Screening,identification and fermentation characteristics of nitrite degradation lactic acid bacteria from Huarong mustard
In order to reduce nitrite accumulation during the fermentation process of mustard,lactic acid bacteria were isolated from fermented mus-tard by traditional culture separation method,and the strains with excellent performance of acid production and nitrite degradation were screened.The strains were identified by morphological observation and molecular biology techniques,and their growth,acid production,nitrite resistance,gastric juice and bile salt resistance,and antibacterial ability were studied to evaluate their fermentation performance.The results showed that two superior lactic acid bacteria strains were screened and identified as Lactiplantibacillus plantarum,which were numbered as SYS-2 and SYS-4.The nitrite degra-dation rate was all higher than 90％,the pH was lower than 4.0,and the total acid contents of the two lactic acid bacteria strains reached 18.68 g/100 ml and 16.50 g/100 ml,respectively after cultivation for 24 h.They had strong tolerance to NaNO2(≤200 µg/ml),and the survival rates in simulated artifi-cial gastric juice(pH 2.5)and 0.3％bile salt solution were greater than 50％after digestion for 3 h.The two lactic acid bacteria strains had certain in-hibitory effects on pathogenic bacteria,among which strain SYS-4 had better antibacterial effect,with inhibition circle diameters for Staphylococcus aureus,Escherichia coli,and Salmonella were 22.84 mm,25.51 mm,and 19.78 mm,respectively.The screened L.plantarum SYS-2 and SYS-4 had stronger nitrite degradation ability and good fermentation characteristics,which could provide safe and high-quality microbial agents for the subse-quent production of low nitrite fermented mustard.
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