FOOD SCIENCE ›› 2012, Vol. 33 ›› Issue (22): 217-220.

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Rapid Detection of Live E. coli O157: H7 by PMA-qPCR Method

  

  • Received:2011-09-29 Revised:2012-10-23 Online:2012-11-25 Published:2012-11-20

Abstract: In this work, a method to detect live E. coli O157:H7 was established using propidium monoazide (PMA) coupled with quantitative polymerase chain reaction (qPCR). The minimum inhibitory concentration against DNA amplification from dead bacteria was 10 µg/mL, and PMA did not inhibit DNA application from live bacteria at concentrations equal to or lower than 20 µg/mL. Covalent cross-linking of PMA with DNA was induced by strong light illumination for 5 min and meanwhile, free PMA was completely inactivated, resulting in the avoidance of false negative results. When the live to dead bacteria ratio was more than 1%, PMA pretreatment allowed the elimination of DNA interference from thermally inactivated bacteria and therefore live bacteria could be quantified.

Key words: propidium monoazide (PMA), quantitative polymerase chain reaction (qPCR), live bacteria, detection

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