Award Abstract #0456689
Collaborative Research: MIP: Physiology and Molecular Ecology of Thermophilic Nitrate-reducing Microorganisms at Deep-sea Hydrothermal Vents

NSF Org:	MCB Division of Molecular and Cellular Biosciences
Initial Amendment Date:	June 20, 2005
Latest Amendment Date:	April 11, 2007
Award Number:	0456689
Award Instrument:	Continuing grant
Program Manager:	Matthew Kane MCB Division of Molecular and Cellular Biosciences BIO Directorate for Biological Sciences
Start Date:	June 15, 2005
Expires:	May 31, 2008 (Estimated)
Awarded Amount to Date:	$110019
Investigator(s):	Karen Casciotti kcasciotti@whoi.edu (Principal Investigator) Stefan Sievert (Co-Principal Investigator)
Sponsor:	Woods Hole Oceanographic Institution 183 OYSTER POND ROAD WOODS HOLE, MA 02543 508/289-2462
NSF Program(s):	MICRO OBS & MICRO INTER & PRO
Field Application(s):
Program Reference Code(s):	BIOT, 9104, 1114
Program Element Code(s):	1089

ABSTRACT

This study will investigate the physiology and ecology of thermophilic, nitrate-reducing microorganisms at deep-sea hydrothermal vents. Since the microbial contribution to the nitrogen cycle at deep-sea hydrothermal vents remains largely unknown, this study is designed to fill this gap. Recent studies revealed the occurrence of novel thermophilic microorganisms that couple the reduction of nitrate with autotrophic CO2 fixation in marine geothermal environments. The ecological significance of such a microbial community at deep-sea vents is twofold: 1) these organisms contribute to the primary productivity by fixing CO2, and 2) their nitrate respiratory metabolism (namely, the reduction of NO3- to NO2-, N2, or NH4+) imply that nitrogen is conserved within the vent system and is recycled into the vent nitrogen cycle. This research will integrate novel cultivation and molecular techniques with stable isotope analyses to explore the physiology of nitrate-reducing microorganisms, and to assess their functional diversity and activity. By establishing a link between physiology, phylogeny and activity, this study will contribute to our understanding of the ecological relevance of nitrate-reducing organisms at deep-sea vents, as well as their contribution to both the carbon and nitrogen cycling. This research will also contribute to the expansion of the database of genes relevant to CO2 fixation and NO3- reduction, allowing for the improvement of detection tool for monitoring these microbial processes in the environment. Training opportunities will be offered to one graduate student and several undergraduate students, and educational and outreach activities associated with several NSF-sponsored programs (e.g., the Mid-Atlantic Center for Ocean Science Education Excellence and the Student Experiments at Sea) will be supported as well.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

Hugler, M., Huber, H., Molyneaux, S.J., Vetriani, C., and Sievert, S.M.. "Autotrophic CO2 fixation via the reductive tricarboxylic acid cycle in different lineages within the phylum Aquificae: Evidence for two ways of citrate cleavage.," Environmental Microbiology, v.9, 2007, p. 81.

Voordeckers, J.W., Do, M. H., Hugler M., Ko V., Sievert, S.M., and Vetriani, C.. "Culture dependent and independent analyses of 16S rRNA and ATP citrate lyase genes: a comparison of microbial communities from different black smoker chimneys on the Mid-Atlantic Ridge," Extremophiles, 2008.

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