Lactic acid bacterium F. sanfranciscensis impairs fitness of yeast M. humilis in a synthetic wheat sourdough medium.

F. sanfranciscensis impairs the growth of M. humilis in sourdough, with bacteria dominating and consuming less maltose than when grown alone.

• Why it matters: Understanding microbial interactions in sourdough is crucial for controlling bread quality and ecosystem stability, especially as assumptions about mutualism are challenged.
• What they did: The study used a synthetic wheat sourdough medium and flow cytometry to compare co-cultures of M. humilis and F. sanfranciscensis, analyzing cell viability and metabolite consumption.
• The result: Findings reveal that F. sanfranciscensis does not support M. humilis growth through glucose cross-feeding and may even compete, indicating that their relationship is neutral or competitive rather than mutualistic.