Fermentation And Structure Study On Anthraquinone Pigment By Medical Fungi-Shiraia Bambusicola

Shiraia bambusicola P. Hennigs is a worthy exploitation medical fungus, which contains some active natural pigments. The culture condition of Shiraia bambusicola P. Hennigs was optimized and determined, and an anthraquinone pigment was obtained. The isolation, structural elucidation and stability analysis of the pigment were carried out.The optimal fermentation condition and medium were selected by mono-factor design and orthogonal experiment. The optimal culture conditions were as follows: lactose 3.5%, sodium nitrate 3.0%, K2HPO4 0.05%, MgSO4·7H2O 0.025%, KCl 0.05%, FeSO4·7H2O 0.001%, temperature 26℃, initial pH 8.0, shaker rotate speed 150 rpm, volume loading 60 mL of 250 mL Erlenmeyer flask. Under this optimal condition, the pigment could reach an absorbance (493 nm) of 0.946 at the end of fermentation. In the scale-up test, the anthraquinone pigment was also successfully obtained with an absorbance (493 nm) of 0.471 at the end of fermentation by 15 L mechanical type fermenter tank.The paper also proposed a feasible and effective method to purification of the pigment obtained by Shiraia bambusicola P. Hennigs. The purity was more than 97% after the purification of organic solvent, silica gel column chromatography and reverse-phase C18 column chromatography.The result of Feigl, Borntrager's, MgAc2 and concentrated sulfuric acid color reaction showed that the natural pigment was hydroxyanthraquinone. Based on the spectrum of LC-MS, UV, IR and NMR, the pigment formula was C16H12O5 and the molecular weight was 284. The result also displayed that besides the mother nuclide, the structure of the pigment includes twoα-OHs, a methyl and a methoxyl group. The pigment systematic nomenclature was 1,5-dihydroxy-3-methoxy-7-methylanthracene-9,10-dione. Up to now, the pigment from microorganism in this study was the first report.At last, the paper studied the pigment stability. The result showed that some factors, such as temperature, light, heat, oxidant, reducing agent, saccharoseand citric acid, have no effect on the pigment stability. However, the Fe3+ ion affected much on the pigment stability. The result of pigment antioxidation and bacteriostasis test demonstrated that the pigment has antioxidation and bacteriostasis effect.