Studies in carotenogenesis. 16. The action of some antibiotics, especially streptomycin, on carotenogenesis in Phycomyces blakesleeanus

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Abstract
On a glucose/asparagine medium, streptomycin inhibits carotenogensis, but not growth. Maximal inhibition is obtained with 0.05-0.1% (w/v) streptomycin; increased concentrations of streptomycin up to 1.6% (w/v) do not further effect carotenogenesis. Carotenogenesis in the dark and the carotenogenic action of leucine and B-ionone are also streptomycin-sensitive. Replacement of asparagine in the glucose/asparagine medium wholly or partly by an ammonium salt results in failure of streptomycin to inhibit carotenogenesis. Stimulation of growth and carotenogenesis on the glucose/NH4N03 medium by (0.02 [image]) carboxylic acids is unaffected by streptomycin, with the exception of carotene stimulation in the presence of succinate. Streptobiosamidine dimethyl acetal, but no other component of the streptomycin molecule, inhibits carotenogenesis. On a medium in which acetate replaces glucose, streptomycin inhibits growth and carotenogenesis equally. Two carbonyl compounds occur in the P. blakesleeanus medium; one is almost certainly methylglyoxal and the other is an ene-diol related to hydroxytetronic acid. Synthesis of the enediol is almost completely suppressed in the presence of streptomycin and that of methylglyoxal reduced. A brief survey of the effect on carotenogenesis of a number of other antibiotics is recorded.