A comparative study on the structure of lignin-carbohydrate complexes in alkali-soluble hemicellulose from bamboo (Bambusa chungii) fibers and parenchyma cells

Recognized as a high-quality biomass resource, bamboo presents challenges in its effective utilization owing to its complex cellular structure and diverse cell types. Thus, identifying differences in the recalcitrant structures within distinct cells is of paramount importance for bamboo chemical processing. In this study, alkaline treatment was employed to extract hemicellulose and lignin-carbohydrate complexes (LCC) separately from bamboo fibers (BF) and parenchyma cells (PC), and the chemical composition, structural characteristics, and distribution of LCC were analyzed. The results revealed that the LCC in alkali-soluble hemicellulose was primarily derived from the secondary cell wall (S-layer) and cell corner middle lamella (CCML) regions of BF, as well as the S-layer of PC. Compared to LCCA-F, a higher content of condensed lignin structures and a greater abundance of Syringyl (S) structural units were observed in LCCA-P. Furthermore, an increased proportion of lignin-arabinose and lignin-glucan linkage structures was detected in the phenyl glycosidic (PhGlc) bonds of LCCA-P. These findings provide valuable insights into the disparities between the chemical compositions and structural characteristics of LCCs within the alkali-soluble hemicelluloses of different bamboo cell types, thereby providing essential guidance for the preparation of functional materials from BF and PC substrates.