Characterization of melanin pigment produced by Aspergillus nidulans

Abstract

Although most of the Ascomycetes present DHN-melanin, some reports suggest that A. nidulans does not produce this type of melanin. In this study, we analyzed the pigment extracted from highly melanized strains (MEL1 and MEL2) of Aspergillus nidulans to determine the type of melanin present in this fungus. Our results showed that the pigment produced by MEL1 and MEL2 mutants possesses physical and chemical properties and UV- and IR-spectra very similar to synthetic DOPA-melanin. The characterization of this pigment in terms of its degradation products indicated the presence of indolic units, which were also found in synthetic DOPA-melanin. The analyses of the elemental composition showed that the pigment extracted from these mutants has a high percentage of nitrogen and, therefore, it cannot be DHN-melanin, which presents only trace of nitrogen. This observation was confirmed in the test with tricyclazole because this inhibitor of DHN-melanin biosynthesis did not suppress pigment production in the MEL1 and MEL2 strains. On the other hand, in a medium containing tropolone, an inhibitor of DOPA-melanin biosynthesis, the dark pigmentation of the colonies was not observed indicating that this compound inhibited melanin production in these strains. Taken together, the results obtained in this study indicate that melanin produced by these mutants is DOPA type, representing the first report on characterization of this type of melanin in A. nidulans.

Purification and characterisation of a sulphur rich melanin from edible mushroom Termitomyces albuminosus Heim

“…tritici, Magnaporthe grisea, Alternaria alternata, Colletotrichum lagenarium, Cochliobolus heterostrophus (Henson et al 1999), Paecilomyces variotti (Babitskaya et al 2000a), Rhizoctonia solani (Chen et al 2015) and Aspergillus spp. (Babitskaya et al 2000a; Schmaler-Ripcke et al 2009; Gonçalves et al 2012; Pal et al 2013). Melanins are reported from mushrooms such as Agaricus bisporus (Mendoza et al 1979), Inonotus obliquus (Babitskaia et al 2000b; Babitskaya et al 2002), and Schizophyllum commune (Arun et al 2015).…”

Spectrophotometric detection of Pigments from Aspergillus and Penicillium isolates

“…Our results are in confirmation with this study, showing Penicillium isolates DUMB12 and DUMB15 producing orangered pigment soluble in ethyl acetate. Even in case of Aspergillus nidulans, dark brown melanin pigments are produced in the mycelium [9]. In our study, the Aspergillus isolate DUMB14 produced brown pigment soluble in ethyl acetate.…”

“…The present result clearly indicated observation of orange colour and detection of the compound by spectrophotometry. Species of Aspergillus are known to produce different coloured pigments including melanins [9]. Probably, the strains tested here could produce related pigments.…”

“…and Aspergillus sp. have been found to produce different kinds of pigments [9,17]. Hence, selection of fungal isolates was found to be appropriate for pigment detection and analysis.…”

“…However, various types of fungal pigments may be exploited in biotechnology industry. Common fungal pigments detected belong to the group of melanins, carotenoids, lycopene and xanthophylls [8,9,10,11]. These pigments offer protection to fungi and show diverse biological activity [12,13].…”