传统发酵牦牛乳制品中微生物群落及其与代谢产物相关性

Microbial Community Structure and Correlation with Metabolites in Traditional Fermented Yak Milk Products

为研究传统发酵牦牛乳制品中微生物多样性及其代谢产物的相关性,本实验采用高通量测序和气相色谱-飞行时间质谱仪技术分别解析酥油、曲拉、牦牛酸奶3?种传统牦牛乳制品的微生物多样性和代谢物谱。结果显示:3种乳制品的微生物群落在属水平上存在明显差异。酸奶及曲拉优势细菌属为乳杆菌,酥油中以乳球菌为主导;在真菌属中均发现地霉和酵母菌的存在。其中,在酸奶及曲拉中均检测到高丰度的毕赤酵母,酸奶中还存在独特的克鲁维酵母,而酥油组内真菌属组成差异较大。代谢组学结合多元统计分析共鉴定了51种差异代谢物。酥油的特征代谢物主要为脂质及类脂分子;曲拉和酸奶类似,特征代谢物除了脂质和类脂质分子,还有有机酸及其衍生物。共探索12条参与调控乳制品风味和品质的代谢途径。相关分析表明,乳球菌和地霉与筛选的代谢物呈负相关,乳杆菌和克鲁维酵母与大部分代谢物呈正相关。微生物群落结构的差异会导致发酵牦牛乳制品代谢产物的迥异,研究结果可为更好地调控牦牛乳发酵产品的品质提供理论基础。

To investigate the microbial diversity and the correlation with metabolites in traditional fermented yak milk products,the study used high-throughput sequencing and gas chromatography-time-of-flight mass spectrometry(GC-TOF-MS)to analyze the microbial diversity and metabolite profiles of yak ghee,Qula,and yogurt.Results showed that the microbial communities of the three dairy products differed significantly at the genus level.The dominant bacterial genus in yak yogurt and Qula was Lactobacillus,while Lactococcus was dominant in ghee.The fungi Geotrichum and yeast were found in all samples.In particular,a high abundance of Pichi was detected in yak yogurt and Qula,and Kluyveromyce was exclusively present in yogurt,whereas the fungal genus composition varied considerably among ghee samples.Using metabolomics combined with multivariate statistical analysis,a total of 51 differential metabolites were identified.The characteristic metabolites of ghee were lipids and lipid-like molecules,and the characteristic metabolites of Qula and yogurt were similar,including organic acids and their derivatives as well as lipid and lipid-like molecules.A total of 12 metabolic pathways were found to be involved in the regulation of the flavor and quality of fermented yak milk products.Correlation analysis showed that Lactococcus and Geotrichum were negatively correlated with selected metabolites,while Lactobacillus and Kluyveromyce were positively correlated with most of the metabolites.Differences in the microbial community structure could lead to differences in the metabolite profile of fermented yak milk products.The results from this study provide a theoretical basis for better regulating the quality of fermented yak milk products.