Adenine toxicity and transport in the moderately halophilic eubacterium Halomonas elongata

The presence of adenine in the L-alanine defined medium substantially inhib ited the growth of the moderately halophilic eubacterium Halomonas elongata . Extensive attempts to reverse the adenine toxicity for growth were made u sing a variety of purine and pyrimidine compounds. vitamins, and amino acid s. Of the compounds tested, only cytosine was found to reverse the adenine growth inhibition, This indicates a mechanism similar to that found for som e strains, of Escherichia coli in which the pretence of exogenous purines ( e.g. adenine) was found ro stop purine dr novo synthesis and repress the sy nthesis of the pyrimidine salvage enzyme cytosine deaminase. H. elongata wa s found to possess an active adenine uptake system that was sodium dependen t with only lithium having a considerable capacity to replace the sodium. A competition study indicated that the adenine transport system was quite sp ecific. This paper represents the initial study of purine and pyrimidine sa lvage pathways and adenine uptake for the moderately halophilic eubacteria.