Pleurotus ostreatus is found in dead and living tree branches, especially hornbeam (Carpinus sp.), beech (Fagus sp.), willow (Salix sp.), poplar (Populus sp.), birch (Betula sp.) and the common walnut (Juglans regia) trees [51]. This species produces grouped fruiting bodies of various sizes, similar to oyster mushroom colonies. The fruiting body is pink, gray-to-dark brown, and is 4 to 15 cm in size. In the wild, its offspring generally appear between October and November (Figure 2). However, they can be encountered in mild winters or in early, warm springs. Their cap is 3–15 cm in diameter; broadly convex, flat or depressed flat; kidney shaped-to-fan shaped in outline, or nearly spherical when growing on tree trunks; young and fresh and somewhat greasy; bald; pale-to-dark brown; fade to buff; sometimes slowly fading and becoming two-toned; and the edge is slightly curled when young [52]. Gills can run down the trunk (or pseudo stem); close, short gills are common; and can be whitish or grayish, turning yellowish with age and sometimes with brownish edges [52]. A salient feature of these gilled mushrooms is their ability to capture and feed nematodes to the gills using a “lasso” made of hyphae. Their stem is whitish, hairy to velvety, and hard. Moreover, their flesh is thick, white and unchanging when cut.

These mushrooms are edible, in addition to having several important applications in biotechnological [7], nutraceutical [15,22,53], medicinal [54,55,56,57], and environmental fields [12,58]. Due to their exceptional ligninolytic attributes, the Pleurotus genus is considered as one of the most extensively investigated types of white-rot fungi. These species also have a significant role in the global initiative towards the “zero waste economy”, as a result of their ability to convert or biodegrade waste for biomass production using various enzyme properties, such as endoglucanase and laccase [12]. This distinguished role of Pleurotus spp. in the biodegradation of agro-industrial residues has been confirmed by many published reports, such as those published by Kumla et al. [59], Mahari et al. [60], Durán-Aranguren et al. [18], Ogidi et al. [61], Caldas et al. [15], and Melanouri et al. [11,12,30,31,62].

In the Pleurotus mushroom cultivation industry, it is important to meet the increased demands of human consumption of Pleurotus mushrooms, for which new methods of mushroom cultivation are needed to reduce global waste and increase mushroom productivity [34,60]. The cultivation of Pleurotus mushrooms depends on both intrinsic factors (i.e., substrate type, pH, C:N ratio, levels of spawning, surfactants, the content of N, C and moisture) and extrinsic factors, which include temperature, relative humidity, luminosity, air composition, and light [30,31,36,58,60,62,63]. The growth and cultivation of mushrooms can be achieved using growth media or substrates, which have a vital impact on the functional, chemical, and sensorial characteristics of mushrooms [58,64,65]. Solid substrates can be used traditionally in cultivating many species of mushrooms for fruiting body formation, which usually needs several months with a non-stable quality of harvested materials [66]. The technology of solid phase cultivation in the bioreactors of mushrooms can reduce the required time for producing the biomass, depending on the control of several physical process parameters, such as the aeration temperature and pH [66]. This technology may include the production of mushrooms in submerged liquid culture or sterilized solid substrates inside static or mixed chambers with a reduced amount of water, compared to submerged liquid cultivations, which allows for a nature-like growth of mycelium on the substrate [66].