Inhibition of Growth of Lactobacillus bulgaricus by Purine Deoxyribonucleotides.

Morris, George K. (University of Georgia, Athens), and William L. Williams. Inhibition of growth of Lactobacillus bulgaricus by purine deoxyribonucleotides. J. Bacteriol. 90:715-719. 1965.-An inhibition of growth of Lactobacillus bulgaricus GS was observed with deoxyadenylic acid and deoxyguanylic acid. Deoxynucleotides of cytosine, thymine, and uracil, and the deoxynucleosides of adenine, guanine, cytosine, and thymine were inactive as inhibitors. The inhibition was reversed by liver extract (a crude source of two unidentified growth factors for this organism). With suboptimal concentrations of liver extract, the inhibition was reversed by nucleotides of adenine, guanine, uracil, cytosine, and thymine. When the medium contained partially purified sources of the two growth factors rather than crude liver extract, fewer compounds reversed the inhibition. Adenylic acid and guanylic acid reversed the action of either inhibitor. Inosinic acid reversed inhibition caused by deoxyguanylic acid, but not that caused by deoxyadenylic acid. Thymidylic acid reversed inhibition caused by deoxyadenylic acid better than that caused by deoxyguanylic acid. Uridylic acid and cytidylic acid were no longer effective in reversing the inhibitions. This organism preferentially responded to monophosphorylated compounds as inhibitors and as reversers of inhibitions. Studies on the acid-soluble nucleotide pool revealed an accumulation of adenosine triphosphate, guanosine triphosphate, and an unidentified compound which resembled a nucleotide in its physical properties. These data cannot be explained by known metabolic pathways of nucleic acid biosynthesis. This organism responds differently from other related organisms to nucleic acid derivatives; therefore, it may be a new useful tool for studying nucleic acid metabolism and biosynthesis.