Bioabatement with hemicellulase supplementation to reduce enzymatic hydrolysis inhibitors

• Bioabatement removes enzyme inhibitors except xylo-oligomers from biomass liquors.
• Hemicellulase addition to bioabated biomass liquors enhanced cellulose conversion.
• Cellulase-boosting effects possibly due to the hydrolysis of xylo-oligomers.
• Hemicellulase-aided bioabatement effectively removes inhibitors from LHW liquors.

A stepwise removal of inhibitory compounds by bioabatement combined with hemicellulase supplementation was conducted to enhance cellulose hydrolysis of liquid hot water-pretreated corn stover. Results showed that the fungus Coniochaeta ligniaria NRRL30616 eliminated most of the enzyme and fermentation inhibitors from liquid hot water-pretreated corn stover hydrolysates. Moreover, addition of hemicellulases after bioabatement and before enzymatic hydrolysis of cellulose achieved 20% higher glucose yields compared to non-treated samples. This work presents the mechanisms by which supplementation of the fungus with hemicellulase enzymes enables maximal conversion, and confirms the inhibitory effect of xylo-oligosaccharides in corn stover hydrolysates once the dominant inhibitory effect of phenolic compounds is removed.