Optimization Of Aureobasidium Pullulans Producing Melanin And Extraction Of Melanin Englisn

The analytical method of melanin, melanin separation, the antioxidant activity of melanin, screening method and optimization of fermentation conditions have been studied. The results of studies were as follows:Aureobasidium pullulans M1609was mutated by He-Ne and UV laser. A high melanin producing strain Aureobasidium pullulans M61was obtained by resistance screening. The22.5u/mL melanin was obtained in flask and which was2.16times higher than that of original strain. The results showed that the strain was genetic stability.In order to improve the melanin production, the response surface methodology (RSM) was used to optimize the conditions of melanin production using Aureobasidium pullulans. Results of the statistical analysis showed that the concentration of melanin was mainly influenced by the concentration of initial MgSO4.7H2O, KH2PO4, and beef extract. The optimal fermentation medium was:glucose60g/L,(NH4)2SO410g/L,Tyrosine2.5g/L,KH2PO40.25g/L, Beef extract15.08g/L, ZnSO47mg/L, MgSO4·7H2O1.29mg/L The optimal fermentation conditions:liquid load50mL/500mL, temperature25℃, agitation speed200r/min, and incubation time96h. The53.1u/mL melanin was obtained in flask and which was1.36times higher than that of original medium.The effective method of separating for the Aureobasidium pullulans and melanin was found:The results were summarized as followings:The melanin was obtained by centrifugaling the fermentation liquor to get rid of Aureobasidium pullulans and concentrating with rotatory evaporator. Then the pure melanin was obtained with acid hydrolysis the melanin to get rid of the polysaccharose and adding trichloroacetic acid0.2%and ethyl acetate (1mol/L) to remove the protein and the yield of freeze dried melanin was0.3%.The antioxidant activity of melanin was studied by detecting the scavenging capacity. The results show that the scavenging capacity of melanin about (.OH) and (O2-·) was more positive than that of Vc and TBHQ. The scavenging capacity of (O2-·) was the best when the concentration of melanin was0.04mg/mL.