Rates in vitro changes of gonococcal colony opacity phenotypes

Abstract

The rate of change of colony opacity phenotype was determined for 12 strains of Neisseria gonorrhoeae. The average rate of change was .apprx. 2 .times. 10-3/colony-forming unit/generation with a range of 0.2-4 .times. 10-3/colony-forming unit/generation. Transition from opaque to transparent occurred at the same rate as transition from transparent to opaque. The following factors were shown to have no effect on the transition rate: the state of piliation; the number of passages as a particuliar phenotype; alteration in the temperature, pH or amount of O2 in the atmosphere during growth; the addition of any of 194 compounds or mixtures to the growth media; the addition of DNase or of DNA from opaque or transparent gonococci; and incubation under conditions for optimum or poor transformation. No apparent association between the opacity-transparency transition and the change resulting in the loss of piliation was seen. Some implications of the high transition rate are discussed.