Dichomitus squalens partially tailors its molecular responses to the composition of solid wood

PD was supported by a grant of the Netherlands Scientific Organization NWO 824.15.023 to RPdV. The Academy of Finland grant no. 308284 to MRM is acknowledged. Part of the research was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research, located at the Pacific Northwest National Laboratory in Richland, WA, USA. The work conducted by the U.S. Department of Energy Joint Genome Institute (JGI), was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE‐AC02‐05CH11231. CSL was supported by the CatchBio program. White‐rot fungi, such as Dichomitus squalens, degrade all wood components and inhabit mixed‐wood forests containing both soft‐ and hardwood species. In this study, we evaluated how D. squalens responded to the compositional differences in softwood [guaiacyl (G) lignin and higher mannan content] and hardwood [syringyl/guaiacyl (S/G) lignin and higher xylan content] using semi‐natural solid cultures. Spruce (softwood) and birch (hardwood) sticks were degraded by D. squalens as measured by oxidation of the lignins using 2D‐NMR. The fungal response as measured by transcriptomics, proteomics and enzyme activities showed a partial tailoring to wood composition. Mannanolytic transcripts and proteins were more abundant in spruce cultures, while a proportionally higher xylanolytic activity was detected in birch cultures. Both wood types induced manganese peroxidases to a much higher level than laccases, but higher transcript and protein levels of the manganese peroxidases were observed on the G‐lignin rich spruce. Overall, the molecular responses demonstrated a stronger adaptation to the spruce rather than birch composition, possibly because D. squalens is mainly found degrading softwoods in nature, which supports the ability of the solid wood cultures to reflect the natural environment. Publisher PDF