Can Wild Herbivores Survive if their Food Source Changes?
Microbiome in gut of wild moose is vital for adapting to likely increase in the prevalence of woody vegetation.
The abundance of woody deciduous shrubs is increasing in the Arctic and this changing vegetative landscape could profoundly impact the entire regional food web, including herbivorous mammals such as moose, and the microbial communities they host in their rumens. A recent study highlighted the vital and previously unappreciated role of Bacteroidetes bacteria in helping Arctic moose break down and extract energy from tough, woody shrubs.
The findings reveal how alterations in the gut microbiome could provide wild herbivores with energy to nutritionally adapt to environmental conditions. Moreover, knowledge of enzymes and metabolic pathways used by these microbes to degrade woody shrubs could be very useful for the development of better strategies for producing biofuels.
Herbivores such as moose depend on their microbial symbionts for the degradation of plant biomass. Yet little is known about the relationship between diet, microbial metabolism and host nutrition in Arctic moose exposed to a changing vegetative environment. To address this knowledge gap, a multi-institutional team of scientists fitted Alaska moose with cannulae and used meta-omics approaches to sample in real time microbial communities in the moose rumens as they foraged in the spring on highly digestible grasses and leaves and through the winter on woody biomass. The rumen fluid samples from each season were analyzed using an Orbitrap mass spectrometer together with 600 MHz NMR spectrometers at the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility. In winter months, the rumen microbiome was strongly enriched for the BS11 family of bacteria from the phylum Bacteroidetes. Very little is known about the genomes, phylogeny and physiology of these bacteria, even though they are prevalent in the gastrointestinal tracts of ruminants and other mammals. Using metagenomics, the researchers reconstructed the first four BS11 genomes and discovered two new BS11 genera. By combining metaproteomic data with analysis of rumen metabolites, they found members of this bacterial family express genes for converting woody plant material into metabolites called short-chain fatty acids, which are vital for ruminant energy. Taken together, the findings reveal a previously unknown role of BS11 gut bacteria in helping ruminants extract energy from woody plant material predominant in winter months. Given that woody shrubs are increasing in abundance in Arctic and boreal ecosystems, the results shed new light on how the microbiome of moose rumen may help the moose adapt to changes in the vegetative landscape. Moreover, knowledge of the enzymes and metabolic pathways used by these microbes to degrade woody shrubs could be used to optimally engineer bacterial strains capable of breaking down tough plant cell walls for the efficient production of biofuels. This research represents a highly collaborative effort that included scientists from The Ohio State University; EMSL; the Alaska Department of Fish and Game; and the University of Alaska Anchorage.
Mary Lipton, Orbitrap mass spectrometer
David Hoyt, NMR
The Ohio State University
This work was supported by the U.S. Department of Energy’s Office of Science (Office of Biological and Environmental Research), including support of the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science User Facility.
L.M. Solden, D.W. Hoyt, W.B. Collins, J.E. Plank, R.A. Daly, E. Hildebrand, T.J. Beavers, R. Wolfe, C.D. Nicora, S.O. Purvine, M. Carstensen, M.S. Lipton, D.E. Spalinger, J.L. Firkins, B.A. Wolfe and K.C. Wrighton, “New roles in hemicellulosic sugar fermentation for the uncultivated Bacteroidetes family BS11.” ISME Journal (2016). [DOI: 10.1038/ismej.2016.150]