Meeting Abstract

86.3  Monday, Jan. 6 10:30  Toxin Degradation is a Community Effort in the Gut Microbiota of Mammalian Herbivores MILLER, A.W.*; DEARING, M.D.; University of Utah; University of Utah aaron.w.miller@utah.edu

Mammalian herbivores are routinely faced with toxic challenges resulting from the regular consumption of plant secondary compounds (PSCs) in their diet. The PSC oxalate is widely produced by plants and can have significant physiological consequences e.g., kidney stones. Oxalate-degrading bacteria (ODB) in the gut microbiota of mammals metabolize oxalate thereby decreasing absorption by the host. We expanded upon our understanding of the role that gut microbes play with respect to oxalate degradation using a mammalian herbivore, the white-throated woodrat (Neotoma albigula), which naturally consumes a diet rich in oxalate. We inventoried the distribution of ODB along the gastrointestinal tract, isolated bacteria from each of the chambers, and assayed in vitro oxalate-degrading efficiencies. Finally, we transferred the gut microbiota into hyperoxaluric Sprague-Dawley rats and quantified the change in oxalate excreted in the feces and urine. We found that ODB were primarily concentrated in the foregut, which is where oxalate concentration is greatest. ODB were dominated by the genus Lactobacillus, but rare taxa were distributed throughout the gastrointestinal tract. Oxalate-degrading efficiencies of isolates ranged from 18.4-40.3% over 48 hours. Dietary oxalate degradation in N. albigula exceeded 90% across variable oxalate loads. Transfer of the microbiota from N. albigula to lab rats significantly increased dietary oxalate degradation from 17% to 52%. The results demonstrate that toxin degradation by the gut microbiota is facilitated by consortia of bacteria distributed differentially throughout the gut, which can be transferred between hosts to introduce the toxin degrading function.