The growth of pneumococcal phages at high cell and phage densities is enhanced strongly by the substitution of potassium for sodium in the medium. Initial titers of 2 x 1010 to 4 x 1010 PFU/ml are readily obtained, and concentrated stocks are stable in a storage buffer described here. The mechanism of the cation effect is obscure. Phages ω3 and ω8 each have linear double stranded DNA of 33 x 106 daltons per particle, with an apparent guanine plus cytosine content of 47 to 49 mol%, as determined by buoyancy and melting temperature, but with an unusual absorbance spectrum. Efficiency of plating is high if sufficient time is allowed for relatively slow adsorption, which differs severalfold in rate between the two phages. Morphologically, these and other pneumococcal phages are similar to coliphage lambda but with a longer tail and tail fiber. Upon UV inactivation, ω3 and ω8 have D37 values of 33 and 55 J/m2, respectively, and each shows multiplicity reactivation. A total of 13 ts mutants have been isolated from the two phages, representing only two complementation groups; complementation and recombination occur between ω3 and ω8 mutants. Both phages provoke high titer antisera with extensive cross reactivity against a number of newly isolated pneumococcal phages.
All Science Journal Classification (ASJC) codes
- Insect Science