Rainbow trout (Oncorhynchus mykiss) identification in processed fish products using loop‐mediated isothermal amplification and polymerase chain reaction assays

Abstract

BACKGROUND Financial loss and health risk caused by the substitution of rainbow trout for other salmonid species have become a common issue around the world. The situation could be further exacerbated in China by the ‘abused’ common name of San Wen Yu (the corresponding Chinese ideogram 三文鱼) for salmonids, considering the absence of a standardized naming system for seafood species. To prevent such episodes, the present study aimed to develop novel loop‐mediated isothermal amplification (LAMP) and polymerase chain reaction (PCR) assays targeting the mitochondrial cytochrome b gene for rapid identification of rainbow trout in processed fish products. RESULTS Rainbow trout‐specific primers (LAMP and PCR) were designed, and the specificity against 23 different fish species was confirmed. The minimum amount of detectable DNA for LAMP assay reached 500 pg, up to 10‐fold less than for PCR assay. In addition to agarose gel electrophoresis, naked‐eye inspection of the LAMP‐positive samples using SYBR Green I under daylight or ultraviolet light was also validated. Finally, commercial San Wen Yu products made from rainbow trout could be accurately identified using the newly developed LAMP and PCR assays, further cross‐confirmed by mini DNA barcoding and neighbor‐joining dendrograms. CONCLUSIONS The LAMP and PCR assays established in the study allow a fast and accurate identification of rainbow trout in processed fish products. © 2020 Society of Chemical Industry

Visual detection of rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) simultaneously by duplex loop-mediated isothermal amplification

“…1 ). Particularly, LAMP primers (FIP, BIP, F3, B3 and LB) were obtained from our previous studies ( Li et al, 2022 , Xiong et al, 2020 ), with one exception of R-LB designed in the present work ( Table 1 ). In order to meet the labeling criteria in self-quenched approach ( Gadkar et al, 2018 ), the 3′ end of S-BIP, R-FIP, and R-LB was slightly modified, and two different fluorophores (FAM and ROX) were attached ( Table 1 ), which are self-quenched in unbound state and become de-quenched after binding to the dumbbell-shaped target DNA specifically ( Li et al, 2022 ).…”

Development of loop-mediated isothermal amplification (LAMP) assay for rapid and direct screening of yellowfin tuna (Thunnus albacares) in commercial fish products

“…Among them, LAMP has gained in popularity in recent decades and is one of the most widely researched methods for species identification [ 11 , 23 ]. Thus, it has already been used to detect several fish species such as eel ( Anguilla anguilla ) [ 12 ], salmon ( Oncorhynchus mykiss ) [ 24 ], cod ( Gadus morhua ) [ 14 ] and skipjack tuna ( Katsuwonus pelamis ) [ 15 ]. LAMP was applied successfully in various contexts and appears to be a fast and efficient alternative to PCR in the case of food fraud monitoring due to its low equipment requirements, easy handling and ability to be used in field [ 11 ].…”

Identification of Gyromitra infula: A Rapid and Visual Method Based on Loop-Mediated Isothermal Amplification

“…In the selection of LAMP primer design sites, to ensure the specificity of the primers, there should be a certain number of mismatches between the sequence bases of the target species and the closely related species to reduce nonspecific amplification. For example, Xiong et al (2020) found mismatch sites between Oncorhynchus mykiss and closely related species when designing LAMP primers for O. mykiss so that the primers were highly specific for O. mykiss. The G. infula LAMP primer set I designed in this study had some mismatches with other Gyromitra species at the 3' end of G.mol-F3/B3 and the 5' end of G.mol-F1c/ B1c, showing that the G. infula LAMP primers designed in this study had high specificity.…”