Bioabatement with xylanase supplementation to reduce enzymatic hydrolysis inhibitors

Bioabatement, using the fungus Coniochaeta ligniaria NRRL30616 can effectively eliminate enzyme inhibitors from pretreated biomass hydrolysis. However, our recent research suggested that bioabatement had no beneficial effect on removing xylo-oligomers which were identified as strong inhibitors to cellulase. Here, we evaluated bioabatement with xylanase supplementation to mitigate potential enzyme inhibitors observed in corn stover liquors after pretreatment with liquid hot water at 10% (w/v) solids. Results showed that cellulose conversion in the presence of 10% (w/v) LHW-preteated liquor reached 70.5% and 57.4%, for conversion of Solka Flock cellulose and pretreated corn stover solids, respectively, after bioabatement and xylanase supplementation. These represent an increase of 21.6% and 17.6%, respectively, in comparison with non-treated samples. The sequence in which xylanase and cellulase are added affects cellulose conversion, possibly as a result of competition between xylanase and cellulase binding to xylo-oligomers. Replacement of xylanase with maleic acid to hydrolyze xylo-oligomers to xylose at 120°C for 20 min yielded equivalent increases in efficiency of cellulase hydrolysis.