Novel, Deep-Branching Heterotrophic Bacterial Populations Recovered from Thermal Spring Metagenomes.Thermal spring ecosystems are a valuable resource for the discovery of novel hyperthermophilic Bacteria and Archaea, and harbor deeply-branching lineages that provide insight regarding the nature of early microbial life.  We characterized bacterial populations in two circumneutral (pH ~8) Yellowstone National Park thermal (T ~80°C) spring filamentous "streamer" communities using random metagenomic DNA sequence to investigate the metabolic potential of these novel populations.  A survey of similar phylotypes (>97% nt identity) within 16S rRNA gene datasets suggest that the newly described organisms are restricted to terrestrial thermal springs ranging from 70 to 90°C and pH values of ~7-9. 
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