Lignin-carbohydrate complex degradation

CORNU A, BESLE J M, MOSONi p, GRENET E (1994) Lignin-carbohydrate complexes in forages structure and consequences in the ruminal degradation of cell-wall carbohydrates. Reprod Nutr Dev. 34 385-98. 

JP Joseleau, C Gancet. Selective degradation of the lignin-carbohydrate complex from aspen wood. Sven Papperstidn iA R123-R121, 1981. 

Soil organic matter (SOM) is often referred to as humus and is derived primarily from the degradation of plant material lignin, carbohydrates, protein, fats, and waxes. Mineral soils may contain 0.5-3.0% of soil organic matter while muck soils and peat contain 50% and higher. Operationally, the material that cannot be extracted by alkaline agents is called humin. The material that precipitates from the alkaline extract on acidification is called humic acid, and what remains in solution fulvic acid. Felback summarized some of the properties of these complex polymeric materials as follows ... 

In conclusion, DOM in water is a complex mixture of degraded moderate-sized biomolecules. As degradation proceeds in the aquatic environment, carbohydrates and lignin degradation products disappear within days to a few years. Only the carboxylated aliphatic alicyclic component persists for thousands of years in the marine environment (35) or in isolated lake environments like Big Soda Lake, Nevada. 

Organic matter deposited in sedimentary or wetland habitats is composed of a complex mixture of biopolymers. Some of these compounds, such as proteins, carbohydrates, and lipids are easily degraded by microorganisms (i.e., labile), while other compounds, such as lignin and hemiceUulose, are resistant to decomposition (i.e., recalcitrant). Biopolymers are degraded in a multistep process. First, microorganisms simplify polymers to monomers such as amino acids, fatty acids, and monosaccharides (Figure 4). The monomers are further mineralized to CO2, or to a combination of CO2 and CH4. 

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