2.1. Biomass, IL, cellulase, and yeast cells
2.2. Assay of inhibition by IL on cellulase and yeast activity
2.3. IL-assisted pretreatment and washing of biomass
For PD 0332991 pretreatment, 0.5 g of bagasse powder was added to a 15-mL polypropylene tube (Corning Inc., New York, United States) containing 5 g of IL (EmimOAc or ChOAc). After vortexing, the biomass/IL mixture in the tube was sonicated for 60 min at 24 kHz and an emission power of 35 W using an ultrasonic processor (UP200S with sonotrode S3, Hielscher Ultrasonics GmbH, Teltow, Germany) in a water bath maintained at 25 °C.
For washing the IL from the pretreated biomass, 45 mL of deionized water was then added to the bagasse/IL mixture in a 50-mL tube, which resulted in the precipitation of the biomass. After mixing with inversion for 3 min, the 50-mL tube was centrifuged (8000g) for 10 min at 25 °C and the supernatant was removed. The washing procedure was repeated 1–5 times. For respective washing procedures, the removed supernatant was subjected to measurement of IL concentration using HPLC. The amount of residual IL in the biomass was indirectly determined from the IL amount in the supernatant. The precipitated wet bagasse was stored at 4 °C until use for subsequent enzymatic saccharification.