Identification Of An Antarctic Fungus And Rresearch On The Characterization And Structure Of Red Pigment From It

With the increasing of the negative reports of synthetic pigments,their harmful have known by people.Natural pigments are popular which are not only safer than synthetic ones,but also have special nutritional and health-keeping functions and the demands of them surge.Subjected by supplies of raw materials,previous natural pigments mostly extracted from plant were expensive,variable qualitative and low yield.It is important to finding a new resource of valuable natural pigments.A fungus named WNF-15 A which secreted a special amaranthine pigment was isolated from soil collected from Antarctic.For the special location,harsh climate and environment,antarctic is a potential treasure trove of microbial species.Therefore,we did the in-depth researches of WNF-15 A.WNF-15 A was determined as a member of Geomyces based on colony morphologic characteristics,microscopic morphology and the phylogenetic analysis of ITS,and it was a psychrophiles which has optimum growth temperature between 15-20 ?.The analysis of condition for pigment production showed that low temperature and low level of nitrogen would promote the synthesis and accumulation of pigment,and the optimum conditions was concluded as following: cultivated in 200 g/L potatoes soaking liquid with 1% glucose at 10?.On the sixth day incubation a red colorant was released into the broth,increasing up to the maximum afer 14 days.By comparing the adsorption capacities and desorption rates,DPH-722 was selected as the optimum one from 7 kinds of macroporous resin.The specific practice was: the resin which had adsorbing red colorant from the fermented liquid was put into a chromatographic column,and was eluted by 70% ethanol.The red powder was obtained from the eluant with the pigment by vacuum freeze-drying,and its color value unit increased 10.4-144.05 times.1.71 g red powder could be collected from 1L fermentation broth.The red colorant was extracelluar secretion,water-soluble,and insoluble in organic solvents such as ethyl acetate,chloroform and so on.It has the maximum absoption at 533 nm wavelength.The results of its thermal degradation dynamics show that the colorant was not sensitive to heat.With the same hue in p H less than 3,the colorant stable in the p H range from 3 to 9.Although the pigment was faded quickly when it exposed to sunlight,scattered light was almost ineffective on its stability.Reducing of water activity improved the stability of it.Its antioxidant capability was demonstrated by scavenging measures of DPPH· and·OH.This pigment was nontoxic determined by LD50>15000mg/kg observed from mice toxicity test.Thus,This pigment could be exploited as a natural pigment..This pigment may be a mixture of several amaranthine materials,and two of them were isolated by using of negative-phase silica gel chromatography and HPLC.The one 2-C-1-1 was identified as a benzene ring conjugated substance with a molecular weight of 480.8 by MS and 1H-NMR.