Comparison of Undefined Medium and Its Dialyzable Fraction for Growth of Mycoplasma

In examining the medium used in cultivation of Mycoplasma for deoxyribonucleic acid isolation, it was found that an aggregate was present which sedimented with the organisms and which was ethyl alcohol-precipitated during deoxyribonucleic acid purification. To eliminate the contaminating material, a method was devised to obtain only the dialyzable constituents of the medium. This report describes the preparation of a dialysate of soy peptone-yeast extract. The medium, obtained by immersion of the encased dehydrated ingredients in sodium chloride solution for 5.5 hr at approximately 80 C, has been employed as the basal medium for cultivation of a number of Mycoplasma species. Comparative growth curves of two saprophytic strains and two parasitic species indicated that multiplication in dialysate, with suitable supplement, followed the pattern typical of the common eubacteria. Thus, by elimination of the sediment which occurred in nondialyzed medium, Mycoplasma could be concentrated without concomitant accumulation of contaminating macromolecules.