A Synthetic Medium for the Cultivation of C. diphtheriae

Abstract

This paper reports a continuation of earlier studies in which it was shown that certain strains of the diphtheria bacillus can be grown on media containing nothing more complex than amino acids, lactic acid or glycerol, nicotinic acid, [beta]-alanine and pimelic acid, and the usual inorganic salts. On such media growth of the organism was good, but not as good as could be obtained on more complete and more complex media.[long dash]With the strain used, growth could be increased to approx. 4 times that obtained in the earlier exps., by modifying the media along 3 lines: by adding to it certain inorganic ions, particularly Fe, Mn, Zn and Cu, shown to be deficient in the earlier medium; by use of more cystine; and by use of a higher conc. of lactic acid than originally employed. The d-isomer is the form of lactic acid that is utilized by this organism, and since the increase in growth continues up to a point where the lactate conc. becomes inhibitory, heavier growth was obtained by the use of pure d-lactic acid than by the commercial dl-form.