Quantitative strain-specific detection of Lactobacillus rhamnosus GG in human faecal samples by real-time PCR.
OBJECTIVE
To develop a strain-specific rapid assay for identification and quantification of Lactobacillus rhamnosus GG in human faecal samples.


RESULTS
A unique random amplified polymorphic DNA (RAPD) band of the L. rhamnosus GG strain was isolated and sequenced. Strain-specific polymerase chain reaction (PCR) primers and probes were designed based on the sequence. Quantification was performed by the real-time PCR using a fluorescent resonance energy transfer (FRET) system. The specificity of the assay was tested with DNA isolated from a set of known strains and human faecal samples. The analytical sensitivity of the method for L. rhamnosus GG was about 10 CFU per assay, which corresponds to 10(5) CFU g(-1) of wet faeces.


CONCLUSIONS
Quantitative real-time PCR is a suitable method for strain-specific identification of L. rhamnosus GG in human faecal samples.


CONCLUSIONS
Lactobacillus rhamnosus GG is one of the most studied probiotic strains in clinical trials but still lacks a DNA-based identification method. This study describes a real-time PCR method for strain-specific identification and quantification of L. rhamnosus GG in human faecal samples.
Ahlroos
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Valio Ltd, R&D, Helsinki, Finland.
Tynkkynen
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D015373:Bacterial Typing Techniques; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005243:Feces / Q000382:microbiology*; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D052201:Lacticaseibacillus rhamnosus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D019105:Random Amplified Polymorphic DNA Technique; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D004269:DNA, Bacterial