Rapid detection of microorganisms in the dairy value chain by MALDI-TOF MS

Master's thesis in Biological chemistryRecently, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has developed as vigorous method for the identification of microorganisms in the clinical sector. MALDI-TOF MS is able to detect different chemical components such as peptides, proteins, and other biomolecules. Identification of microorganisms by this tool has been demonstrated to be accurate, rapid and lower cost than conventional methods. Safety and quality are keywords for food industry, and in particular dairy industry; consequently there is a requirement for rapid identification of the pathogenic and spoilage microorganisms. From a variety of raw milk and milk products, strains have been collected from different culture media and identified by MALDI-TOF MS (Biotyper, Bruker Daltoniks). Identification was made by comparison with the Bruker database, or to a reference library created. Detection of β-lactamase resistance has been studied using mastitis samples collected from the TINE Mastitis. The results demonstrate that MALDI-TOF MS is an effective tool for microorganisms identification. Collection strains (such as ATCC strains) or strains identified by other methods can be incorporated into the database which was made for the identification of clinical strains. Detection of β-lactamase resistance is achieved faster than using antibiotic diffusion disk methods even if some of the parameters used in the method have potential for further improvement.Tin