3.3.2. Optical Research Microscopy Studies of the Fungal Hyphae

The optical research microscopy of the mycelial growth at the fringes of the colony exhibited variation in the hyphal morphology as observed through appearance of swelling/ rolling, thinning, fragmentation, and hyper-branching of the mycelia. The hyphae of all the three fungal genera sampled near the well containing NaOH (RA) (40 mg L −1 concentration) showed cell wall distortion, cytoplasmic shrinkage, oozing out of the cytoplasmic material, and hyphal fragmentation. The optical micrographs of the *Fusarium oxysporum* hyphae in NaOH (RA), Albumin (CA), and Starch (CA) ZnNPs (40 mg L −1 concentration) treatment showed extensive leakage of the cytoplasmic material from the hyphal tissue (Figure 8). The swelling of the hyphae cells can also be identified in the Thiourea (RA) ZnNPs and NaOH (RA) ZnNPs for *Curvularia lunata*, and *Macrophomina phaseolina* respectively.

**Figure 8.** Optical micrographs of the three test fungal cultures depicting cytological events such as hyphal fragmentation, clearing of the cell cytoplasm, hyphal thinning, and dissolution of the fungal cell wall on incubation with ZnO nanoparticles derived from various reducing and capping/complexing agents. (**a**) Control, (**b**) Sodium hydroxide (RA), (**c**) Thiourea (RA), (**d**) Starch (RA), (**e**) Bovine serum albumin (CA), (**f**) Starch (CA), and (**g**) Cellulose (CA). Magnification-400×. The solid arrow indicates the thickening of the hyphae, dotted arrow indicates the clearing of cell cytoplasm.
