Analysis Of Microorganisms And Metabolites In The Water Fermentation Of Celery Syrup And Its In Vitro Regulation Of Mouse Intestinal Flora

Serofluid dish is a traditional Chinese salt-free fermented vegetable.It is a kind of fermented vegetable with unique flavor and rich nutrition.It has great effect on health and has broad market prospects.In Northwest China,the serofluid dish is much loved by consumers and is a staple food in the Chinese daily life,so that the researches are mostly concentrated in Shaanxi and Gansu,but fragmented and not systematic totally.At present,further systematic researches are needed in terms of fermentation mechanism,probiotic effects,and dominant microbiota of serofluid dish.In this study,the fermentation quality of serofluid dish was firstly analyzed.Then the celery was selected as the raw material,the high-throughput sequencing technology was used to explore the composition and diversity of microorganisms in the fermentation process of serofluid dish.The gas chromatography-time-of-flight mass spectrometry(GC-TOF-MS)approach was applied to analyze the changes of metabolites during the fermentation period.Simultaneously,the influence of temperature on microorganisms and metabolites was also initially explored and the relationship between the microorganisms and metabolites was further analyzed.In addition,the effects of microorganisms and metabolites in celery serofluid on the intestinal microflora in vitro were investigated by simulating the intestinal anaerobic environment system of mice.The main conclusions are as follows:1.The fermentation quality of the serofluid dish was analyzed by measuring the pH,nitrite content,the total bacterial count and sensory indicators during the fermentation process of three vegetables.The results showed that the fermentation quality of the celery serofluid dish was the best,and microbial community and metabolites in the fermentation process were dynamic change.2.During the fermentation process of the celery serofluid dish,the microbial community in the fermentation process changed with the change of fermentation time.During the entire fermentation period,the celery serofluid was dominated by the Lactobacillaceae and Saccharomycetaceae at the bacterial and fungal family level.The leading genera of bacteria were Lactobacillus and Pediococcus.Debaryomyces was the dominant fungal genus,followed by Saccharomyces.3.A total of 182 metabolites were identified by GC-TOF-MS in this experiment,mainly organic acids and amino acids.The relative content and types of metabolites showed certain changes with the fermentation time and temperature.As a result,it found that 30? may be more suitable for fermenting the celery serofluid dish to produce more beneficial metabolites to give unique flavour.Correlation analysis revealed an important link between microbial communities and metabolites of the celery serofluid.4.The microbial communities and metabolites of the celery serofluid had relatively obvious inhibitory effects on the intestinal main strain of mice-Enterococcus faecalis,and had no obvious influence on the growth of other potentially beneficial microbial communities.Results revealed that celery serofluid has a potential regulatory effect on the overall change of the gut microbiota of mice.