Insights into Ionic liquids-resistance mechanism and lignocellulose-degradation model of Aspergillus terreus in 1-ethyl-3-methylimidazolium acetate

Ionic liquids (ILs)-assisted microbes and enzymes are potential approaches for converting lignocellulosic biomass into fermentable sugars in a biorefinery. In the present study, an ILs-tolerant strain Aspergillus terreus NEAU-7 with ILs-stable cellulase production ability was isolated and identified. A comparative transcriptome analysis revealed that A. terreus NEAU-7 could promote ion transport and acquire metabolic energy to reduce the adverse effect of ILs. The results further confirmed that the strain could increase the accumulation of compatible solutes to offset the osmotic pressure of ILs and reduce the cell membrane permeability to prevent ILs. A secretome analysis of Carbohydrate-Active Enzymes (CAZymes) showed no significant reduction in the Glycoside Hydrolases (GH) families of cellulolytic enzymes, while a significant reduction was observed for Carbohydrate Esterases (CE) families and Glycoside Hydrolase 43 (encoding α-L-arabinofuranosidases and β-xylosidases), indicating that the presence of ILs could decrease the expression of hemicellulolytic enzymes. Herein, a model for lignocellulose degradation of A. terreus NEAU-7 was interpreted. Overall, this study will provide insights into further exploration of the ILs-resistance mechanism of lignocellulolytic fungi and employment of ILs-assisted fungi in the degradation of lignocellulosic biomass into value-added products.