Kate will speak about yeast and bacterial diversity in applied ecosystems and how these microbes interact to make delicious and nutritious foods and beverages. Of particular interest is the sourdough starter ecosystem, comprising of yeasts and bacteria. Sourdough fermentation is a model to study interkingdom communication and interaction between yeast and bacteria. While the species present have been comprehensively catalogued, the interactions and persistence of yeast and bacteria have not been characterised. Ongoing work in my laboratory investigates the interactions of yeast and bacteria and consider the impact of nutrient availability to persistence and activity of fermenting microbes and the impact on dough and bread composition. Saccharomyces cerevisiae is either dominant or co-dominant in every reconstructed sourdough fermentation, while Kazachstania humilis is only able to persist in a simulated dough fermentation if in combination with S. cerevisiae. Inoculating Fructilactobacillus sanfranciscensis (previously named Lactobacillus sanfranciscensis) in reconstructed sourdoughs has not been successful, and there are no antagonistic interactions between yeast and bacteria detected. Construction of the sourdough microbial communities in wheat flour dough was able to produce attractive loaves of bread, with an enrichment of small molecule volatiles. Inclusion of bran particles increased the small molecules produced. Interactions between sourdough microbes may affect longevity and diversity of the fermenting population, and these results have implications for deliberate construction of sourdough communities for bread production. Interkingdom communication in this ecosystem, like other food fermentations, can alter the flavour, aroma and health benefits for humans.