**2. Green Synthesis of Metal-Based Nanoparticles Mediated by Genus** *Pleurotus*

Fungal exploration and implications in the area of nanotechnology are very significant. In previous literature, it was reported that microorganisms, including bacteria, fungi, and yeast, could be used for the synthesis of metal NPs (metal = calcium, gold, silicon, iron, silver, lead, and gypsum) [21]. We observed that fungi have received immense attention owing to their metal bioaccumulation properties, to produce metal NPs [22]. The fungal material includes mycelia, polysaccharides, and proteins are used in the formation of metal nanoparticles; metal NPs of oyster mushroom species were synthesized using mineral salts [23]. Fungi have intracellular metal uptake capabilities and maximum wall binding abilities because they have high metal tolerance plus bioaccumulation abilities [24–27]. In comparison with other plants and microbes, the mycelia of fungi provides effective hold ability in the bioreactor, as well as in agitation and high flow pressure [28]. Moreover, fungi secrete extracellular enzymes in high amounts, leading to the massive production of enzymes [29]. Reduction of the enzyme, using both intracellular and extracellular ways, help in metal NP synthesis, nanostructure, and biomimetic mineralization [30,31].

During synthesis, fungi extracts serve the function of capping and reducing agents. At the same time, the fungal mycelium exposed to the metal precursor induces fungus to liberate metabolites and enzymes for its survival [11]. Both the fruiting bodies and mycelium of the mushrooms can be utilized for the synthesis of NPs. It has been reported that the *Pleurotus* species, such as *P. ostreatus,* are capable of synthesizing NPs, both intracellularly and extracellularly, while other species, such as *P. florida*, *P. cornucopiae var. citrinopileatus*, *P. platypus*, *P. ostreatus*, *P. sajor-caju*, *P. eous*, and *P. djamor var. roseus* synthesize NPs extracellularly [32–37]. Synthesis of *Pleurotus* derived metal NPs is shown in Table 2 and Figure 1.

**Figure 1.** Graphical representation of green-synthesis of nanoparticles from *Pleurotus* (Oyster) **Figure 1.** Graphical representation of green-synthesis of nanoparticles from *Pleurotus*(Oyster) mushroom.


**Table 2.**Varieties of*Pleurotus* spp. and their nanoparticles.


**Table 2.** *Cont.*

Note: RT—room temperature; ND—not detected.
