FIG 4.

Differences in in vitro protein secretion. The proteins secreted into the culture supernatant from the log-phase wild-type strain and the AMPR mutants were extracted, separated using 2D SDS-PAGE, and analyzed densitometrically. The ΔvirK ΔybjX mutant displayed the greatest differences in spot densities (indicated by lowercase letters) compared to the wild-type strain. Representative 2D SDS-PAGE gels are shown as follows: lane M, protein ladder (kDa); lane A, wild-type S. Enteritidis (ZM100); lane B, S. Enteritidis ΔvirK ΔybjX (ZM124); lane C, S. Enteritidis ΔvirK (ZM122); lane D, S. Enteritidis ΔybjX (ZM123). Experiments were repeated three times with triplicate cultures in each run.