Abstract: 【Aim】 Symbiotic microbiota in the alimentary canal of Cyrtotrachelus buqueti participate in the degradation of bamboo lignocellulose. This study aims to reveal the heterogeneity and lignocellulose degradation ability of symbiotic microbiota in different sections of the alimentary canal of larval C. buqueti. 【Methods】 The composition analysis and functional prediction of microbiota in different sections of the alimentary canal including mouthpart (YB), foregut (YFG), midgut (YMG) and hindgut (YHG) of larval C. buqueti were carried out using 16S rRNA sequencing. The carbohydrate active enzyme (CAZy) genes in the genomes of bacteria belonging to core genera in each alimentary canal section were analyzed to predict the lignocellulose degradation ability. The liquid suspensions of mouthpart mixed bacteria (MPJ), foregut mixed bacteria (FJ), midgut mixed bacteria (MJ) and hindgut mixed bacteria (HJ) of C. buqueti larva were used to degrade bamboo shoot particles in vitro and to verify their lignocellulose degradation ability. 【Results】 The diversity analysis of microbiota in the alimentary canal of larval C. buqueti showed that the diversity of microbiota from YFG, YMG and YHG were higher than that from YB, and the species diversity of microbiota from YFG was the highest, while that of YB was the lowest. In YFG, YMG and YHG samples, Firmicutes, Bacteroidetes and Proteobacteria showed the highest relative abundance, while Proteobacteria, Firmicutes and Actinobacteria were the most abundant in YB. The analysis of CAZy genes in the genomes of bacteria belonging to core genera showed that most microbial genomes in the alimentary canal of larval C. buqueti contain abundant CAZy genes, especially in that of the genus Bacteroides, indicating their relationship with lignocellulose degradation. The experiment results of in vitro bamboo shoot particle degradation by MPJ, FJ, MJ and HJ of C. buqueti larva showed that their cellulose degradation efficiencies were 21.7%, 39.9%, 44.2% and 21.0%, respectively, their hemicellulose degradation efficiencies were 72.7%, 52.3%, 65.7% and 61.5%, respectively, and their lignin degradation efficiencies were 20.5%, 41.3%, 39.9% and 37.9%, respectively. 【Conclusion】 The heterogeneity of microbiota in the alimentary canal of larval C. buqueti can affect the lignocellulose degradation ability, so the microbiota can be used as one of the important sources for the separation of high.efficiency lignocellulose.degrading bacteria. This study provides some reference information for the industrial transformation and utilization of bamboo biomass.

Key words: Cyrtotrachelus buqueti, symbiotic bacterium, heterogeneity, 16S rRNA sequencing, carbohydrate active enzyme, lignocellulose degradation