Intraspecific and Interspecific Transformation in Streptococci.

Perry, Dennis (Northwestern University Medical School, Chicago, Ill.), and Hutton D. Slade. Intraspecific and interspecific transformation in streptococci. J. Bacteriol. 88:595-601. 1964.-Interspecific transformation reactions, employing streptomycin resistance as a marker, were performed with eight strains of streptococci belonging to three serological groups (F, H, and O) and one ungroupable (UG) strain. Generally, autotransformation (within the same strain) was most efficient. Homotransformation (between different strains of the same serological group), however, was sometimes as efficient or slightly better. Heterotransformation (between different serological groups) yielded the least number of transformants or none at all. The rate of transformation of different strains varied from 2.0 x 10(-7) to 7.6 x 10(-3). Group H streptococci exhibited the highest rate of autotransformation, followed by groups F and O, and strain UG. The results of heterotransformation reactions revealed that a genetic relationship exists between various strains of different serological groups. No transformation, however, occurred between F and O strains, indicating a lack of genetic homology between these serological groups of streptococci. Deoxyribonucleic acid (DNA), isolated by physical and enzymatic methods from a group O and a UG strain, failed to induce transformation. DNA from these strains, however, significantly inhibited the transforming ability of other DNA preparations. Heat and mechanical shear resulted in a marked decrease in this inhibitory property.