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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Research » Publications at this Location » Publication #66975
Title: A ROLE FOR FRUCTOSE 1,6-DIPHOSPHATE IN THE ATPASE-MEDIATED ENERGY SPILLING REACTION OF STREPTOCOCCUS BOVIS

Author
item BOND, DANIEL - CORNELL UNIVERSITY
item Russell, James

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: In ruminant animals, microbial protein is the major source of amino acids reaching the small intestine, and the efficiency of microbial protein synthesis can have a large impact on animal performance. Previous work indicated that ruminal bacteria could spill energy in futile reactions and decrease microbial protein flow to the intestines. Using the ruminal bacterium Streptococcus bovis as a model, we demonstrated that the membran bound ATPase was the energy spilling enzyme. In this paper we showed that the metabolic intermediate fructose 1,6 diphosphate was able to activate the membrane bound ATPase. Information on energy spilling may provide a means of increasing microbial flow from the rumen and improving the efficiency of animal production.

Technical Abstract: The ATP production rate of Streptococcus bovis was higher than what could be attributed to growth and maintenance, and even glucose-limited continuous cultures used ATP inefficiently (spilled ATP). Intracellular ATP and energy spilling were not correlated, but the rate of energy spilling was dilution rate- and nitrogen source-dependent. Energy spilling gwas greatest when the dilution rate was rapid and the rate of lactate production was high. The potential relationship between lactate production and energy spilling was supported by the observation that slow dilution rate continuous cultures spilled more energy and produced more lactate when amino acids were replaced by ammonia. The lactate dehydrogenase of S. bovis is activated by fructose 1,6-diphosphate (FDP) (Wolin, M.J. 1964. Science 146:775-777), and the lactate production rate of non-growing (energy spilling) S. bovis cells was FDP-depdendent. S. bovis spills energy yvia a reaction involving its membrane bound ATPase (Russell, J.B., and H.J Strobel. 1990. Arch. Microbial. 153:378-383), and this ATPase was stimulated in vitro by addition of FDP, which reduced the Km for ATP 5- fold. Other glycolytic intermediates could not stimulate the ATPase of washed membrane preparations, and FDP had no effect on soluble ATPase activity.