AMAZ-LIFE

This project aims to cross anthropological and microbiological expertise through an interdisciplinary approach in order to identify how the diversity of fermentation processes of Amazonian cassava beers impacts microbiological diversity and complexity, and suggests new domestication processes. It builds on a previous study involving 17 months of ethnographic fieldwork among two neighboring Amazonian indigenous groups (Maijuna and Napuruna) with distinct food systems and sensory preferences. One particular feature of these beer-making processes is that they may include a step in which cassava is chewed by humans, which can explain the presence of oral bacterial species in the final product. A complementary ethnographic fieldwork will be conducted in this project to achieve the three following objectives.

First, the investigation intends to describe through in-depth ethnography the detailed techniques used to prepare distinct cassava beers and to examine their relationships with the final beer microbiota.

Second, with oral streptococci part of the beer microbiota, we could be facing a domestication process comparable to the one coming from mouth to milk giving rise Streptococcus thermophilus. The objective is to determine whether the Streptococcus strains of these beers are undergoing adaptation to this environment. Functional adaptation will be assessed through fitness and metabolic analyses, and studies of microbial interactions. Genomic adaptation will be examined by comparison with reference genomes to identify potential genetic losses or gains.

Third, the project seeks to examine the typicity of cassava beers regarding the characterization of the microbiota and of basic physico-chemical properties, and sensory perceptions related to them. The links between the process and composition of the beers and the resulting chemical properties and microbiota will be established. In order to identify sensory perceptions locally related to the broad range of cassava beers, ethnographic fieldwork will be conducted by focusing on the sensory characteristics (odors, tastes, colors, etc.), preferences, properties, and identity aspects expressed by the Maijuna and Napuruna on them. This articulation between anthropology and microbiology will allow to examine how cultural practices shape microbial assemblages, and conversely, how microbial dynamics influence taste, texture, preservation, and social uses of these beverages.