COMPARISON OF POLYSACCHARIDES ISOLATED FROM THE MYCELIA OF A CULTIVATED STRAIN OF PORIA COCOS GROWN IN DIFFERENT LIQUID CULTURE MEDIA

摘要

Mycelium of a cultivated strain of Poria cocos was grown by submerged fermentation in a liquid medium containing com steep liquor with orbital shaking. Six polysaccharides coded as ac-PCM 1, ac-PCM2, ac-PCM3-I and II, acPCM4-I and II were isolated from the mycelium by extracting with 0.9% NaC1 aqueous solution, hot water, 0.5 mol/L NaOH aqueous solution and 88% formic acid. Exo-polysaccharide was obtained from the culture medium and coded as ac-PCM0.The monosaccharide composition and molecular weights of these polysaccharides were characterized by using infrared spectroscopy, gas chromatography, elemental analysis, 13C-NMR, viscometry and light scattering. The results indicated that ac-PCM0, ac-PCM1 and ac-PCM2 are heteropolysaccharides containing glucose, galactose, mannose and fucose, and acPCM3-I and ac-PCM3-II mainly consist of D-glucose. The content of the glucose in the polysaccharides increased with the isolation progress. Remarkably, a-glucan and β-glucan coexisted in the extract by NaOH aqueous solution (ac-PCM3), and could be separated by chemical methods. The protein in the ac-PCM polysaccharides cultured from the medium containing com steep liquor was higher than that in the ab-PCM from the medium with bran extract. Therefore, the polysaccharides from Poria cocos mycelia cultured in different media have different chemical composition, molecular weights and conformations.