Monitoring the bacterial community during fermentation of sunki, an unsalted, fermented vegetable traditional to the Kiso area of Japan

Aims: To investigate the microbial community in sunki, an indigenous, unsalted, fermented vegetable, made from the leaves of red beet. Methods and Results: Fermenting samples were collected at 1- to 2-day intervals from four houses and investigated by culture-dependent and culture-independent techniques. PCR-Denaturing-Gradient-Gel-Electrophoresis profiles indicated that the bacterial community was stable and Lactobacillus delbrueckii, Lact. fermentum and Lact. plantarum were dominant during the fermentation. This result agreed well with that obtained by the culturing technique. Moulds, yeasts or bacteria other than lactic acid bacteria (LAB) were not detected. Conclusions: The bacterial community was stable throughout the fermentation, and Lact. delbrueckii, Lact. fermentum and Lact. plantarum were dominant. The acidic pH and lactic acid produced by LAB probably preserve the sunki from spoilage. Significance and Impact of the Study: This is the first report on the use of both culture-dependent and culture-independent techniques to study the bacterial community in sunki. A combination of culture-dependent and culture-independent techniques is necessary for the analysis of complex microbial communities.