Identification of Lactic Acid Bacteria Isolated from Freeze-dried Kefir Grains (Georgia, Russia).

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Lactic acid bacteria isolated from freeze-dried Georgian (Russia) kefir grains were compared with those in the flora of other kefir grains. The 6 representative isolates were identified as Weissella confusa (GKL1), Lactobacillus kefir (GKL2) and Lactobacillus kefiranofaciens (GKL5, GKL7, GKL9, GKL28) based on phenotypic characteristics and DNA-DNA relatedness. Three of the L. kefiranofaciens strains might be identified as Lactobacillus acidophilus (GKL5, GKL7) and Lactobacillus delbrueckii subsp. lactis (GKL9) from their phenotypic characteristics. L. acidophilus and L. bulgaricus reported previously were presumed to be mutants of L. kefiranofaciens which had lost the productivity of polysaccharide. L. kefir and L. kefiranofaciens have been reported to be constituent strains of the kefir grains but Leuconostoc mesenteroides and Lactococcus lactis described previously were not isolated from either the kefir or kefir grains in this study. Instead of these two species, W. confusa strains were isolated from kefir as a dominant species, but those were not isolated from the kefir grains. These findings suggested that the Leuconostoc and Lactococcus strains disappeared due to the cultural conditions before freeze-drying, and that the fast growing strains of W. confusa contaminated the kefir during activation of the freeze-dried kefir grains.
日本食品微生物学会の論文