Article (Scientific journals)
A PCR method for detection of bifidobacteria in raw milk and raw milk cheese: comparison with culture-based methods
Delcenserie, Véronique; Bechoux, Nathalie; China, Bernard et al.
2005In Journal of Microbiological Methods, 61 (1), p. 55-67
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Keywords :
PCR; hsp60 gene; Bifidobacterium; detection; fecal indicators; raw milk; raw milk cheese; mupirocin
Abstract :
[en] Bifidobacteria are well known for their beneficial effects on health and are used as probiotics in food and pharmaceutical products. As they form one of the most important groups in both human and animal feces, their use as fecal indicator organisms in raw milk products has recently been proposed. Bifidobacteria species isolated in humans are different from those isolated in animals. It should therefore be possible to determine contamination origin (human or animal). A method of detecting the Bifidobacterium genus was developed by PCR targeting the hsp60 gene. The genus Bifidobacterium was identified by PCR amplification of a 217-bp hsp60 gene fragment. The degenerated primer pair specific to the Bifidobacterium genus used was tested for it specificity on 127 strains. Sensitivity was measured on artificially contaminated samples. Food can however be a difficult matrix for PCR testing since it contains PCR inhibitors. So an internal PCR control was used. An artificially created DNA fragment of 315 bp was constructed. The PCR detection method was tested on raw milk and cheese samples and compared with three culture-based methods, which comprised enrichment and isolation steps. The enrichment step used Brain Heart Infusion medium with propionic acid, iron citrate, yeast extract, supplemented with mupirocin (BHMup) or not (BH) and the isolation step used Columbia blood agar medium, supplemented with mupirocin (CMup) or not (C). The method using mupirocin at both enrichment and isolation steps and the PCR method performed from the culture in BHMup enrichment medium were shown to be the most efficient. No significant difference was observed in raw milk samples between PCR from BHMup and the culture-based method BHMup/CMup, while a significant difference was noticed between the same methods in raw milk cheese samples, which would favor using PCR. The results suggested that PCR on the hsp60 gene was convenient for a rapid detection of bifidobacteria in raw milk and raw milk cheese samples and that bifidobacteria always present throughout raw milk cheese production could be efficiently used as fecal indicators.
Disciplines :
Microbiology
Food science
Author, co-author :
Delcenserie, Véronique ;  Université de Liège - ULiège > Département de sciences des denrées alimentaires > Gestion de la qualité dans la chaîne alimentaire
Bechoux, Nathalie ;  Université de Liège - ULiège > Département de sciences des denrées alimentaires > Microbiologie des denrées alimentaires
China, Bernard
Daube, Georges  ;  Université de Liège - ULiège > Département de sciences des denrées alimentaires > Microbiologie des denrées alimentaires
Gavini, Françoise;  Institut Scientifique de Recherche Agronomique - INRA
Language :
English
Title :
A PCR method for detection of bifidobacteria in raw milk and raw milk cheese: comparison with culture-based methods
Publication date :
2005
Journal title :
Journal of Microbiological Methods
ISSN :
0167-7012
eISSN :
1872-8359
Publisher :
Elsevier Science Bv, Amsterdam, Netherlands
Volume :
61
Issue :
1
Pages :
55-67
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
DG RDT - Commission Européenne. Direction Générale de la Recherche et de l'Innovation [BE]
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since 20 October 2008

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