Enhanced laccase production from Funalia trogii by addition of p-coumaric acid via a specific mechanism of gene activation and a growth–defense trade-off

A green strategy for enhancing laccase production by Funalia trogii in submerged fermentation using p-coumaric acid (pCA) as an inducer was investigated. Supplementation with 0.026% (w/v) pCA increased extracellular laccase activity to a maximum of 9.82 U/mL without suppressing biomass accumulation. Transient increases in intracellular CAT and SOD activities indicated a moderate oxidative-stress response during the early induction phase. Comparative RNA-seq further revealed selective upregulation of two laccase genes (Cluster-205.3418 and Cluster-205.4519), together with repression of DNA replication/cell-cycle pathways and changes in P450-associated metabolism, ABC transporters, and redox-related processes. These results suggested a dual-action mechanism in which pCA functioned as a specific transcriptional activator of the two laccase-associated transcripts while simultaneously eliciting stress-associated transcriptional reprogramming, which were consistent with a shift from growth-associated programs toward defense and secretion.