Isolation of Listeria monocytogenes dna from meat products for quantitative detection by real-time PCR

We report a study of two different procedures for extraction of Listeria monocytogenes genomic DNA from cooked pork ham products, to be coupled to a specific real-time (RTi-) PCR assay, an open formula protocol based on the Chelex-100 resin and the Wizard DNA kit. The reliability of each DNA extraction was evaluated by performing three independent experiments using eight replicates. The quality and quantity of the L. monocytogenes DNA were tested using both a fluorescence-based DNA measuring protocol and a specific quantitative RTi-PCR assay. The total DNA yield was similar for both extraction protocols. However, the Wizard-based protocol produced a better quality of L. monocytogenes DNA, as it enhanced the RTi-PCR results (approximately one order of magnitude greater than the Chelex-based protocol). Thus, the protocol based on the Wizard DNA kit was more suitable for L. monocytogenes DNA extraction from meat samples when sensitive and accurate results are needed.