Studies on soil polysaccharides. I. The isolation of polysaccharides from soil

Abstract

Methods for extracting polysaccharides from soil have been evaluated with respect to yield and polymer degradation. Maximum extraction with a single non-degradative treatment was obtained by shaking soil with 0.5N NaOH for 16 hr at 20�C. Pretreatment of the soil with cold dilute hydrochloric and hydrofluoric acids raised the extraction efficiency to over 40% of the total soil carbohydrate. The carbohydrates removed by 0.5N NaOH at 20�C and by hot water and other lower-yielding reagents were of comparable molecular size. Hot 0.5N NaOH treatment and acidic acetylation both removed more carbohydrate than cold 0.5N NaOH but caused considerable degradation. About 80% of the carbohydrate was removed from a range of soils by extracting first with 1N HCl, followed by 0.5N NaOH, and finally acetic anhydride containing 2.5 % conc. H2SO4. Humic materials were removed from the 0.5N NaOH by passing the extract upwards through a column of Dowex 50 (H+). Other coloured materials were adsorbed from the effluent by a water-insoluble cross-linked polyvinyl-pyrrolidone, and final purification and desalting were achieved by gel filtration. The 'purified' polysaccharide contained neutral sugars 55%, hexosamines 6%, uronic acids 10% (minimal value), amino acids 6 %, nitrogen 2.1%, and ash 1.8%. At least 10 neutral sugars, 2 hexosamines, 2 uronic acids, and 16 amino acids were present. The polysaccharides had a wide molecular weight distribution.

Decomposition of Soil Polysaccharide

“…The fulvic acid solution contained about a quarter of the total soil carbohydrate but the polysaccharide material usually obtained from the charcoal column, Fraction C, represented only 2-3 per cent of the total (Table I). Using Polyclar, as described by Swincer et al (1968), almost all the fulvic acid carbohydrate has been recovered and could not be distinguished from that of batches isolated with charcoal-Celite. Des ite the low recovery, charcoal column separations were used to is0 P ate the polysaccharide material because of the relative ease of purification of the polysaccharide material from salts and humic materials, and because they allowed the isolation of other fractions for examination.…”

Evolution of Concepts of Environmental Natural Nonliving Organic Matter

“…Procedures for the isolation of polysaccharides from soil and their fractionation have been reviewed by Mehta et al (1961) , Swincer et al (1968) , Greenland and Oades (1975) , Hayes and Swift (1978) , Cheshire (1979) , Cheshire and Hayes (1990) , Stevenson (1994) , and Clapp et al (2005) . Sodium hydroxide is probably the best of the aqueous solvents used.…”

“…The introduction of XAD resin technology (see Section 1.3.2 ) for the fractionation of soil organic extracts has allowed some separation of saccharides from what are considered to be the true FAs. Swincer et al (1968) deserve to be credited with that concept. They used Polyclar -AT [a (poly)vinylpyrrolidone resin used for clarifying wine] to remove color (HS) from soil saccharide extracts, but XAD -8 has been found to be superior for that purpose.…”

Soil saccharide extraction and detection

“…The association between saccharides and soil constituents is believed to involve hydrogen and covalent bonds (Parson and Tinsley, 1961). Many extractants including water, aqueous buffers, complexing agents, mineral acids, organic reagents, alkali and combinations of the above are often used to extract saccharides from biological matrices (Swincer et al, 1968). However, the extraction efficiency of these solutions for saccharide determination has received little attention because of problems associated with method detection.…”

“…However, the extraction efficiency of these solutions for saccharide determination has received little attention because of problems associated with method detection. Problems associated with the quantitative extraction of soil saccharides have been reviewed by Ivarson and Sowden (1962), Swincer et al (1968), Oades (1972) and Greenland and Oades (1975).…”