Biodegradation characteristics and mechanism of citrinin by Rhodotorula mucilaginosa LWJJ06 from metabolomic and transcriptomic perspectives.

Liupao tea, a type of dark tea produced through pile fermentation, is susceptible to contamination by mycotoxin citrinin (CIT), posing significant health risks due to its nephrotoxic and hepatotoxic properties. In this study, Rhodotorula mucilaginosa LWJJ06, isolated from Liupao tea fermentation samples, completely degraded 10~ 100 µg/mL of CIT within 48 h under optimized conditions (28 °C, pH: 4.0, inoculum size: 1 × 107 CFU/mL). Metabolomic and transcriptomic analyses suggested that extensive metabolic adjustments accompanied CIT degradation, including apparent reallocation of energy resources, responses indicative of oxidative stress, and changes in membrane lipid profiles potentially linked to toxin transport. Two key degradation products, dihydrocitrinin and dihydrocitrinone, were tentatively identified, and the degradation pathway was preliminarily elucidated with reduced cytotoxicity confirmed. The cell counting kit-8 cytotoxicity assay demonstrated that the degradation products were significantly less toxic to alpha mouse liver 12 cells than CIT. These findings highlighted the potential of Rhodotorula mucilaginosa LWJJ06 as a probiotic agent for mycotoxin mitigation in food systems, offering a sustainable strategy and theoretical basis for controlling mycotoxin in Liupao tea.