Abstract: Objective: To evaluate the composition of microbial communities adhered to the surface of shrimp (Litopenaeus vannamei) under different conditions. Methods: Genomic DNA was extracted from bacteria adhered to the surface of live shrimp, fresh shrimp, fresh peeled shrimp and frozen peeled shrimp and was sequenced by using high-throughput sequencing. Results: 1) A total of 30 591–42 043 valid sequences and 68–168 operational taxonomic units (OTUs) were obtained from each sample, and the number of OTUs was lowest in frozen peeled shrimp and relatively high in live shrimp and fresh shrimp. 2) Among all samples investigated, frozen peeled shrimp exhibited the lowest ACE, Chao1 and Shannon indices and highest Simpson index, suggesting lower bacterial abundance and diversity. 3) At the family level, compared to live shrimp, the relative abundance of Moraxellaceae in fresh shrimp was significantly increased, which might be related to the death of shrimp and microbial contamination and growth; the abundance of Vibrionaceae in fresh peeled shrimp was significantly increased and the highest content was observed, which was caused by microbial contamination from the environment and the devices used during shrimp processing. The dominant spoilage bacteria in frozen peeled shrimp were Moraxellaceae, Pseudomonadaceae, and Listeriaceae. 4) Heatmap analysis showed that the similarity in bacterial flora between live shrimp and fresh shrimp was higher, whereas they were significantly different from fresh peeled shrimp and frozen peeled shrimp, indicating that the preparation of peeled shrimp and frozen storage had a great impact on shrimp bacterial flora. 5) Principal component analysis (PCA) indicated that there was significantly difference in microbial community composition between frozen peeled shrimp and other samples. Conclusion: There were significant differences in the dominant microorganisms, flora structure, abundance and composition among shrimp samples under different conditions. Different control processes are necessary for different types of shrimp products to ensure the quality and safety of shrimp products.

Key words: Litopenaeus vannamei, surface microorganism, high-throughput sequencing, microbial diversity