Comparison of microbial communities and physiochemical characteristics of two traditionally fermented vegetables

Guangxi Suansun (Guangxi SS) and Guangxi Suancai (Guangxi SC) are two kinds of traditionally fermented vegetables consumed as cooking ingredients in Guangxi Province, China, for thousands of years. However, little is known about their microbial communities as well as the differences between them. Thus, this study was aimed to investigate and compare the physicochemical indexes as well as the bacterial and fungal profiles of Guangxi SS and Guangxi SC. Results showed that the titratable acidity, lactic acid and acetic acid content in SS were significantly higher than those in SC, while the salinity of SS was significantly lower than that in SC, and the nitrite contents in all samples were are far lower than the limit of nitrite contents in fermented vegetables. Firmicutes, Proteobacteria, Ascomycota and Basidiomycota were the main phyla observed in both SS and SC samples. Lactobacillus, Serratia, Stenotrophomonas and Lactococcus were the major bacterial genera in both SS and SC samples, the predominant fungal genera in SS group were Kazachstania, Debaryomyces and Pichia, while the major genera in SC group were Kazachstania, Debaryomyces and Nakaseomyces. At the species level, Lactobacillus acetotolerans, Pichia kudriavzevii, Debaryomyces hansenii, Pichia norvegensis, Kazachstania exigua and Kazachstania humilis were the major species observed in SS, while L. delbrueckii, L. fermentum, L. aviarius, and Pichia kudriavzevii and Debaryomyces hansenii were the predominant species in SC. Salinity was found to be more strongly correlated to the bacterial and fungal communities of both SS and SC than other physicochemical factors (pH, the titratable acidity, lactic acid and acetic acid content). This study provided detailed insight into the microbial communities of Guangxi SS and Guangxi SC, and the findings may help understand the microbial structures of Chinese traditional fermented vegetables.