Biochemical Profiling of Extracellular Pigment Metabolites of Aspergillus ustus Strain KUMBASBT-52

Filamentous fungi are the mesmerizing glory of an extensive variety of pigments. Compared to other microorganisms, they produce pigments of different shades as their secondary metabolites. The study intensified on the cultivation of Aspergillus ustus strain KUMBASBT-52 under submerged fermentation and extraction of extracellular pigment metabolites. The extracted pigment metabolites were analyzed via different analytical techniques. The yield of urochrome-yellow pigment extracted from A. ustus was 2.39 g/L, which is water-soluble in nature. The UV-Vis analysis exhibited absorption peaks at 300 nm and 340 nm. The FT-IR analysis transmits the incidence of different functional groups i.e. 3282cm-1 (Hydroxy group; H-bonded OH stretch), 2921cm-1 (Methylene; C-H stretch), 2111cm-1 (C≡C Terminal alkyne), 1629 cm-1 (Secondary amine; >N-H bend), 1390cm-1 (Phenol or tertiary alcohol; OH bend), 1233cm-1 (Aromatic phosphates; P-O-C stretch), 1016 cm-1 (Aliphatic phosphates; P-O-C stretch), 512cm-1 (Polysulfides; S-S stretch) and 425cm-1 (Aryl disulfides; S-S stretch). OHR-LC/MS analysis discloses the incidence of 15 bioactive endogenous metabolites, including yellow pigment metabolites 3-(2-methylpropyl)-octahydropyrrolo[1,2-a] pyrazine-1,4-dione and 5-Methoxysterigmatocystin. The A. ustus strain KUMBASBT-52 produces urochrome yellow pigments as their endogenous metabolites, which are more stable than other natural pigments and can be used as a colorant to counter the carcinogenic synthetic azo dyes.