Understanding how Saccharomyces cerevisiae naturally adapts to varying nutrient conditions is essential for optimizing metabolic engineering and bioprocess applications. While carbon-limited metabolism has been extensively studied, the impact of nitrogen availability remains less explored. This study utilizes a coarse-grained kinetic model that integrates metabolism, signaling, and gene regulation to investigate yeast behavior under carbon- and nitrogen-limited conditions. The model effectively captures distinct metabolic shifts in chemostat cultures, particularly the transition to overflow behavior, across different carbon-to-nitrogen (C/N) ratios. The analysis examines metabolic trade-offs between flux distribution and biomass accumulation, providing insights into differential metabolic regulation. Findings indicate that protein activity plays a more significant role than protein expression in driving metabolic adaptations. Additionally, ATP homeostasis explains the metabolic shift by linking energy demands to nutrient availability. This work advances the understanding of yeast metabolism and provides a computational framework for further studies on yeast physiology.
