Spatial characterization of the prokaryotic community within the gut of the patent-leather beetle, Odontotaenius disjunctus, using 16S rRNA PhyloChips

Background/Question/Methods: The patent-leather beetle, Odontotaenius disjunctus (family Passalidae), is a large beetle with a wide range in North America extending from Florida, north to Canada, and west to the Rocky Mountains. Both the larvae and adults of this subsocial beetle live in and feed on partially decayed wood which is low in readily available nitrogen but rich in complex polysaccharides and lignins. The recent discovery of microbes similar to those found in the gut of termites and wood roaches led us to hypothesize that the beetles require symbiotic gut microbes to aid in the digestion of lignocellulosic food substrate. We began to investigate this relationship by identifying the bacterial community within each of the 4 beetle gut sections using a 500,000-probe PhyloChip that targets the 16S rRNA gene.
Results/Conclusions: Our results show that each of the four distinct gut regions has a distinctive microbial community and that each gut region was highly similar across different beetles. The anterior hindgut was most distinctive with higher relative abundance of clostridia, Bacteroidetes, sulfate reducers, and potential nitrogen fixing spirochetes. The same region was also the only location where methanogens were detected. In contrast, the midgut and posterior hindgut community clustered tightly and contained higher proportions of α-Proteobacteria and lactobacilli. Through understanding of the partitioning of microbial communities in each of the gut compartments, we can begin to study the symbioses between the complex microbial populations inhabiting the gut and their beetle host. Furthermore, understanding how the microbes deconstruct lignocellulosic material as it passes through the gut may aid in the optimization of industrial lignocellulosic conversion into biofuel.