Title: Studies with the Cellulolytic Fraction of Rumen Bacteria Obtained by Differential Centrifugation
Abstract: Suspensions of bovine and ovine rumen bacteria were separated into several different fractions by means of differential centrifugation. That fraction of bacteria still in suspension at 1500 × G but sedimented at 3000 × G was found to contain the majority of the cellulolytic rumen bacteria. This fraction contained only 21% of the TCA insoluble nitrogen (bacterial protein) found in the whole suspension of rumen micro-organisms. Photomicrographs are shown of the bacteria in the various fractions. Fermentation studies with the 3000 × G sediment showed that after incubation with cellulose as the sole carbohydrate source, a predominance of Gram-negative micrococci were present along with a lesser number of very small Gram-negative rods. These observations indicate that the Gram-negative micrococci are the principal cellulose-digesting organisms which proliferate in vitro. These same organisms were also found in large numbers in the inoculum obtained from the rumen. Incubation of the 3000 × G sediment with cellulose as the sole carbohydrate substrate resulted in the formation of large amounts of acetic and propionic acid, a lesser amount of succinic acid and traces of butyric and higher acids. The microorganisms showed a strict requirement for both valeric acid and biotin. Further studies showed that the fatty acid requirement could be satisfied by valeric acid, and that a branched-chain acid was not required.
Publication Year: 1960
Publication Date: 1960-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 28
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