Table 1.

Oxygen sensitivities of the B. hyodysenteriaewild-type strain B204 and the nox mutant strains Nox-Cm and Nox-Kma

Exposure time (h)Highest culture dilution yielding detectable growthb
B204 (nox+)Nox-Cm (noxmutant)Nox-Km (nox mutant)
010−5 10−5 10−6
210−6 10−5 10−5
410−5 10−4 10−3
610−4 10−1 10−2
810−4 NGNG
1010−2 NGNG
  • a Under anaerobic conditions, spirochete cultures were serially diluted 10-fold and the dilutions were spotted on TSB agar plates (Fig. 4). Each plate was exposed to oxygen (laboratory air) at 38°C for 0 to 12 h as indicated and then incubated anaerobically at 38°C. Two cultures of each strain were tested in each of three experiments.

  • b From experiment to experiment, the cell dilution at which growth was inhibited could vary by 1 dilution. For this reason, median dilution values are reported. In any single experiment, the dilution at which growth of a mutant strain was inhibited was always 100- to 10,000-fold greater than the dilution of the wild type that was inhibited. NG, no detectable growth of cells at any dilution.