STUDIES ON ISOLATION, BIOPRODUCTION AND CHARACTERIZATION OF MELANIN PRODUCED FROM NEWLY SCREENED BACTERIAL CULTURES FROM DTU LAKE

Abstract

Melanins are composed of polymerized phenolic and/or indolic compounds, commonly found in organisms across all biological kingdoms. In this study, a total of 11 melanin producing bacterial strains were screened from lake water sample collected from DTU Lake, Delhi Technological University, India, using nutrient media supplemented with LTyrosine. Further these pigment producing strains were subjected for various biochemical tests to indicate the organism. Two strains RT3 and Ep1 were sent for microbial identification based on 16S rDNA molecular techniques, consensus sequences were obtained and were utilized for 16S rRNA sequence comparison and phylogenetic tree analysis. After phylogenetic identification, these two bacterial strains RT3 and Ep1 were identified as Stenotrophomonas spp. and Bacillus oleronius respectively. All the screened bacterial strains produced nearly black colored pigment which was tentatively inferred to as melanin only due to its ability to utilize L-tyrosine as precursor. One of the strains, designated RT 3, produced the maximum amount of pigment ~ 149μg/mL of bacterial culture utilized. The pigment was further characterized by UV and FT-IR spectroscopy, and its qualitative analysis was done by performing Thin Layer Chromatography and High Performance Liquid Chromatography. UV-vis wavelength scan showed the strong absorbance peaks in the region 200 to 240 nm, and further gradual decline when the wavelength is increased towards the infrared region. FT-IR and Thin Layer Chromatography results also confirmed the pigment to be melanin. However, after performing High Performance Liquid Chromatography for the synthetic and bacterial melanin pigment, no trend could be obtained for significant peak analysis in order to quantify the pigment. It still needed further improvisation by trying more solvent systems, so that the results obtained could be relatable.