TITLE:
Evaluation of the Method Based on Restriction Fragment Length Polymorphism Analysis as Simple Analysis Method of Lactic Acid Bacteria in Foods
AUTHORS:
Kunimasa Matsumoto, Kouya Shimada, Naoto Horinishi, Katsuji Watanabe
KEYWORDS:
Multiple Enzyme Restriction Fragment Length Polymorphism Analysis, Most Probable Number Method, Lactic Acid Bacteria, Komekouji-Miso, Kimuchi, Yoghurt
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.7 No.3,
March
21,
2016
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.