Inhibition of growth and nucleic acid synthesis in zinc-deficient Mycobacterium smegmatis.

Abstract

SUMMARY The growth of Mycobacterium smegmatis was inhibited by lack of zinc in a glycerol + asparagine medium depleted of trace metals but enriched with iron. Addition of zinc to this medium supported full growth of the organism. Both zinc-deficient and zinc-replete cultures had the same exponential doubling time. In zinc-deficient organisms the synthesis of RNA and DNA varied with growth rate in a manner typical for nutrient-induced decreases in a variety of organisms. Zinc-deficiency led to inhibition of nicotinamide synthesis and an increase in phosphate storage as compared with zinc-replete cultures. The pH value of zinc-deficient cultures was preponderantly alkaline. The results are discussed with reference to the metabolic role of zinc ions, and the effects of zinc deficiency is compared to the effects of iron deficiency as previously reported for the same organism.