Quantitative PCR Assays for the Strain-Specific Identification and Enumeration of Probiotic Strain <i>Lacticaseibacillus rhamnosus</i> X253
Lei Zhao,
Dong Zhang,
Yang Liu,
Yi-Nan Zhang,
Dong-Qing Meng,
Qiong Xu,
Jiang Zhong,
Qiu-Yue Jiang,
Yu Zhao,
Shi-Jie Wang
Affiliations
Lei Zhao
Key Laboratory of Milk and Dairy Products Detection and Monitoring Technology for State Market Regulation, Shanghai Institute of Quality Inspection and Technical Research, Shanghai 200233, China
Dong Zhang
Junlebao Dairy Group, Shijiazhuang 050221, China
Yang Liu
Key Laboratory of Milk and Dairy Products Detection and Monitoring Technology for State Market Regulation, Shanghai Institute of Quality Inspection and Technical Research, Shanghai 200233, China
Yi-Nan Zhang
Key Laboratory of Milk and Dairy Products Detection and Monitoring Technology for State Market Regulation, Shanghai Institute of Quality Inspection and Technical Research, Shanghai 200233, China
Dong-Qing Meng
College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
Qiong Xu
Key Laboratory of Milk and Dairy Products Detection and Monitoring Technology for State Market Regulation, Shanghai Institute of Quality Inspection and Technical Research, Shanghai 200233, China
Jiang Zhong
Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China
Qiu-Yue Jiang
Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China
Yu Zhao
College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
Probiotics are universally recognized for their health benefits, despite the fact that their effects depend on the strain. Identification and enumeration of probiotic strains are required prior to evaluating their effectiveness. Lacticaseibacillus rhamnosus X253 is a potential probiotic strain with antioxidant capacity. Comparative genomics and single nucleotide polymorphisms (SNPs) were used to identify a strain-specific locus within the holA gene for strain X253 that was distinct in 30 different L. rhamnosus strains. Using quantitative PCR, the primers and probe designed for the locus were able to distinguish L. rhamnosus X253 from the other 20 probiotic strains. The chosen locus remained stable over 19 generations. The sensitivity of the assay was 0.2 pg genomic DNA of L. rhamnosus X253, or 103 cfu/mL bacteria of this strain. In terms of repeatability and reproducibility, relative standard deviations (RSD) were less than 1% and 3%, respectively. Additionally, this assay achieved accurate enumerations of L. rhamnosus X253 in spiked milk and complex powder samples. The strain-specific assay could be used for quality control and compliance assessment of dairy products.