COMPARING MICROBIAL COMMUNITIES ACROSS THE GASTROINTESTINAL TRACT OF MOOSE

Abstract

Coevolution of microbial communities and their hosts has allowed herbivores to extract energy from recalcitrant complex carbohydrates in plants, and benefit from synthesized protein and vitamins. Ruminants have further evolved 3 locations within their gastrointestinal (GI) tract that house and that facilitate fermentation of plant fiber, the rumen/reticulum, cecum, and colon, but little is known about how the microbiome varies across these organs, especially in free-ranging browsing herbivores like moose (Alces alces). Therefore, we took advantage of a unique opportunity to sample each of these organs from vehicle-struck and hunter-harvested moose in south-central Alaska and eastern Washington/northwestern Idaho, USA. Using culture-free microbial techniques to extract, identify, and quantify microbes in the samples, we found few differences in microbial composition, richness, and diversity among fermentation organs, but large differences between geographic regions. Our results suggest that differences in the macroenvironment and diets across regions play a greater role in microbial communities than different microenvironmental conditions within organs of the GI tract. Furthermore, our findings support microbiome measurements from fresh fecal samples as a surrogate for microbial communities in the rumen and cecum. Understanding the function and composition of microbial communities within the fermentation organs is increasingly important for quantifying how ruminants such as moose will respond to changes in diet and environment, and how these changes may influence their interactions with plant resources.