Nevada hot springs pool produces extreme-heat-tolerant enzyme

| July 07, 2011

A microbe found in a Nevada hot springs pool can not only eat cellulose at temperatures above the boiling point of water, but the team of researchers who found the super-bug believe it might be well-suited for extreme industrial biofuels production processes. The team, made up of researchers from the University of California Berkeley and the University of Maryland School of Medicine, found the hyperthermophilic microbe in a 95-degree Celsius pool. The microbe, according to UCB, is only the second member of a group of ancient microbes known as Archaea that are known to grow by eating cellulose above 80 degrees C.

Douglas S. Clark, a professor of chemical and biomolecular engineering at UCB, said that the team was surprised to find the bug in its first sampling, also adding that the version of the microbe found is “the most thermophilic Archaea discovered that will grow on cellulose.”

The team of researchers is being funded through a grant from the Energy Biosciences Institute, a public-private collaboration that has been given $500 million over 10 years by the oil giant BP.

The discovery of the heat-tolerant microbe and the enzyme within it capable of breaking down cellulose isn’t the first finding of an enzyme from extreme conditions. UCB notes that a commonly used enzyme for amplifying DNA in a chain reaction process was originally found in another thermophilic organism located in a geyser in Yellowstone National Park.

“Our hope is that this example and examples from other organisms found in extreme environments—such as high temperature, highly alkaline or acidic, or high salt environments—can provide cellulases that will show improved function under conditions typically found in industrial applications, including the production of biofuels,” Clark said.

This particular discovery, Clark also said, “is interesting because it helps define the range of natural conditions under which cellulytic organisms exist and how prevalent these bugs are in the natural world,” adding that, “it indicates that there are a lot of potentially useful cellulases in places we haven’t looked yet.”

To find the microbe, Frank Robb from the University of Maryland School of Medicine and his team, used sediment and water samples from the Great Boiling Springs, close to the town of Gerlach, Nev., eventually growing microbes from the samples on pulverized miscanthus grass, all so that the team could “isolate those that could grow with plant fiber as their only source of carbon.”

In addition to testing the most suitable microbes, the team also sequenced the microbes to determine which were best for utilizing cellulose as food, finding that the most active and high-temperature were in the EBI-244 class.

Clark, who said that the hyperthermophilic enzymes may actually work at too high of temperatures, said his team will continue looking at testing extreme condition-based enzymes on the possibility that an enzyme could be used “as-is” at certain temperatures but still maintain the “robust structural stability of the wild microbe.”