本文采用二代高通量测序技术研究北京、河北、内蒙古、天津四地区不同季节原料乳样品中的细菌多样性并对其进行功能预测。收集四地区不同季节原料乳样品23份，提取基因组DNA后使用IlluminaMiSeq测序平台对细菌16S rRNA的V3-V4“可变区”进行测序，结合数据库对原料乳中微生物群落分布、相对丰度和细菌功能基因代谢途径进行分析。原料乳中的细菌可分为33门732属，其中变形菌门（Proteobacteria），厚壁菌门（Firmicutes），拟杆菌门（Bacteroidetes）和放线菌门（Actinobacteria）为主要菌门，平均相对丰度占微生物总数的99.37%。优势菌属为假单胞菌属（Pseudomonas）和不动杆菌属（Acinetobacter）,平均相对丰度之和为60.55%。不同地区、不同季节原料乳微生物群落的结构组成和相对丰度存在差异，且假单胞菌属和气单胞菌属的相对丰度在不同季节原料乳中存在显著性差异（p<0.05）。氨基酸代谢、碳水化合物代谢和膜运输为原料乳细菌主要的代谢途径。

Second-generation high-throughput sequencing was used in this study to analyze the bacterial diversity of raw milk samples and predict their functions. A total of 23 raw milk samples were collected from four regions, Beijing, Hebei, Inner Mongolia, and Tianjin, during different seasons. Genomic DNA was sequenced using Illumina MiSeq sequencing platform for the V3-V4 "variable regions" of 16SrRNA. Using the RDP classifier database, the community distribution, relative abundance, and metabolic pathways of the functional genes of bacteria in raw milk were analyzed. The bacteria in raw milk can be divided into 33 phyla and 732 genera. Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria are the main phyla, and their average relative abundances account for 99.37 % of the total number of microorganisms. The dominant genera are Pseudomonas and Acinetobacter, with a sum of average relative abundance of 60.55 %. There are differences in the structural composition and relative abundance of the microbial communities in the raw milk samples collected from different seasons and regions. The relative abundances of Pseudomonas and Aeromonas are significantly different during different seasons (p<0.05). Finally, amino acid metabolism, carbohydrate metabolism, and membrane transportation are the main metabolic pathways of bacteria in raw milk.

国家重点研发计划项目（2018YFC1604201-2）