Enrichment and isolation of Acetitomaculum ruminis,gen. nov., sp. nov.: acetogenic bacteria from the bovine rumen |
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Authors: | R C Greening J A Z Leedle |
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Institution: | (1) Microbiology and Nutrition Research, The Upjohn Company, 49001 Kalamazoo, MI, USA |
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Abstract: | Five strains of acetogenic bacteria were isolated by selective enrichment from the rumen of a mature Hereford crossbred steer
fed a typical high forage diet. Suspensions of rumen bacteria, prepared from contents collected 7 h postfeeding, blended and
strained through cheesecloth, were incubated in a minimal medium containing 10% clarified rumen fluid under either H2:CO2 (80:20) or N2:CO2 (80:20) headspace atmosphere. The selection criterion was an increment of acetate in the enrichments incubated under H2:CO2. Periodically, the enrichment broths were plated onto agar media and presumed acetogenic bacteria subsequently were screened
for acetate production. Selected acetogenic bacteria utilized a pressurized atmosphere of H2:CO2 to form acetate in quantities 2 to 8-fold higher than when grown under N2:CO2. All presumptive acetogenic isolates were derived from either the 10-7 or 10-8 dilutions of rumen contents. All 5 strains were Gram-positive rods, and all utilized formate, glucose and CO. One strain
required, and all were stimulated by, rumen fluid. No spores were observed with phase-contast microscopy and two strains were
motile. No methane was detected in the headspace of pure cultures grown under either gas phase. The isolation of these bacteria
indicates that acetogenic bacteria are inhabitants of the rumen of the bovine fed a typical diet and suggests that they may
be participants in the utilization of hydrogen in the rumen ecosystem. Strain 139B (= ATCC 43876) is named Acetitomaculum ruminis gen. nov., sp. nov. and is the type strain of this new species.
Portions of this work were presented previously (Greening RC, Leedle JAZ (1987) Abstr Annu Meet Am Soc Microbiol I 131, pp
194) |
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Keywords: | Acetitomaculum ruminis Hydrogen oxidation Acetate production Rumen |
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