Enhanced enzymatic saccharification of corn stover by in situ modification of lignin with poly (ethylene glycol) ether during low temperature alkali pretreatment

•In situ lignin modification was performed during alkali pretreatment with PEGDE addition.•In situ lignin modification enhanced enzymatic hydrolysis of corn stover.•Lignin modification reduced the non-specific binding of exo-glucanase and β-glucosidase.•Lignin-based surfactant showed no positive effect on enzymatic hydrolysis of PAPCS.

A novel pretreatment process of corn stover was established in this study by in situ modification of lignin with poly (ethylene glycol) diglycidyl ether (PEGDE) during low temperature alkali pretreatment. The addition of PEGDE obviously improved the enzymatic hydrolysis by covalently modifying the residual lignins in substrates. Under the optimized conditions (pretreated with 10% (w/w) NaOH and 10% (w/w) PEGDE at 70 °C for 2.5 h), the total fermentable sugar yield was increased by 46.4%, from 23.7 g to 34.7 g per 100 g raw materials. Additionally, the remaining activities of exo-glucanase and β-glucosidase in supernatant were increased by 58.6% and 40.6% respectively, demonstrating that the enhancement of enzymatic hydrolysis was mainly due to the alleviation of enzyme non-productive binding. Although the isolated lignin modified with PEGDE enhanced the enzymatic hydrolysis of substrates as well, this in situ lignin modification provided an efficient but simple way to improve enzymatic saccharification.