The substrate used for mushroom cultivation is primarily based on sawdust. In Korea, waste wood (domestic waste wood, construction waste wood, and forestry waste wood) is utilized as the raw material for sawdust production. However, due to the insufficient production of waste wood, the supply of high-quality sawdust required for mushroom cultivation is limited, leading to reliance on imports. Furthermore, when sawdust-based substrates are used, the sterilization process generates unpleasant odors, causing complaints from local residents. Additionally, only about one-third of the nutrients in sawdust are utilized by mushroom mycelium during the cultivation process. To address these issues and enhance the nutrient utilization efficiency of sawdust, this study aims to develop a mushroom mycelium and fruiting body cultivation technique using a mineral-based substrate.
Eringi mushroom (Pleurotus eryngii) was used as the test species, and vermiculite with a particle size of 1.0–1.5 mm was employed as the mineral matrix. Flour was used as the nutrient source for mycelial growth. The experimental conditions for optimal mycelial growth included pH (4–7), C/N ratio (10–30), flour content (10–30 wt%), moisture content (40–70 wt%), and sawdust content (0–75%). The base substrate consisted of a mixture of 75% vermiculite and 25% sawdust, with pH 5.5 and a moisture content of 67%. The control group used a traditional sawdust substrate composed of sawdust mixed with rice bran. The spawn used for inoculation was prepared by cultivating P. eryngii on a sawdust substrate, and approximately 10 wt% of the substrate was inoculated with the spawn. Mycelial growth characteristics were observed by placing the prepared substrates in cultivation molds of a fixed shape and incubating them at 22°C for 7 and 14 days under the specified experimental conditions.
The optimal conditions for mycelial growth were found to be a C/N ratio of 20, flour content of 30 wt%, and pH 6. Although mycelial growth showed a slight decrease with an increasing vermiculite content (and corresponding decrease in sawdust content), no significant difference was observed within the range of 25–75% vermiculite. Additionally, the effects of pH, C/N ratio, flour content, and sawdust content on the growth of Eringi mushroom fruiting bodies were investigated, using the same conditions as those for mycelium cultivation. Fruiting body cultivation was conducted in cultivation bottles with a capacity of 850 mL. The fruiting body yield from the sawdust substrate was 100 g. In contrast, fruiting body yield from the base substrate increased linearly with higher flour content, reaching approximately 49 g at 30 wt% flour content.
These findings suggest the potential of cultivating mushrooms using a mineral-based matrix, such as vermiculite, instead of organic materials. Although further research is required to enhance the growth of mycelium and fruiting bodies, this approach could significantly reduce waste generation by enabling the recovery and reuse of the mineral matrix after mushroom cultivation.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (2020R1A6A1A03044977)