Live yeast cells have been isolated from ancient clay vessels

Yeast cells were found specifically in fermented beverages containers

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Scientists from several Israeli institutes and sciences centres have made an incredible discovery, combining two of the most amazing sciences: (micro)biology and archaeology. 

The authors presented a method for live yeast isolation from ancient clay vessels. In the report, Aouizerat et al. describe a screening for yeast cells in different matrices: beverage-related and non-beverage-related ancient vessels and sediments from several archaeological sites. They were capable of isolating yeasts from the clay containers of the fermented brews. More interestingly, the phenotypic and genotypic analysis revealed that the microorganisms were similar to the ones present in traditional African beverages and that they are descendants of the original fermenting yeast strains. 
How cool can bio-archaeology be?

Ancient fermented food has been studied based on recipes, residue analysis, and ancient-DNA techniques and reconstructed using modern domesticated yeast. Here, we present a novel approach based on our hypothesis that enriched yeast populations in fermented beverages could have become the dominant species in storage vessels and their descendants could be isolated and studied today. We developed a pipeline of yeast isolation from clay vessels and screened for yeast cells in beverage-related and non-beverage-related ancient vessels and sediments from several archaeological sites. We found that yeast cells could be successfully isolated specifically from clay containers of fermented beverages. The findings that genotypically the isolated yeasts are similar to those found in traditional African beverages and phenotypically they grow similar to modern beer-producing yeast strongly suggest that they are descendants of the original fermenting yeast. These results demonstrate that modern microorganisms can serve as a new tool in bio-archaeology research.

IMPORTANCE So far, most of the study of ancient organisms has been based mainly on the analysis of ancient DNA. Here we show that it is possible to isolate and study microorganisms—yeast in this case—from ancient pottery vessels used for fermentation. We demonstrate that it is highly likely that these cells are descendants of the original yeast strains that participated in the fermentation process and were absorbed into the clay matrix of the pottery vessels. Moreover, we characterized the isolated yeast strains, their genomes, and the beer they produced. These results open new and exciting avenues in the study of domesticated microorganisms and contribute significantly to the fields of bio- and experimental archaeology that aim to reconstruct ancient artifacts and products.

Reference: Tzemach Aouizerat et al. Isolation and Characterization of Live Yeast Cells from Ancient Vessels as a Tool in Bio-Archaeology. DOI: 10.1128/mBio.00388-19.

Celia Fortuna Rodrigues

PharmD, PhD , University of Porto