Transcriptional reprogramming in Trametes versicolor reveals gene candidates involved in universal stress response to hydrothermal liquefaction aqueous phase

Industrial wastewater contains a variety of persistent pollutants that are difficult to treat and pose significant risks to ecosystems. One such waste stream, hydrothermal liquefaction (HTL) aqueous phase (AP), is a nutrient-rich yet toxic byproduct generated during the conversion of biomass to biocrude oil. APs are chemically heterogeneous, posing substantial challenges for detoxification, nutrient reclamation, and commercial application of HTL technology. Fungi exhibit a wide breadth of metabolic capabilities that respond dynamically to their environment, making them promising candidates for degrading or transforming recalcitrant compounds from waste streams. Understanding the genetic basis of fungal tolerance in such environments is critical to fully realize their bioremediation capacity. This work leverages transcriptomic analyses to identify gene families broadly associated with fungal stress tolerance in Trametes versicolor challenged by three distinct APs. Upregulated genes encoding NAD(P)-binding proteins, alpha/beta-hydrolases, aldo/keto reductases, and cytochrome P450s were identified across all conditions, along with concomitant changes in biochemical composition of the APs. These results build greater understanding of fungal responses to HTL-AP exposure and identify gene candidates for future functional validation, a crucial first step toward the development of stress-tolerant strains capable of reclaiming nutrients from diverse and hostile wastewater environments.