A novel ionic liquid-tolerant Fusarium oxysporum BN secreting ionic liquid-stable cellulase: Consolidated bioprocessing of pretreated lignocellulose containing residual ionic liquid

• A novel ionic liquid-tolerant fungus secreting ionic liquid-stable cellulase.
• Enhanced stability of the cellulase in the presence of ILs than in buffer.
• Direct biosynthesis of ethanol from IL-pretreated rice straw.
• The coupling of saccharification and fermentation phase by one fungus.

In this study, microbial communities from chemicals polluted microhabitats were cultured with the addition of imidazolium-based ionic liquid (IL) to enrich for IL-tolerant microbes. A strain of Fusarium oxysporum BN producing cellulase from these enrichments was capable of growing in 10% (w/v) 1-ethyl-3-methylimidazolium phosphinate, much higher than the normal IL concentrations in the lignocellulose regenerated from ILs. Cellulase secreted by the strain showed high resistance to ILs based on phosphate and sulfate radicals, evidencing of a high conformational stability in relevant media. Gratifyingly, F. oxysporum BN can directly convert IL-pretreated rice straw to bioethanol via consolidated bioprocessing (I-CBP). At optimum fermentation condition, a maximum ethanol yield of 0.125 g ethanol g−1 of rice straw was finally obtained, corresponding to 64.2% of the theoretical yield.