Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2010
Publication Date: 10/19/2010
Citation: Looft, T.P., Stanton, T.B. 2010. Selective culturing of swine gastrointestinal bacteria on substrates simulating the intestinal mucosa [abstract]. 3rd ASM Beneficial Microbes Meeting. p. 35.
Technical Abstract: Many gastrointestinal (GI) microbes are in intimate contact with the host tissues, and characterizing these tissue-associated communities is important for elucidating their role in animal and human health. The GI mucosa is an environment distinct from the intestinal lumen and is covered by a mucus layer that encases microbes. A sampling of mucus-degrading bacteria has been previously identified in humans, and it is likely that additional tissue-associated microbes can use host products such as mucin and sloughed epithelial cells as energy sources. We hypothesize that there is a sub-population of obligatorily mucosa-associated bacteria in the gastrointestinal tract actively degrading host-produced substances. Here, we present the preliminary identification of swine bacterial isolates that are able to grow on host produced substrates simulating the intestinal mucosa. Six pigs were reared on standard feed and euthanized at 18 to 20 weeks of age. Tissue samples and lumen contents were taken from the cecum, ileum, and mid-colon. Samples were cultured anaerobically on agar plus salts and 1% wt/vol hog gastric mucin or 20% vol/vol lysed defibrinated bovine blood cell ghosts to assess the mucolytic and lipolytic abilities of the isolates, respectively. The 16S rRNA genes of isolates that metabolized these substrates were sequenced and analyzed. The majority of the isolates grouped with the Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria and Synergistetes phyla. Many genera were shared between the tissue-associated and lumen contents samples, but some were specific: Enterobacter, Arcanobacterium, Finegoldia, and Butyricicoccus were only cultured from tissues, and Fusobacterium and Dorea were only cultured from the contents. In addition to these assignments, five isolates did not have cultured representatives in GenBank and may represent up to four new species or genera. The physiology and ecology will be further evaluated for these isolates. The results of this research inform our understanding of the distribution of microbes with specific metabolic properties in the swine GI tract. The bacteria that we have isolated are of interest because they possess all of the enzymes needed to use mucin or phospholipids as a sole energy source. Both their habitat and their niche suggest that these bacteria may be important in influencing tissues of the intestinal tract and mucosal health.