From waste to resource: Sustainable reuse of spent shiitake mushroom substrate in subsequent production cycles

The valorization of agricultural waste a substrate in mushroom cultivation promotes a circular economy and environmental sustainability. However, after food producing, a byproduct spent mushroom substrate (SMS) is generated. Reusing SMS in new mushroom production cycles presents an opportunity for recycling and cost reduction. This study aimed to utilize SMS from shiitake (Lentinula edodes) cultivation in subsequent cycles while reducing the bran concentration in the substrate. Three cultivation cycles were conducted using two initial substrates (high-N and low-N). SMS was added at 5, 10, and 20% w/w, along with a control formulation without SMS. Results indicated that reducing bran in the low-N substrate decreased shiitake yields, regardless of SMS addition. SMS was effective in the third cycle, particularly for the high-N substrate with 5 or 10% SMS. The effectiveness of replacing bran with SMS depended on nutrient availability, especially nitrogen. Further studies should explore the economic feasibility, energy consumption, emissions, and carbon sequestration associated with this technology.