Isolation of Brucella melitensis phage of broad biotype and species specificity

A Brucella melitensis phage was isolated. Stocks of phage were established which produced early large plaques. The phage host range included all smooth Brucella species.

The influence of subcellular fractions on the enzymic methylation of DNA in ascites cell nuclei

Soluble factors appear to be present in both nuclei and cytoplasm of Krebs 2 ascites tumour cells capable of stimulating the enzyme catalysed methylation of DNA in isolated nuclei from these cells.

Induction and reversion of the L-form of Neisseria gonorrhoeae

Massive induction of Neisseria gonorrhoeae to the L-form was achieved on L-media consisting of brain heart infusion broth, 1% agar, 10% horse serum, and 100 units per milliliter penicillin. This medium was supplemented with polyvinylpyrrolidone (PVP) for stabilization. Frequencies greater than 10% were routinely found with all 11 strains tested. Five of the 11 strains were also transformed to the L-form on L-media supplemented with 10% sucrose but at efficiencies much lower than on PVP L-media. Rare L-colonies (less than 1 in 107 gonococci) of these same five strains were also isolated on unstabilized L-media. No L-forms were ever isolated from the remaining six strains on sucrose or on unstabilized L-media. The penicillin concentration in the media, if above a lethal amount, had little effect on the efficiency of L-phase induction on PVP L-media but was critical for isolation on sucrose L-media. Colonial growth of the L-form was much more rapid and luxuriant on PVP than on sucrose L-media. In addition, subculture by the agar-block technique of L-phase colonies induced on PVP L-media routinely occurred while growth was seldom obtained on subculture from sucrose L-media. Reversion to the gonococcal parent occurred (1) on transfer of growth by the agar-block technique to similar media without penicillin or to Mueller Hinton blood agar, (2) in L-broth into which an agar block containing L-colonies was placed and time allowed for decay of penicillin, (3) on sucrose but not PVP L-media, within the original transformed L-colonies after penicillin decay. Growth in PVP L-broth was achieved. On transfer from broth culture to growth media without penicillin, reversion to the parental gonococci occurred.