Identification Of Fermented Bean Curd Microorganisms Based On Highthroughput Gene Sequencing And Development Of Innovative Compound Fermented Bean Curd

As a fermented food,fermented bean curd had a delicious taste and was loved by everyone.It was an essential condiment on people's table.At present,the fermented bean curd in the market is of different quality and many flavors,mainly affected by the fermentation strain and the production environment.In the whole process of the production of fermented bean curd,some bacteria will cause the fermented bean curd to be black,smelly,white spots,gffas production,hardening,oil leakage and other quality problems,which will bring considerable losses to the enterprise.With the factory production of fermented bean curd,a large number of products were sold all over the country,so the safety and taste of fermented bean curd products seem to be important.The hygienic conditions of the current family-style naturally fermented bean curd cannot be guaranteed,and it may introduce miscellaneous bacteria to cause quality problems of the bean curd.The pure-breeding of the factory is due to different strains,and also introduces bacteria in the production process,resulting in unstable quality.Therefore,it was necessary to analyze the microbial community structure in the fermented bean curd clearly in order to make the right medicine and make high-quality products.Because the original laboratory isolation and cultivation method could not fully identify the microorganisms in the bean curd,this paper used high-throughput gene sequencing to analyze the diversity of bean curd microorganisms and the effects of strains on the quality of bean curd on the Yongfeng market in Jiangxi.In order to improve the quality of fermented bean curd and reduce the influence of harmful microorganisms on the quality of fermented bean curd,the dynamic changes of the types and abundance of microorganisms at different stages of fermented fermented bean curd were detected by controlling environmental microorganism.In addition,the effects of fermentation temperature,bacterial liquid concentration,and water content of white blank on the quality of pure fermented bean curd were explored.On this basis,the compound fermentation of Rhizopus arrhizus and Mucor elegans was carried out to explore the effects of fermentation time,fermentation temperature,and ratio of bacterial solution on the quality of fermented bean curd.Provide data reference for the production of fermented bean curd industry to guide production.The specific research results are as follows:(1)Illumina MiSeq sequencing platform for high-throughput sequencing of microorganisms in fermented bean curd,bacteria using 16S rDNA amplicon for sequencing,and fungi using ITS1 amplicon for sequencing.Found at the level of bacterial phylum,Proteobacteria,Firmicutes and Bacteroidetes were the main phylum of sufu.The level of fungal phylum were mainly Ascomycetes,Unclassified_k_Fungi,Basidiomycetes and Mucor subphylum.At the bacterial species level,the abundance of Pseudomonas_fragi was very high in A,B,C and D samples,with contents of 2.30%,20.95%,12.51%and 48.75%,and the content in natural fermented bean curd was higher than that in purebred fermented bean curd.The main fungus was yeast,and sample A mainly included Unclassified_k_Fungi(63.20%)and Millerozyma_farinosa(25.80%).In the three samples of B,C and D,the main content was Debaryomyces_prosopidis,which respectively was 37.60%,51.70%and 85.90%.Bacillus sp.,Bacillus thuringiensis,Micrococcus luteus,Bacillus amyloliquefaciens,Actinomucor elegans,and Millerozyma farinosa were obtained through isolation and culture.(2)By analyzing the dynamic changes of microorganisms in the process of fermented fermented bean curd,it was found that by controlling the fermentation environment,Pseudomonas strawberry in fermented bean curd disappeared,indicating that the fermented environment has a great influence on the quality of fermented fermented bean curd.However,in E1-E6,Pseudomonas_monteilii were 0.46%,7.91%,15.93%,3.13%,9.43%,7.05%,although the abundance was lower than that of P.strawberry strawberry However,it also reflects that the nutritional conditions of bean curd are very suitable for the growth and survival of Pseudomonas.Bacillus existed in these stages of E1-E6,and their contents were 73.56%,4.50%,6.42%,6.00%,12.58%,25.38%,showing dynamic changes.At the same time,it was found that in these 6 stages,the colony structure and species richness of the microorganisms were constantly changing,which indicated that the self-capacity of the strains or the competition was eliminated during the fermentation process.At the same time,new strains appeared due to changes in the environment.By controlling the microorganisms in the environment,it was found that the bacterial colony structure is simple,the species species are few,and the species diversity of the fungus is rich.It may be that some bacteria that inhibit the growth of the fungus are no longer present,causing a variety of fungi to survive.(3)The effects of three single factors,including moisture content,fermentation temperature,and bacterial solution concentration on the quality of fermented bean curd by a single strain of Mucor radiata,were investigated.Based on this,through orthogonal experiments,the optimal fermentation combination conditions were finally obtained:the fermentation temperature was 24?,the white water content was 70%,and the bacterial solution concentration was 1.0×106cfu/ml.(4)The effects of three single factors,fermentation time,fermentation temperature,and bacterial solution ratio,on the quality of fermented bean curd by Rhizopus rhizopus and Mucor radiata were investigated.The advantages and disadvantages of compound fermented fermented bean curd were found.The advantages are shortened fermentation time,increased fermentation temperature,and overall acceptability is better than single strain fermentation.The disadvantage is that the rhizopus is easier to age and produce black spores,which causes the surface of the fermented bean curd to be black.Therefore,strict control of the fermentation time is required.The optimal fermentation condition combination was obtained through orthogonal experiments.The fermentation temperature was 28?,the fermentation time was 24 h,and the bacteria mixture ratio was 40:1.