Study On Pigment Extraction And Its Characteristics

The in question large mushroom, Trametes sanguinea (syn. Pycnoporus sanguineus) was collected from Fenglin national nature reserves of Heilongjiang province in this study. Mor phological characteristic of the fruiting body was observed, and through plate separation, the pure strain was isolated. Afterwards, the isolated strain was re-culture on plates with sold medium and in shake flask with liquid medium, colonial morphology observation with naked eye and hypha morphology check under microscope were carried out, combining with ITS-rDNA information from PCR amplification using universal fungal ITS1/ITS4as primers followed by sequencing, the isolated fungus showing99%similarity with Trametes sanguinea, and was confirmed to be the target fungus, T. sanguinea.Interestingly, during the liquid culture process in shake flask of T. sanguinea, pigment produced by the fungus was observed. Through investigation, the pigment was found to have great polarity and could dissolve in water, while was insoluble in organic solvent such as ethyl acetate, acetone, chloroform and hexane, and etc. Adding large amount of absolute ethyl alcohol could precipitate the pigment with little water containing. The pigment produced during the liquid fermentation process of T. sanguinea was purified via static adsorption by macroporous resin and subsequent dynamic elution, the color value (CV) was elevated from2.59to19.06by6.36fold. As such, the elimination of impurity substances including most of the polysaccharides and proteins in the fermentation broth suggested the method could effectively purify this pigment.Results of the stability experiments on T. sanguinea pigment under different pH values showed that T. sanguinea pigment displayed stable in poor acidic/alkaline environment, however, the absorbance of which showed large change under strong alkaline condition, with poor stability. Regarding to pigment stability effected by metal ions, K+, Na+and Al3+had no significant effects on the pigment absorbance, while, the absorbance of T. sanguinea pigment raised with significance in the present of Gu2+and Zn2+, hinting the hyperchromic effect of Gu2+and Zn2+on T. sanguinea pigment. The effects of temperature on T. sanguinea pigment stability mainly because long time high temperature processing could lead to its decomposition, which cause the decrease in absorbance. Furthermore, the influence of oxidizing/reducing agents on T. sanguinea pigment was surveyed, which showed that T. sanguinea pigment had good tolerance to reducing agent such as Na2SO3, while its stability to H2O2was poor.The culture condition for producing T. sanguinea pigment were optimized by single factor experiments and orthogonal tests, which turned out to be26g/L of maltose,5g/L of peptone,7.5of pH,30℃of culturing temperature and120r/min of shake speed. Under this condition, the pigment yield elevated by75.05%compared to primary un-optimized culture condition.Fungal pigments, with their non-toxic and pharmacological effects have very broad prospects for development, however, their stability is usually poor, which direct impact the color and quality of the coloring matters. Thus, the investigation on T. sanguinea stability will provide a certain theoretical basis for the application scope of T. sanguinea pigment in the future. When put into actual production and application, as for natural pigments, in addition to assure the color value and stability, the yield of pigment is also very important. Therefore, the optimized results of the culture conditions for T. sanguinea pigment production in this study would provide a theoretical basis for the next development and utilization of T. sanguinea pigment, as well as for large-scale production and application of the pigment.