Predominant lactic acid bacteria in mukeunji, a long-term-aged kimchi, for different aging periods

Abstract

The distribution of dominant lactic acid bacteria (LAB) in mukeunji was examined at different stages of long-term aging. A total of 87 isolates from 3 samples were classified into 13 groups based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis whole-cell protein patterns and identified using 16S rRNA gene sequencing. The 13 LAB were also identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and API® strips. Weissella cibaria and Leuconostoc mesenteroides were the most abundant LAB in freshly prepared samples, followed by Lactobacillus (Lact.) curvatus and Lact. sakei, based on 16S rRNA gene sequencing. The species diversity of LAB in samples aged for 12 and 24 months was reduced over time, and Pediococcus sp. was the dominant LAB species in mukeunji samples. MALDI-TOF MS enabled rapid identification of Lactobacillus species. Identification results with similarities higher than 90% using API® strips provided the same results as 16S rRNA gene sequencing.