Characterization of polysaccharides isolated from forest soils

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Abstract
Polysaccharide complexes were extracted with M/15 phosphate buffer (pH 7.0) from a variety of forest soils associated with both mull and mor types of humus and were purified. Attempts to fractionate the polysaccharide complexes by fractional precipitation with ethanol, paper electrophoresis and fractionation of the acetylated derivatives from chloroform solutions with light petroleum were not completely successful. However, the last two methods of fractionation indicated that at least one polysaccharide preparation might be a mixture of substances. This was confirmed by free-boundary electrophoresis, which indicated that the material contains at least 3 components. Fractionation of this heterogeneous polysaccharide preparation was partially achieved by means of formation of a copper complex with Benedict''s solution. By viscosimetric measurements and application of Staudinger''s equation the polysaccharides were found to have molecular weights varying from 10 x 103 (preparation from a soil associated with mor) to 124 x 103 (preparation from a mull soil). Hydrolysis and paper chromatography revealed that the polysaccharides isolated from all the soils investigated were complex heteropolysaccharides. Except the high-molecular-weight preparation, from a mull soil, which did not contain any arabinose and the two preparations from soils associated with mor, which did not contain fucose, all polysaccharides contained the following sugar constitutents: glucuronic acid, galactose, glucose, mannose, arabinose, xylose, fucose and rhamnose. There was, however, some variation in the proportion of the sugar constituents.