Abstract: In this study, high-throughput sequencing technology was adopted to analyzed the V3-V4 region of the bacterial 16S rRNA gene in pasteurized milk stored at different temperature (0, 4, and 10 ℃) for 0, 3, 6, 9, 12 or 15 d. Our aim was to reveal the dynamic changes in the microbial community composition. The results showed that a total of 1 887 operational taxonomic units (OTUs) were obtained and 34 genera of bacteria, including Mycoplasma, Oxalobacteraceae, Pseudomonas, Actinetobacter, and Streptococcus were detected. Bacterial diversity analysis showed that the composition and diversity of the bacterial community in pasteurized milk were significantly different at both the phylum and genus levels. The bacterial diversity in pasteurized milk stored at 0 ℃ for day was the most intact of all samples and its nutritional quality was also maintained well. Nonetheless, both the bacterial diversity and the nutritional quality were greatly affected by storage at 4 and 10 ℃. Under this circumstance, the flora composition and the dominant bacterial community both changed. The dominant bacteria became Pseudomonas and Aeromonas with the increase of storage temperature. Furthermore, this study found that days 3 and 9 of storage at 4 ℃ and day 6 at 10 ℃ were key points of time for pasteurized milk spoilage because Paenibacillus and Serratia were detected at this time point but not earlier. It is speculated that these two genera are the key determinants of pasteurization dairy product spoilage.

Key words: pasteurized milk, storage conditions, microbial diversity, high throughput sequencing technology