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Title: Enumeration of Viable Listeria monocytogenes Cells by Real-Time PCR with Propidium Monoazide and Ethidium Monoazide in the Presence of Dead Cells

Author
item PAN, YOUWEN - NC STATE UNIVERSITY
item Breidt, Frederick

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2007
Publication Date: 12/1/2007
Citation: Pan, Y. and Breidt, F. 2007. Enumeration of Viable Listeria monocytogenes Cells by Real-Time PCR with Propidium Monoazide and Ethidium Monoazide in the Presence of Dead Cells. Appl. Environ. Microbiol. 73(24):8028-8031

Interpretive Summary: The manuscript describes methods that can be used for bacterial ecology studies. The research was about using DNA binding dyes to aid in counting only the live bacterial cells there are in mixtures of live and dead cells, and does not use traditional Petri plate methods. These dyes are used in conjunction with DNA amplification and fingerprinting methods. An optimized procedure was developed for use of the dyes. This work will aid researchers using DNA amplification methods for rapid assessments of bacterial populations in films on surfaces, and in broth cultures.

Technical Abstract: Propidium monoazide (PMA) and ethidium monoazide were used for enumeration of viable Listeria monocytogenes cells in the presence of dead cells. PMA had no antimicrobial effect on L. monocytogenes. Viable cell counts were linearly related to real-time PCR threshold cycle values for PMA-treated cells from planktonic and biofilm sources over a 4-log range.