The study of high temperature ecosystems (>73°C) is a frontier in biology because energy that supports these ecosystems is derived from chemical disequilibria rather than light. Some continental hot springs are hot spots of novel biodiversity, with an abundance of phylum- to class-level groups that have no cultured representatives, so-called biological dark matter. The expertise of our team enables us to test the central hypothesis that geographically distinct hot spring systems host genetically distinct microbial communities with similar C- and N-cycle functions. This hypothesis will be tested by focusing on bulk water and sediment microbial communities in source pools of that represent major physicochemical classes.


1) to define hot springs as physicochemical habitats for microorganisms through extensive geochemical analysis and thermodynamic modeling;

2) to robustly define microbial community structure from both a phylogenetic and gene content perspective through deep sequencing of 16S rRNA gene fragments, whole community metagenomics, and fluorescent in situ hybridization;

3) to measure rates of C-cycling processes and trace assimilated carbon into key players in the C-cycle through DNA and lipid stable isotope probing, and C and H natural abundance stable isotope measurements;

4) to apply a comprehensive suite of N-cycle process rate measurements combined with deep sequencing of Ncycle genes and transcripts to link processes to key players in the N-cycle; and

5) to sequence genomes of cultivated organisms and biological dark matter to reveal possible roles in biogeochemical cycles, particularly C- and N-cycles, and microbial endemism on the genome scale.

The combination of careful site characterization, direct measurement of microbial activities, and genomic approaches will lead to an unprecedented, integrated understanding of this system. When combined with similar work underway in the US, we will gain a detailed window into the relative roles of geochemistry and biogeography in controlling microbial community structure and function.