Physical-chemical properties of cell wall interface significantly correlated to the complex recalcitrance of corn straw

Background: Tissue heterogeneity significantly influences the overall saccharification efficiency of plant biomass. However, the mechanisms of specific organ or tissue recalcitrance to enzymatic deconstruction are generally complicated and unclear. A multidimensional analysis of the anatomical fraction from 12 corn cultivars was conducted to understand the essence of recalcitrance.

Results: The results showed that leaf, leaf sheath, stem pith and stem rind of corn straw exhibited remarkable heterogeneity in chemical composition, physical structure and cell type, which resulted in the different saccharification ratio of cellulose. The high saccharification ratio ranging from 21.47 to 38.96% was in stem pith, whereas the low saccharification ratio ranging from 17.1 to 27.43% was in leaf sheath. High values of lignin, hemicelluloses, degree of polymerization and crystallinity index were critical for the increased recalcitrance, while high value of neutral detergent soluble and pore size generated weak recalcitrance. Interestingly, pore traits of cell wall, especial for microcosmic interface structure, seemed to be a crucial factor that correlated to cellulase adsorption and further affected saccharification.

Conclusions: Highly heterogeneity in cell wall traits influenced the overall saccharification efficiency of biomass. Furthermore, the holistic outlook of cell wall interface was indispensable to understand the recalcitrance and promote the biomass conversion.