The uptake of iron by Corynebacterium diphtheriae growing in submerged culture.

Abstract

SUMMARY: The uptake of iron by Corynebacterium diphtheriae growing in complex medium was found to be rapid and quantitative, even when the iron concentration of the medium was high enough to abolish toxin production completely. The presence of this inhibitory concentration of iron (3 μg./ml.) did not alter the duration of logarithmic growth nor did it affect the shape of the growth curve in any other way. The ferrous and ferric forms of iron were taken up equally well by the organism and appeared, weight for weight, to give the same final toxin titres. Ferrous iron, however, appeared to begin to exert its effect on toxin synthesis much earlier in the growth period than did ferric iron. It is suggested that perhaps only ferrous iron is inhibitory and that ferric iron requires to be converted to the ferrous form before exerting its effect.