STUDIES ON THE STREPTOMYCIN RESISTANCE SYSTEM OFNEISSERIA MENINGITIDIS

Relationship of Neisseria elongata subsp. Glycolytica to other members of the family Neisseriaceae

Neisseria elongata subsp. glycolytica strain 6171/75 is closely similar to the type strain of N. elongata, M2, as regards DNA base composition, fatty acid content and electrophoretic mobility of two glutamate dehydrogenases, one of which showed a reaction of identity with the corresponding enzyme from M2 in double immunodiffusion in agar. The strain showed genetic homologies with strain M2 in genetic transformation at a level suggesting species identity, and with N. meningitidis at a lower level. No affinity to Moraxella species or "false neisseriae" was demonstrated, with the exception of a production of a few transformants in the 6171/75 recipient by DNA from Kingella kingae. The strain showed the same pattern of associated variation of colony type, fimbriation and competence in transformation as that found in other Neisseria and Moraxella species. After continuous subcultivation for some time some clones of the strain appeared to have lost the ability to produce acid from glucose.

Relationship of serogroups of Neisseria meningitidis. II. R variants of Neisseria meningitidis

Meningococci isolated in primary cultures from nasopharyngeal carriers occasionally consisted of mixtures of smooth (S) and rough (R) strains. The R strains were separated from the S strains and their morphological and serological characteristics were studied. Some of these R strains reverted spontaneously to S strains which subsequently produced group-specific polysaccharide. Several R strains, grown in the presence of deoxyribonucleic acid from either an R strain of known parentage or an S strain, formed recombinants with serological group specificity.

Polarity of chromosome replication in Neisseria meningitidis

Jyssum, Kaare (University of Oslo, Oslo, Norway). Polarity of chromosome replication in Neisseria meningitidis. J. Bacteriol. 90:1182-1187. 1965.-Relative frequencies of various genetic markers in the deoxyribonucleic acid of Neisseria meningitidis in exponential- and stationary-growth phases were compared by use of a transformation system. On the basis of an analysis of eight genetic markers, including a competence factor, it is assumed that a polarity exists in the chromosome replication. A genetic map has been constructed according to the model of Yoshikawa and Sueoka. Chromosome replication has been compared in genetically competent and genetically incompetent strains. The change from genetic competence to genetic incompetence seems to result in a change in the replication of the chromosome. The results are discussed in relation to findings from other transformation systems, particularly that of Bacillus subtilis.