Abstract:

In order to improve melanin production by Streptomyces G-HD-4 fermentation, the optimal conditions for fermenting L-tyrosine by this strain were investigate by single factor and uniform design methods. The optimal medium compositions (on the basis of 100 mL medium) were 15 g potato, 2.5 g lactose, 2.07 g casein, 0.25 g KH2PO4, 0.11 g MgSO4, and 0.25 g L-tyrosine. The optimal fermentation process was that 25 mL of medium was contained in a 250 mL flask for 5-day fermentation at initial pH 6.0, 28 ℃ and 150 r/min shaking speed. As a result, the maximum melanin yield reached up to (13.4 ± 0.05) g/L, approximately 2.3 times higher than that obtained using preoptimization fermentation medium.

Key words: Streptomyces G-HD-4, melanin, fermentation, uniform-design