Characterization of brown-black pigment isolated from soil bacteria, Beijerinckia fluminensis

Abstract

Melanin is a ubiquitous pigment found in most organisms, it is a dark-brown or black pigment formed by the oxidation of phenolic compounds. They are negatively charged amorphous compounds having quinone groups. In this study; melanin-producing microorganism was isolated from soil obtained from iron ore mine. The soil was enriched in modified Ashbys glucose broth for 15 days at 30{degrees}C further to which it was isolated on modified Ashbys agar at 30{degrees}C for seven days; the colonies showing pigmentation were selected for further study. Conditions were optimized for maximal production of melanin pigment. The effect of carbon, nitrogen, tyrosine, and metal salts on pigment production was studied. Alkaline conditions were used to extract the pigment from cells, further characterized by UV-VIS spectroscopy for {lambda}-max. FTIR was done to identify the native functional groups, and XRD was performed to determine the melanins structure. TGA analysis was done to check its thermal stability. SEM was carried out to check the 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.