Isolation and Identification of Dominant Spoilage Bacteria in Refrigerated Catfish Fillets

In order to discuss the species of dominant spoilage bacteria in refrigerated 7 d catfish fillets,the squid was taken in a 4℃ sterile cold storage and placed in a vacuum oven at 4℃ for 7 days. Three strains of bacteria,numbered x1-1,y1-1,and y2-1,were isolated from the corrupted fish meat for bacterial morphology observation,physiological and biochemical tests,and 16S rDNA sequence determination.The results showed that all the strains were Gram-negative Brevibacterium spp,and both were facultative anaerobic bacteria. The results of sequencing and phylogenetic tree analysis showed that x1-1 was closely related to Aeromonas hydrophila,reaching 99.9%. The relationship between y1-1 and Aeromonas veronii was up to 99.79%;y2-1 was similar to Aeromonas allosaccharopila,reaching 99.8%.Combined with the above research results,x1-1 is A.hydrophila;y1-1 is A.veronii;y2-1 is A. allosaccharophila.In summary,the dominant spoilage bacteria in refrigerated catfish fillets is Aeromonas.