Transcriptomic Insights into Caffeine Degradation Pathways in Desarmillaria tabescens.

Caffeine contamination threatens ecosystems and human health, with conventional remediation methods facing limitations. This study identified Desarmillaria tabescens as a potent caffeine-degrading fungus, achieving efficient degradation under optimized conditions (malt extract medium, 900 mg/L caffeine, 28 °C, pH 8). HPLC analysis revealed key intermediates such as theobromine and 3-methylxanthine, confirming a branched catabolic pathway involving N-demethylation and C8 oxidation. Transcriptomic profiling identified nine consistently upregulated cytochrome P450 genes as core catalytic components, with three adjacent to a polyketide biosynthetic gene cluster potentially supporting oxidative reactions. A three-phase "Stress-Degradation-Homeostasis" regulatory model was proposed, coordinating detoxification, energy metabolism, and secondary metabolism. These findings advance understanding of fungal caffeine degradation mechanisms and provide valuable genetic resources for bioremediation and low-caffeine product development.