Integrative microbial and transcriptomic analysis reveals the lignocellulosic biomass degrading mechanism by bamboo snout beetle

Insects and gut symbiotic bacteria have shown promise in the degradation of lignocellulosic biomass (LCB). Cyrtotrachelus buqueti is being studied as a resource for LCB degradation, but its mechanisms are not fully understood. This study investigates the host transcriptome and gut microbiome to identify the inherent mechanisms behind efficient LCB degradation. The gut secretory protein showed degradation rates of 30.23%− 38.24% for cellulose, 58.56%− 70.96% for hemicellulose, and 28.71%− 43.43% for lignin, while microbiota had degradation rates of 28.41%− 38.31% for cellulose, 53.45%− 66.15% for hemicellulose, and 25.65%− 38.37% for lignin. Core genera (>80%) of bacteria are identified in the foregut, midgut, and hindgut, with the hindgut containing the most abundant lignin degradation potential genera Serratia and Dysgonomonas, and the midgut has the highest abundance of cellulose and hemicellulose degradation likely genera Lactococcus and Enterococcus. The transcriptome reveals highly abundant and diversified lignocellulolytic genes encoding carbohydrate-active enzymes (CAZymes), with lignin-modifying enzyme genes highly expressed in the hindgut and cellulase and hemicellulase genes highly expressed in the foregut and midgut. Integrative analysis reveals a significant correlation between the gut microbiome and transcriptome, contributing to efficient LCB degradation. This study first provides a deeply comprehensive insight into the unique mechanisms of LCB degradation by C. buqueti.