[Effect of certain factors on the variability of strains of pertussis microbes]

The population of degraded cells having stable changes in some phenotypical properties were isolated after subculturing some laboratory Bordetella pertussis strains in Bordet-Gengou culture medium and casein-charcoal agar with blood, treated with mitomycin C and allowed to proliferate in the spleen of mice injected intravenously with microbial suspensions. The characteristics indicative of cell degradation were the growth of large yellowish-white colonies appearing in 24 hours, the destruction of the agglutinogenic complex and toxic substances causing the atrophy of the spleen in mice, the increased capacity for active proliferation in the spleen. Electron-microscopic study revealed that the variants obtained by subculturing in culture media had the damaged membrane with the formation of cell-wall invaginations having rounded membrane-like formations on their surface, disappearing after treatment with mitomycin C; the treatment of the initial strains with mitomycin C resulted in cytoplasmic damage with the coagulation of the nucleoid.