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Granular ark (Tegillarca granosa), broughton's ribbed ark (Anadara broughtonii), and half-crenate ark (Anadara kagoshimensis) are important fishery resources throughout Asia; granular ark exhibiting a higher economic value due to its rarity. However, due to the similar morphological characteristics of the three species, the less valuable species could be exploited for food fraud. In this study, we developed a rapid on-site identification method based on a microfluidic chip for the detection of the three ark shell species. We designed new species-specific primers, targeting the genes encoding mitochondrial cytochrome b or cytochrome c oxidase I, for the identification of the three ark shells and estimated their specificity against 17 species, which amplified only the target species. The sensitivity of each primer was 0.001 ng. In addition, this method was further improved to develop a direct ultrafast polymerase chain reaction (PCR) for on-site food monitoring, which would allow for completing the entire procedure (from sampling to obtaining the results) within 25 min without DNA extraction. Our direct, ultrafast PCR was successfully applied to differentiate the three species from 29 commercial products. Therefore, this assay could be used as a rapid and cost-effective approach for the on-site identification of ark shells in commercial food products. [ABSTRACT FROM AUTHOR]

Granular ark (Tegillarca granosa), broughton’s ribbed ark (Anadara broughtonii), and half-crenate ark (Anadara kagoshimensis) are important fishery resources throughout Asia; granular ark exhibiting a higher economic value due to its rarity. However, due to the similar morphological characteristics of the three species, the less valuable species could be exploited for food fraud. In this study, we developed a rapid on-site identification method based on a microfluidic chip for the detection of the three ark shell species. We designed new species-specific primers, targeting the genes encoding mitochondrial cytochrome b or cytochrome c oxidase I, for the identification of the three ark shells and estimated their specificity against 17 species, which amplified only the target species. The sensitivity of each primer was 0.001 ng. In addition, this method was further improved to develop a direct ultrafast polymerase chain reaction (PCR) for on-site food monitoring, which would allow for completing the entire procedure (from sampling to obtaining the results) within 25 min without DNA extraction. Our direct, ultrafast PCR was successfully applied to differentiate the three species from 29 commercial products. Therefore, this assay could be used as a rapid and cost-effective approach for the on-site identification of ark shells in commercial food products.

The conventional Salmonella serotyping methods are labor intensive and time-consuming; therefore, rapid identification method is needed to detect outbreaks early and prevent their spread. In this study, we developed for the first time a detection method for the rapid and accurate on-site serotyping of Salmonella enterica subsp. enterica serovar Enteritidis, Thompson, and Typhimurium, all of which have epidemiological importance worldwide. This method, which is based on specific marker genes, was constructed with portable equipment and a simple DNA extraction step. For the specific detection of the three serovars, genetic markers obtained via a bioinformatics analysis were selected and showed high specificity for 97 strains. The ultrafast polymerase chain reaction (PCR) showed high linearity (≥0.997) in both pure culture and a spiked food sample, with a detection specificity of 102 colony forming unit (CFU)/ml; these results are consistent with real-time PCR. Moreover, ultrafast PCR was further improved for developing direct ultrafast PCR method for field detection, the entire procedure of which could be completed within 25 min. The test results of an artificially contaminated food sample showed that the three serovars could be detected using the direct ultrafast PCR with a very short (3 h) enrichment step when inoculated at 1 CFU/g. This method exhibited various advantages, such as its ultrafast and labor-saving characteristics, which can be applied to the diagnosis of Salmonella serovar in the field. • This was the first study to develop direct ultrafast PCR for detecting Salmonella. • The detection specificity was 102 CFU/ml, which is consistent with real-time PCR. • Total detection time from sampling to confirmation of results was less than 25 min. • It could be used to detect and monitor three Salmonella serovars in the field. [ABSTRACT FROM AUTHOR]