FIG. 6.

Susceptibilities of 7169 (open bars) and 7169fur1 (solid bars) to the bactericidal activity of NHS. 7169 was compared to 7169fur1 in 10 and 25% NHS. Negative controls included buffer alone (PBSS) and HI NHS (50% pooled NHS inactivated by incubation at 56°C for 30 min). Means from three separate experiments are shown. Error bars, standard deviations. By use of Student's t test, the differences between results for 7169fur1 in 10 and 25% NHS and results for the wild type are statistically significant (P < 0.001).