内蒙古科尔沁地区食疗用酸马奶发酵引子化学成分及细菌多样性分析

Analysis of Chemical Components and Bacterial Diversity of Fermentation Starter for Dietotherapeutic Koumiss in Kerqin, Inner Mongolia

对内蒙古科尔沁地区食疗用酸马奶发酵引子部分化学指标,包括pH值、糖类、有机酸、游离脂肪酸等进行分析,同时为调查其中细菌多样性,应用Illumina MiSeq第2代测序技术测定其细菌的16S rDNA V3-V4高变区序列,分析物种的丰度、物种分布和Alpha多样性。结果:该酸马奶引子样品pH值为3.54,乳糖、半乳糖质量分数分别为(0.281±0.011)%和(0.100±0.003)%,未检测到葡萄糖;乳酸质量分数为(1.506±0.069)%,丙酸质量分数为(0.053±0.002)%,乙酸质量分数为(0.345±0.014)%,丁酸质量分数为(1.143±0.061)%;共检测到19种脂肪酸,包括12种饱和脂肪酸和7种不饱和脂肪酸;不饱和脂肪酸中α-亚麻酸质量浓度最高,为(14.12±0.36)mg/L;细菌多样性检测结果表明,该样品所获优化序列为(62 082.7±4 868.8)条,可操作分类单元(operational taxonomic units,OTU)数为34.3±2.3;稀释曲线表明该测序深度充分,OTU数接近于饱和。该酸马奶引子细菌主要分布于以下4个属:乳杆菌属(Lactobacillus)84.08%、醋杆菌属(Acetobacter)9.83%、乳球菌属(Lactococcus)2.41%、链球菌属(Streptococcus)2.18%;其优势菌属为乳杆菌属。以上结果表明,该酸马奶引子不饱和脂肪酸含量丰富,益生菌占主要地位,食品安全有保障。

In this study, some chemical properties including pH, carbohydrates, organic acids and free fatty acids of a fermentation starter for dietotherapeutic koumiss in Kerqin, Inner Mongolia were analyzed. To investigate the diversity of the bacterial community in the starter culture, second-generation sequencing of the V3-V4 region of the 16 S rDNA genes was performed on the Illumina MiSeq platform. Thereafter, the species abundance, distribution and alpha diversity were analyzed. The analytical results indicated that the pH averaged at 3.54;the mean values of lactose and galactose were(0.281 ± 0.011)% and(0.100 ± 0.003)% respectively, and no glucose was detected. The levels of lactic acid, propanoic acid,acetic acid and butyric acid were(1.506 ± 0.069)%,(0.053 ± 0.002)%,(0.345 ± 0.014)%, and(1.143 ± 0.061)%, respectively.A total of 19 fatty acids were detected, including 12 saturated fatty acids and 7 unsaturated fatty acids.α-Linolenic acid was the most abundant unsaturated fatty acid at a level of(14.12 ± 0.36) mg/L. The results of bacterial diversity detection showed that(62 082.7 ± 4 868.8) clean reads were obtained, and the number of operational taxonomic units(OTUs) was 34.3 ± 2.3.The rarefaction curve showed that the sequencing depth was sufficient and the number of OTUs was close to saturation. The bacteria community in this sample was mainly distributed in the following 4 genera: Lactobacillus(84.08%), Acetobacter(9.83%), Lactobacillus(2.41%), and Streptococcus(2.18%) with the dominant genus being Lactobacillus. The above results showed that this fermentation starter sample was rich in unsaturated fatty acids and probiotics, and could guarantee food safety.