Visitors to Yellowstone National Park’s geothermal springs are struck as much by the stench as by the landscape. The sulfur compounds emanating from the springs bear a rotten-egg odor, and they have long been regarded as a major source of energy for the springs’ rich community of microorganisms. New research, however, suggests this positive spin on sulfur may be overblown. Most microorganisms in the springs seem to live off hydrogen, scientists report.
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To find out what kinds of microbes inhabit these extreme environments, where water temperatures can surpass 70°C, researchers at the University of Colorado at Boulder collected bacteria-bearing sediment samples from Yellowstone’s geothermal system. Then, the team sequenced some of the microbes’ genes. Much to the researchers’ surprise, the sequences in most of the microbes closely resembled those of hydrogen-metabolizing bacteria that had been characterized elsewhere.