Ethanol production from xylan-removed sugarcane bagasse using low loading of commercial cellulase

•Xylan-removed residue was used to produce bioethanol.•Enzymatic digestibility was 82% by using cellulase of 7.5 FPU/g cellulose.•Increasing cellulase loading from 7.5 FPU/g cellulose showed no improvement.•Ethanol concentration reached 40.59 g/L by using fed-batch mode.

Xylan was always extracted as the feedstock for xylooligosaccharides production. The xylan-removed residue may contain high content of cellulose and thus had a possibility to be converted into ethanol. After soaked in 12% of NaOH at room temperature overnight, solubilization of cellulose, xylan, and lignin was 4.64%, 72.06%, and 81.87% respectively. The xylan-removed sugarcane bagasse (XRSB) was enzymatically hydrolyzed by using decreased cellulase loadings. The results showed that 7.5 FPU/g cellulose could obtain a cellulose conversion yield of 82%. Increasing the cellulase loading did not result in higher yield. Based on this, bioethanol production was performed using 7.5 FPU/g cellulose by employing fed-batch fermentation mode. The final ethanol concentration reached 40.59 g/L corresponding to 74.2% of the theoretical maximum. The high titer ethanol and low cellulase loading may reduce the overall cost.