Industrial Fungal Bio-Modification of Hardwood: Parameters, Mechanisms, and Performance

This paper reconstructs mykoholz, a mid-20th-century East German, white-rot–mediated bio-modification of solid hardwood, as a missing link in fungal materials engineering. From patents, factory records, declassified reports, and recent literature, we recover process parameters (end-grain inoculation; 3-4 mo incubation in controlled vaults; staged drying/impregnation) and performance outcomes (75-90% density reduction, high porosity, stress relief) enabling uses from pencils to glass-molding and acoustic parts. We benchmark mykoholz against modern mycelium-based composites (MBCs) across substrate, process control, mechanics, energy, scalability, and environmental profile, showing complementarity: mykoholz reconfigures solid wood in situ, whereas MBCs grow moldable composites from lignocellulosic waste. We trace the 1965 industrial decline to quality variance and insufficient climate control, and show how AI-assisted bioprocessing, climate-controlled incubation, and selective delignification could resolve these limits. We propose hybrid fungal systems, and a research agenda covering standardized replication, LCA, acoustic/thermal benchmarks, and pilot-scale automation, positioning mykoholz as low-energy circular bioengineering with actionable principles for scalable, eco-compatible materials.