Qualitative differences in the behavior of pneumoncoccal deoxyribonucleic acids transforming to the same capsular type

Bernheimer, H.P.; Wermundsen, I.E.; Austrian, R.

Journal of Bacteriology 93(1): 320-333


ISSN/ISBN: 0021-9193
PMID: 4381317
Accession: 025326169

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A method is described for estimating quantitatively the frequency of transformation of pneumococci to new capsular types. It is found that, when S -III cell are exposed to deoxyribonucleic acid(DNA) from wild-type I strains transformation to SI occurs at a frequency 20 to 60 times that of transformation to the binary type SI-III. SI markers on DNA isolated from binary strains behave qualitatively and quantitatively in a different manner from the same markers on DNA from wild-type I straina and will transform S-III cells only to SI-III. Strains are described which produce only one capsular polysaccharide, but which are genetically binary and carry a second capsular genome with a mutated gene so that the second polysaccharide is not produced. Stability and other characteristics of binary strains are discussed, and one hypothesis for the genetic organization of binary strains is presented.