Growth and survival of Mycoplasma neurolyticum in liquid media

Hottle, G. A. (Naval Biological Laboratory, University of California, Berkeley), and D. N. Wright. Growth and survival of Mycoplasma neurolyticum in liquid media. J. Bacteriol. 91:1834-1839. 1966.-Maximal growth of Mycoplasma neurolyticum (between 10(8) and 10(9) colony-forming units per ml) was obtained after 3 days of incubation at 36 C in broth media containing 10% agamma horse serum. When whole horse serum was used in the medium, a complement-mediated inhibition was observed. This inhibition could only be detected when growth was followed by daily plate counts. Maximal growth was delayed for about 24 hr by the horse serum, and the inhibition was spontaneously reversed at the temperature of incubation. Penicillin G was also found to have a temporary inhibitory effect. This was detected with as little as 40 units per ml. Maximal growth was delayed until the 6th day of incubation, when 200 units per ml was present, and until the 16th day, when 1,000 units per ml was present. The survival of M. neurolyticum at undetectable levels in cultures during the incubation period presented an "eclipse" phenomenon which has not been explained. The recrudescence of growth in such cultures late in the incubation period illustrates the events which may occur when mycoplasmas are isolated from clinical material by prolonged incubation in the presence of inhibitors. Survival data showed that M. neurolyticum had greatest stability at pH 8.0, with reduced viability at pH 9.0, 7.0, 10.0, and 6.0, in that order The data on growth and stability suggest a close relationship between the species. of Mycoplasma studied and bacteria.