Candidate Genes Involved in Lignin Degradation Found in Wood-Boring Beetle’s Mid Gut


The Asian longhorned beetle (Anoplophora glabripennis ) is an invasive species first discovered in the United States in 1996. It attacks both healthy and stressed hardwood trees, including the bioenergy candidate feedstocks poplar and willow, and has no natural enemies in this environment. The microbial community in the beetle’s midgut is capable of breaking down the lignin, cellulose, and hemicellulose in the trees to acquire needed nutrients, but little is known about the processes involved. To learn more about how microbial communities in the guts of such wood-boring insects break down these woody tissues, a team including researchers from the Department of Energy’s (DOE) Joint Genome Institute (JGI) sequenced, assembled, and analyzed the Asian longhorned beetle’s midgut metagenome.

In the study published in Plos ONE , the team compared the metagenome assembly from the wood beetles to annotated assemblies in DOE JGI’s IMG/M database. These datasets came from microbial communities associated with herbivores that feed to plant tissues, insects that feed on specific plant tissues, and insects (e.g., termites) that feed on woody tissues. The findings revealed that the beetle’s midgut contained a community dominated by aerobes, which research­ers expected, noting that large-scale lignin-degrading reactions require oxygen and have only been demonstrated in aerobic environments. They identified several genera of fungi and bacteria in the assembly; many of the microbes have been associated with break down of lignocellulose, hemicellulose, and other similar compounds. The metagenome assembly also led to the identifi­ca­tion of candidate genes for a variety of functions, including lignin-degrading enzymes, cellu­lases, xylose utilization, and fermentation as well as for nitrogen and nutrient acquisition.

This study is the first large-scale functional metagenomic analysis of the midgut micro­bial community of a beetle with known lignin-degrading capabilities. Lignin is one of the most recalcitrant components of plant biomass. The candidate genes identified from by the functional profile could lead to novel enzymes that might either be useful for industrial biofuels applications or else be used to control this invasive insect.


Scully, E. D., et al. 2013. “Metagenomic Profiling Reveals Lignocellulose Degrading System in a Microbial Community Associated with a Wood-Feeding Beetle,” PLoS ONE 8(9), e73827. DOI: 10.1371/journal.pone.0073827.