Fermentative Production of Melanin by the Fungus Auricularia auricula Using Wheat Bran Extract as Major Nutrient Source

Abstract

Melanin is a natural pigment with great development potential as a healthful food colorant. Low cost fermentation medium using wheat bran extract as a major nutrient source, was evaluated for production of melanin from the fungus Auricularia auricula in submerged culture. Effects of wheat bran extract, l-tyrosine and CuSO₄ on tyrosinase activity and melanin yield were investigated. Results showed that wheat bran extract, l-tyrosine and CuSO₄ concentrations influenced tyrosinase activity and increased melanin yield. Box-Behnken design indicated the following optimal medium composition: wheat bran extract 26.80% (v/v), l-tyrosine 1.59 g/L and CuSO₄ 0.11 g/L. Under these conditions, the highest melanin yield (519.54 mg/L) was obtained. The present study avoids the use of purified tyrosinase, expensive chemical methods or the cumbersome extraction of melanin from animal or plant tissues. These results might provide a reference for the development of a cost-effective medium for commercial production of melanin used in food industry.