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4th International Caparica Conference in Antibiotic Resistance, Caparica, Portugal, 13th – 17th June 2021, Streptococcus spp. are among the main mastitis pathogens present in dairy products [1]. The major species involved in both clinical and subclinical mastitis are Streptococcus agalactiae, Streptococcus canis, Streptococcus dysgalactiae and Streptococcus uberis, which produce a variety of virulence factors that are involved in streptococcal pathogenicity. These include neuraminidase, pyrogenic exotoxin, and M protein, and in addition they might produce bacteriocins and antibiotic-resistance proteins [2]. Unjustifiable misuse of antimicrobials has led to an increase in antibiotic-resistant bacteria present in foodstuffs [3]. Identification of the mastitis-causing bacterial strain, as well as determining its antibiotic resistance and sensitivity is crucial for effective therapy. Classic culture-based methods used for the detection of pathogenic bacteria are time-consuming and laborious procedures. The present work focused on the LC–ESI–MS/MS (liquid chromatography–electrospray ionization tandem mass spectrometry) analysis of tryptic digestion peptides from mastitis-causing Streptococcus spp. isolated from milk. A total of 100 μg of protein extraction was digested with trypsin, cleaned on a C18 microSpinTM, and analyzed by LC-MS/MS. Proteomic data were processed by SEQUEST (Proteome Discoverer 1.4 package, Thermo Fisher Scientific) against bacteria in the UniProt/TrEMBL database. A total of 2706 non-redundant peptides belonging to 2510 proteins was identified and analyzed. Among them, 168 peptides were determined, representing proteins that act as virulence factors, toxins, anti-toxins, provide resistance to antibiotics that are associated with the production of lantibiotic-related compounds, or play a role in the resistance to toxic substances. Protein comparisons with the NCBI database allowed the identification of 134 peptides as specific to Streptococcus spp., while two peptides (EATGNQNISPNLTISNAQLNLEDKNK and DLWC*NM*IIAAK) were found to be species-specific to Streptococcus dysgalactiae. This proteomic repository might be useful for further studies and research work, as well as for the development of new therapeutics for the mastitis-causing Streptococcus strains

Poster.-- 4th Meeting of Medicinal Biotechnology, Porto, May 17th 2019, Streptococcus includes numerous mastitis causing species, being responsible for high economic losses as well as human health issues Recently, new rapid molecular microbial diagnostic methods based on genomics and proteomics have been developed in order to achieve faster and more effectively species identification than classical and culture based methods which are labour intensive Liquid chromatography electrospray ionization tandem mass spectrometry (LC ESI MS/MS) has been used for the analysis of bacterial pathogen strain specific diagnostic peptides 1 2 As bacteriophages are high specific to their host pathogens, their nucleic acids, antibodies, phage display peptides ( and most recently phage’s receptor binding proteins ( have been studied as biosensor for pathogen detection 3 4 In addition, LC ESI MS/MS techniques have been employed for the identification and detection of bacterial bacteriophages 5 However, any study has been published for Streptococcus phage detection and identification by LC MS MS so far, This work was funded by the Spanish Ministry of Economy and Competitivity Project AGL 2013 48244 R and by the European Regional Development Fund ( 2007 2013 Ana Gonzalez Abril pre doctoral scholarships was funded by Xunta de Galicia and the European Union (European Social Fund ESF)

Poster.-- Congreso Nacional de Biotecnología Biotec, Vigo, 10-13 de junio de 2019, Some bacterial strains have the ability to decarboxylate specific amino acids producing biogenic amines (such as histamine from histidine). The detection of these strains having amino acid decarboxylase activity is important to lower the risk of biogenic amine in food products, especially histamine. Histamine is regulated in fish (lower than 100 mg/Kg-1, but it is generally recognized that the presence of other biogenic amines aggravate symptoms from histamine. Molecular methods for the detection of biogenic amine-producing bacteria in foods are based on the specific detection of decarboxylase genes by PCR allowing the detection before the biogenic amine is produced [1]. However, the difficulty is the availability of universal primers. Mass spectrometry [2] can provide a useful tool for the detection of strain-specific diagnostic decarboxylase peptides. In this study, proteins from biogenic amine producing strains were isolated, after tryptic digestion, the resulting peptides were analysed by LC-ESI-MS/MS (Liquid chromatography-electrospray ionizationtandem mass spectrometry). A total of 100μg protein extraction was digested with trypsin, cleaned on a C18 microSpinTM, following by LC-MS/MS analyse. Proteomic data was processed by SEQUEST (Proteome Discoverer 1.4 package, Thermo Scientific) against Bacteria in the UniProt/ TrEMBL database. MS data was analysed to identify the peptides from the amino acid decarboxylases and then compared to the GenBank database using the Blast tool (NCBI) to achieve peptide/protein identification. Thus, decarboxylase peptides were detected in studied strains that could be used as biomarkers in further studies, This work was funded by the Spanish Ministry of Economy and Competitivity Project AGL2013-48244-R and by the European Regional Development Fund (ERDF) (2007-2013). Ana Gonzalez Abril pre-doctoral scholarships was funded by Xunta de Galicia and the European Union (European Social Fund - ESF)