Foods (Jul 2022)

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

DOI
https://doi.org/10.3390/foods11152282
Journal volume & issue
Vol. 11, no. 15
p. 2282

Abstract

Read online

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.

Keywords