Enumeration of anaerobic oxalate-degrading bacteria in the ruminal contents of sheep |
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Authors: | Steven L Daniel Herbert M Cook Paul A Hartman Milton J Allison |
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Institution: | National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, U.S.A.;Department of Microbiology, Iowa State University, Ames, IA, U.S.A. |
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Abstract: | Abstract Concentrations of oxalate-degrading anaerobes in ruminal contents of sheep were determined from counts of colonies producing clear zones on a calcium oxalate medium (D agar with 7 mM CaCl2). Viable counts of oxalate degraders from a 55-kg sheep fed a diet containing 32% halogeton (4.6% oxalate) averaged 2.6 × 106/ g (dry weight). When the halogeton concentration in the diet was reduced to 16%, counts of oxalate degraders decreased nearly 300-fold. Oxalate-degrading isolates from this sheep were similar to OxB, the type strain of Oxalobacter formigenes . When a 45-kg sheep was fed diets containing 2.2, 1.5, and 0.8% oxalate, viable counts of oxalate degraders (enumerated on D agar with 14 mM CaCl2 and 20% filter-sterilized ruminal fluid) represented 0.85, 0.52, and 0.06% of the total viable population, respectively; total viable counts were essentially unchanges by these concentrations of dietary oxalate. Similar percentages of oxalate degraders were also observed when a 23-kg sheep was fed diets containing 1.5 or 0.8% oxalate. This report presents the first direct measurements of the concentrations of oxalate-degrading bacteria in the rumen and supports the concept that the availability of oxalate in the diet influences the proportion of oxalate-degrading bacteria in the rumen |
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Keywords: | Oxalic acid Ruminant adaptation Oxalate degradation Ruminal bacteria Oxalobacter formigenes |
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