Bacterial dynamics and diversity during traditional sauerkraut fermentaiton

To provide an effective basis for selecting the inoculant to control sauerkraut fermentation,the bacteria succession and diversity were investigated during sauerkraut fermentation. The p H of the fermentation system decreased from 7.3 at 0d to 4.1 at 8d of fermentation.Subsequently,the p H remained at approximately 4.0.Watersoluble carbohydrate( WSC) content decreased from 11.4% dry matter( DM) to 3.9% DM during the first 18 days of fermentation.The highest nitrite value was 31.3mg / kg fresh matter( FM) at 6d.At 30 d,the nitrite content descreased to 4.8mg / kg FM. The concentrations of lactic acid and acetic acid in fermented juice were 6.7g / L and 0.6g / L,respectively.The bacteria detected in the fermentation system included Acinetobacter sp.,Pseudomonas fragi,Klebsiella sp.,Citrobacter sp.,Betaproteobacteria sp. and lactic acid bacteria( LAB). The LAB contained Leuconostoc mesenteroides,Lactobacillus curvatus,Lactobacillus plantarum and Lactobacillus oligofermentans.At6 d,LAB comprised 63.8% of the bacterial population,with the heterofermentative LAB Leuconostoc mesenteroides comprising 32.9%. Subsequently,the proportion of LAB increased continuously. At 30 d,all microorganisms were LAB. Lact. curvatus comprised 21.1% of the population at 6d,41.1% at 12 d,and greater than 45% at 30 d,dominating the fermentation process. For the first time,Lact. oligofermentans was found to be involved in the fermentation.The highest level of Lact.oligofermentans( 21.1%) was detected at 12 d.Based on the above results,the dominant microorganisms involved in suan- cai fermentation were LAB and Lact. curvatus was the predominant microorganism in the fermentation. This study provides a foundation for screening the inoculant to control the sauerkraut fermentation.