PSM concentrations in <i>S. epidermidis</i> culture filtrates.

<p>PSM concentrations in 18-h <i>S. epidermidis</i> and <i>S. aureus</i> LAC culture filtrates were determined by HPLC/MS. Peaks corresponding to N-formylated and deformylated PSM versions were measured separately and the percentage of deformylated peptides is shown as checkered bars. No PSMs were detected in the natural and constructed <i>agr</i> mutants (O47, 1457 <i>agr</i>). Relative PSM composition (α-type, δ-toxin, β-type) is shown at the right for <i>S. aureus</i> LAC and <i>S. epidermidis</i> 1457. Relative compositions were similar to that of 1457 in the other <i>S. epidermidis</i> strains (except in <i>agr</i>-negative O47 and 1457 <i>agr</i>).