Thermophilic viruses (phages) were first reported decades ago; however, our knowledge of their diversity, biology and ecological significance is still very limited.
More...Thermophilic viruses (phages) were first reported decades ago; however, our knowledge of their diversity, biology and ecological significance is still very limited. Previous research on thermophilic viruses has focused on cultured viruses. This study examined the genomic profiles and morphological diversity of uncultured viruses directly isolated from 74� to 93�C alkaline hot springs in Yellowstone National Park. Viral abundance ranged from 1E5 to 1E6 particles per milliliter, and a variety of bacteriophage and crenarchaeal virus-like morphologies were observed. Using a new method for constructing metagenomic libraries from nanogram amounts of viral DNA, nearly 30 Mb of DNA sequence from two of these hot springs was determined. Between 400 and 1400 different viral types probably inhabit each hot spring. Although most sequences were unrelated to known viral or cellular genomic sequences, hundreds of BLASTx similarities to genes associated with replication, recombination, lysis, transcription, lysogeny, and viral structural were identified. A significant portion of the viral metagenome was shared between the two hot springs, suggesting substantial overlap of the populations. Certain cultured viral genomes had remarkable similarity to the metagenomic sequences. Regions spanning almost the entire 28 kb genome of Pyrobacculum spherical virus have apparent homologs in libraries. Similarities to bacteriophages and acidophilic archaeal viruses isolated on other continents were limited to specific open reading frames, but were equally strong.
A metagenomic library was constructed from viral communities from Octopus Hot Spring (N 44�32'3.0 W 110�47'52.6, pH 8.0, 93�C) in Yellowstone National Park. This is the first metagenomic analysis of a viral community in a thermal environment. Numerous inferences about diversity, lifestyle and evolution have been made using this data and will be published.
Sequences deposited into the Trace Archive can be found using the Project data link. Less...