Melanin Extraction and Identification

Melanin pigment extraction and purification process was carried out following the Gadd (1982) protocol with some modification. After 10 days of incubation, the culture was centrifuged at 10,000 rpm for approximately 10 min, the supernatant was discarded, and pellets were rinsed with distilled water and then collected for the extraction step. Melanin was recovered from yeast biomass by autoclaving it with 1N NaOH. In order to obtain the supernatant containing the desired melanin pigment, centrifugation of the treated biomass for about 10 min at 8,000 rpm was performed. After that, concentrated HCl was added to acidify the supernatant to pH 2 followed by a centrifugation step for 10 min at 10,000 rpm, which resulted in precipitating the melanin pigment. The extracted melanin was then dried in a dehumidified environment and characterized using ultraviolet-visible (UV-Vis) spectrophotometry, Fourier transform-infrared spectroscopy (FTIR), elemental analysis, and scanning electron microscopy (SEM) (Elsayis et al., 2022).