New Observations on Pneumococcal Transformations in vivo.

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Abstract
Bacterial transformation was studied in vivo using purified preparations. Lysates were prepared from cultures of Pneumococcus strains SV1 and A-68 (Types I and III, virulent) by heating 25 minutes with deoxy-cholate at 65[degree]C. The SV1 lysate was active initially in vivo, but lost its ability to transfer virulence to strain R36NC (Type n, avirulent). The A-66 lysate was precipitated with ethanol and the precipitate was washed with saline. The residue had as much transforming activity as a comparable quantity of original lysate. Mild deproteinization by chloroform or detergents inactivated this residue. When injection of lysate preceded injection of R36NC culture by as long at 24 hours, transformation to virulent would still occur in almost all the mice. This indicated that the deoxyribonucleic acid retained its transforming ability in vivo for at least 24 hours.