Dynamics of Microbiota in Three Backslopped Liquid Sourdoughs That Were Triggered with the Same Starter Strains

The preparation of sourdough may include the use of starter microorganisms to address the fermentation process toward specific conditions. The aim of this work was to study the dynamics of the microbial ecosystem in three liquid sourdoughs (SD1, SD2 and SD3) triggered with the same microbial strains. Lactiplantibacillus plantarum (formerly known as Lactobacillus plantarum), Saccharomyces cerevisiae and Candida lambica strains were inoculated as starters, and sourdoughs were differentiated for the fermentation conditions and for the method of starter inoculation. The analyses were performed on the three sourdoughs propagated in the laboratory for 22 days and on the sample SD1, which was transferred to a bakery and refreshed over many months. The dynamics of microbial communities were studied by plate-count analysis and metataxonomic approach. The acidity of sourdough was evaluated over time. Metataxonomic analysis highlighted a large heterogeneity of fungi microbiota in all sourdough preparations, many of them probably originated from the flour, being pathogens of plants. Few yeast species were found, and S. cerevisiae was plentiful but did not predominate over the other species, whereas the C. lambica species decreased over time and then disappeared in all preparations. The bacterial microbiota was less heterogeneous than the fungi microbiota; the species L. plantarum, Leuconostoc citreum and Levilactobacillus brevis (formerly known as Lactobacillus brevis) were always present in all sourdoughs, whereas Fructilactobacillus sanfranciscensis (formerly known as Lactobacillus sanfranciscensis) became the dominant species in bakery-propagated SD1 and in SD2 at the end of the propagation period.