Peptide biomarkers for mastitis producing Streptococcus spp. identification and characterization by LC-ESI-MS/MS

Abstract

Classical and culture-based methods for pathogen identification and characterization of their biochemical properties are slow and labour-intensive. Molecular microbial diagnostic methods based on genomics and proteomics allow a faster and more effectively species identification. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) has been used for the analysis of bacterial pathogen strain-specific diagnostic peptides allowing the characterization of bacterial strains. In this study, tryptic digestion peptides from mastitis producer Streptococcus spp. isolated from milk have been analysed by LC-ESI-MS/MS to search for specific biomarkers useful for a rapid identification of both, the bacterial species and the physiological and biochemical characteristics such as the expression of virulence factors including toxins, immune-modulatory factors, exoenzymes and so on. Thus, a total of 100 μg protein extraction was digested with trypsin, cleaned on a C18 microSpinTM, and then analysed by LC-MS/MS. Proteomic data was processed by SEQUEST (Proteome Discoverer 1.4 package, Thermo Scientific) against Bacteria in the UniProt/ TrEMBL database. Specific peptides from proteins such as bacteriophage proteins, toxins and M protein, were found and could be useful as specific biomarker peptides