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Appl Environ Microbiol. 1969 May; 17(5): 737-741
Copyright © 1969 American Society for Microbiology. All Rights Reserved.

Growth Factor Requirements of Ruminococcus flavefaciens Isolated from the Rumen of Cattle Fed Purified Diets1

L. L. Slyter and J. M. Weaver

a Agricultural Research Service, Animal Husbandry Research Division, U.S. Department of Agriculture, Beltsville, Maryland 20705

ABSTRACT

Eight strains of cellulolytic cocci were isolated from a 10-8 dilution of rumen ingesta and were presumptively identified as Ruminococcus flavefaciens. Four strains were isolated from a steer fed a purified diet which contained isolated soy protein, and four strains were isolated from a steer fed a purified diet which contained urea. Certain growth factor requirements of these bacteria were determined. All strains grew with clarified rumen fluid added to the medium. However, fatty acids could substitute for rumen fluid in four strains. Two strains isolated from each steer either required or their growth was stimulated by isobutyric and/or isovaleric and/or 2-methyl-butyric acid. These results indicate that, even when a diet was fed which contained no branched-chain amino acids, the carbon skeleton precursors of branched-chain fatty acids, the cattle were still able to maintain a large population of cellulolytic bacteria that require fatty acids for growth. Therefore, the fatty acids appear to be provided by other bacteria, by protozoa, or by the host animal.

FOOTNOTES

1 Presented in part at the meeting of the North Atlantic Section of the American Society of Animal Science, June 28, 1967, Ithaca, N.Y.

Appl Environ Microbiol. 1969 May; 17(5): 737-741
Copyright © 1969 American Society for Microbiology. All Rights Reserved.





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