Making yogurt with the ant holobiont uncovers bacteria, acids, and enzymes for food fermentation.

Milk fermentation has a rich history in which food culture, the environment, and microbes intersect. However, traditional practices and their associated microbes have largely been replaced by industrial processes. We investigate a historical fermentation originating from Turkey and Bulgaria - ant yogurt. By examining the traditional practice, gastronomic applications, and experimentally derived yogurts, we uncover that the red wood ant holobiont facilitates fermentation. Bacteria hosted by the ants can proliferate in the milk. Specifically, live ants contribute lactic and acetic acid bacteria, including Frutilactobacillus sanfranciscensis, normally related to sourdough. Consequently, the bacterial community introduces lactic and acetic acid, while the ants provide formic acid, collectively advantageous for yogurt acidification and coagulation. Last, the ants and bacteria produce potential casein-active proteases that may further alter the yogurt texture. Our findings highlight the value of integrating traditional and biological frameworks to uncover the origins and applications of fermented food microbes.