Yarrowia lipolytica

Yarrowia lipolytica accumulates lipids to extraordinary levels—up to 50% of cell dry weight—when nitrogen becomes limiting while carbon remains available. This metabolic response parallels caloric restriction physiology: the yeast senses nutrient imbalance and shifts from growth toward storage and stress resistance. Understanding how Y. lipolytica integrates nutrient signals and redirects metabolism illuminates the physiological changes underlying caloric restriction's effects on longevity.

The lipid accumulation response involves major metabolic reprogramming. When nitrogen limits growth, Y. lipolytica continues consuming carbon but channels it toward triglyceride synthesis rather than biomass. This stored fat represents an energy reserve for surviving extended nutrient limitation—a bet-hedging strategy where current growth is sacrificed for future survival capacity. The regulatory systems controlling this switch involve pathways (TOR, protein kinases) implicated in yeast longevity.

Y. lipolytica has become an industrial platform for producing lipid-derived chemicals and biofuels. Engineering the yeast's natural lipid accumulation pathways enables production of fatty acids, biodiesel precursors, and specialty lipids. This biotechnological application emerges directly from understanding the yeast's stress-response physiology. Basic research on how fungi respond to nutrient limitation—motivated by questions about caloric restriction and aging—yields practical applications for sustainable chemical production.