Old oil palm trunk fibres: A viable alternative for Ganoderma lucidum (Curtis) P. Karst cultivation

Oil palm trunks (OPT) present a major waste management challenge in Malaysia. This study evaluated OPT fibres as a sustainable alternative substrate to traditional rubberwood sawdust (RWS) for Ganoderma lucidum cultivation across five formulations (0–100% OPT substitution). Notably, 100% OPT (Formulation D) achieved the highest yield (30.40 ± 7.42 g/kg) and biological efficiency (15.20 ± 3.88%), producing larger fruiting bodies with enhanced carbohydrate (19.0%), protein (10.9%), crude fibre (16.3%), and potassium content. Ethanolic extracts from this formulation also exhibited superior bioactive properties, including high total phenolic (220.66 ± 10.52 mg GAE/g) and triterpenoid (450.33 ± 0.96 mg UAE/g extract) contents, alongside potent antioxidant activity (EC 50 : 66.83 ± 0.41–240.63 ± 1.95 μg/mL). These findings demonstrate that OPT fibres are a highly viable, eco-friendly alternative substrate that reduces RWS reliance while offering an effective strategy for agro-waste valorization and sustainable mushroom production.