Multi-scale visualization and characterization of lignocellulosic plant cell wall deconstruction during thermochemical pretreatment

• DOI: 10.1039/c0ee00574f
• Publication Date: 2011-01-12T11:06:36Z
• Authors: Shishir P. S. Chu...; Bryon S. Donohoe; Leonardo da Costa...; Thomas Elder; Umesh P. Agarwal; Fachuang Lu; John Ralph; Michael E. Himmel; Venkatesh Balan; Bruce E. Dale
• Keywords: Corn stover; Enzymatic Hydrolysis

Deconstruction of lignocellulosic plant cell walls to fermentable sugars by thermochemical and/or biological means is impeded several poorly understood ultrastructural and chemical barriers. A promising pretreatment called ammonia fiber expansion (AFEX) overcomes the native recalcitrance through subtle morphological physicochemical changes that enhance cellulase accessibility without extracting lignin hemicelluloses into separate liquid streams. Multi-scale visualization characterization Zea mays (i.e., corn stover) were carried out laser scanning confocal fluorescence microscopy (LSCM), Raman spectroscopy, atomic force (AFM), electron (SEM, TEM), nuclear magnetic resonance (NMR), spectroscopy for analysis (ESCA) elucidate mechanism AFEX pretreatment. first dissolves, then extracts and, as evaporates, redeposits wall decomposition products (e.g., amides, arabinoxylan oligomers, lignin-based phenolics) on outer surfaces. As a result, nanoporous tunnel-like networks, visualized 3D-electron tomography, are formed within walls. We propose this highly porous structure greatly enhances enzyme embedded cellulosic microfibrils. The shape, size (10 1000 nm), spatial distribution pores depended their location conditions used. Exposed pore surface area per unit pretreated volume, estimated via TEM-tomogram image analysis, ranged between 0.005 0.05 nm2 nm3. results in modifications enzymatic hydrolysis yield 4–5 fold over untreated