Dataset Information

DNA Extraction and PCR Methods for the Detection of Listeria monocytogenes in Cold-Smoked Salmon.

ABSTRACT: Protocols for the specific detection of Listeria monocytogenes in cold-smoked salmon were developed. PCR was used as the method of detection. Inhibitors of PCR present in the food samples were removed by ether extraction or column purification, or their effect was overcome by the use of Tween 20 as an enhancer. These protocols are many times more rapid than conventional detection methodologies and also have the potential for automation.

SUBMITTER: Simon MC

PROVIDER: S-EPMC1388797 | biostudies-other | 1996 Mar

REPOSITORIES: biostudies-other

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DNA Extraction and PCR Methods for the Detection of Listeria monocytogenes in Cold-Smoked Salmon.

Simon M C MC Gray D I DI Cook N N

Applied and environmental microbiology 19960301 3

Protocols for the specific detection of Listeria monocytogenes in cold-smoked salmon were developed. PCR was used as the method of detection. Inhibitors of PCR present in the food samples were removed by ether extraction or column purification, or their effect was overcome by the use of Tween 20 as an enhancer. These protocols are many times more rapid than conventional detection methodologies and also have the potential for automation. ...[more]

PMID: 16535272

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Project description:Cold-smoked salmon are ready-to-eat products that may support the growth of pathogenic Listeria monocytogenes during their long shelf-life. Consumption of such contaminated products can cause fatal listeriosis infections. Another challenge and potential risk associated with CS salmon is their high levels of sodium salt. Excess dietary intake is associated with serious health complications. In the present study, anti-listerial bacteriocin (nisin), P100 bacteriophages (Phageguard L, PGL) and fermentates (Verdad N6, P-NDV) were evaluated as commercial bio-preservation strategies for increased control of L. monocytogenes in standard (with NaCl) and sodium-reduced (NaCl partially replaced with KCl) CS salmon. Treatments of CS salmon with nisin (1 ppm) and PGL (5 × 107 pfu/cm2) separately yielded significant initial reductions in L. monocytogenes (up to 0.7 log) compared to untreated samples. Enhanced additive reductions were achieved through the combined treatments of nisin and PGL. Fermentates in the CS salmon inhibited the growth of Listeria but did not lead to its eradication. The lowest levels of L. monocytogenes during storage were observed in nisin- and PGL-treated CS salmon containing preservative fermentates and stored at 4 °C, while enhanced growth was observed during storage at an abusive temperature of 8 °C. Evaluation of industry-processed standard and sodium-replaced CS salmon confirmed significant effects with up to 1.7 log reductions in L. monocytogenes levels after 34 days of storage of PGL- and nisin-treated CS salmon-containing fermentates. No differences in total aerobic plate counts were observed between treated (PGL and nisin) or non-treated standard and sodium-reduced CS salmon at the end of storage. The microbiota was dominated by Photobacterium, but with a shift showing dominance of Lactococcus spp. and Vagococcus spp. in fermentate-containing samples. Similar and robust reductions in L. monocytogenes can be achieved in both standard and sodium-replaced CS salmon using the bio-preservation strategies of nisin, PGL and fermentates under various and relevant processing and storage conditions.

Dataset Information

DNA Extraction and PCR Methods for the Detection of Listeria monocytogenes in Cold-Smoked Salmon.

Publications

DNA Extraction and PCR Methods for the Detection of Listeria monocytogenes in Cold-Smoked Salmon.

Similar Datasets

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