title: The dnaK gene as a molecular marker for the classification and discrimination of the Lactobacillus casei group.
abstract: It is hard to accurately identify specific species of the Lactobacillus casei group using phenotypic techniques alone. Some strains of this species group are considered to be probiotic and are widely applied in the food industry. In this study, we compared the use of two phylogenetic markers, the 16S rRNA and dnaK genes, for species discrimination of the members of the L. casei group using sequencing and RFLP. The results showed that L. casei, Lactobacillus paracasei, Lactobacillus zeae and Lactobacillus rhamnosus could be clearly distinguished based on the dnaK gene. The average sequence similarity for the dnaK gene (87.8%) among type strains was significantly less than that of the 16S rRNA sequence (99.1%). Therefore, the dnaK gene can be proposed as an additional molecular phylogenetic marker for L. casei that provides higher resolution than 16S rRNA. Species-specific RFLP profiles of the Lactobacillus strains were obtained with the enzyme ApoI. Our data indicate that the phylogenetic relationships between these strains are easily resolved using sequencing of the dnaK gene or RFLP assays.
authors.affiliation: Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan, ROC.
authors.forename: Chien-Hsun
authors.initials: CH
authors.lastname: Huang
authors.forename: Fwu-Ling
authors.initials: FL
authors.lastname: Lee
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007780:Lacticaseibacillus casei / Q000145:classification* / Q000235:genetics*; D018832:Molecular Chaperones / Q000235:genetics*; D008969:Molecular Sequence Data; D058889:Molecular Typing; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D018832:Molecular Chaperones; D012336:RNA, Ribosomal, 16S