Deoxyribonucleic acid base composition of Staphylococcus epidermidis and its phages.

The base composition of DNA preparations from 16 strains of staphylococci, belonging to different subgroups, and from 10 staphylococcal phages were determined from the denaturation temperature (T') and from the buoyant density. The GC (guanine + cytosine) content of the DNA of the strains ranged from 29.3 to 33-9 % (calculated from Tm) and from 28.5 to 34-0 % (calculated from the buoyant density). No significant difference was observed between the GC content of the DNA of the strains of Staphylococcus aureus and S. epidermidis nor between its various biotypes. The mole fraction GC of staphylococcal phage DNA (31.4 to 34-6 % GC) is somewhat higher than the GC content of the DNA of the strains.