Rapid identification of Staphylococcus species isolated from food samples by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)

species have a ubiquitous habitat in a wide range of foods, thus the ability to identify staphylococci at the species level is critical in the food industry. In this study, we performed rapid identification of species using Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectrometry (MALDI-TOF MS). MALDI-TOF MS was evaluated for the identification of reference strains (n=19) and isolates (n=96) from various foods with consideration for the impact of sample preparation methods and incubation period. Additionally, the spectra of isolated strains were analyzed using principal component analysis (PCA) and main spectra profile (MSP)-based dendrogram. The MALDI-TOF MS accurately identified reference strains and isolated strains: the highest performance was by the EX method (83.3~89.5% accuracy) at species level identification (EDT, 70.3~78.9% accuracy; DT, less than 46.3~63.2% accuracy) of 24 h cultured colonies. Identification results at the genus level were 100% accurate at EDT, EX sample preparation and 24 h incubation time. On the other hand, the DT method showed relatively low identification accuracy in all extraction methods and incubation times. The analyzed spectra and MSP-based dendrogram showed that the isolated strains were characterized at the species level. The performance analysis of MALDI-TOF MS shows the method has the potential ability to discriminate between Staphylococcus species from foods in Korea. This study provides valuable information that MALDI-TOF MS can be applied to monitor microbial populations and pathogenic bacteria in the food industry which contributes to food safety.