TABLE 1.

Effect of antimicrobial peptides on capsule polysaccharide production and transcriptiona

Induction conditionMean ± SD
Amt of capsule (μg/104 CFU)RLU
None76.3 ± 71,269 ± 80
Protamine sulfate (50 μg/ml)78.0 ± 51,223 ± 50
Polymyxin B (0.5 U/ml)114.1 ± 4*1,708 ± 40*
Lactoferrin (100 μg/ml)108.4 ± 10*2,989 ± 97*
  • a The amount of capsule was quantified by measuring uronic acid (a component of the K2 polymer). Luciferase activity was measured in a strain carrying the transcriptional fusion cps::lucFF and expressed as relative luminescence units (RLU). *, Significantly different from the result in the absence of inducing conditions (P < 0.05, [two-tailed t test]).