Temperature-sensitive mutants of Streptococcus pneumoniae. I. Preparation and characterization in vitro of temperature-sensitive mutants of type I S. pneumoniae.
After exposure of type I Streptococcus pneumoniae to nitrosoguanidine, 13 temperature-sensitive (ts) mutants were selected that were restricted in capacity to form colonies on blood agar at 38 C. Whereas colony formation by the type I parent (ts+) was unaffected by a temperature of as high as 39 C, the ts mutants exhibited a spectrum of temperature sensitivity in which colony formation was inhibited significantly at 36 C, 37 C, 38 C, or 39 C. Growth of ts mutants at 38 C in broth was reduced or delayed relative to that of ts organisms under identical conditions. In general, there was a direct correlation between degree of temperature sensitivity and genetic stability. Mutants grown at a permissive temperature resembled the ts+ type I parent in colonial morphology and properties of alpha-hemolysis, bile solubility, optochin sensitivity, and antibiotic sensitivity. Moreover, in vitro studies indicated that the mutants retained capsules of immunochemically reactive type I capsular polysaccharide.
D001646:Bile; D001666:Binding Sites, Antibody; D003470:Culture Media; D004917:Erythromycin; D009154:Mutation / Q000187:drug effects; D009604:Nitrosoguanidines / Q000494:pharmacology; D010403:Penicillin Resistance; D010406:Penicillins; D012995:Solubility; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*; D013696:Temperature
D003470:Culture Media; D009604:Nitrosoguanidines; D010406:Penicillins; D004917:Erythromycin