Separation of Neisseria meningitidis competence variants by sucrose gradient centrifugation.

Transformable (cp+) and non transformable (cp-) variants of the Neisseria meningitidis Strain M1 could be separated on the basis of their sedimentation velocity in sucrose gradients. The cp+ cells sedimented slightly more slowly than the cp- ones. This supports previous observations that the change from cp+ to cp- is followed by alterations in cell structures. In cp+ populations, the transformable fraction banded with the bulk of the cells in sucrose gradients, indicating that the density of the phenotypically competent cell is identical to the rest of the cp+ population.