Catechin-driven dual metabolic modulation enhances docosahexaenoic acid biosynthesis and oxidative stability in Schizochytrium sp.

This study investigated the application of catechin to achieve concurrent improvement in docosahexaenoic acid (DHA) yield and oxidative resilience of microbial lipids in Schizochytrium sp. Process optimization established that 20 mg/L catechin increases 24.0% lipid and 42.9% DHA yield via redirected carbon flux. Mechanistic investigations revealed enhanced polyketide synthase expression redirecting acetyl-CoA toward polyunsaturated fatty acids (PUFAs) synthesis, coupled with phosphoenolpyruvate carboxylase inhibition favoring pyruvate flux. Concurrently, catechin attenuated intracellular oxidative stress, reducing cellular reactive oxygen species and malondialdehyde by 34.8% and 35.1%. Crucially, the high-PUFAs lipid exhibited superior oxidative stability across 360-day storage. At 40 °C, acid value remained below 4.0 mg KOH/g, demonstrating enhanced robustness despite elevated unsaturation. This phenomenon was further demonstrated to stem from the contributory role of endogenously co-enriched carotenoids toward exceptional DHA retention. This strategy establishes a promising framework for sustainable production of oxidatively stable, DHA-enriched functional lipids suitable for nutraceutical and infant formula applications.