Figure 2.

PGA production in S. epidermidis. (A) Relative expression of PGA determined by immuno-dot blot analysis. PGA was extracted from bacterial cell surfaces as described in Methods. A calibration curve was obtained by dilution of the most intensive sample obtained from the PGA-overexpressing complemented strain S. epidermidis Δcap (pRBcapBCAD). Results are the mean ± SEM of 4 experiments for the samples and the mean ± SEM of 4 different serial dilutions for the calibration curve. A representative blot is shown at the top. (B) Detection of S. epidermidis PGA with immunoscanning electron microscopy. PGA was detected with anti-PGA antiserum. (C) Analysis of D-glutamic (D-Glu) and L-glutamic (L-Glu) acid in S. epidermidis PGA by stereoselective chromatography and liquid chromatographic–mass spectrometric detection of glutamic acid. To determine D- and L-glutamic acid amounts, the L-glutamic acid background detected in the cap mutant strain (Δcap) was subtracted from PGA expression strains. (A–C) Δcap, isogenic cap deletion strain; capBCAD, complemented strain S. epidermidis Δcap (pRBcapBCAD).