Melanins are commonly produced by bacteria, fungi, plants and animals, where they play a role in many biological functions. They protect organisms against UV and ionizing radiations. Their potential applications in biotechnological industries such as cosmetics and paints, where UV protection is required, are hampered by the lack of suitable organisms or methods to produce them abundantly. We report here the production of high amounts of extracellular melanin by the fungus Gliocephalotrichum simplex in cultures supplemented with tyrosine. Their typical UV-absorbance, as well as i.r., (13)C solid-state and (1)H NMR spectra indicated that the melanin is a eumelanin, being a copolymer of dihydroxyindole carboxylic acid and dihydroxyindole, associated with some carbohydrates and proteinaceous matter. Optimal culture conditions established by a Plackett-Burman experiment, followed by a full factorial experiment based on tyrosine and peptone yielded a maximum of up to 6.6 g melanin l(-1). The high yields of extracellular melanin from G. simplex enables its use in biotechnology.

Qualitative screening of 295 fungi for laccases yielded 125 laccase positive ones, mostly basidiomycetes. Fifty of these were tested for laccase activity at pH 3.0, 4.5 and 6.0. Most showed maximum activity at pH 4.5, a few showed a broad activity range, two were optimal at pH 3.0 and only the mitosporic fungus Beltraniella sp. was best at pH 6. Most of the 25 fungi assayed at three different temperatures had an optimum at 45°C. The basidiomycete Auricularia sp. acted best at 30°C, while three others showed best activity at 60°C. This study shows the potential of screening diverse fungi for laccase with varying pH and temperature preferences for different applications.

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