| ObjectiveTo analyze microbial population characteristics of traditional dairy products in Inner Mongolia and get more resources of probiotics.Method20 kinds ofhand-made dairy products purchased from the eastern Inner Mongolia region were taken as the research object.According to their texture,they were divided into two groups: soft(R)and hard(Y).The combination of Pacbio SMRT sequencing technology and traditional culture and isolation method was used to analyze the composition of its flora and the differences between groups.Enterococcus,one of the most common contaminating bacteria isolated from dairy products by traditional culture methods,was used as the host to test its ability to produce biofilms and biogenic amines.For the first time,based on the fixed wooden model required in the process of handmade cheese and the 304 stainless steel media used in modern industry,the enterococcal biofilm produced by the simulation construction on the wood chips and 304 stainless steel was explored to explore the effect of the mixed preparation of bacteriophage lyase on the biofilm.Result1.After 20 samples are detected by Pacbio SMRT sequencing method,a total of261797 CCS sequences were obtained through Barcode recognition,with an average of 13090 CCS sequences.According to Alpha diversity analysis,dilution curve and Shannon index curve,the sequencing quality is better.33 phyla,73 classes,178 orders,326 families,664 genera and 953 species were detected.Among them,Firmicutes accounted for 82.59% at most,Proteobacteria 10.43% and 4.50%.At the genus level,the largest proportion is Lactococcus(46.41%),then Anoxybacillus,Lactobacillus and Leuconostoc occupied 7.75%,6.56% and 6.35% respectively,and the rest genera occupied less than 3.5%.At the species level,Lactococcus＿lactis,Leuconostoc＿pseudomesenteroides,and Lactobacillus helveticus occupied 7.75%,6.35% and 6.25% respectively.2.74 strains are isolated and identified from 20 dairy products by traditional culture method.34 strains of Pediococcus(28 strains of Pediococcusacidilactici,7strains of Pediococcuspentosaceus);10 strains of Enterococcus(5 Enterococcus durans,4 Enterococcus faecalis,1 Enterococcus faecium);There are 8 strains of Bacillus(1 Bacillus cereus,1 Bacillus paramycoides,1 Bacillus pumilus,2 Bacillus thuringiensis,1 Bacillus velezensis);8 strains of Lactobacillus(4 strains of Lactobacillus gallinarum and 4 strains of Lactobacillus reuteri);7 strains of Streptococcus genus(3 strains of Streptococcus gallolyticus,4 strains of Streptococcus macedonicus);4 strains of Lactococcus(3 strains of Lactococcus lactis,1 strain of Lactococcus lactis subsp.hordniae);2 strains of Lactobacillus,1 strain of Limosilicobacillus fermentum,1 strain of Limosilicobacilluspontis;The proportion of other species and genera is small,including 1 Acetobacter tropicalis,1 Clostridium perfringens,1 Kurthiagibsoniiand 1 Weissellaparametersentoides.3.PCR detection of biogenic amine gene showed that all the tested strains have the potential to produce biogenic amine.In addition,in the food industry,the anti-disinfection ability of biofilms prevents food safety from being guaranteed.Among 31 strains of lactic acid bacteria detected by culture method,only 2 strains of Lactobacillus reuteriwere identified that they could not produce biofilm,and 10 strains of detected Enterococcus could produce biofilm.4.Enterococcus is more prone to form biofilm on wooden products than on stainless steel surfaces.And bacteriophage and lyase preparation inhibited biofilm on both surfaces of wood and stainless-steel.Conclusion1.Preliminary obtain the distribution characteristics of microbial communities in dairy products in the eastern Mongolian region.2.Obtained 74 lactic acid strains from dairy products in the eastern region of Inner Mongolia;Most lactic acid bacteria have the potential to produce biogenic amines.3.Phage and lyase preparations can effectively inhibit Enterococcus biofilm and have the potential to remove harmful bacteria from dairy product preparation. |
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