Identification and Characterization of Antimicrobial Lactobacillus Strains

Example 3

3.1 Sequence Analysis and Phylogenetic Tree Identification of MG4272 and MG4288 Strains

16S rRNA gene sequencing was performed using universal rRNA gene primers (27F, 1492R) of MG4272 and MG4288 strains. Each process was performed through Sol-gent (Daejeon, Korea). The analyzed sequences were compared and identified with the Genebank database using the Basic Local Alignment Search Tool (Blast) of the National Center for Biotechnology Institute (NCBI). The phylogenetic tree was created using the neighbor joining method of MEGA 7.0 software. The 16s rRNA sequence of the analyzed MG4272 strain was shown as SEQ ID NO: 1, and 16s rRNA base sequence of the MG4288 strain was shown in SEQ ID NO: 2. The phylogenetic tree of the MG4272 and MG4288 strains was shown in FIG. 3.

As shown in FIG. 3, the two strains with superior antimicrobial activity against Gardnerella vaginalis and Candida albicans were identified to be Lactobacillus paracasei MG4272 and Lactobacillus rhamnosus MG4288 based on the 16S rRNA sequences analysis. The identified Lactobacillus paracasei MG4272 was deposited on Mar. 12, 2019 on the Korean Collection for Type Culture (Korea) and was assigned accession number KCTC13822BP. Lactobacillus rhamnosus MG4288 was deposited on Mar. 12, 2019 on the Korean Collection for Type Culture (Korea) and was assigned accession number KCTC13823BP.

3.2 Identification of Morphological Characteristics of MG4272 and MG4288 Strains

To identify the morphological characteristics of MG4272 and MG4288 strains, the MG4272 and MG4288 strains were immobilized in 1% glutaraldehyde (Sigma-Aldrich, Saint Louise, USA) solution at 4° C. for 24 hours, and were dehydrated with ethanol and observed using a scanning electron microscope (Field emission scanning electron microscope, 54300, Hitach, Tokyo, Japan). The observed results are shown in FIG. 4.

As shown in FIG. 4, the cell morphology of the MG4272 and MG4288 strains was identified to be bacillus by the scanning electron microscope.

The MG4272 and MG4288 strains selected in accordance with the present disclosure were Lactobacillus paracasei or Lactobacillus rhamnosus strains, respectively. Both Lactobacillus paracasei and Lactobacillus rhamnosus strains are listed in the standards and specifications of the Ministry of Food and Drug Safety and functional foods and are safe.