Screening and characterization of Auricularia delicata strain for mushroom production under tropical temperature conditions to make use of rubberwood sawdust

The renewal of rubber trees produces a huge amount of wood waste yearly. Auricularia delicata is an edible wild mushroom species occurring naturally in the tropics. This work aimed at screening an A. delicata strain suitable for cultivation under the tropical temperature conditions to make use of the rubberwood waste. Chemical analysis showed that rubberwood was suitable for mushroom cultivation. Two new A. delicata strains were isolated. Optimal carbon source, inorganic and organic nitrogen sources, culture temperature and medium pH for strain A. delicata were determined for mycelial growth. Optimal temperature range for fruiting body differentiation was 20-28 degrees C. 5 tested substrate formulations with rubberwood sawdust as main composition significantly affected fruiting body differentiation time; the best formulation contained 68% rubberwood sawdust. At an industrial scale culture, the average mushroom yield was 750 +/- 60 g/kg substrate. The micronutrient contents of the cultured mushrooms were higher than those of the wild mushrooms. The spent substrate was found to be a good organic fertilizer. Results show a novel utilization of rubberwood waste in producing A. delicata mushroom and simultaneously producing organic fertilizer in tropical regions. A. delicata was proposed as a novel species for mushroom cultivation especially in the tropical and sub-tropical regions.