Characterization of Brown-Black Pigment Isolated From Soil Bacteria, Beijerinckia Fluminensis

Mahesh Haribhau Joshi, Ashwini Ankush Patil, Ravindra Vithal Adivarekar*

Department of Fibers & Textile Processing Technology, Institute of Chemical Technology (ICT), 
Matunga, Mumbai 400 019, Maharashtra, (INDIA)

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ABSTRACT – DOI: https://dx.doi.org/10.47204/EBR.3.1.2022.018-029

Melanin is a pigment that is ubiquitous in nature, being found in most organisms including animals, microorganisms and humans. It is a dark-brown or black pigment formed by the oxidative polymerization of phenolic compounds. These high-molecular-weight pigments have been extensively studied and are characterized as negatively charged amorphous compounds with quinone groups. Till date the function of melanin is not accurately defined but the extensive research over last decade, identifies it as a potential UV protectant. In this study; melanin producing microorganism was isolated from soil obtained from iron ore mine. The soil was enriched in modified Ashby’s glucose broth for 15 days at 30°C further to which it was isolated on modified Ashby’s agar at 30°C for 7 days, the colonies showing pigmentation were selected for further study. Conditions were optimized for maximal production of melanin pigment. Effect of carbon, nitrogen, amino acids and metal salts on pigment production were studied. The pigment was extracted in alkaline conditions and was characterized by UV-VIS spectroscopy for λ-max. FTIR was done to identify the native functional groups and XRD was performed to identify the fine structure of the melanin. TGA analysis of pigment was done to check its thermal stability. SEM was carried out to check size and shape of the melanin pigment. The melanin pigment was also analyzed for UV protectant property which was studied by exposure of both melanized and non-melanized cells to UV light at 254nm.