Technology Snapshot: Hygiena, a company in rapid microbial detection, monitoring, and identification technology, has introduced the BAX System Free DNA Cleanup Kit, which degrades external contaminant target DNA, further reducing the possibility of false positive results during polymerase chain reaction (PCR) runs.
While PCR allows for precise identification of low levels of target DNA, one criticism of the technique is that it amplifies DNA from both live cells and “free” DNA released from dead cells. “Free” DNA from dead cells can be present due to processing, cleaning, or bacteriophage preparations which are used to control pathogens.
The BAX System Free DNA Cleanup Kit easily integrates with the BAX System workflow and has been internally validated to degrade any “free” contaminating DNA. Hygiena scientists successfully demonstrated the use of the kit for degradation of “free” contaminant DNA from samples of bacteriophage solutions for Listeria and Salmonella. The kit degrades very large amounts of target DNA (up to 400 ng). Most importantly, the kit does not interfere with intact DNA within living bacterial cells and their subsequent detection by PCR assays. Additional studies by a large poultry processing company and a prominent southeast Asia government agency resulted in similar results.
“We’re delighted to announce this new addition to our product line, which will make PCR reactions more reliable, which is vital for securing a safe food supply,” said Martin Easter, chief scientific officer of Hygiena. “The BAX System Free DNA Cleanup Kit more reliably degrades contaminating DNA, ensuring accurate results and providing the peace of mind that our customers have come to expect from Hygiena products.”
Interference from “free” DNA is generally not an issue when using the BAX System because food or environmental samples are enriched prior to testing. Enrichment provides the nutrients for live bacterial growth; dead cells are not affected. Therefore, dead cells would need to be present at a sufficient level prior to enrichment to yield the concentration required for BAX System detection (approximately 10,000 cells/ml). However, certain product types and process conditions can result in the presence of contaminating extraneous “free” DNA leading to unconfirmable positive PCR results which impair the ability to make rapid, confident decisions on food safety.