Author
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Rasmussen, Mark |
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WICKMAN, TARA - 3625-30-05 |
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Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only Publication Acceptance Date: 8/9/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The reduction and precipitation of selenium by ruminal microbes decreases its availability to the host animal. This metabolic capacity has nutritional, toxicological, and environmental consequences. Few reports have identified the bacteria responsible for selenium metabolism in the rumen. A strictly anaerobic, gram-negative, selenium-reducing bacterium was isolated from the rumen of sheep using hydrogen and selenate. Based upon 16S ribosomal RNA analysis, this isolate had a similarity coefficient of 94% when compared to the one other W. succinogenes sequence available in the database. The new isolate failed to grow on a common Wolinella medium that contained formate/fumarate and the microbe appeared to use selenate specifically as an electron acceptor. Sulfate and nitrate could not be substituted for selenium and lactate and acetate could not replace hydrogen. A 22-base oligonucleotide probe, specific for this new isolate was prepared. This probe also hybridized to nucleic acid isolated from W. succinogenes (ATCC 29543) but did not bind to preparations from other ruminal bacteria. The probe was used to examine the ecology of the rumen when ruminants were adapted to increasing levels of selenium (0-3 ppm). When dietary selenium was increased to 3 ppm, the relative intensity of this probe's hybridization to total rumen nucleic acid increased 18-fold. These results indicate that the population of W. succinogenes in the rumen will increase in response to increased levels of dietary selenium. |
