The Origin of Purine and Pyrimidine Deoxyribose in Escherichia coli Systems

An extracellular material elaborated by Micrococcus sodonensis

Campbell, J. N. (American Meat Institute Foundation, Chicago, Ill.), James B. Evans Jerome J. Perry, and C. F. Niven, Jr. An extracellular material elaborated by Micrococcus sodonensis. J. Bacteriol. 82:828-837. 1961.-When actively growing in a yeast extract-tryptone broth, Micrococcus sodonensis produced rather large quantities of an extracellular material. On a dry weight basis, this material consisted of approximately 80% deoxyribonucleic acid (DNA), 6% ribonucleic acid, 13% protein, and a small quantity of a cell pigment which contained an associated iron porphyrinlike compound. The extracellular material was not produced in other complex or synthetic media. Removal of cells from the appropriate growth medium and suspension in distilled water resulted in the prevention of formation of the material if it had not already begun, or its immediate cessation in those cells which had been actively producing the material. Cells producing the extracellular material exhibited an increasingly higher concentration of intracellular DNA as incubation proceeded, whereas cells growing under conditions not supporting such production showed a decline in intracellular DNA as the culture aged. A similar increase of intracellular DNA, but not release of extracellular material, could be effected by addition of yeast extract or high levels of purine compounds to a medium which did not support the production of extracellular material. The base composition and ratios of both extracellular and intracellular DNA produced under all conditions tested were compared and found to be similar or identical, and to correspond to the classical Watson-Crick structure for DNA.

Phenethyl Alcohol II. Effect on Thymine-Requiring Escherichia coli

Rosenkranz, Herbert S. (Columbia University, New York, N.Y.), Howard S. Carr, and Harry M. Rose . Phenethyl alcohol. II. Effect on thymine-requiring Escherichia coli . J. Bacteriol. 89: 1370–1373. 1965.—Phenethyl alcohol (PEA) at levels (0.05%) presumed to interfere with messenger ribonucleic acid synthesis also inhibits thymineless death, when the agent is added prior to the exponential killing phase. The addition of more concentrated solutions of PEA (0.5%) during this initial starvation leads to an immediate killing. Identical results were obtained when 0.5% PEA was added to cells growing in the presence of thymine. The addition of this high level (0.5%) of PEA to bacteria undergoing thymineless death results in the rescue of the survivors.