Rapid and accurate identification of species of the genus Pediococcus isolated from Korean fermented foods by matrix-assisted laser desorption/ionization time-of-flight MS with local database extension

Pediococci are halophilic lactic acid bacteria, within the family Lactobacillaceae, which are involved in the fermentation of various salted and fermented foods, such as kimchi and jeotgal. In this study, a matrix-assisted laser desorption/ ionization time-of-flight (MALDI-TOF) MS method was developed for the rapid identification of species of the genus Pediococcus. Of the 130 Pediococcus spectra aligned with the Biotyper taxonomy database, 122 isolates (93.9 %) yielded log scores <1.7, which means they were not identifiable. After registering the spectra of 11 reference strains of the genus Pediococcus, all of the isolates were correctly identified, of which 84 (64.6 %) and 46 (35.4 %) were identified at the species and genus level, respectively. In comparing food origins, no relationship was found between the bacterial characteristics and food environment. We were able to produce a Biotyper system for identification of members of the genus Pediococcus with locally extended Pediococcus reference strains. The MALDI-TOF MS method is fast, simple and reliable for discriminating between species in the genus Pediococcus and therefore will be useful for quality control in determining the spoilage of alcoholic beverages or in the production of fermented food.