FLUOROMETRIC QUANTITATION OF BROTH-CULTURED MYCOPLASMAS BY USING ALKALINE ETHIDIUM-BROMIDE

We developed a fluorometric system which does for broth-grown mycoplas mas what turbidimetric analysis does for broth-grown bacteria. It allo ws one to monitor the growth of broth-grown mycoplasmas at any interva l desired. The entire procedure is quick, taking not more than 20 min. The fluorometric readings correlate with colonial growth on agar, mak ing it possible, for the first time, to take readings which closely es timate the CFU present in the culture at a given moment in time. We sh ow that this system can be used to assess the effectiveness of an anti mycoplasmal antibiotic and to optimize medium components and that fluo rometer readings taken during the logarithmic phase of growth correlat e with the DNA content of the viable cells. Use of this methodology wi ll permit investigators to know absolutely the phase of the growth cyc le of the culture concomitant with the growth of the culture itself, a nd since fluorometer readings of culture aliquots can be converted to DNA equivalents, the standardization of mycoplasmal cultures within an d between laboratories will be a possibility.