Transcriptome insight into lignin utilization by Curvularia clavata and identification of regulators of laccase activity

Filamentous fungi are promising organisms for lignin degradation and mineralization. However, novel lignin-degrading fungal species are underexplored. Here, we isolated a fungal strain of Curvularia clavata that can utilize lignosulfonate as the carbon source and exhibited a relative high laccase activity during growth on lignosulfonate. Comparative transcriptomic analysis of the WT strain grown on glucose and lignosulfonate indicates that lignosulfonate and/or its metabolites have a significant effect on the gene expression profiles of C. clavata J1. Three regulators of laccase activity were identified, including a methyltransferase CcLaeA and two transcription factors, Rpn-4 and Tah-1. When grown on lignosulfonate, the laccase activity of the CclaeA and rpn-4 disrupted mutants (ΔCclaeA and Δrpn-4) increased by 49.2% and 43.5%, respectively, compared to the wild-type (WT) strain, whereas the tah-1 disrupted mutant (Δtah-1) decreased by 59.2%. The transcriptional response of WT strain to glucose and lignosulfonate was determined by RNA-Seq. And the comparative transcriptomic analysis of ΔCclaeA, Δrpn-4, Δtah-1 mutants and WT strain grown on lignosulfonate were performed.