The quantitative amino acid economy of yeast reveals public versus private goods and guides syntrophic community design.

Saccharomyces cerevisiae exhibits a dynamic amino acid economy with distinct public and private pools, including five amino acids that remain privatized even in nutrient-rich conditions.

• Why it matters: Understanding amino acid exchange is crucial for deciphering microbial metabolic interactions and designing stable synthetic communities, yet the scale of this economy was previously unknown.
• What they did: The study used quantitative measurements to map production, secretion, and consumption fluxes of amino acids over 24 hours, identifying specific public goods and privatized resources in yeast.
• The result: Findings show that public amino acids like Ala are secreted and re-consumed, while privatized amino acids such as Asp sustain carbon metabolism; nitrogen limitation shifts pools toward privatization, enabling rational community design.