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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 15 (1993), S. 220-224 
    ISSN: 1432-0789
    Keywords: Actinomycetes ; Melanins ; Growth media ; Tropical soil ; Streptomyces spp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Melanogenic actinomycetes were isolated from cerrado soils. Starch agar with a neutral pH was the best medium for selecting pigment-producing colonies. A pigmentation screening test selected 52% of these as possible melanin producers. Tests on liquid (organic and inorganic) and solid (peptone and tyrosine) media, and enzymatic tests, confirmed about 90% as melanin producers, 68% as dihydroxyphenylalanine (DOPA)-melanin and 32% as possible other kinds of melanin producers. Melanin production occurred mostly with an organic N, or an inorganic N with an additional organic N source. An exception was observed with three strains, which were able to produce melanins with an entirely inorganic N source in the medium. Instability of melanin production was a common feature in many strains. Further characterization of melanins produced by actinomycetes compared with soil humic acids may clarify the possible role of melanogenic actinomycetes in soil organic matter formation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0789
    Keywords: Actinomycetes ; Melanins ; Infrared analysis ; Soil humic acids ; Tropical soil ; Aromatic central core
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eleven actinomycete melanins were characterized by elemental and functional group and infrared analysis. A soil humic acid from a Brazilian topsoil, a darkred latosol under savanna grassland, analysed previously, was used for comparative purposes. C, N, total acidity, COOH, and phenolic OH contents were within the ranges reported for soil humic acids and fungal melanins. Compared to the soil humic acid, the actinomycete melanins showed greater detail, indicative of higher aliphaticity. Most of these were, in varying degrees, similar to the type III IR spectra of humic acids, which are characteristically high in proteinaceous material, and with variable amounts of polysaccharides. The exceptions were two melanin spectra that showed more resemblance to the humic acid from the dark-red latosol, which belongs to the type I spectra of soil humic acids, a category that includes most soil humic acids. The probable participation of melanic actinomycetes in the formation of humic polymers in discussed.
    Type of Medium: Electronic Resource
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