Rapid Identification and Classification of Psychrotrophic Lactic Acid Bacteria by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

Psychrotrophic lactic acid bacteria strains potentially used for the fermentation of meat were characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using ribosomal proteins as biomarkers. The sample strains of a commercial starter culture (strain D-1001) and 15 similar strains were thought to be Lactobacillus sakei, based on their biochemical properties and the 16S rRNA partial gene sequence. By comparing the mass spectra of cell lysates to the calculated masses of ribosomal proteins of genome-sequenced Lactobacillus sakei 23K, all sample strains were definitely identified as L. sakei. Sample strains were further classified into 4 groups based on the mass differences of the 16 biomarkers selected from ribosomal subunit proteins, which could not be discriminated using the 16S rRNA partial gene sequence analysis.