基于下一代测序技术分析巴氏杀菌乳中残留细菌在贮藏期间的动态变化

采用高通量测序技术，分析巴氏杀菌乳在常见贮藏温度0、4、10 ℃条件下分别贮藏0、3、6、9、12、15 d内细菌16S rRNA的V3-V4区基因序列，进而比较不同贮藏条件下巴氏杀菌乳中微生物的群落组成及动态变化。结果共获得1 887 个可操作分类单元，共检测到支原菌属（Mycoplasma）、草酸杆菌属（Oxalobacteraceae）、假单胞菌属（Pseudomonas）、不动细菌属（Actinetobacter）、链球菌（Streptococcus）等34 类细菌菌属。多样性分析表明，不同贮藏温度条件下巴氏杀菌乳中微生物的组成及多样性在门、属水平上有明显差异。在0 ℃贮藏15 d内的巴氏杀菌乳微生物多样性保持最完整，并且0 ℃其营养品质也保持较好；而在4、10 ℃贮藏期间巴氏杀菌乳的微生物多样性及营养品质都有较大影响，菌群构成及优势菌群都发生了变化，主要菌群也随贮藏温度的升高变为假单胞菌属、气单胞菌属等。研究表明，在4 ℃贮藏3 d和9 d、10 ℃贮藏6 d作为巴氏杀菌乳品质腐败的关键时间点，都出现了之前未被检测出的类芽孢菌属（Paenibacillus）、沙雷氏菌属（新Serratia），初步推测此两种菌属是导致巴氏杀菌乳品质腐败的关键决定因素。

Dynamic Analysis of Changes in Residual Bacteria in Pasteurized Milk during Storage Based on Next-Generation Sequencing

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.