Proteins found in different amounts in the culture supernatants of the wild type and ΔsecDF mutant (P-value <0.005).

1according to prediction of PSORTb algorithm (version 3.0.2; [26]): EC extracellular, C cytoplasmic, U unknown, M membrane; references for experimentally defined locations are given for proteins with predicted unknown localization.2Normalized Spectral Abundance Factor, mean average of three biological replicates; the NSAF normalizes across samples and takes protein sizes into account; values range between 0 and 1, increasing values indicate higher abundance [27], stdev standard deviation of the means of three biological replicates; probability ranges associated with Students t-test (Scaffold 4.0.5).3ND not detected (NSAF 0 in at least two biological replicates and *due to high sequence similarity all peptide hits for “flagellin” (Q81FD3, Q81FD4, Q81FD5) were combined.