Our research investigates how ingredient supplementation in sourdough starters influences the growth dynamics of Saccharomyces and Galactomyces species, aiming to understand how microbial composition affects the quality of baked sourdough. Saccharomyces is a yeast commonly used in bread-making, producing carbon dioxide and ethanol essential for leavening. In contrast, Galactomyces is a fungus typically associated with dairy fermentations, which may compete with Saccharomyces under certain conditions. The research examines how flour supplementation impacts the balance between these species and compares the microbial dynamics of sourdough starters to kefir fermentation. By isolating and sequencing microbial colonies and performing metagenomic and whole-genome analyses, this study provides insights into microbial interactions in fermented foods. These findings have practical implications for optimizing fermentation processes and understanding the role of nutrient supplementation in shapin