Dynamic Analysis Of Bacterial Communities And Isolation Of Dominant Strains From Self-made Enzymes And Their Tolerance To Heavy Metals

Enzymes are microbial preparations in which natural fermentation of fruits and vegetables,medicinal plants and the like,or artificial fermentation of lactic acid bacteria,acetic acid bacteria,and yeast are performed.The traditional Enzyme application is often used as a health effect to regulate body immunity,slimming,lowering blood pressure,and anti-cancer.In recent years,Enzymes and Enzyme bacteria produced during fermentation process have been widely used to inhibit bacteria,degrade pesticide residues,restore soil biochemical characteristics,regulate water quality and other fields.However,there are relatively few researches on the microbial community changes and bacterial dynamics analysis and comparison of Enzymes in the fermentation process.In recent years,there have been many studies on the adsorption and removal of heavy metals by microorganisms.However,the advantages of Enzymes and Enzyme bacteria in the removal of heavy metals in food safety have attracted attention.In this article,self-made Enzyme samples(AA and AB)were studied.Firstly,high-throughput sequencing technology was used to analyze and compare the dynamics of microbial community structure in different fermentation stages of the Enzyme samples.Secondly,32 strains of Lactobacillus and 7 strains of Pediococcus and 1 yeast were purified and isolated from the Enzyme samples.The phylogenetic analysis of the above isolated strains was performed.Finally,the tolerance,adsorption and accumulation characteristics of heavy metal Pb and Cd were analyzed for representative strains of lactic acid bacteria.The results of the study are as follows:1.The results of high-throughput sequencing showed that Lactobacillus(relative abundance,65.4-70.93%),Weissella(4.2-6.58%),Pediococcus(8.44-13.4%),and Leuconostoc(0.94-2.76%)were the predominant bacteria in both fermentation samples AA and AB at 20 days.The relative abundance of the predominant bacteria in the two groups of enzyme samples at the 20-day stage was basically the same.2.During the fermentation the Shannon index H? varies greatly in AA(2.21-6.07)and AB(2.21-6.53).The two groups of samples had the lowest diversity at the 20-day fermentation stage and the highest diversity at the 120-day stage.In addition,during the 120-day fermentation stage,due to the influence of p H and Lactobacillus entering the decline stage,the growth of miscellaneous bacteria was caused.The above results show that the 20-day fermentation stage is optimal.3.A total of 40 strains were isolated from the two Enzyme samples.At the genus level,including Lactobacillus(32 isolates),Pedicoccus(7)and Yeast(1).At the species level,17/32 strains of Lactobacillus were closely related to Lactobacillus brevis ATCC 14869,8/32 strains were closely related to Lactobacillus plantarum JCM 1149 and the other 7 strains were related to different species of Lactobacillus.7 strains of Pedicocus were closely related to Pediococus cellicola.The Yeast strian is closely related to the Wickerhamomyces anomalus VIT-ASN0.The similarity of all isolates and relatives reached 99%.4.Representatives of Lactobacillus brevis AA1,Lactobacillus plantarum AA11 and Pediococus cellicola AA12 showed high tolerance to lead(Pb)(>300 ppm)and sensitive to cadmium(<50 ppm).In addition,Lactobacillus plantarum AA11 has a good lead ion adsorption capacity.The highest adsorption rate of 100 ppm lead ion is up to 78.74%,and the accumulated amount in cell was 2.27 mg/ dry g.This study provides a basis for revealing the characteristics of changes in the microbial community structure during fermentation of Enzymes,and provides basic data for the use of Enzymes to remove heavy metal contamination in foods.