Rapid identification of Enterobacteriaceae in milk and dairy products with the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS)

Abstract

Identification of microorganisms by MALDI-TOF MS Biotyper has been demonstrated to be accurate, rapid and lower cost than conventional food investigation methods. Rapid identification of pathogenic and spoilage microorganisms is crucial for dairy industry to ensure the quality and safety of milk and milk products. In this study, the bacterial species representing the Enterobacteriaceae family were identified in raw milk and milk products using the MALDI-TOF MS mass spectrometry. Altogether, 20 samples of Slovak milk and milk products were examined. Samples were cultured on VRBG agar at 37 °C for 24-48 h. Typical bacterial colonies were selected for identification with MALDI-TOF MS Biotyper. Escherichia coli and Enterobacter sp. were the most abundant  Enterobacteriaceae family representatives identified. E. coli was found in nine  and Enterobacter sp. in eight samples. Enterobacter sp. comprised 49 % and Escherichia coli 23 % of all bacterial isolates. The study shows that MALDI-TOF MS Biotyper was reliable identification method of Enterobacteriaceae in milk and dairy products. This method was helpful in evaluation of bacterial contamination of milk.