发酵乳中风味物质指纹图谱的构建及其相关功能基因调控机理的研究

这项课题依托内蒙古农业大学乳酸菌菌种资源库资源，结合已筛选出来的具有良好风味的12株嗜热链球菌和8株保加利亚乳杆菌，开展以下研究工作：首先，使用气相色谱-质谱联用(GC-MS)、超高效液相色谱-四极杆飞行时间串联质谱(UPLC-Q-TOF-MS)等技术对单一或复合乳酸菌在发酵过程中产生的风味物质进行定性、定量分析，构建指纹图谱；其次，采用主成分分析、聚类相关性分析以及聚类分析等方法分析指纹图谱，确定其特征性风味物质，探讨主要特征性风味物质的动态变化及其与发酵乳品质的互作效应；之后，采用生物信息学方法，预测、分析主要特征风味物质的代谢通路，同时采用q-PCR技术对相关功能基因进行分析，比较分析和特征性风味物质生产相关的基因表达的差异，完成乳酸菌生产特定风味物质功能基因的精细定位，最终实现乳酸菌生物学特性与功能基因关联分析，为发酵乳的品质评价和工业化生产提供原始数据和理论指导。

The subjects used in this study include 20 flavor-contributing strains selected from the existing 333 strains of Streptococcus thermophilus and 411 strains of Lactobacillus delbrueckii subsp. bulgaricus from the Lactic Acid Bacteria Collection Center of Inner Mongolia Agricultural University. Gas chromatography-mass spectrometry (GC-MS)and ultra performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) were conducted for the qualitative and quantitative analyses of the flavors produced in the fermentation of a single or composite lactic acid bacteria. Principal component analysis, cluster correlation analysis, cluster analysis, and other methods were used for fingerprinting. The dynamic changes in the principal volatile flavors and their influence on the quality of fermented milk were analyzed. Bioinformatics was employed to predict and analyze the metabolic pathways of the principal characteristic flavors. q-PCR technology was used to identify related functional genes. The expression levels of genes related to characteristic flavor production were compared. This study elucidated the presence of genes related to characteristic flavor production in lactic acid bacteria and found a correlation between the biological characteristics of lactic acid bacteria and functional genes. The results of this study could serve as a theoretical basis for increasing the quality of fermented milk for industrial-grade production.