Effect of Different Incubation Temperatures, Times, and Colored Lights on Fungal Biomass and Black Pigment (Melanin) Production in Exophiala crusticola

Background: Adverse effects of synthetic pigments used in pharmaceutical and food industries and etc, have created a tendency toward the application of natural pigments. Environmental conditions are important factors in the growth and physiological function of different organisms. The aim of this study was to evaluate the growth rate of fungal biomass and production rate of black pigment (melanin) in fungus Exophiala crusticola under different incubation time, temperature, and light conditions to obtain an optimal condition for their production. Materials and Methods: After obtaining an optimal incubation temperature, cultured fungus in potato dextrose agar and broth media was exposed to blue, yellow, white, red, green, and darkness light conditions with 14-35 days of incubation times. The average amount of produced dry weight of fungal biomass and pigment were measured, and the results were statistically analyzed with SPSS software ver.22. Results: Suitable incubation temperature for fungal growth was 22°C.The maximum average amount of fungal biomass (0.17 g)and pigment production (OD = 0.94) were after 35 days of incubation (p< .05) and under yellow light (0.135 g) (OD= 0.98), respectively (p< .05). Conclusion: By optimization the incubation time, temperature, and light for the growth and production of pigment in fungus E. crusticola, it is possible to produce a large amount of fungus and its related pigment in order to be utilized in a variety of industrial and pharmaceutical use, and etc. Also, due to the fungus rapid growth in response to the yellow light, it is possible to use this feature in isolation and early diagnosis of this fungus in suspected pathogenesis cases.