Determination of the rate of transformation from growth curves of transformed streptococci.

A rapid method of determining the rate of transformation of group H streptococci to streptomycin resistance has been developed. The new technique, which involves analysis of the growth response of transformed streptococci in liquid medium containing streptomycin, is independent of chain length fluctuations and is demonstrably more accurate than the standard plating method. The relatively short generation time of streptococci under these conditions permits transformation rates to be estimated in 9 to 14 hr depending on the number of transformants in the inocula as compared to 50 hr by the agar plate procedure.