Meeting Abstract

P2.120  Sunday, Jan. 5 15:30  Toxin-degrading gut bacteria facilitate ingestion of tannin-rich foods STENGEL, A.*; KOHL, K.D.; DEARING, M.D.; Univ. of Utah; Univ. of Utah; Univ. of Utah ashley.stengel@comcast.net

Plant polyphenolics, such as tannins, can significantly impair digestibility of food for mammals. It has long been hypothesized that mammals might host beneficial microbes that degrade these compounds. Indeed, tannin-degrading bacteria (TDB) have been isolated from over 20 mammal species, yet their functional significance to the host has never been tested. We investigated whether TDB allow mammals to consume greater amounts of tannins in their diets. We transplanted microbes into a naïve host the lab rat (Rattus norvegicus), which does not naturally host TDB, and measured their tolerance to tannic acid. One group was inoculated with isolated TDB cultured from the feces of the desert woodrat, Neotoma lepida, a wild rodent that regularly consumes tannin-rich plants. A second group received a full-community transplant of woodrat feces, and a third group received autoclaved feces as a control. Rats were then fed a diet with increasing concentrations of tannic acid (3-12%), and animals were removed from the trial when they lost more than 10% of their body mass. We found that animals inoculated with TDB, either as isolates or full communities, persisted in the trial longer and were able to consume higher doses of tannic acid. Because the groups had no differences in food intake or dry matter digestibility, we hypothesized that TDB facilitate the ingestion of tannin-rich diets by reducing the costs of hepatic detoxification. This is the first demonstration that TDB facilitate ingestion of tannins by mammals. Symbiotic relationships with these bacteria may have influenced the feeding niches of many mammals that consume tannin-rich foods.