The alkaline extraction efficiency of bamboo cell walls is related to their structural differences on both anatomical and molecular level

Biomass recalcitrance is believed to be related to the hierarchical and heterogeneous structures of plant cell walls. In this study, the alkaline extraction efficiency of bamboo fibers and parenchyma cells is found to be highly related to their structural differences on both anatomical and molecular level. Advanced NMR spectroscopy demonstrated the lignin and hemicelluloses (mainly xylan) from fibers and parenchyma cells are significantly different in their molecular structure. The parenchyma lignin contains more beta-O-4 linkages with much higher syringyl/guaicyl (S/G) ratio. By contrast, the fiber lignin contains more stable beta-beta and beta-5 linkages as compared to parenchyma lignin. Although the hemicelluloses from both bamboo fibers and parenchyma cells shows similar molecular structure of L-arabino-4-O-methyl-D-glucurono-D-xylan, the latter contains more 4-O-methyl-alpha-D-glucuronic acid units. These structural discrepancies can provide explanations why the parenchyma cells have much higher alkaline extraction efficiency than fibers, further indicating the former is a promising feedstock in the current biorefinery scenario.

Automated summary

This study reveals that the alkaline extraction efficiency of bamboo fibers and parenchyma cells is highly related to their structural differences on both anatomical and molecular level. The lignin and hemicelluloses from fibers and parenchyma cells have significant discrepancies in molecular structure, leading to the higher extraction efficiency of parenchyma cells. This indicates that parenchyma cells could be a promising feedstock in the current biorefinery scenario.