Succession of Microbial Community in Giant Salamander (Andrias davidianus) Meat during Cold Storage Investigated by Illumina MiSeq High-Throughput Sequencing

To explore the microbial community and special spoilage bacteria in pallet-packaged giant salamander (Andrias davidianus) meat during cold storage, the total volatile basic nitrogen (TVB-N) content and total bacterial count of giant salamander meat were evaluated after different refrigeration durations (0, 2, 4, 6 and 8 d) at 4 ℃ , and the changes and diversity of the microbial flora were explored by Illumina MiSeq sequencing. The results showed that the total count of bacteria and TVB-N levels in salamander meat showed an upward trend during refrigeration, and exceeded the safety limit on the 6th and 8th days, respectively. The results of high-throughput sequencing showed that the microbial abundance in giant salamander meat decreased with storage time. The dominant phyla of bacteria were Bacteroidetes and Firmicutes during the early storage period (0 and 2 d), and Proteobacteria during the middle (4 d) and late (6 and 8 d) storage periods. The dominant genera were Bacteroidetes and Faecalibacterium during the early storage period, and Pseudomonas, Aeromonas, Hafnia-Obesumbacterium and Serrella during the middle and late storage periods. Principal coordinate analysis showed that there were great differences in microbial community structure between the three storage periods, and the degree of superposed interpretation of the two principal coordinates was 80.92%. Linear discriminant analysis effect size (LEfSe) analysis showed that Proteobacteria, Actinobacteria, Bacteroides, Fibrinobacteria and Firmicutes were the major bacterial phyla that significantly changed during cold storage. The main bacterial genera that significantly changed during storage were Pseudoxanthomonas, Bauldia, Serrella, Acinetobacter, Aeromonas, Pseudomonas, ambiguous_taxa, Hafnia-Obesumbacterium, Rikenellaceae_RC9_gut_group, Prevotella_9, Bacteroides, Fibrobacter, Lachnospira, Faecalibacterium, Clostridium_sensu_stricto_1. Evolutionary analysis showed that there was a strong correlation between the succession of microflora and storage time. Overall, the dominant spoilage microorganisms in giant salamander meat are Pseudomonas, Aeromonas, Hafnia-Obesumbacterium and Serrella. This study provides a reference for the targeted bacteriostasis of spoilage bacteria in giant salamander meat during cold storage to extend its shelf life in the future.