Yuan Huizhi, Han Sufang, Zhang Shufei, Xue Yuling, Zhang Yaoguang, Lu Han, Wang Shijie
College of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang 050018, China.
Junlebao Dairy Group Co., Ltd., Shijiazhuang 050221, China.
Foods. 2022 Oct 4;11(19):3077. doi: 10.3390/foods11193077.
Raw milk microbiota is complex and influenced by many factors that facilitate the introduction of undesirable microorganisms. Milk microbiota is closely related to the safety and quality of dairy products, and it is therefore critical to characterize the variation in the microbial composition of raw milk. In this cross-sectional study, the variation in raw milk microbiota throughout the year (n = 142) from three farms in China was analyzed using 16S rRNA amplicon sequencing, including α and β diversity, microbial composition, and the relationship between microbiota and milk quality parameters. This aimed to characterize the contamination risk of raw milk throughout the year and the changes in quality parameters caused by contamination. Collection month had a significant effect on microbial composition; microbial diversity was higher in raw milk collected in May and June, while milk collected in October and December had the lowest microbial diversity. Microbiota composition differed significantly between milk collected in January−June, July−August, and September−December (p < 0.05). Bacterial communities represented in raw milk at the phylum level mainly included Proteobacteria, Firmicutes and Bacteroidota; Pseudomonas, Acinetobacter, Streptococcus and Lactobacillus were the most common genera. Redundancy analysis (RDA) found strong correlations between microbial distribution and titratable acidity (TA), fat, and protein. Many genera were significantly correlated with TA, for example Acinetobacter (R = 0.426), Enhydrobacter (R = 0.309), Chryseobacterium (R = 0.352), Lactobacillus (R = −0.326), norank_o__DTU014 (R = −0.697), norank_f__SC-I-84 (R = −0.678), and Subgroup_10 (R = −0.721). Additionally, norank_f__ Muribaculaceae was moderately negatively correlated with fat (R = −0.476) and protein (R = −0.513). These findings provide new information on the ecology of raw milk microbiota at the farm level and contribute to the understanding of the variation in raw milk microbiota in China.
生乳微生物群复杂，受多种因素影响，这些因素会促使不良微生物的引入。乳微生物群与乳制品的安全性和质量密切相关，因此，表征生乳微生物组成的变化至关重要。在这项横断面研究中，使用16S rRNA扩增子测序分析了中国三个农场全年（n = 142）生乳微生物群的变化，包括α和β多样性、微生物组成以及微生物群与乳品质参数之间的关系。这旨在表征全年生乳的污染风险以及污染导致的品质参数变化。采集月份对微生物组成有显著影响；5月和6月采集的生乳中微生物多样性较高，而10月和12月采集的乳中微生物多样性最低。1月至6月、7月至8月和9月至12月采集的乳中微生物群组成存在显著差异（p < 0.05）。生乳在门水平上的细菌群落主要包括变形菌门、厚壁菌门和拟杆菌门；假单胞菌属、不动杆菌属、链球菌属和乳杆菌属是最常见的属。冗余分析（RDA）发现微生物分布与可滴定酸度（TA）、脂肪和蛋白质之间存在强相关性。许多属与TA显著相关，例如不动杆菌属（R = 0.426）、嗜水生菌属（R = 0.309）、金黄杆菌属（R = 0.352）、乳杆菌属（R = -0.326）、未分类的o__DTU014（R = -0.697）、未分类的f__SC-I-84（R = -0.678）和亚群10（R = -0.721）。此外，未分类的f__毛螺菌科与脂肪（R = -0.476）和蛋白质（R = -0.513）呈中度负相关。这些发现提供了关于农场层面生乳微生物群生态学的新信息，并有助于理解中国生乳微生物群的变化。
