Enzymes produced by extremophile archaeabacteria can catalyze the breakdown of cellulose to glucose because they continue to function even under extremely hot, salty conditions.

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Researchers have recently isolated the same cellulase enzyme from a number of strains of archaeabacteria found in a hot spring in Nevada. The enzyme is able to catalyze the breakdown of cellulose to glucose at high temperatures (above 100 degrees C), and function under a wide range of harsh conditions including the presence of detergents, high salinity, and high ionic content.

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"Here we describe a consortium of three hyperthermophilic archaea enriched from a continental geothermal source by growth at 90 °C on crystalline cellulose... [the cellulase] enzyme has optimal activity at 109 °C, a half-life of 5 h at 100 °C, and resists denaturation in strong detergents, high-salt concentrations, and ionic liquids. Cellulases active above 100 °C may assist in biofuel production from lignocellulosic feedstocks by hydrolysing cellulose under conditions typically employed in biomass pretreatment." (Graham et al. 2011:1)

"The tight structure of lignocellulose is primarily responsible for its inherent stability and strength but presents a barrier to efficient hydrolysis, a significant problem when considering lignocellulose for biofuel production. Consequently, cellulosic biomass must first be subjected to pretreatment to increase the accessible surface area, and undergo either chemical or enzymatic deconstruction to release sugars that can be subsequently fermented to biofuels. Generally, enzymatic deconstruction and hydrolysis occurs slowly under conditions typically around 50 °C and pH 5.0. The conditions of many pretreatment processes are much more extreme, employing high temperatures combined with low or high pH, or steam explosion, for chemical pretreatment of feedstocks...Therefore, thermophilic cellulases have been targets of research to engineer durable enzymes that can withstand harsher conditions." (Graham et al. 2011:2)

"[T]he protein retained activity after boiling...The enzyme was active on a range of high molecular weight carbohydrate substrates containing β-1,4-linked glucose, including CMC, Avicel, and filter paper." (Graham et al. 2011:13)

Journal article
Identification and characterization of a multidomain hyperthermophilic cellulase from an archaeal enrichmentNature CommunicationsJuly 5, 2011
Joel E. Graham, Melinda E. Clark, Dana C. Nadler, Sarah Huffer, Harshal A. Chokhawala, Sara E. Rowland, Harvey W. Blanch, Douglas S. Clark, Frank T. Robb

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