Analysis Of Fungal Diversity In Vinegar Brewing With RAW Materials By DNA High-throughput Sequencing

In China,the traditional vinegar brewing has a history of thousands of years.The most representative ones are Shanxi Laochen Vinegar,Zhenjiang Balsamic Vinegar,Fujian Yongchun Vinegar and Sichuan Baoning Vinegar.With the continuous development and optimization of the traditional vinegar brewing process,the vinegar brewing technology has also been greatly developed.In the late 1970 s,some vinegar production enterprises in Beijing,Tianjin,Shanxi and other places began research and production of raw vinegar technology.After decades of development,raw vinegar has achieved good results.Lucheng Shengtang Food Co.,Ltd.,which located in Changzhi City,Shanxi Province,is a company specializing in the production of vinegar by raw material vinegar process.51 samples were collected from the company,including raw materials,daqu,fermentation tank samples(13samples at different fermentation time points),vinegar samples and fumigated vinegar samples.There were 17 groups of samples,three parallel samples in each group.In this study,51 samples were used to amplify the nrDNA ITS region and conduct high-throughput DNA sequencing to analyze the changes of fungal diversity in raw material vinegar production process.The main results are as follows:(1)In raw materials,Saccharomyces cerevisiae was the dominant species(relative abundance was 99.73%),Aspergillus niger was the dominant species(relative abundance was 98.86%)in Daqu;the community structure of each group of samples in fermentation tank was similar,but the relative abundance of each species in each group was different;the community composition and species richness of fumigated vinegar and leached vinegar were significantly different from those of other samples.(2)The fungal community structure of samples collected from fermentation tanks was compared.Sample hierarchical clustering resultsshowed that all samples of 2,6,10 and 13 days of fermentation were clustered into one branch,belonging to the pre-fermentation stage,while samples of 17,22,26,29,32,35,39 and 46 days of fermentation were clustered into one branch,collectively referred to as the late fermentation stage.There were significant differences in the community structure of fungi between early and late fermentation stages(P value),especially in Saccharomyces cerevisiae,unclassified Davidiellaceae,unclassified Alternaria and Monascus purpurpureus.(3)The source analysis of fungi in fermentation period showed that the proportion of fungi from raw materials and Daqu was 1.44% and2.26% respectively,almost all of them belonged to ascomycetes,but there were also a small proportion of conjugated and basidiomycetes fungi;about 94.6% of them came from fermentation chamber or workers' turning over process.(4)The results of cluster analysis,Heatmap plot analysis and inter-group difference test showed that there was almost no difference in the structure of fungal community between the top and bottom of fermentation vat(the sample representing the bottom of fermentation vat)and the non-top of fermentation vat(the sample representing the top of fermentation vat).The 51 samples collected in this study involved the whole process of raw vinegar production,and carried out a comprehensive study on the taxonomic level of the gate,the class,the eye,the genus,the genus,and the species.The research results can reflect the actual life.The structure,changes and diversity of fungal community during the process of vinegar production provide a theoretical basis for the development of raw vinegar technology.