US scientists hail a 'Siberian microorganism' that can double the speed of cellulose digestion

'Researchers at the National Renewable Energy Laboratory in the US  have discovered that an enzyme that can digest cellulose almost twice as fast as the current leading component cellulase enzyme on the market,' reported Renewable Energy Magazine.

'That enzyme is derived from a microorganism first found in the Valley of Geysers on the Kamchatka Peninsula in Siberia, Russia in 1990. If it continues to perform well in larger tests, it could help drive down the price of making lignocellulosic fuels, from ethanol to other bio-fuels that can be dropped into existing infrastructure'.

A paper outlining the findings appears in the journal Science entitled 'Revealing Nature's Cellulase Diversity: The Digestion Mechanism of Caldicellulosiruptor bescii CelA'.

'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,' states Renewable Energy Magazine. 

The US 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).'

NREL Scientist Yannick Bomble, one of the paper's authors, stated: 'Microorganisms and cellulases operating at such high temperatures have several biotechnological advantages. CelA is the most efficient single cellulase we've ever studied - by a large margin.

'It is an amazingly complex enzyme, combining two catalytic domains with three binding modules. The fact that it has two complementary catalytic domains working in concert most likely makes it such a good cellulose degrader.'

The magazine highlighted the potential advantages of the Kamchatka microorganism.

'If an enzyme can produce sugars more efficiently, it means lower cost for the enzyme cocktail, which is a major cost driver in the process of converting biomass into fuel,' it explained. 'The findings have important implications for industry, but also were fascinating for the scientists.'

'This discovery could reshape the landscape of commercial cellulase cocktail design,' said Paul Gilna, director of the BioEnergy Science Center, which funded the research. 

It is one of three Bioenergy Research Centers supported by the Office of Biological and Environmental Research in Energy Department's Office of Science.