Dual effect of soluble materials in pretreated lignocellulose on simultaneous saccharification and co-fermentation process for the bioethanol production

•Effect of different additions of soluble materials in biomass on SSCF was studied.•Soluble materials inhibit enzymatic hydrolysis but stimulate fermentation.•Soluble lignins at low concentrations stimulates xylose consumption in yeast.•YP addition enhances ethanol yield in SSCF containing high inhibitor concentrations. In this study, wash liquors isolated from ethylenediamine and dry dilute acid pretreated corn stover were used to evaluate the effect of soluble materials in pretreated biomass on simultaneous saccharification and co-fermentation (SSCF) for ethanol production, respectively. Both of the wash liquors had different impacts on enzymatic hydrolysis and fermentation. Enzymatic conversions of glucan and xylan monotonically decreased as wash liquor concentration increased. Whereas, with low wash liquor concentrations, xylose consumption rate, cell viability and ethanol yield were maximally stimulated in fermentation without nutrient supplementary. Soluble lignins were found as the key composition which promoted sugars utilization and cell viability without nutrient supplementary. The dual effects of soluble materials on enzymatic hydrolysis and fermentation resulted in the reduction of ethanol yield as soluble materials increased in SSCF.