Abstract:

The fermentation conditions of Lachmum YM-223 including medium composition and period were optimized to achieve the maximum melanin production using single-factor and orthogonal array methods and the melanin obtained was subjected to analysis of antioxidant activities such as reducing power, ·OH radical scavenging activity and inhibition activity towards autoxidation of soybean oil. When Lachmum YM-223 was cultured using a medium consisting of potato juice 200 g/L, glucose 20 g/L, tryptone 5.0 g/L, tyrosine 1.0 g/L and CuSO4 0.32 g/L at initial pH 7.0 with shaking speed 200 r/min at 25 ℃ for 12 d, the melanin yield was up to the maximum, higherthan that using basic culture medium by 53.6%. The reducing power of 0.5 g/L melanin was equivalent to 0.05 g/L VC system and the scavenging effect of 1.0 g/L melanin on ·OH radicals reached 50.6% and the autoxidation of soybean oil was obviously inhibited by the addition of 0.05% melanin. The melanin produced by Lachmum YM-223 can be used as a widespread new-style natural pigment in food, cosmetics and medicine industry.

Key words: Lachmum, melanin, fermentation, antioxidant activity