Optimization of fermentation medium formula for increasing melanin yield and physicochemical properties of melanin of Auricularia heimuer
For increasing the melanin yield in Auricularia heimuer fermentation broth,fermentation medium formula of the experimental strain A.heimuer 1703 was optimized by single factor experiments and response surface methodology.The stability and antioxidant activities of melanin were determined.The results showed that sucrose,peptone,and MgSO4 had a significant impact on the melanin yield of A.heimuer fermentation broth.The optimal fermentation medium for increasing A.heimuer melanin yield was potato of 200 g/L,sucrose of 21.40 g/L,peptone of 5.34 g/L,and MgSO4 of 0.56 g/L.Under these conditions,the melanin yield was 0.050 g/100 mL.A.heimuer melanin has good stabilities under different illumination condition and temperature,and in solution containing different metal ions,showing pigment retention rate of over 90％.A.heimuer melanin has strong DPPH free radical,superoxide anion free radical scavenging abilities,and iron reducing ability.The IC50 values for DPPH free radical and superoxide anion free radical were 0.021 mg/mL and 0.90 mg/mL,respectively.This study provides theoretical reference for the liquid fermentation production and application of A.heimuer melanin.
Auricularia heimuermelaninliquid fermentationresponse surface methodologyphysical and chemical propertiesantioxidant
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