《食品工业科技》F5000论文展播：传统发酵乳制品中微生物多样性研究（2022年）

Objectives: Traditional fermented dairy products contain extremely rich microbial diversity. These microorganisms have a significant impact on the flavor, texture, and stability of traditional fermented dairy products. A comprehensive analysis of the biodiversity, microbial community, and their correlation in traditional fermented dairy products is of great significance for the scientific screening and development of high-quality industrial starter. In this paper, 454 high-throughput sequencing technology is used to analyze the microbial community diversity of traditional fermented yogurt, koumiss, and kurut, and explore the core microbial communities in traditional fermented dairy products.

Methods: Analyze the microbial diversity of yogurt, koumiss, and kurut prepared by traditional fermentation methods collected from herdsmen's homes in Mahong (Qile Wuzeke village), Xinjiang Autonomous Region. Firstly, used a kit to extract the microbial metagenomics DNA from the sample. Secondly, 16S rRNA V1-V3 and 18S rRNA primers were used for amplification, and 454 Roche GS-FLX was used for sequencing. Subsequently, screening and quality control would be carried out based on the evolving barcode changes. Calibrate and align the sequence using PyNAST, and divided the Operational taxonomic unit (OTUs) at a given similarity level of 97%, removing OTUs belonging to chimeras detected by ChimeraSLayer software. The representative OTUs sequences were compared through RDP (Ribosomal database project, Release 11.5) and Greengenes (Release 13.8) databases, and the comparison results of the two databases were integrated to determine the final taxonomy status of each OTU. Draw a phylogenetic evolution tree based on OTUs representative sequences using FastTree software and calculate the α and β diversity.

Results: From the analysis of microbial diversity, it could be seen that different traditional fermented dairy products have certain common communities: a. With the increased of sequencing quantity, new fungi or bacteria would be found from the samples, but the diversity of fungi and bacteria in the samples had no longer changed. b. Six bacterial OTUs were found in the three traditional fermented dairy products, including yogurt, koumiss, and kurut, containing 24,777 sequences, accounting for 71.4% of the total sequences. There were 59, 9, and 99 unique bacterial OTUs, respectively, containing 5143, 16, and 1112 unique sequences, accounting for 14.8%, 0.05%, and 3.2% of the total sequences. c. Firmicutes was the dominant phylum of bacterium and Ascomycota was the dominant phylum of fungi in the three samples. Lactococcus was the dominant genera in bacterium and Galactomyces was the dominant genera in bacterium in the yogurt sample. Lactobacillus and Vanderwaltozyma were there respectively dominating bacteria and fungi, in the koumiss sample. And Lactobacillus was the dominant genera in bacterium and Galactomyces was the dominant genera in bacterium in the kurut sample. d. Three traditional fermented dairy products shared 5 fungal OTUs, including 13,936 sequences, accounting for 80.4% of the total sequences; there are 30, 12, and 1 unique OTU, respectively, containing 480, 405, and 18 unique sequences, accounting for 2.8%, 2.3%, and 0.1% of the total sequences in the sample. e. There was a significant negative correlation (P<0.05) between the relative content of Lactococcus and Galactinomyces, and between Lactococcus and Leuconostoc, while there was a significant positive correlation (P<0.05) between Leuconostoc and Galactinomyces, Gibberella and Pseudomonas.

Conclusion: Traditional fermented dairy products are rich in microbial resources. Therefore, this paper analyzed the microbial diversity, especially the core community, of traditional fermented yoghurt, koumiss, and kurut by 454 high-throughput sequencing technology, and found that there are core microbial community in traditional fermented dairy products, and there is a certain correlation between the core microbial communities.