Asmaa Elsayis1, Sahar W M Hassan1, Khaled M Ghanem2, Heba Khairy3. 1. National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt. 2. Department of Botany and Microbiology, Faculty of Science, Alexandria University, Alexandria, Egypt. 3. Department of Botany and Microbiology, Faculty of Science, Alexandria University, Alexandria, Egypt. heba.khairy@alexu.edu.eg.
Abstract
BACKGROUND: Melanins are one of the magnificent natural pigments synthesized by a wide range of microorganisms including different species of fungi and bacteria. Marine black yeasts appear to be potential prospects for the synthesis of natural melanin pigment. As a result, the goal of this research was to isolate a marine black yeast melanin-producing strain and improve the culturing conditions in order to maximize the yield of such a valuable pigment. RESULTS: Among five locally isolated black yeast strains, the only one that demonstrated a potent remarkable melanin pigment production was identified using ITS rDNA as Hortaea werneckii AS1. The extracted pigment's physiochemical characterization and analytical investigation with Ultraviolet-Visible (UV) spectrophotometry, Fourier Transform-Infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM) confirmed its nature as a melanin pigment. The data obtained from the polynomial model's maximum point suggested that CaCl2, 1.125 g/L; trace element, 0.25 ml/L; and a culture volume 225 mL/500 mL at their optimal values were the critical three elements impacting melanin production. In comparison with the baseline settings, the response surface methodology (RSM) optimization approach resulted in a 2.0 - fold improvement in melanin output. CONCLUSIONS: A maximum melanin yield of 0.938 g/L proved the halotolerant H. werneckii AS1 potentiality as a source for natural melanin pigment synthesis 'when compared to some relevant black yeast strains' and hence, facilitating its incorporation in a variety of pharmaceutical and environmental applications.
BACKGROUND: Melanins are one of the magnificent natural pigments synthesized by a wide range of microorganisms including different species of fungi and bacteria. Marine black yeasts appear to be potential prospects for the synthesis of natural melanin pigment. As a result, the goal of this research was to isolate a marine black yeast melanin-producing strain and improve the culturing conditions in order to maximize the yield of such a valuable pigment. RESULTS: Among five locally isolated black yeast strains, the only one that demonstrated a potent remarkable melanin pigment production was identified using ITS rDNA as Hortaea werneckii AS1. The extracted pigment's physiochemical characterization and analytical investigation with Ultraviolet-Visible (UV) spectrophotometry, Fourier Transform-Infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM) confirmed its nature as a melanin pigment. The data obtained from the polynomial model's maximum point suggested that CaCl2, 1.125 g/L; trace element, 0.25 ml/L; and a culture volume 225 mL/500 mL at their optimal values were the critical three elements impacting melanin production. In comparison with the baseline settings, the response surface methodology (RSM) optimization approach resulted in a 2.0 - fold improvement in melanin output. CONCLUSIONS: A maximum melanin yield of 0.938 g/L proved the halotolerant H. werneckii AS1 potentiality as a source for natural melanin pigment synthesis 'when compared to some relevant black yeast strains' and hence, facilitating its incorporation in a variety of pharmaceutical and environmental applications.
Authors: Zheng Wang; Tanya Tschirhart; Zachary Schultzhaus; Erin E Kelly; Amy Chen; Eunkeu Oh; Okhil Nag; Evan R Glaser; Eunkyoung Kim; Pamela F Lloyd; Paul T Charles; Weiyao Li; Dagmar Leary; Jaimee Compton; Daniel A Phillips; Ali Dhinojwala; Gregory F Payne; Gary J Vora Journal: Appl Environ Microbiol Date: 2020-02-18 Impact factor: 4.792