Differentially Expressed Proteins in <em>Corynebacterium pseudotuberculosis </em>During Biofilm Formation

Corynebacterium pseudotuberculosis is a non-motile, β-hemolytic bacterium and causative factor of caseous lymphadenitis. The disease affects sheep and goats causing impaired wool production, weight loss and carcass condemnation. Our previous work has elucidated the morphology, heterogeneity, and antimicrobial susceptibility of C. pseudotuberculosis biofilm. However, the information of proteome expression underlying C. pseudotuberculosis biofilm development remains scarce. Thus, the objective of the present work is to compare the whole-cell proteome profiles between planktonic and biofilm fractions of C. pseudotuberculosis and identify C. pseudotuberculosis proteins and biological pathways showing differential expressions. C. pseudotuberculosis biofilm was grown in a six-well microplate for 24 h at 37°C. Polyacrylamide gel electrophoresis combined with tandem mass spectrometry and bioinformatics analysis was conducted to analyze proteome expression. Results demonstrated differential expression of seven SDS-PAGE protein bands (33.7 – 150 kDa) in comparison between the planktonic and biofilm fractions of C. pseudotuberculosis. Overall, 711 proteins that showed differential expression were successfully identified while the protein-protein interaction network revealed a total of 1206 functional linkages among the differentially expressed proteins. Fifty-seven hub proteins with more than 10 functional linkages were identified, including large subunit ribosomal protein L3, translation initiation factor IF-2, multifunctional oxoglutarate decarboxylase and DNA-dependent RNA polymerase. Functional enrichment analysis showed the association of differentially expressed C. pseudotuberculosis proteins with amino acid metabolism (p-value: 0.0243) and secondary metabolite metabolism (p-value: 0.0198). In conclusion, the formation of C. pseudotuberculosis biofilm may involve changes in multiple metabolic pathways.