Baker’s bread-making practices and house microbiota shape fungal species diversity in french sourdoughs

International audienceDomestication of plants and animals has been accompanied by domestication of microbial community for processing fermented food. Although the industrialization led to the selection and spread of specific fermenting microbial strains, there are still ongoing artisanal process that may allow the conservation of a higher microbial community diversity. We asked whether and how the diversity of human artisanal practices contribute to the conservation of microbial community diversity. We used an interdisciplinary participatory research approach including bakers, psycho-sociologists, bio mathematician and microbial ecologists, to analyse French bread making practices and their impact on microbial diversity in the low-input sourdough bread making food chain. We analysed the microbial diversity of a collection of French sourdoughs and investigated bread making practices. We found that the rupture of the dominant way of producing bread, lead to a higher diversity of bread-making practices which are beneficial for the conservation of yeast species diversity. We then realized an experiment of domestication in action where farmers grew wheat landraces and modern varieties, and bakers made flours, initiated new sourdoughs and propagated them by adding flour and water. We showed that the dynamic of sourdough microbial communities over time results from the interplay of human mediated microbial dispersion and selection. The local environment, i.e. the bakery house microbiota, is the main driver of the sourdough microbial community composition. Selection, through the use of different wheat varieties but also different baker’s practices, also appears to drive the divergence of sourdough microbial community. Overall, our results highlight the role of human artisanal practices in the dynamic and conservation of microbial community diversity