Design and Optimization of a -PCR to Detect in Meat Food.

In this study, a polymerase chain reaction (PCR) directed to the chromosomal gene (-PCR) was used as a rapid, sensitive, and specific method to detect strains belonging to different biotypes in foods; a competitive Internal Amplification Control (cIAC) is also developed. The cIAC had a molecular weight of 417 bp and was detected until a concentration of 0.85 ng/μL. No other strains of other species, nor order were detected by this PCR. In pure culture, the detection limit (DL) of the -PCR was lower for strain (10 colony-forming unit [CFU]/mL) than for strain (1 × 10 CFU/mL); which was the concentration detected in inoculated minced meat. The proposed protocol included an enrichment step in peptone sorbitol bile (PSB) broth at 25°C for 24 h followed by isolation on Mac Conkey agar and chromogenic medium. An aliquot of the PSB broth homogenate and a loopful from the confluent zone of solid media were collected to perform DNA extraction for -PCR, and typical colonies were characterized by biochemical assays. Among 30 non-contaminated food samples, 4 samples were positive and no isolates were obtained. It is suggested that this -PCR could be used in the investigation of in foods.