FIG. 2.

Effect of OAg structure on resistance to polymyxin or complement. WT S. enterica serovar Typhimurium and various mutant strains with defects in OAg synthesis were incubated with buffer containing 100 or 500 ng ml⁻¹ polymyxin B (A) or with 50% HIS or NHS (B). (A) After incubation for 60 min, serial dilutions of the suspensions were plated onto LB plates for the determination of the number of surviving bacteria. (B) For complement survival, the ratio of survival in NHS and HIS was calculated. Means and standard deviations for three assays are shown and are expressed as percentages of the survival of the WT strain. For statistical analysis, Student's t test was applied. The mutant strains were compared to the WT strain, and significance is expressed as follows: ns, not significant (P ≥ 0.05); *, P < 0.05; **, P < 0.01; and ***, P < 0.01.