Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2013
Publication Date: 6/20/2013
Citation: Levine, U.Y., Looft, T.P., Allen, H.K., Stanton, T.B. 2013. Butyrate-producing bacteria, including mucin degraders, from the swine intestinal tract. Applied and Environmental Microbiology. 79(12):3879-3881. Available: http://aem.asm.org/content/79/12/3879.long. Interpretive Summary: Butyrate is a beneficial compound produced by bacteria in the gut that has been shown to promote good health in humans. Similar health benefits are likely occuring in other animals from butyrate, but most research has been focused on the human gut. To gain a better understanding of the butyrate-producing bacteria in pigs, the research reported here found 15 bacteria from the pig digestive system that produce butyrate. Five of the 15 bacteria are newly identified species, and some of the other bacteria have rarely been recovered from humans or other animals. Tests for butyrate production found activity in all of the 15 bacteria, but the gene responsible for the activity could only be found in five of the bacteria. This demonstrates a need to improve the standard method to finding the gene. Three of the 15 butyrate-producing bacteria were found to break down mucin, compounds produced by host cells that line the gut. It is thought that the ability to degrade mucin allows a bacterium to live close to host cells, and we theorize that a mucin-degrading butyrate-producing bacteria that live close to host cells could greatly influence host health. This research will lead to new investigations of the butyrate-producing bacteria in swine, and hopefully lead to improvements in swine health to the benefit of both the consumer and the farmer.
Technical Abstract: Butyrate-producing microbes promote gastrointestinal health in the human gut, and similar benefits are likely derived from butyrate-producing microbes in other animal hosts. Consequently, there is considerable potential for butyrate-producing microbes to be utilized in health-promoting applications. However, the composition of butyrate-producing microbes in hosts other than humans remains largely unknown. In this study we investigated the butyrate-producing bacterial community in swine by culturing and screening 980 anaerobic isolates from swine for butyrate production. Fifteen isolates were identified as butyrate producers from clostridial clusters IV, IX, XI, XIII, and XIVa. Five of the isolates, belonging to clusters IV, XI, and XIVa, are new species (less than 97% 16S rRNA sequence identity to the nearest cultured relative). In functional assays for butyrate production, all isolates had measurable butyryl-CoA:acetate CoA-transferase (E.C. 22.214.171.124) activity. Nevertheless, when PCR assays were performed with published primers for the butyryl-CoA:acetate CoA-transferase gene, it could only be amplified from five isolates. Therefore, new molecular probes capable of recovering the entirety of the butyrate-producing microbial community in swine are needed in order to fully understand their ecology. Three isolates were also capable of utilizing O-linked glycans for carbon and energy. The ability for microbes to produce butyrate and consume mucin has rarely been reported previously, but the two traits may be indicative of butyrate producers that hold particular promise in health-promoting applications.