A coordinated study of water chemistry, sediment mineralogy, and sediment microbial community was conducted on four >73°C springs in the northwestern Great Basin. Despite generally similar chemistry and mineralogy, springs with short residence time (~5-20 min) were rich in reduced chemistry, whereas springs with long residence time (>1 day) accumulated oxygen and oxidized nitrogen species. The presence of oxygen suggested that aerobic metabolisms prevail in the water and surface sediment. However, Gibbs free energy calculations using empirical chemistry data suggested that several inorganic electron donors were similarly favorable. Analysis of 298 bacterial 16S rDNAs identified 36 species-level phylotypes, 14 of which failed to affiliate with cultivated phyla. Highly represented phylotypes included Thermus, Thermotoga, a member of candidate phylum OP1, and two deeply branching Chloroflexi. The 276 archaeal 16S rDNAs represented 28 phylotypes, most of which were Crenarchaeota unrelated to the Thermoprotei. The most abundant archaeal phylotype was closely related to "Candidatus Nitrosocaldus yellowstonii", suggesting a role for ammonia oxidation in primary production; however, few other phylotypes could be linked with energy calculations because phylotypes were either related to chemoorganotrophs or were unrelated to known organisms.
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Acknowledgments We are grateful to David and Sandy Jamieson for access to the field site and Joy Hallmark and Nicole Fester for assistance in sample collection. We also thank Jeremy A. Dodsworth for assistance in the editorial process and Natasha Zolotova and Panjai Prapaipong at ASU for help with IC and ICP-MS. Harriet Brady and students from Pyramid Lake Junior and Senior High School were important participants in this research. This work was supported by NSF Grant Number MCB-054865 and start up funds from UNLV to BPH. KCC received fellowship support through NSF Grants 0447416 and 0724226. JBN received fellowship support through NIH grant P20 RR16464. CLZ was supported by NSF Grant Number MCB-0348180. Support to the Nevada Genomics Center also made this work possible through Grant Number P20 RR01646 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH).
- Great Basin
- Hot spring
- Thermodynamic modelling