IDENTIFICATION OF CONTAMINATION OF SALMON MEAT BY DNA FROM BACTERIA OF THE PSEUDOMONAS FLUORESCENS GROUP IN THE IMPLEMENTATION OF THE DNA BARCODING OF PRODUCTS OF JAPANESE CUISINE

Abstract

DNA barcoding as a tool for genetic certification and identification of taxonomic membership of organisms has recently become very popular. We have applied DNA barcoding method for taxonomic identification of fish ingredients (salmon, tuna, flying fish roe, shark) in product of Japanese cuisine. We have analyzed 27 samples from 6 retail outlets and 3 restaurants of the city of Voronezh. It was found that for products designated as containing “salmon” in all selected outlets were used as a fillet of Atlantic salmon (Salmo salar), which is considerably less valuable than Pacific salmon. Results of DNA barcoding showed that one of the samples of «salmon» was in fact, yellowfin tuna, whereas one sample of “tuna” was a fillet of Atlantic salmon. However in general, the “salmon” and “tuna” samples were substituted infrequently. Analysis of “flying fish roe” samples revealed that only one sample from 6 was really Fourwing flyingfish (Hirundichthys affinis). The remaining samples were identified as DNA of capelin (Mallotus villosus). By analyzing the “double” sequences in 2 samples, we have found that two samples of «flying fish roe» were mixtures of Fourwing flyingfish roe and capelin roe. A sample labeled “shark” was identified as Mozambique tilapia. This species is a freshwater fish. Bacterium Pseudomonas fluorescens was identified in one of the “salmon” samples. Analysis of “double” sequences of “salmon” samples revealed presence of P. fluorescens DNA. Analysis of salmon meat with the use of species-specific primers for this bacterium revealed contamination of all samples by P. fluorescens. This bacterium causes the disease in salmon and can be harmful to patients with compromised immune systems. Primers used for DNA barcoding were shown to have high homology to DNA of bacterial group P. fluorescens.