(523e) Vegetable fermentation: What is the starter culture?

Fermentation produces thousands of foods, including pickles, cheese, and even coffee. This microbial modification of food is also a commercially and culturally relevant practice that feeds billions around the world. Despite recent interest in microbial communities of fermented foods, there has been little inquiry into the bacterial community dynamics of vegetable fermentation. Utilizing 16S rRNA amplicon sequencing, we can get a novel perspective on the microbial community of naturally fermented products such as sauerkraut and kimchi. For this work, we have partnered with local industrial producers to track the microbial composition of the product from ingredients to the supermarket shelf. In our recent kimchi work, the producer was interested in introducing a vegan version of the product (kimchi typically contains fermented seafood). To determine whether a substitution of miso for seafood confers a difference in the microbiome of kimchi fermentation, we used next-gen sequencing to analyze the microbiome before, during, and after production. The key finding is that both the vegan and nonvegan community start vastly different in composition and then converge to the same community in the final product. This result indicates that both versions would provide the same "probiotic" benefit. Most interestingly, the bacteria in the factory environment look very similar to the microbiome of the kimchi, possibly indicating that the fermentation environment plays a significant role in the final community. One can think of this as a form of terroir (similar to wine). Interestingly, this was not true of sauerkraut as we found that the environmental bacteria of the production facility were not significantly reflected in the final product, possibly due to the more selective environment of sauerkraut fermentation or the multiple-use nature of the sauerkraut producer.