
	pages = {213{\textendash}217},
	type = {Article},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1042-8275},
	author = {Girguis, Peter R and Holden, James F}
}
