Cyclic AMP in ruminal and other anaerobic bacteria

An examination of cAMP levels in predominant species of ruminal bacteria and other anaerobic bacteria was conducted. Cellular cAMP concentrations of glucose-grown cultures of Butyrivibrio fibrisolvens 49, Prevotella ruminicola D31d, Selenomonas ruminantium HD4 and D, Megasphaera elsdenii B159, Streptococcus bovis JB1, Bacteroides thetaiotaomicron 5482, and Clostridium acetobutylicum ATCC 824 were determined at various times during growth by a competitive binding radioimmunoassay procedure. The results were compared to those for Escherichia coli NRRL B3704. The levels of cAMP ranged from undetectable for B. thetaiotaomicron to approximately 15 pmol/mg cell protein for P. ruminicola D31d. Varying the growth substrate in a manner previously shown to elicit regulatory response did not alter the level of cAMP in these organisms. In general, cAMP concentrations present in these organisms were much lower than the 6-25 pmol/mg cell protein observed for E. coli. The levels of cAMP in P. ruminicola were consistently higher than levels in other anaerobes, particularly during the early exponential and stationary phases of growth. Based on these data it seems unlikely that cAMP is involved in regulation of substrate catabolism in the anaerobic bacteria examined except in P. ruminicola where it may have an unknown regulatory function.