(274b) Biodegradation of Hardwood Lignocellulosics by the Western Poplar Clearwing Borer, Paranthrene Robiniae (Hy. Edwards)
Plant lignin is a source of useful chemicals, and also the major barrier for saccharification of lignocellulosic biomass for ethanol conversion. The enzymatic lignin degradation/modification could bypass the need for chemical pretreatment and thereby facilitate bioprocess consolidation. Herein, we reveal our new discovery on the elucidation of the prototype of hardwood lignin modification/degradation in clearwing borer system, Paranthrene robiniae. The wood-boring clearwing borer, P. robiniae, effectively tunnels hardwood structures during the larval stage, and its digestion products from wood components has not yet been investigated. Subsequent solid state 13C cross polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflectance fourier transform infrared (ATR-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and thermogravimetric (TG) analysis on tunnel walls and frass produced, provided evidence for structural alterations and lignin degradation during such hardwood digestion process. Our results strongly suggest that the structural alteration of lignin primarily involved a preferential degradation of syringyl units accompanied with oxidation on the side chains of lignin guaiacyl moieties. This study also further indicated that, unlike the wood-feeding termite, the clearwing borer does not target cellulose as an energy source, and thus its lignin degradation ability should provide potential information on how to disassemble and utilize hardwood lignin. Overall, this new biological model with an efficient lignin disruption system will provide the new insights into novel enzyme system required for effective plant cell wall disintegration for enhanced cellulose accessibility and production of value-added lignin derived products.