## 3 Results and Discussion  
### Bacterial Strains  
In general, the bands at different positions in the DGGE map represent different microbial species, and brighter bands indicates greater number of individual bacteria. It can be seen from Figure 1A that during the ice storage process, with the increase of storage time, more bands can be detected by DGGE, and the brightness of the bands at the same position changed, which indicates that during the storage process, the microbial community structure changed dynamically over time. The dominant bacterial species during different storage periods is different.  
In order to further clarify the relationship of microbial community structure in fish meat with different storage time, an unweighted pair group method with arithmetical means (UPGMA) method was used to construct the DGGE map. The results are as shown in Figure 1B: according to the similarity of bacterial communities, the flora at 0, 3, 6, and 8 days are grouped into one cluster, and that on day 10, 12, 14, and 16 are in a separate cluster. During the storage process, microorganisms need a period of adaptation to the new environment, so the flora changes little during the early stage of storage, and the similarity is greater than 80% among the samples collected at 0, 3, and 6 days; with the increase of storage time, the microorganisms in fish continue to grow and the dominant spoilage bacteria, which causes the fluctuation of the microbial community structure, among which the flora on the eighth day and days 0, 3, and 6 is more than 80%, the similarity was only 50%, but in the subsequent storage stage, the bacterial community structure gradually tended to be stable, and the similarity between the 10 th day and the 12 th day was 84%, and the similarity between the 14 th day and the 16 th day was as high as 92%.  
Figure 1: Analysis of DGGE Atlas. DGGE profile of bacteria from sturgeon stored aerobically on ice (**A**). Cluster analysis of DGGE bacteria profile (**B**). Phylogenetic tree of the 168 rRNA gene of _Shevanella_ sp. isolated from sturgeon fillets (**C**). Phylogenetic tree of the 168 rRNA gene of _Pseudomonas_ sp. isolated from sturgeon fillets (**D**).  
The results of bacteria identification are shown in Table 1. According to DGGE patterns (Figure 1A) and 16S rRNA sequencing analysis (Figure 1C,D), the dominant bacteria in fresh sturgeon were _Pseudomonas_ sp. (bands 7, 14, 18), _Shewanella_ sp. (bands 20), _Acinetobacter_ sp. (bands 19) and _Escherichia_ sp. (bands 22). With the increase of storage time, the brightness of bands 3, 4, 6, 9, 10, 12, and 16 increased, indicating that the dominant position of _Acinetobacter_ sp. in microbial flora gradually lost, while the _Shewanella_ sp., _Pseudomonas_ sp., and other microorganisms gradually became dominant bacteria during the late storage period [31]. _Shewanella_ sp. and _Pseudomonas_ sp. are psychrophilic bacteria and can grow at 0 \({}^{\circ}\)C. _Pseudomonas_ sp. grows rapidly under aerobic conditions and has strong protein decomposition ability; _Shewanella_ sp. can reduce trimethylamine oxide, producing hydrogen sulfide that can react with pigment in meat tissue, resulting in fish discoloration and produced rancid smell [32].