S56: Characterization of a hyperthermophilic cellulase discovered from an archaeal consortium that grows at 90°C

The conversion of lignocellulose into biofuels has been limited by the low activity of cellulases. To assist with the conversion of cellulose to sugars, pre-treatment processes at high temperatures, low pH, and even in ionic liquids are candidates to reduce the recalcitrance of the lignocellulosic substrate. Cellulases that function at high temperatures and are stable to pre-treatment conditions offer the potential advantages of lower cooling costs, reduced risk of contamination, and higher reaction rates. To this end, bioprospecting for thermophilic, cellulose degraders and their enzymes has resulted in the discovery of a unique cellulase, designated EBI244. The 842 amino-acid cellulase contains a proline/threonine rich region at the N-terminus and a catalytic domain homologous to the glycosyl hydrolase family 5 domain. This enzyme has a pH optimum of 4.8, a temperature optimum of 100°C, and is active against soluble and crystalline cellulose substrates. EBI244 is at least four-times more active against ionic liquid pre-treated Avicel than untreated Avicel. EBI244 was also active against CMC and filter paper and remained active in a 50% ionic liquid solution. These results demonstrate the discovery of a novel hyperthermophilic cellulase from a hyperthermophilic enrichment.