Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2008
Publication Date: May 4, 2008
Citation: Grabber, J. H., Hatfield, R. D., Ralph, J., Lu, F. 2008. Coniferyl ferulate incorporation into lignin dramatically enhances the delignification and enzymatic hydrolysis of maize cell walls [abstract]. Proceedings of Biotechnology for Fuels and Chemicals Symposium. 8(05):56. Technical Abstract: Incorporating ester interunit linkages into plant lignins could enhance the delignification and saccharification of fiber for fermentation into ethanol or other industrial products. In this study, we examined how substitution of coniferyl alcohol (a normal monolignol) with 0 to 60% coniferyl ferulate (an ester conjugate from secondary metabolism) influenced the formation and alkaline solubility of lignin and the enzymatic hydrolysis of artificially lignified maize cell walls. Although extensively copolymerized into lignin, coniferyl ferulate unexpectedly accelerated peroxidase inactivation, interfered with cell-wall ferulate copolymerization into lignin, and reduced lignin concentrations in cell walls from about 200 to 160 mg/g. In addition to lowering lignin content, coniferyl ferulate increased the extractability of cell wall lignin by up to two-fold in aqueous 0.5 M NaOH at 30 or 100 ºC. Thus, the conjugate provides a means for delignifying cell walls under milder conditions at lower cost. Coniferyl ferulate incorporation also increased sugar yields at the onset of enzymatic hydrolysis by up to 45% and the final yield of sugars by up to 15% for lignified cell walls, both before and after a 30 oC pretreatment with 0.5 M NaOH. Based on our results, bioengineering of plants to incorporate coniferyl ferulate into lignin should substantially reduce the cost for saccharifying fiber for fermentation into fuels or other industrial products.