Application of SYBR Green I and TaqMan probe-based real-time PCRs for the identification of Listeria spp. and Listeria monocytogenes

Abstract

Abstract The aim of the study was the application and comparison of real-time PCR methods based on the fluorescence of SYBR Green I intercalating dye and TaqMan probes for the detection of the 23S rDNA gene of Listeria spp. and the hlyA gene of Listeria monocytogenes. Five strains of L. monocytogenes and single strains of each of the species: L. ivanovii, L. innocua, L. grayi, L. welshimeri, and L. seeligeri were used for the experiments. Additionally, five strains of other species of bacteria were used for evaluation of the specificity of the tests. QuantiTect SYBR Green PCR and QuantiTect Probe PCR kits were selected for the study. In the first stage of the study, SYBR Green I real-time PCRs were performed under several methods, the first one allowing detection of the 23S rDNA gene and the remainder based on the amplification of the hlyA gene. In the next part, three varied in method TaqMan probe-based real-time PCRs allowing confirmation of strains belonging to Listeria spp. and L. monocytogenes were conducted. The observation of amplification curves in real-time PCR methods enabled the detection of both genes, and these methods demonstrated a significant sensitivity and high specificity. A high regression coefficient of 0.99 was found for all reactions. Specific amplification products were obtained for the 23S rDNA and hlyA genes, which confirmed the tested strains as Listeria spp. and L. monocytogenes respectively. Isolates of other microbial species did not yield real-time PCR products.