A comparative study on the crystalline structure of cellulose isolated from bamboo fibers and parenchyma cells

Bamboo, with a high cellulose content comparable to that of wood, is a potential feedstock for biofuel and nanocellulose production. Mechanically isolated bamboo fibers and parenchyma cells exhibited remarkable differences in enzymatic hydrolysis efficiency as reported in a recent comparative study. It was assumed that cellulose microfibrils in bamboo fibers and parenchyma cells differ in their supramolecular structures. In the present study, X-ray diffraction and solid-state CP/MAS13C NMR studies indicated that, the two types of cells showed similar cellulose crystallinity index. The cellulose from bamboo fibers and parenchyma cells also exhibited differences in microfibril sizes, with lateral sizes of ca. 26.0–41.3 A and ca. 22.7–39.3 A for bamboo fibers and parenchyma cells respectively. It was further found that cellulose chains in bamboo fibers were more closely packed, supported by its smaller d-spacing than that of parenchyma cell cellulose. In addition, FT-IR and NMR spectroscopy revealed that there was a higher Iβ content in fibers than parenchyma cells. These differences in the crystalline structure of cellulose should be related to the lower recalcitrance to chemical degradation of parenchyma cells compared to bamboo fibers. These differences in the crystalline structure of cellulose should be related to the lower recalcitrance to chemical degradation of parenchyma cells compared to bamboo fibers.