FIG 3.

Soluble extracellular proteins of wild-type and ΔgldN mutant cells. Cells of wild-type F. psychrophilum, the ΔgldN mutant, and the ΔgldN mutant complemented with wild-type gldN on pBFp4 were grown in TYES medium at 18°C with shaking until cells reached early stationary phase of growth (Klett readings of 160). Cells were removed by centrifugation followed by filtration (0.45 μm). Proteins from equal amounts of cell-free spent media of wild-type, mutant, and complemented cells were precipitated with TCA, solubilized in loading buffer, and separated by SDS-PAGE. Proteins were detected by silver staining. Lane labeled “TYES” contained an equivalent amount of TYES growth medium that had not been inoculated with F. psychrophilum, indicating bands that correspond to components of the growth medium.