Species-specific quantification of probiotic lactobacilli in yoghurt by quantitative real-time PCR

Abstract

Aims: Lactobacilli strains with probiotic effects have been widely used in dairy products such as yoghurts as well as in food additives and pharmaceuticals. Despite their successful commercial application, the current species identification and quantification methods of the genus Lactobacillus are timeconsuming and labour-intensive. Methods and Results: To fulfil the requirements of a robust quality management, we have developed a quantitative real-time PCR assay based on the heat shock protein 60 gene (hsp60) for accurate identification and quantification of five commercially important Lactobacillus species. The developed assay allows an unambiguous species-specific detection of the species Lact. acidophilus, Lact. brevis, Lact. delbrueckii subsp. bulgaricus, Lact. helveticus and Lact. reuteri from bacterial cultures as well as directly from dairy products for instance yoghurt. Conclusions: With the assay, we were able to specifically detect lactobacilli strains down to 10 5 CFU ml À1 directly from yoghurt, which is a sufficient detection limit as commercial products usually contain 10 6 -10 12 CFU ml À1 of probiotic strains. Significance and Impact of the Study: The real-time PCR assay developed here might become a convenient tool enabling an accurate, fast and sensitive detection of probiotic lactobacilli commercially used in food.

Evaluation of high-resolution melting and other molecular methods in discrimination of Lactobacillus isolates

“…; Herbel et al . ). Therefore, it seems to be a convenient tool for routine applications in preliminary evaluation of bacteria not only in the clinical use but in the food industry, as well (Reed et al .…”

“…HRM has showed its potential in human diagnostic experiments (Erali et al 2008), rapid differentiation of bacteria ( Simenc and Poto cnik 2011) as well as in discrimination of Lactobacillus species (Porcellato et al 2012;Herbel et al 2013). Therefore, it seems to be a convenient tool for routine applications in preliminary evaluation of bacteria not only in the clinical use but in the food industry, as well (Reed et al 2007).…”

Comparison of real-time PCR assay and plate count for Lactobacillus paracasei enumeration in yoghurt

“…Lactobacilli strains have been used commercially over the last years as they are believed to possess probiotic features (Francesca et al 2013;Herbel et al 2013). Probiotics are defined as Blive micro-organisms that when administered in adequate amounts, confer a health benefit on the host^.…”

“…bulgaricus, L. helveticus, and L. reuteri in yoghurt (Herbel et al 2013), and for S. thermophilus, L. delbrueckii, Lactobacillus casei, L. paracasei, L. rhamnosus, L. acidophilus, and L. johnsonii in fermented milk products (Furet et al 2004). Several species-specific primer pairs were designed based on the variability of 16S rRNA sequences for differentiating five strains of lactobacilli that were added into probiotic products in Taiwan (Kao et al 2007).…”

Selection of potential probiotic Lactobacillus strains of human origin for use in dairy industry

“…Polyphasic approach for the identification purposes is recommended. Molecular methods such as PCRs are essential for the identification at the genus and species levels [8][9][10][11][12][13][14]. In recent years, 16S rDNA PCR and 16S rDNA sequencing strategies have been powerful methods for direct analysis of microorganisms and the discovery of novel bacteria [13].…”