Tuesday, May 3, 2011
Lignocellulose recalcitrance to bioprocessing still remains a core problem due to the intrinsic complexity of the plant cell wall structure. In this context, biological systems created by nature over millions of years of evolution can be capitalized for targeted deconstruction of complex plant cell wall structure through selective cleavage and structural modification of lignin. While exploring the mechanisms used by natural biological systems, such as, termites and white rot fungi, our results strongly suggest that there is a critical path for deconstruction of plant cell wall that requires minimal modification of lignin and lignin/hemicelluloses association but lead to adequate initial cellulase access for breakdown of the plant cell wall. Collectively, these findings further establish in relation to the utilization of cellulose: (1) the conservation of the major β–O–4' (β–aryl ether), albeit with sub-structure degeneracy, and (2) the structural alteration associated with preferential degradation of guaiacyl (G) derived units within the lignin primary structure. Additionally, we also reveal our new discovery on the elucidation of the prototype of hardwood lignin modification/degradation in clearwing borer system, Paranthrene robiniae. Unlike the termites and white rot fungi, the clearwing borer does not utilize cellulose as an energy source and appear to specifically degrade lignin at syringyl (S)-lignin sites, thereby, should offer potential information on how to disrupt and deconstruct hardwood lignin. Overall, these results will significantly provide a discrete understanding along with contribution of technological advances towards the optimal deconstruction/degradation of lignin required for effective plant cell wall disintegration.