title: Species-specific quantification of probiotic lactobacilli in yoghurt by quantitative real-time PCR.
abstract: OBJECTIVE
  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 time-consuming and labour-intensive.
  
  
  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(-1) directly from yoghurt, which is a sufficient detection limit as commercial products usually contain 10(6) -10(12)  CFU ml(-1) of probiotic strains.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany.
authors.forename: S R
authors.initials: SR
authors.lastname: Herbel
authors.forename: B
authors.initials: B
authors.lastname: Lauzat
authors.forename: M
authors.initials: M
authors.lastname: von Nickisch-Rosenegk
authors.forename: M
authors.initials: M
authors.lastname: Kuhn
authors.forename: J
authors.initials: J
authors.lastname: Murugaiyan
authors.forename: L H
authors.initials: LH
authors.lastname: Wieler
authors.forename: S
authors.initials: S
authors.lastname: Guenther
keywords: Lactobacillus; fermented foods; food; lactic acid bacteria; probiotics