Molecular characterization of lactic acid bacteria from kimchi fermentation

초록

Lactic acid bacteria have been known as the major component for kimchi fermentations. However, previous classifications of isolates from kimchi are mainly based on biochemical and physiological methods and sometimes lead to misclassification. Here we report the systematic classification of isolates from kimchi using molecular characterization methods including multiplex PCR or amplified ribosomal DNA restriction analysis. These molecular analyses revealed that some subsets of lactic acid bacteria, namely Leuconostoc citreum (70% of 120 isolates from laboratory kimchi, at 20 oC), L. gelidum/ L. gasicomitatum (80% of 60 isolates, 8 oC), Weissella hanii (60% of 30 isolates from commercial kimchi, 4 oC), W. kimchii/ W. cibaria (50% of 60 isolates, 4 oC), or Lactobacillus sake/ Lb. curvatus (70% of 60 isolates, 4 oC), were predominant species for kimchi fermentations. We also found that L. citreum or L. gelidum/ L. gasicomitatum were dominant at the early stage of fermentation (0-3 days) and these species were rapidly disappeared when Lb. sake/ Lb. curvatus were dominant at the later stage of fermentation ( 4 - 6 days at 20 oC). Leuconosotc species were classified by multiplex PCR, containing several different signature primers in same PCR tube, and Weissella species were classified by ribosomal DNA restriction analysis that compared restriction patterns of amplified 16S rDNA fragment (725 bp) by three restriction enzymes, namely, MnlI, MseI, BceAI. Our results contradict previous reports that Leuconostoc mesenteroides is the most frequently isolating organism from kimchi. This discrepancy may result from either misclassification of previous isolates or change of preparation conditions. Our results indicate that Weissella species including Weissella hanii or Lb. sake/Lb. curvatus may also play important role in conferring kimchi quality.