Using metagenomics to resolve the process of wood digestion in the Asian longhorned beetle (Anoplophora glabripennis)

The Asian longhorned beetle (ALB) is an invasive, wood-boring insect with a relatively broad host range. ALB feeds and grows in a harsh environment devoid of many nutritional resources by utilizing intractable components, including xylan and cellulose, for energy and protein. Our lab has previously demonstrated that modification of the lignocellulose macromolecule occurs during passage through the ALB gut and that the gut harbors a rich diversity of microbiota, including several genera known to play significant roles in wood decay and other microbes that could be involved in novel digestive processes. Thus, we hypothesize that the consortium of gut symbionts plays an integral role in lignocellulose digestion.

In order to explore the roles of these symbionts in digestion, we performed shotgun sequencing of metagenomic microbial DNA on a 454-Titanium platform. Analysis of ribosomal RNA genes confirmed the presence of microbes from many phylogenetically diverse bacterial and fungal clades, including alpha-, beta-, and gamma-proteobacteria and ascomycota, while in-depth analysis of other annotated coding regions detected genes with relevance to lignocellulose digestion, including cellulases, xylanases, and glycoside hydrolases. MEGAN (MEtaGenome ANalyzer) analysis revealed that digestion-related genes were distributed throughout many taxa within the community indicating that proteins from multiple symbionts are likely required for digestion. To further elucidate the digestive roles of these symbionts, we will ultimately couple this analysis with shotgun sequencing of the microbial metatranscriptome to determine which microbial genes are actively expressed within the gut.