Applying metagenomics for the identification of bacterial cellulases that are stable in ionic liquids

Abstract

Ionic liquids (ILs) are novel and chemically inert solvents for a wide range of reactions in organic synthesis and biocatalysis, and at least one of them is known to dissolve cellulose. ILs would provide novel options for cellulose degradation in homogenous catalysis if cellulases were sufficiently stable and active. By screening metagenomic libraries 24 novel cellulase clones were identified and tested for their performance in the presence of ILs. Most enzyme clones showed only very poor or no activities. Three enzyme clones (i.e. pCosJP10, pCosJP20 and pCosJP24) were moderately active and stable in the presence of 1-butyl-1-methyl-pyrrolidinium trifluoromethanesulfonate. The corresponding genes of these environment-derived cosmids were similar to known cellulases from Cellvibrio japonicus and a salt-tolerant cellulase from an uncultured microorganism, S.

Identification and characterization of a multidomain hyperthermophilic cellulase from an archaeal enrichment

“…25,26). A GH5 cellulase designated CelA 10 that is 83% similar to Cel5B from Cellovibrio japonicus, a halophile, remained active in 30% (v/v) of six different ionic liquids tested and also retained 50% and 30% activity in 4 M NaCl and 4 M KCl, respectively 26 . EBI-244 showed a similar trend of tolerance with these results from other extremophilic GH5s.…”

Sugarcane and Woody Biomass Pretreatments for Ethanol Production

“…ILs toxicity to enzymes and fermentative microorganisms must also be addressed as ILs trace residues may negatively affect the performance of enzymes [142] and inhibit fermentation [143]. Some research groups are now looking for new enzymes that are stable in ILs [144,145].…”

Cellulases in Ionic Liquids—The Long Term Stability of Aspergillus sp. Cellulase

“…The cellulases derived from Trichoderma reesei and T. viride were almost inactive in the presence of 30% (v/v) of all tested ILs (Figure 1), whereby 30% (v/v) IL was chosen, as it turned out to be a critical concentration in previous studies [3]. The Aspergillus niger preparation was only noticeably active in the presence of [BMIM]Cl, but the cellulase derived from Aspergillus sp.…”

“…The majority of cellulases, including a preparation from Trichoderma reesei, appear to be inactive in the presence of IL concentrations above 20% (v/v) [3,4]. In contrast, some thermostable cellulases have shown high activity in the presence of about 30% (v/v) IL [5,6].…”