## 3 Results and Discussion
### 16S rRNA High-Throughput Sequencing Analysis
The decrease in _Acinetobacter_ during the storage period in this study indicated that this genus contributed negligibly to fillet spoilage. Similar results have been reported by previous reports [12; 20]. In the distilled water treated fillets, _Flavobacterium_, _Chryseobacterium_, and _Enhydrobacter_ reduced dramatically to 0.2, 0.2, and 0.1%, respectively, while the other genera, _Sphingomonas_ and _Cetobacterium_, disappeared after 6 days. These five genera disappeared in the fillet treated with tea polyphenols during the storage period, thereby indicating that these genera do not contribute to the spoilage of crisp grass carp. In the fresh crisp grass carp fillets, the bacterial community and its abundance were slightly different in comparison to those reported by a previous study [12]. For example, the bacterial communities included the genera _Cetobacterium_ and _Limobacter_, but did not include the genera _Sphingobacterium_ and _Macroaccocus_; this could be explained by the difference in capture times and locations. Unlike the aforementioned microorganisms that are not related to the spoilage process, _Pseudomonas_ and _Aeromonas_ play an important role in the spoilage of crisp grass carp. The minor genus _Pseudomonas_ in the fresh fillets increased rapidly and became dominant in tea polyphenol treated and distilled water treated samples by the end of their shelf life (from an initial 0.4% to 50.4% after 6 days for the distilled water treated fillets, and to 97.4% after 12 days for the tea polyphenol-treated fillets). This showed that _Pseudomonas_ spp. are the main spoilage organisms responsible for the spoilage of crisp grass carp treated with tea polyphenols, in accordance with a previous study that identified species of this genus as the spoilage organisms of freshwater fish [7; 22]. Compared to the increased abundance of _Pseudomonas_, the fluctuations of the abundance of _Aeromonas_ were found to be of interest in the two treated samples during the storage period. In the distilled water treated fillets, the proportion of _Aeromonas_ increased from 1.5% on day 0 to 50.1% on day 3 but declined to 30.3% after 6 days. In addition to _Pseudomonas_, _Aeromonas_ was another major dominant bacterium in spoiled crisp grass carp treated with distilled water, and this was in agreement with the findings of previous studies [7; 12]. _Aeromonas_ species have also been reported to be the main spoilage organisms for many freshwater fish species [7; 20; 21; 23; 24]. These two genera had strong spoilage potential, which may be the reason why the value of TVB-N increased rapidly in the control samples. However, in the tea polyphenol-treated fillets, _Aeromonas_ increased from an initial 1.5% on day 0 to 21.0% after 6 days but declined dramatically to just 0.2% after 12 days. We found that _Aeromonas_ and _Pseudomonas_ accounted for 30.3% and 50.4% of the bacteria in non-treated fillets with a TVC value of 7.32 log CFU g\({}^{-1}\) on day 6 but accounted for only 21% and 16.2% in tea polyphenol-treated fillets with a TVC value of 5.24 log CFU g\({}^{-1}\) (Figures 1 and 4b). At the end of storage, the main spoilage bacteria of crisp grass carp fillets changed from _Pseudomonas_ and _Aeromonas_ to _Pseudomonas_ in fillet treated with tea polyphenols. These results indicated that tea polyphenols could inhibit the growth of _Aeromonas_ and _Pseudomonas_ and alter the composition of microbiota in crisp grass carp fillets during chilled storage.