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Optimization of nested polymerase chain reaction assays for identification of Aeromonas salmonicida, Yersinia ruckeri and Flavobacterium psychrophilum

January 1, 2002

Nested polymerase chain reaction (PCR) assays were developed using first-round primers complementary to highly conserved regions within the bacterial 16S ribosomal RNA (rRNA) gene (universal eubacterial primers) and second-round primers specific for sequences within the 16S rRNA genes of Aeromonas salmonicida, Yersinia ruckeri, andFlavobacterium psychrophilum. Following optimization of the MgCl2 concentration and primer annealing temperature, PCR employing the universal eubacterial primers was used to amplify a 1,500-base-pair (bp) product visible in agarose gels stained with ethidium bromide. The calculated detection limit of this single-round assay was less than 1.4 × 104 colony-forming units (CFU) per reaction for all bacterial species tested. Single-round PCR using primer sets specific for A. salmonicida, Y. ruckeri, and F. psychrophilumamplified bands of 271, 575, and 1,100 bp, respectively, with detection limits of less than 1.4 × 104, 1.4 × 105, and 1.4 × 105 CFU per reaction. Using the universal eubacterial primers in the first round and the species-specific primer sets in the second round of nested PCR assays improved the detection ability by approximately four orders of magnitude to fewer than 14 CFU per sample for each of the three bacterial species. Such nested assays could be adapted to a wide variety of bacterial fish pathogens for which 16S sequences are available.

Citation Information

Publication Year 2002
Title Optimization of nested polymerase chain reaction assays for identification of Aeromonas salmonicida, Yersinia ruckeri and Flavobacterium psychrophilum
DOI 10.1577/1548-8667(2002)014<0216:OONPCR>2.0.CO;2
Authors P.W. Taylor, J. R. Winton
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Aquatic Animal Health
Series Number
Index ID 70170580
Record Source USGS Publications Warehouse
USGS Organization Western Fisheries Research Center

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