Toxin Production by Corynebacterium diphtheriae under Growth-Limiting Conditions.

uMMARY Gory"ebacteri'"in of4)fitherzhe, Park Williams No. 8 strain, has been shown to produce toxin without apparent concomitant rowth when irondeficient cells, suspended in phosphate buffer, were incubated in the presence of casamino acid (or 19 amino acids), sodium succinate, magnesium sulfate and sodium chloride.Under these conditions, toxin production occurs almost immediateI at the maximal rate and continues for about 2 to 3 hours, whereas the growth of the cells, as measured by the optical density, dry weight and total and viable counts scarcely changes during the incubation.ISOtopic studies witlT L-'C Ieucine revealed that the rate of cellular protein synthesis by diphtheria bacilli with extremel limited growth was less than 15 per cent of that by growing bacilli, and that the toxin protein released extracellularly under the growth~limiting conditions appeared to be s nthesized ofe mooo from amino acids.