Chemische Parallelen beim Abbau der Holzsubstanz durch Organismen

Summary

From the chemical point of view the decomposition of wood is effected by wood-destroying animals and fungi, according to definite laws. This becomes particularly evident when re ferring the consumption of the individual wood components to their original quantity present in the wood. Taking the initial concentration with 100 as a base, the following is resulting for the metabolism: The participation of the carbohydrates takes place within a major range of decomposition when the lignin can be decomposed imperfectly only. If, however, the organism can dissimilate the intermediate products of decomposed lignin, the contribution of the carbohydrates to energy supply falls to a lower range. Hence, the decomposition of wood is decisively determined by the ferment system effective on the lignin. White rot fungi, for instance, possess such a ferment system, whereas with brown rot fungi the decomposition of the wood is restricted to its alkali-soluble portions, as they do not have this ferment system. Hence, the difference of the alkali-solubility between white and brown rot very often mentioned in literature is based on the fact that with brown rot, in the course of the decomposition, the constantly increasing quantities of lignin, which has become alkali-soluble, accumulate in the decayed, indigestible residue of wood. Towards the end of the brown rot, lignin thus in the alkali-portion is present in a far greater quantity than cellulose and pentosans as a whole. The figures obtained seem to prove that the type of wood (coniferous wood, deciduous wood, heartwood, sapwood, etc.) is of no importance to the course of depolymerization. The defensive properties of wood can be detected biologically but not on the basis of values obtained by a chemical analysis. As a remarkable conclusion it can be stated that the activities of the enzymes of the wood destroyers react in the same way as the corresponding substrates are concentrated in the wood. The pictures 1 and 6 are supporting this theory.