Environmental Selection Shapes Bacterial Community Composition in Traditionally Fermented Maize-Based Foods from...

Natural (microbial) communities are complex ecosystems with many interactions and cross-dependencies. Among other factors, selection pressures from the environment are thought to drive the composition and functionality of microbial communities. Fermented foods, when processed using non-industrial methods, harbor such natural microbial communities. In non-alcoholic fermented foods the fermenting microbiota is commonly dominated by 4-10 species of bacteria, which make them suitable model systems to study ecosystem assembly and functioning. In this study, we assess the influence of the environment on the composition of microbial communities of traditional fermented products from Africa. We compare differences between microbial communities that are found in similar products but come from different countries, hypothesizing they experience different environmental selection pressures. We analyzed bacterial community composition in 36 samples of various cereal-based fermented foods from Benin, Tanzania and Zambia using 16S rDNA amplicon sequencing. The differential abundance analysis indicates that the bacterial communities of fermented foods from the three countries are dominated by mostly lactic acid bacteria belonging to the genera of Lactobacillus, Weisella and Curvibacter. The samples from Zambia contain the most dissimilar microbial communities in comparison with samples from Benin and Tanzania. We propose this is caused by the relatively low temperature in Zambia, suggesting that indeed environmental selection can shape community composition of fermenting microbes.