Abstract: The present study investigated the effect of ε-poly-lysine (ε-PL) pretreatment on spoilage bacteria growth in grass carp (Ctenopharyngodon idellus) fillets under refrigerated storage as well as on its microbial diversity using 16S rRNA high-throughput sequencing technique. Results showed that 1.0 mg/mL ε-PL could inhibit the growth of Pseudomonas sp., Shewanella sp. and Aeromonas sp., which were isolated and identified as the dominant spoilage bacteria from grass carp fillets. A total of 858 964 bacterial sequences targeting the V3–V4 region of 16S rRNA and 388 different genera belonging to 28 phyla were observed by high-throughput sequencing. The microbial diversity of both control and ε-PL pretreated groups decreased as the storage time increased. Pseudomonas sp. was the absolute dominant spoilage bacterium in fresh grass carp fillets. ε-PL pretreatment affected both the microbial diversity and abundance. Notably, it had a very significant influence on Flavobacterium in fresh grass carp fillets (P < 0.01), and a significant influence on Pseudomonas in 6-day-stored samples (P < 0.05). In conclusion, ε-PL presents a high performance in inhibiting the growth of fish spoilage bacteria and can lead to changes in the structure of the microbiome in grass carp fillets, which supports its application in fresh fish preservation.

Key words: grass carp; ε-poly-lysine; high-throughput sequencing; microbial diversity