1. Quantitative Detection of Viable Bifidobacterium bifidum BF-1 Cells in Human Feces by Using Propidium Monoazide and Strain-Specific Primers.
- Author
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Fujimoto, Junji and Watanabe, Koichi
- Subjects
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BIFIDOBACTERIUM bifidum , *POLYMERASE chain reaction , *PROPIDIUM monoazide , *GUT microbiome , *HELICOBACTER pylori infections , *FECAL analysis , *AGAR - Abstract
We developed a PCR-based method to detect and quantify viable Bifidobacterium bifidum BF-1 cells in human feces. This method (PMA-qPCR) uses propidium monoazide (PMA) to distinguish viable from dead cells and quantitative PCR using a BF-1-specific primer set designed from the results of randomly amplified polymorphic DNA analysis. During long-term culture (10 days), the number of viable BF-1 cells detected by counting the number of CFU on modified MRS agar, by measuring the ATP contents converted to CFU, and by using PMA-qPCR decreased from about 1010 to 106 cells/ml; in contrast, the total number of (viable and dead) BF-1 cells detected by counting 4',6-diamidino-2-phenylindolee (DAPI)-stained cells and by using qPCR without PMA and reverse transcrip- tion-qPCR remained constant. The number of viable BF-1 cells in fecal samples detected by using PMA-qPCR was highly and significantly correlated with the number of viable BF-1 cells added to the fecal samples, within the range of 105.3 to 10.3 cells/g feces (wet weight) (r> 0.99, P < 0.001). After 12 healthy subjects ingested 1010.3 to 1011.0 CFU of BF-1 in a fermented milk product daily for 28 days, 104.5 ± standard deviation [SD]) BF-1 CFU/g was detected in fecal samples by using strain-specific selective agar; in contrast, 106.2 ± 0.4 viable BF-1 cells/g were detected by using PMA-qPCR, and a total of 1076 ± 0.7 BF-1 cells/g were detected by using qPCR without PMA. Thus, the number of viable BF-1 cells detected by PMA-qPCR was about 50 times higher (P < 0.01) than that de- tected by the culture-dependent method. We conclude that strain-specffic PMA-qPCR can be used to quickly and accurately evaluate viable BF-1 in feces. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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