Author
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SCUPHAM, ALEXANDRA |
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Submitted to: Environmental Microbiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/1/2007 Publication Date: 6/7/2007 Citation: Scupham, A.J. 2007. Examination of the microbial ecology of the avian intestine in vivo using bromodeoxyuridine. Environmental Microbiology. 9(7):1801:1809. Interpretive Summary: The bacteria of the intestinal tract are many (roughly 10**11 organisms per gram feces) and varied (roughly 800 species or 7000 unique sequences per host). These organisms stimulate mucosal angiogenesis and interact with the mucosal epithelium to prevent inflammation while concurrently protecting against pathogens. However, the intestinal community has also been implicated in Crohn’s Disease, obesity and allergy. Identification of the microbes associated with these functions is essential for development of methods for stimulation of the favorable, and suppression of the unfavorable, organisms. The method described here allows identification of microbes that are stimulated by changes in the poultry intestinal ecosystem. Bromodeoxyuridine, (BrdU), a thymidine analog, can be incorporated into the DNA of actively dividing cells. In the current work BrdU was fed to three-week old turkey poults and the compound, sequestered in the ceca, labeled the DNA of bacteria that divided in response to an eight-hour fast. Results indicate that formate-utilizing species are active during host fasting while most Clostridiales reduce their activity. In addition, a group of bacteria closely related to flavenoid-degrading organisms is metabolically dominant during host fasting. This method will allow investigation of many microbial processes that occur in the intestine that cannot be simulated in vitro and thus will expand the current understanding of the roles of intestinal microbes in health and disease. Technical Abstract: Bromodeoxyuridine (BrdU), a thymidine analog that can be incorporated into the DNA of actively dividing cells, has been used in vivo to identify bacteria that are metabolically active during an acute period of feed withdrawal in three-week old turkey poults. The microbiota in the ceca were determined to be more metabolically active during feeding than during fasting. Automated ribosomal intergenic spacer analysis (ARISA) identified amplicons unique to animals subjected to feed withdrawal. One amplicon was unique to fasted birds while two amplicons were present in 60% of fasted birds and absent in all fed birds. Sequence analysis of 16S ribosomal genes indicated the cecal communities of all birds were dominated by Clostridiaceae while also harboring low levels of metabolically active gamma-proteobacteria and Bacteroides. Thirty-one percent of clones from the fasted animals were identified as belonging to the genus Papillibacter, suggesting these microbes may be specifically dividing in response to environmental conditions present in the ceca of fasted birds. |
