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A sequenced hyperthermophile: Pyrobaculum aerophilum
Edward R. Winstead


Scientists have sequenced Pyrobaculum aerophilum, a rod-shaped microorganism that can live in temperatures up to 104°C (219°F). Isolated from a boiling marine water hole at Maronti Beach, Italy, the organism may be useful for investigating the molecular basis of heat resistance. It is a member of the archaea, a branch of life that differs from plants, animals, and bacteria.

Pyrobaculum aerophilum cell, platinum shadowed.

The sequencing revealed that this particular strain, P. aerophilum IM2, had an unexpectedly high number of mutations. The researchers hypothesize that the strain may lack a sufficient complement of genes to repair DNA. The genome sequence, which is 2.2 million base pairs long, may also contain information about why the organism does not tolerate sulfur.

Jeffrey H. Miller, of the University of California, Los Angeles, led the project. His laboratory studies mutations in bacterial cells and how cells use repair strategies to avoid mutagenesis. One of Miller's Ph.D. students, Sorel T. Fitz-Gibbon, did the sequencing, assembly, and annotation of the genome as her graduate work. She is the first doctoral candidate to sequence a complete genome.

"Studies of the genus Pyrobaculum provide important opportunities for understanding the boundaries of life in extreme habitats," the researchers write in Proceedings of the National Academy of Sciences. "In a recent molecular sampling of a deep subsurface geothermal water pool, the only organisms detected were hyperthermophilic archaeal members closely related to Pyrobaculum."

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Fitz-Gibbon, S.T. et al. Genome sequence of the hyperthermophilic crenarchaeon Pyrobaculum aerophilum. Proc Natl Acad Sci USA 99, 984-989 (January 22, 2002). Published online January 15, 2002.

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