Myco-conversion of agro-waste into by-products

Relevance and aim of the study Agriculture is a productive activity producing a large volume of agro-waste, which, if mishandled, poses health, food safety, and environmental risks. Adequate processing of agricultural waste has advantages in reducing greenhouse gas emissions and reducing fossil fuels, as well as contributing significantly to the development of new markets and job opportunities. In this context, fungi are an attractive resource for agro-waste bioprocessing into value-added by-products. Fungal mycelium growth promotes the degradation of the most recalcitrant macromolecules (e.g. lignin, hemicellulose and cellulose) and pollutants (e.g. pesticides, plastics), allowing a significant reduction in the volume of residual waste. In addition, mycelium colonizing the substrate reduces carbon losses and provides nutrients for a wide range of microorganisms that drive the diversity and composition of microbial communities and, thereby, increase biodiversity on the reuse of transformed wastes in soil. This research aimed to exploit the potential of agro-wastes to create a new chain of products obtained through technological innovation. Specifically, we sought to: i) evaluate the potential of waste for the production of low-cost mushrooms; ii) bioconvert waste into new bio-based by-products (e.g. recovery of biopolymers, nutrients, biofertilizers). Materials and methodologies used The experiment was performed on the solid fraction of corn digestate from a biogas plant located in Malalbergo (Bologna, Italy). The high level of nitrogen and lignin in the solid digestate makes it a suitable substrate for growing edible mushrooms. Cyclocybe aegerita, Pleurotus cornucopiae and Pleurotus ostreatus were grown on both corn digestate and conventional substrates. The spent substrates after mushroom production were analyzed in C and N content and structural composition using FT-IR spectroscopy. The mature fruiting bodies were collected for 3 months; the fresh weight was recorded to evaluate biological efficiency. The resulting fruiting bodies were processed to extract chitin, which was characterized by FT-IR and FT-Raman spectroscopies. Major results and findings P. ostreatus showed the highest biological efficiency and fruiting body production on the corn digestate. Pleurotus ostreatus and P. cornucopiae were both able to degrade lignin as detected by FT-IR analysis. Conclusion of your research These results confirmed the possibility of economic use of anaerobic digestate for mushroom production.