EFFECT OF TRICHODERMA FUNGI ON BARK LIGNIN

Abstract

The effect of the enzyme complex of micromycetes on the lignin component of bark was studied by the example of a fungus of the genus Trichoderma. As a biological object, a strain MG 97/6 Trichoderma asperellum Samuels RNCIM F-765 was used. The substrates were Siberian larch (Larix sibirica) bark, pendent birch (Betula pen-dula) bast, and products of dioxane lignin isolated from the larch bark and birch bast according to the Pepper method by treating them with a mixture dioxane-water (9 : 1) in the presence of HCl (0,7 %). The fungus was cultivated for 10 days in Petri dishes thermostated at 25–27 °С, at a humidity of 80 %, and pH = 6.5. The substrate was spawned with a fungus suspension in the amount of 1·106 spores per 1 g of dry substrate. Chemical analysis, UV and IR spectroscopies showed that the enzyme complex of micromycetes induces destructive changes in the lignin both in situ and in vitro. A scheme of oxidative degradation of wood lignin under the action of the fungus was suggested. Microbial decomposition of lignin may be advisable for the production of biologicals (such as Trihodermin) from lignin-containing waste or for the destruction and bleaching of wood fibers for their further industrial use (for example in the production of paper or bioethanol).