Researchers at the Energy Department's National Renewable Energy Laboratory (NREL) have discovered that an enzyme from a microorganism first found in the Valley of Geysers on the Kamchatka Peninsula in Russia in 1990 can digest cellulose almost twice as fast as the current leading component cellulase enzyme on the market.
If the enzyme continues to perform well in larger tests, it could help drive down the price of making lignocellulosic fuels, from ethanol to other biofuels that can be dropped into existing infrastructure. A paper reporting this finding, "Revealing Nature's Cellulase Diversity: The Digestion Mechanism of Caldicellulosiruptor bescii CelA" appears in the journal Science.
The bacterium first found in heated freshwater pools, Caldicellulosiruptor bescii, secretes the cellulase, CelA, which has the complex arrangement of two catalytic domains separated by linker peptides and cellulose binding modules.
NREL researchers put CelA to the test and found that it produced more sugars than the most abundant cellulase in the leading commercial mixtures, Cel7A, when acting on Avicel, which is an industry standard to test cellulose degradation. They found that CelA not only can digest cellulose in the more common surface removal, but that it also creates cavities in the material, which leads to greater synergy with more conventional cellulases, resulting in higher sugar release.
The bacteria that secrete the promising CelA thrive in temperatures of 75 to 90 degrees Celsius (167-194 degrees Farenheit).
"Microorganisms and cellulases operating at such high temperatures have several biotechnological advantages," said NREL Scientist Yannick Bomble, one of the paper's authors.
"CelA is the most efficient single cellulase we've ever studied by a large margin," Bomble said. "It is an amazingly complex enzyme, combining two catalytic domains with three binding modules. The fact that it has two complementar
|Contact: David Glickson|
DOE/National Renewable Energy Laboratory