Abstract
Lactic acid bacteria have not only been used to produce various kinds of fermented food, but also used as probiotic products. As lactic acid bacterial group was consisted from diverse genera, a simple inspection method by which numbers and contained microorganisms could be automatically analyzed without any preliminary information was required to use them more effectively. In this manuscript, lactic acid bacterial groups in commercial products of kimuchi, komekouji-miso, and yoghurt were identified and enumerated by our newly developed method [1]-[3], to evaluate whether the method could be used as an inspection method of various food samples. In kimuchi, numerically dominant bacteria were Lactobacillus sakei, and L. casei (1.4 × 104 MPN g-1) and Leuconostoc spp. (l.4 × 104 MPN). In kouji-miso, numerically dominant bacteria was Bacillus spp. (3 × 103 MPN), which mainly included B. subtilis group and B. cereus group. Lactic acid bacteria such as Lactobacillus spp., or Lactococcus spp., included in the komekouji-miso, could be enumerated after 3 days incubation (1.24 × 104 MPN), but not detected after 7 days incubation. In yoghurt A and C, Lactococcus lactis was detected as numerically dominant lactic acid bacteria (3.0 × 105 MPN). In yoghurt B, Lactobacillus spp., or Lactococcus spp., was detected not only by a culturebased method but also by an unculture-based method, although there was a difference between the both estimated numbers. The present results suggested that the method might become useful as a simple inspection method of food microorganisms, because time and labor of the analysis could be reduced by using an unculture-based method and MCE-202 MultiNA. In this study, Bifidobacteriium spp. was not detected in B and C yoghurt, in spite of indicating their existence, and numbers of lactic acid bacteria were lower than the level of the daily product regulation, because 16S rDNA of Bifidobacteriium spp. might not be amplified by the used PCR condition. The PCR condition must be changed so as to amplify Bifidobacterium spp., before the method will be used as an inspection method for lactic acid bacteria.
Highlights
Lactic acid bacteria have been used to produce various kinds of fermented food, and used as probiotic products to exert a health benefit by eating living cells
The total number of included bacterial group in komekouji-miso (MC7 and 3) and kimuchi (KC) was lower than that of Japanese food sanitary regulations where numbers of microorganisms included in commercial product must be lower than 105 cells/g (Table 2), and most of the detected bacteria were originated from their fermentation process (Table 2)
The total number of lactic acid bacteria, YCC; 3.06 × 105 MPN g−1, YAC; 3.01 × 105 MPN, YBC; 0.6 × 105 MPN, YBU; 4.8 × 105 MPN, was lower than that of Japanese daily product regulation, which indicated that daily product including lactic acid bacteria or yeast over 107 cell/mL could be treated as fermented daily product (Table 3, Figure 2)
Summary
Lactic acid bacteria have been used to produce various kinds of fermented food, and used as probiotic products to exert a health benefit by eating living cells. In the traditional fermentation process, various kinds of lactic acid bacteria were concerned with the fermentation process, which effected taste, texture, and flavor of the final products. As probiotics, their effect was suggested to modulate mucosal and systematic immunity [4], and improve the nutritional and microbial balance in the intestinal tract [5]. They are often used as multispecies containing different probiotic species that belong to one or preferentially more genera These methods were used to demonstrate the effect as probiotics [9] and investigate a mechanism of its functional effect [4]
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