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Application of a convenient DNA extraction method and multiplex PCR for the direct detection of Staphylococcus aureus and Yersinia enterocolitica in milk samples.

Ramesh, A. and Padmapriya, B. P. and Chandrashekar, A. and Varadaraj, M. C. (2002) Application of a convenient DNA extraction method and multiplex PCR for the direct detection of Staphylococcus aureus and Yersinia enterocolitica in milk samples. Molecular and Cellular Probes, 16 (4). pp. 307-14. ISSN 0890-8508

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Abstract

The application of PCR for the direct and sensitive detection of food-borne pathogens is largely affected by the quality of the template DNA prepared from food samples. In the present study, a chemical extraction method of bacterial DNA from spiked milk samples for the direct detection of Staphylococcus aureus and Yersinia enterocolitica was evaluated by PCR. Gene specific primers were designed to target the nuclease (nuc) and the attachment invasion locus (ail) genes of S. aureus and Y. enterocolitica, respectively and used in PCR. A combination of organic solvents, detergents and alkali in the DNA extraction method permitted a detection limit of 10 cfu ml(-1) milk for both the pathogens. When equal numbers of S. aureus and Y. enterocolitica were spiked in milk samples, the individual detection limit was determined to be 10(3) cfu ml(-1) milk. Simultaneous amplification of 482 and 359 bp fragments of the nuc and ail genes was obtained using the primer pairs in a single reaction. Multiplex PCR enabled the detection of 10(4) cfu ml(-1) milk of S. aureus and Y. enterocolitica without any pre-enrichment step. A combination of conventional isolation technique and PCR using DNA extracted by the proposed method was used to test raw milk samples for possible contamination with S. aureus and Y. enterocolitica. The presence of S. aureus in the tested samples was indicated by both the methods while Y. enterocolitica could not be detected in any of the samples. The template DNA extraction method developed in this study is rapid, sensitive and avoids interference from potential PCR inhibitors and demonstrates the potential of detecting multiple pathogens in milk samples without any enrichment.

Item Type: Article
Uncontrolled Keywords: PCR, Staphylococcus aureus, Yersinia enterocolitica, multiplex PCR, detection, milk.
Subjects: 600 Technology > 01 Medical sciences > 07 Food borne disease
600 Technology > 08 Food technology > 27 Dairy products
Divisions: Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 25 May 2012 06:37
Last Modified: 25 May 2012 06:37
URI: http://ir.cftri.com/id/eprint/2098

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