Mushroom By-Products as a Source of Growth Stimulation and Biochemical Composition Added-Value of Pleurotus ostreatus, Cyclocybe cylindracea, and Lentinula edodes

Spent mushroom substrates (SMSs) and mushroom basal bodies (MBBs) are significant by-products because of their nutrient content even after harvesting. This study aimed to evaluate the effect of these two by-products, derived from <i>Agaricus bisporus</i> (Ab) and <i>Cyclocybe cylindracea</i> (Cc) cultivation, as potential growth and biochemical composition add-value enhancers of edible mushroom mycelia such as <i>Pleurotus ostreatus</i>, <i>C. cylindracea</i>, and <i>Lentinula edodes</i>. Fungal growth substrates enriched with SMS and MBB extracts significantly affected the growth of mushroom mycelia. In particular, on <i>P. ostreatus</i>, the MBBs Ab and Cc extracts determined an increase in mycelial weight by 89.5%. Also, by-products influenced mushrooms' mycelial texture, which appeared more floccose and abundant in growth. FT-IR analysis showed that <i>L. edodes</i> mycelium, grown on MBB substrates, showed the highest increase in bands associated with proteins and chitin. Results demonstrated that mushroom by-products enhance mycelial growth and confer an enrichment of compounds that could increase mycelial resistance to pathogens and make a nutraceutical improvement.