Although considered relatively sustainable, mushroom production generates significant waste at the end of cultivation. This study investigated the reuse of Spent Mushroom Substrate (SMS) to formulate new substrates for Pleurotus ostreatus cultivation. Substrates with high (higher bran content) and low (lower bran content) nitrogen levels were prepared and supplemented with 5%, 10%, or 20% SMS across three successive cycles P. ostreatus crops. Cultivation performance was evaluated based on biological efficiency, number of mushrooms, fresh weight, and number of clusters. Substrates were chemically characterized for total nitrogen, carbon, C/N ratio, electrical conductivity, and pH. The inclusion of SMS, along with reduced bran content, did not improve P. ostreatus yield and led to lower productivity compared to control substrates. No consistent correlations were observed between chemical variables and yield, although high-N substrates generally performed better. SMS reuse, under these conditions, is not viable, but results encourage further research.

Shiitake grows on lignin-rich materials and can be cultivated on wood substrate (sawdust), to which wheat, rice, and/or corn bran is added to correct the C/N ratio. In addition to the C/N ratio, another concern regarding substrate production is pH and calcium supply. Therefore, this manuscript seeks to elucidate the agronomic parameters of shiitake mushrooms (Lentinula edodes) cultivated with different doses of calcium carbonate (CaCO₃) and gypsum (calcium sulfate, CaSO₄) in a substrate based on eucalyptus sawdust. Three doses of carbonate (0, 1, and 2%) and three doses of gypsum (0, 2.5, and 5%) were used, totaling nine treatments. Two experiments were conducted, each with a different strain (LED 19/11 and LED 22/02). The results indicate that gypsum supplementation is not required, as it led to a decrease in yield and biological efficiency. Conversely, the incorporation of 1% calcium carbonate enhanced productivity in the LED 19/11 strain. Calcium source and dosage significantly influenced the agronomic performance of L. edodes, with 1% calcium carbonate providing the most consistent positive effects on yield and biological efficiency. These findings emphasize the importance of strain-specific mineral management to optimize productivity and substrate chemical balance in shiitake cultivation.

The valorization of agro-industrial residues is essential for advancing circular bioeconomy systems. This study integrated the natural colorant and edible mushroom industries by evaluating annatto (Bixa orellana) residues as substrates for Pleurotus ostreatus cultivation. Two experiments were conducted, testing field and industrial residues at three incorporation levels (32.5%, 42.5%, and 52.5%, w/w on a dry weight basis) combined with different supplementation strategies (corn bran, wheat bran, and their mixture) in a completely randomized design. Field residues showed greater yield and biological efficiency, while industrial residues exhibited higher variability. Total yield reached 38.92%, while the lowest value was 24.28%, representing an increase of up to 65% depending on residue origin and supplementation strategy. Biological efficiency exceeded 140% under optimal conditions, with gains above 70% compared to the lowest-performing treatments. Field residues also promoted a higher number of bunches and greater average bunch mass. Overall, substrate origin, supplementation, and residue proportion were decisive for fungal performance, demonstrating that annatto residues are promising low-cost substrates for scalable mushroom production within circular economy systems.

Mushroom production is a sustainable practice but requires improvements, such as in Lentinula edodes (Berk) Pegler cultivation, which has high water and labor demands. In this context, this study proposed replacing the traditional primordia induction method by submersion with a water injection method. Two primordia induction methods (submersion and injection) and two cultivation block formats were compared: rectangular cube (2 kg) and cylindrical (3.5 kg). The substrate, composed of eucalyptus sawdust (72%), wheat bran (12.5%), rice bran (12.5%), CaCO₃ (1%), and CaSO₄ (2%), was inoculated with strain LED 19/11 and incubated for 80 days at 26 ± 5 °C and 85 ± 15% humidity. After this period, the blocks were washed and transferred to the production environment. Fruiting was induced either by submersion or water injection, and production was evaluated over four harvest flushes. The 2 kg blocks had higher yields with submersion (16.62%), while the 3.5 kg blocks responded better to injection (13.01%), showing more homogeneous production. Increasing the substrate quantity contributes to greater harvest stability across production cycles. Water injections proved to be a viable alternative, reducing handling and facilitating large-scale production. The use of this technique demonstrates great importance in reducing water use and also the need for labor in cultivation.