To study the production and transformation of nitrite in the early stage of Sichuan paocai fermentation,total acidities and nitrite contents of white radish paocai fermented in the first 5 days were measured and metagenomic analysis was conducted.Results showed that the total acidity of paocai brine rapidly increased from(0.03±0.00)g/100 g in the beginning to(0.74±0.04)g/100 g in the 5th day.Nitrite content rose rapidly,reaching a peak amount(20.681 mg/L)in the first day and gradually decreased to a low level.Pseudomonas and other miscellaneous microbial genera dominated the system before fermentation started,while Enterobacter became the dominant microbe in after one day.Lactiplantibacillus quickly increased and became main genus subsequently.Genes of nitrogenase(1.18.6.1),assimilatory nitrate reductase(1.7.1.1/1.7.7.2),dissimilatory nitrate reductase(1.7.5.1),and nitrite reductase(1.7.1.15)were relatively abundant in the early stage of fermentation.A significant positive correlation was found between Lactiplantiba-cillus and total acidity and negative correlation was found between Lactiplantibacillus and nitrite content.Genes of nitrogen metabolic en-zymes was positively were correlated with most of the miscellaneous microbes.Nitrite might be reduced from nitrate by 1.7.1.1,1.7.7.2 and 1.7.5.1 and reduced further to ammonia by 1.7.1.15 nitrite metabolism might be catalyzed mainly by miscellaneous microbes while lactic acid bacteria scavenge nitrite by producing acid.
维普
万方数据