Isolation and Identification of Dominant Spoilage Bacteria in Trachinotus ovatus during Chilled Storage and Their Spoilage Capability

In order to study the dominant spoilage bacteria and their spoilage capability of Trachinotus ovatus fillets at the end of chilled storage,traditional selective medium method and 16S rDNA sequence analysis method were taken to isolate,purify,analyze and determine the spoilage bacteria in Trachinotus ovatus during chilled storage. The spoilage capability of dominant spoilage bacteria at the end of storage was quantitatively analyzed by Y_TVB-N/CFU. The results showed that 16 strains of bacteria(10 Gram-negative strains and 6 Gram positive strains,belonging to 6 bacterial genus)were isolated from Trachinotus ovatus during storage. The microbial species was rich at the beginning of the storage(0 d),Shewanella sp,Pseudomonas sp,Staphylococcus sp,Bacillus sp,Lactobacillus sp and Enterobacter sp all appeared. The microbial species were decreased in the middle of storage(3 d),only Shewanella sp and Pseudomonas sp were dominant in quantity. The microbial species were further decreased at the end of storage,which only 3 strains were dominant. They were Shewanella putrefaciens(No.2)48%,Shewanella oneidensis(No.5)26.6% and Enterobacter hormaechei(No.16)19.4%. The order of spoilage capabilities was as follows: Shewanella putrefaciens > Shewanella oneidensis > Enterobacter hormaechei. The spoilage ability of Shewanella putrefaciens is much higher than that of two species. Based on the results of the proportion and the spoilage capacity at the end of the storage,it was determined that Shewanella putrefaciens was the dominant Spoilage Bacteria in Trachinotus ovatus during 4 ℃ storage.