Old Faithful cooks, stinks and is the perfect home for these living creatures

Yellowstone National Park is a North American wildlife hotspot. The park’s mountains, forests, and meadows are home to the largest concentration of mammals in the lower 48 states, including native bison and a recovered population of gray wolves. Millions of visitors flock to the park every year, waiting for a glimpse of its diverse wildlife.

It turns out that other popular attractions in Yellowstone – hydrothermal vents, pools and geysers that steam and bubble – are also unique habitats for living things. Instead of charismatic mammals and birds, they are home to chaos-loving microbes.

Scientists have long studied the hydrological characteristics of Yellowstone’s springs and pools, “but no one has ever studied the microbiology of a geyser,” says Eric Boyd, a professor of microbiology at Montana State University.

One reason they were ignored? Geysers are fleeting. Old Faithful, a popular attraction in Yellowstone, erupts about every 90 minutes, shooting boiling water 100 feet or more into the air. The water tumbles through the cold air, crashes, and then sinks back into the hot pools below.

It was hard to believe that anything could survive this cruel cycle. But in research presented last week at the Annual Meeting of the Geological Society of Americahave Dr. Boyd and colleagues demonstrated that Yellowstone’s geysers are perfect homes for some small creatures.

To test the water, the team captured falling liquid during Old Faithful’s eruption. Back in the lab, the samples were doused with a chemical designed to make tiny microbes fluoresce.

“We saw cells, and that was really exciting,” said Lisa Keller, a doctoral candidate at Montana State. “But we had to rule out that it wasn’t contamination because we were catching water flying through the air.”

After the microbes were fed and the Old Faithful samples warmed to their home temperatures, there was a flurry of activity at about 195 degrees Fahrenheit and a glimmer of action at 160 degrees. Ms Keller explained that this showed that the microorganisms were not only accustomed to the higher temperatures, but that they also preferred the heat.

The team used DNA testing to identify the microorganisms living in the geyser’s vents and pools. Thermocrinis, a group of bacteria species that love heat and convert chemicals into energy, made up more than 60 percent of the microbes at Old Faithful. Members of two other heat-loving microorganism genera, Thermus and Pyrobaculum, contributed to the plume’s microdiversity.

The researchers “correlated the different groups of microorganisms with different environmental conditions, which is very cool,” says Alfonso Davila, an astrobiologist at NASA Ames who was not part of the study. He said the work showed that a diverse microbiome could develop within a relatively small geyser system.

The team suggested that the diversity was caused by the dynamic environment at Old Faithful, which provides everything some microbes need to thrive: sulfur compounds, carbon and steaming water.

In support of their hypothesis, Ms. Keller noted that calm pools without turbulent eruptions had much less population-level biodiversity than they saw in the geyser.

“The geyser is a hostile, inhospitable environment. Yet it is almost a cradle for biodiversity,” said Dr. Boyd, adding that in the sulphurous, volcano-warmed, carbon dioxide-laden waters of Old Faithful, Thermocrinis is “as happy as a clam.”

And what about geysers outside our home planet? Evidence of geysers on Saturn’s ice-covered ocean moon, Enceladus, and Jupiter’s moon Europa could create the conditions necessary for microbes to bloom. Finding evidence beyond Earth is not far-fetched.

Discovering life in Old Faithful helps astrobiologists better understand life in such extremes, said Dr. Davila.

“The fact that life on Earth can grow under these specific conditions tells us something about the biological potential” on places like Enceladus, Europa or even Mars, he said.

While it may take many years for scientists to see potential evidence of life on these distant worlds, here at home we have Yellowstone, which Dr. Boyd said it is home to half of the world’s roughly 1,000 geysers. And the more scientists study geysers in Yellowstone and other parts of the world, the more they can find.

“I would be confident that any geyser we sample on Earth will support microbial life,” said Dr. Boyd.