Application of PCR Technique in Combination with DN ase Treatment for Detection of Viable L actobacillus acidophilus Bacteria

• Published in: Journal of food quality Vol. 37; no. 4; pp. 291 - 295
• Main Authors: Shakeri, Monir‐Sadat, Shahidi, Fakhri, Mortazavi, Ali, Bahrami, Ahmad R., Nassiri, Mohammad R.
• Format: Journal Article
• Language: English
• Published: 01.08.2014
• ISSN: 0146-9428; 1745-4557
• DOI: 10.1111/jfq.12093

Abstract In this study, we examined whether application of DN ase I can serve as differential eliminator of DNA s from dead cells, leaving viable probiotic lactic acid bacteria such as L actobacillus acidophilus to be assessed by polymerase chain reaction ( PCR ). When dead cells were treated with DN ase I , DNA amplification was not completely suppressed. Increasing the concentration of DN ase I , up to 66 u/100 μL, and the preparation of dead cells using high temperatures did not seem to make difference in the level of PCR product from the dead bacteria. Assessment of free DNA degradation, when mixed with dead cells, showed that stability of free DNA s or their degradation by DN ase I was not affected by presence of the dead cells. In conclusion, we tend to suggest that for using this technique, one should take great deal of caution and that its reliability should be tested for different species independently. Practical Applications L actobacillus acidophilus is one of the most common probiotic bacteria incorporated into food products. To have their health‐promoting properties, consumption of high levels of the viable bacteria is recommended. Meanwhile, access to reliable protocols for assessment of viable bacteria remains elusive. Recent studies have focused on providing differential conditions for clearance of DNA material of the dead cells followed by quantification of the viable bacteria by molecular techniques. Despite the previous reports on application of DN ase treatment along with PCR assays, for evaluation of viable harmful food bacteria, our data do not support the notion to be applied for detection of L . acidophilus .