Enrichment, isolation and characterization of fungi tolerant to 1-ethyl-3-methylimidazolium acetate

Abstract

Aims: This work aimed to characterize microbial tolerance to 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), an ionic liquid that has emerged as a novel biomass pretreatment for lignocellulosic biomass.

Methods and results: Enrichment experiments performed using inocula treated with [C2mim][OAc] under solid and liquid cultivation yielded fungal populations dominated by Aspergilli. Ionic liquid-tolerant Aspergillus isolates from these enrichments were capable of growing in a radial plate growth assay in the presence of 10% [C2mim][OAc]. When a [C2mim][OAc]-tolerant Aspergillus fumigatus strain was grown in the presence of switchgrass, endoglucanases and xylanases were secreted that retained residual enzymatic activity in the presence of 20% [C2mim][OAc].

Conclusions: The results of the study suggest that tolerance to ionic liquids is a general property of the Aspergilli.

Significance and impact of the study: Tolerance to an industrially important ionic liquid was discovered in a fungal genera that is widely used in biotechnology, including biomass deconstruction.

Keywords: Aspergillus; compost; endoglucanase; ionic liquid; xylanase.