Screening and Identification of Specific Spoilage Bacteria in Chilled Grouper Based on High-throughput Sequencing and Protein Degradation Ability
[Objective]To study the microbial phase changes of dominant spoilage bacteria in pearl gentian grouper(Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂)during chilled storage,and to screen and identify specific spoilage bacteria with strong protein decomposition ability.[Method]The spoilage process of grouper meat was judged by quality index method(QIM),colony count and TVB-N content.Fresh(0 d chilled),sub-fresh(4 d chilled)and spoilaged(8 d chilled)samples were subjected to high-throughput sequencing of bacterial 16S V3-V4 region,and the structure,diversity and differences of the flora were analyzed by species composition,Alpha and Beta diversity analysis,and species Venn diagram.The putrefied sample strains were isolated by traditional culture method,and the protein-decomposing bacteria were screened by casein AGAR and identified by Gram staining and 16S rDNA sequencing.[Result]The sensory rejection point of chilled grouper QIM came on 12th,the total number of colonies(TVC)exceeded the limit critical period on the 4th day,and the TVB-N exceeded the limit critical period on about 10th day.With the extension of refrigeration time,the diversity of surface microbiota decreased.There were significant differences in the composition of microbiota among fresh grouper,4 d and 8 d chilledstorage grouper at the genus level.The main flora of bacteria in fresh grouper were Acinetobacter,Psychrobacter,and Chrysobacter(relative abundance were 20.44%,15.93%and 9.24%respectively).Shewanella,Aeromonas,Psychrobacter and Acinetobacter,with relative abundance of 32.27%with 34.89%,30.28%with 16.02%,12.90%with 16.65%and 13.99%with 5.67%were the main bacteria in chilled fish meat stored for 4 days and 8 days,respectively.Aeromonas and Shewella had good protein-degrading ability in fish chilled stored for 8 days,and their composition ratio was close to the results of high-throughput sequencing.[Conclusion]Aeromonas and Shewanella were the dominant bacteria in the chilled grouper,with strong protein degradation ability.This study could provide a basis for further exploration of the spoilage ability of dominant bacteria in chilled grouper and the development of targeted antibacterial preservation technology.
国家科技期刊平台
NSTL
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