Label-free proteomics study on Shewanella putrefaciens regulated by ε-poly-lysine treatment

Aims The purpose of this study was to investigate the regulatory mechanism of epsilon-PL on Shewanella putrefaciens. Methods and Results Proteomics analysis of inhibitory effect of epsilon-PL against S. putrefaciens was performed by label-free quantitative assay based on high-resolution mass spectrometry (MS). Quantification of 2206 proteins was obtained with high confidence, and a total of 36 differentially expressed proteins (DEPs), with 10 and 26 proteins showing upregulation and downregulation, respectively, were identified. Upon Go functional enrichment, 11, 5 and 8 specific Go terms in biological processes, molecular functions and cellular components were identified, respectively. Six KEGG pathways, including 'ribosome', were significantly enriched. Among the ribosome pathway, there were seven DEPs and all of them were distributed on large and small subunits of ribosome. Conclusions The significant downregulation of proteins, large subunits of ribosomal proteins RP-L18, L30 and L27, small subunits ribosomal proteins S16 and S20, and RNA polymerase beta' subunit protein rpoC were the critical action sites of epsilon-PL to inhibit S. putrefaciens growth. Significance and Impact of the Study Shewanella putrefaciens is one of the representative fish-spoilage bacteria regardless of fish type, and poses significant problems for the fish brewery. A better understanding of the antibacterial mechanism of epsilon-PL on S. putrefaciens could make important contributions to development of biological control strategies of these economically important pathogens.