@article {ISI:000372931000004,
	title = {{Hydrogen and thiosulfate limits for growth of a thermophilic, autotrophic Desulfurobacterium species from a deep-sea hydrothermal vent}},
	journal = {ENVIRONMENTAL MICROBIOLOGY REPORTS},
	volume = {8},
	number = {2},
	year = {2016},
	month = {apr},
	pages = {196{\textendash}200},
	type = {Article},
	abstract = {Hydrothermal fluids (341 degrees C and 19 degrees C) were collected {\textless}1m apart from a black smoker chimney and a tubeworm mound on the Boardwalk edifice at the Endeavour Segment in the northeastern Pacific Ocean to study anaerobic microbial growth in hydrothermal mineral deposits. Geochemical modelling of mixed vent fluid and seawater suggests the mixture was anoxic above 55 degrees C and that low H-2 concentrations (79molkg(-1) in end-member hydrothermal fluid) limit anaerobic hydrogenotrophic growth above this temperature. A thermophilic, hydrogenotrophic sulfur reducer, Desulfurobacterium strain HR11, was isolated from the 19 degrees C fluid raising questions about its H-2-dependent growth kinetics. Strain HR11 grew at 40-77 degrees C (T-opt 72-75 degrees C), pH 5-8.5 (pH(opt) 6-7) and 1-5{\%} (wt vol(-1)) NaCl (NaClopt 3-4{\%}). The highest growth rates occurred when S2O32- and S degrees were reduced to H2S. Modest growth occurred by NO3- reduction. Monod constants for its growth were K-s of 30M for H-2 and K-s of 20M for S2O32- with a (max) of 2.0h(-1). The minimum H-2 and S2O32- concentrations for growth were 3M and 5M respectively. Possible sources of S2O32- and S degrees are from abiotic dissolved sulfide and pyrite oxidation by O-2.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1758-2229},
	doi = {10.1111/1758-2229.12368},
	author = {Stewart, Lucy C and Llewellyn, James G and Butterfield, David A and Lilley, Marvin D and Holden, James F}
}
@article {ISI:000345292900023,
	title = {{Diversity and abundance of Bacteria and nirS-encoding denitrifiers associated with the Juan de Fuca Ridge hydrothermal system}},
	journal = {ANNALS OF MICROBIOLOGY},
	volume = {64},
	number = {4},
	year = {2014},
	month = {dec},
	pages = {1691{\textendash}1705},
	type = {Article},
	abstract = {Denitrification, which results in the loss of bioavailable nitrogen-an essential macronutrient for all living organisms-may potentially affect chemosynthetic primary production in hydrothermal vent ecosystems where sub-oxic conditions favorable to denitrification are common. Here we describe the diversity and abundance of denitrifying bacteria in the subsurface biosphere at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge using a combination of quantitative polymerase chain reaction assays, and small subunit ribosomal RNA (SSU or 16S rRNA) pyrotag and nitrite reductase (nirS) clone library sequencing methods. Bacterial communities were diverse and dominated by members of the epsilon- and gamma-proteobacteria, including taxonomic groups containing known denitrifiers. Assemblages of denitrifiers that could be evaluated by nirS gene sequence comparisons showed low diversity. The single nirS sequence shared by the two locations, affiliated with a gamma-proteobacteria isolated from estuarine sediments (Pseudomonas sp. BA2), represented more than half of all sequences recovered when clustered at 97 {\%} identity. All other nirS sequences clustered into different taxonomic groups, indicating important differences in denitrifier community membership between the two sites. Total nirS gene abundance was at least two orders of magnitude lower than 16S rRNA abundance. Overall, our results demonstrate that the diversity and abundance of the nirS gene-containing bacterial community are rather low, as might be expected under the extreme conditions encountered in the subsurface biosphere of hydrothermal vent systems, and do not correlate clearly with any environmental variables investigated (i.e., pH, temperature, and H2S, NO3-, NH4+ concentrations).},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {1590-4261},
	doi = {10.1007/s13213-014-0813-3},
	author = {Bourbonnais, Annie and Juniper, S Kim and Butterfield, David A and Anderson, Rika E and Lehmann, Moritz F}
}
@article {ISI:000325142700005,
	title = {{Growth kinetics and energetics of a deep-sea hyperthermophilic methanogen under varying environmental conditions}},
	journal = {ENVIRONMENTAL MICROBIOLOGY REPORTS},
	volume = {5},
	number = {5},
	year = {2013},
	month = {oct},
	pages = {665{\textendash}671},
	type = {Article},
	abstract = {{A hyperthermophilic deep-sea methanogen, Methanocaldococcus strain JH146, was isolated from 26 degrees C hydrothermal fluid at Axial Volcano to model high temperature methanogenesis in the subseafloor. Emphasis was placed on defining growth kinetics, cell yields and growth energy demand (GE) across a range of conditions. The organism uses H-2 and CO2 as its sole carbon and energy sources. At various temperatures, pHs, and chlorinities, its growth rates and cell yields co-varied while GE remained uniform at 1.69x10(-11) J cell(-1)s(-1)+/- 0.68x10(-11) J cell(-1)s(-1) (s.d.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {1758-2229},
	doi = {10.1111/1758-2229.12065},
	author = {Eecke, Helene C Ver and Akerman, Nancy H and Huber, Julie A and Butterfield, David A and Holden, James F}
}
@article {ISI:000331246100002,
	title = {{Phylogenetic diversity and functional gene patterns of sulfur-oxidizing subseafloor Epsilonproteobacteria in diffuse hydrothermal vent fluids}},
	journal = {FRONTIERS IN MICROBIOLOGY},
	volume = {4},
	year = {2013},
	month = {jul},
	type = {Article},
	abstract = {Microorganisms throughout the dark ocean use reduced sulfur compounds for chemolithoautotrophy. In many deep-sea hydrothermal vents, sulfide oxidation is quantitatively the most important chemical energy source for microbial metabolism both at and beneath the seafloor. In this study, the presence and activity of vent endemic Epsilonproteobacteria was examined in six low-temperature diffuse vents over a range of geochemical gradients from Axial Seamount, a deep-sea volcano in the Northeast Pacific. PCR primers were developed and applied to target the sulfur oxidation soxB gene of Epsilonproteobacteria. soxB genes belonging to the genera Sulfurimonas and Sulfurovum are both present and expressed at most diffuse vent sites, but not in background seawater. Although Sulfurovum-like sox8 genes were detected in all fluid samples, the RNA profiles were nearly identical among the vents and suggest that Sulfurirnonas-like species are the primary Epsilonproteobacteria responsible for actively oxidizing sulfur via the Sox pathway at each vent. Community patterns of subseafloor Epsdonproteobactena 16S rRNA genes were best matched to methane concentrations in vent fluids, as well as individual vent locations, indicating that both geochemistry and geographical isolation play a role in structuring subseafloor microbial populations. The data show that in the subseafloor at Axial Seamount, Epsilonproteobacteria are expressing the soxB gene and that microbial patterns in community distribution are linked to both vent location and chemistry.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2013.00185},
	author = {Akerman, Nancy H and Butterfield, David A and Huber, Julie A}
}
@article {ISI:000299990700001,
	title = {{Subseafloor nitrogen transformations in diffuse hydrothermal vent fluids of the Juan de Fuca Ridge evidenced by the isotopic composition of nitrate and ammonium}},
	journal = {GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS},
	volume = {13},
	year = {2012},
	month = {feb},
	type = {Article},
	abstract = {Little is known about dissolved inorganic nitrogen (DIN) transformations in hydrothermal vent (HV) fluids. Here, we present the first isotopic measurements of nitrate (delta N-15 and delta O-18) and ammonium (delta N-15) from three HV fields on the Juan de Fuca ridge (NE-Pacific). The dominant process that drives DIN concentration variations in low-T diffuse fluids is water mass mixing below the seafloor, with no effect on the DIN isotope ratios. Strong inter-site variations in the concentration and delta N-15 of NH4+ in high-T fluids suggest different subsurface nitrogen (N) sources (deep-sea nitrate versus organic sediments) for hydrothermally discharged ammonium. Low NH4+ community N isotope effects ({\textless}3 parts per thousand) for net NH4+ consumption suggest an important contribution from gross ammonium regeneration in low-T fluids. Elevation of HV nitrate N-15/N-14 and O-18/O-16 over deep-sea mean isotope values at some sites, concomitant with decreased nitrate concentrations, indicate assimilatory or dissimilatory nitrate consumption by bacteria in the subsurface, with relatively low community N isotope effects ((15)epsilon(k) {\textless} 3 parts per thousand). The low N isotope effects suggest that nitrate assimilation or denitrification occur in bacterial mats, and/or in situ production of low delta N-15 nitrate. A significantly stronger relative increase for nitrate delta O-18 than for delta N-15 was observed at many sites, resulting in marked deviations from the 1:1 relationship for nitrate delta N-15 versus delta O-18 that is expected for nitrate reduction in marine settings. Simple box-model calculation show that the observed un-coupling of N and O nitrate isotope ratios is consistent with nitrate regeneration by either nitrite reoxidation and/or partial nitrification of hydrothermal ammonium (possibly originating from N-2 fixation). Our isotope data confirm the role of subsurface microbial communities in modulating hydrothermal fluxes to the deep ocean.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2011GC003863},
	author = {Bourbonnais, Annie and Lehmann, Moritz F and Butterfield, David A and Juniper, S Kim}
}
@article {ISI:000280633000011,
	title = {{Isolated communities of Epsilonproteobacteria in hydrothermal vent fluids of the Mariana Arc seamounts}},
	journal = {FEMS MICROBIOLOGY ECOLOGY},
	volume = {73},
	number = {3},
	year = {2010},
	month = {sep},
	pages = {538{\textendash}549},
	type = {Article},
	abstract = {Low-temperature hydrothermal vent fluids represent access points to diverse microbial communities living in oceanic crust. This study examined the distribution, relative abundance, and diversity of Epsilonproteobacteria in 14 low-temperature vent fluids from five volcanically active seamounts of the Mariana Arc using a 454 tag sequencing approach. Most vent fluids were enriched in cell concentrations compared with background seawater, and quantitative PCR results indicated that all fluids were dominated by bacteria. Operational taxonomic unit-based statistical tools applied to 454 data show that all vents from the northern end of the Mariana Arc grouped together, to the exclusion of southern arc seamounts, which were as distinct from one another as they were from northern seamounts. Statistical analysis also showed a significant relationship between seamount and individual vent groupings, suggesting that community membership may be linked to geographical isolation and not geochemical parameters. However, while there may be large-scale geographic differences, distance is not the distinguishing factor in the microbial community composition. At the local scale, most vents host a distinct population of Epsilonproteobacteria, regardless of seamount location. This suggests that there may be barriers to exchange and dispersal for these vent endemic microorganisms at hydrothermal seamounts of the Mariana Arc.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0168-6496},
	doi = {10.1111/j.1574-6941.2010.00910.x},
	author = {Huber, Julie A and Cantin, Holly V and Huse, Susan M and Welch, David B Mark and Sogin, Mitchell L and Butterfield, David A}
}
