Humic acid transformation by the fungus Cerrena unicolor growing on cellulose and glucoseстатья
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Дата последнего поиска статьи во внешних источниках: 17 июля 2020 г.
Аннотация:Microbial degradation of lignocellulose and soil organic matter is an important process controllingCO2 flow into the atmosphere, which is mostly carried out by fungi. The alkali-soluble fraction, which is representedmostly by the so-called humic acids (HA), dark-colored compounds of phenolic nature, constitute~30‒70% of soil Corg. This is the first report on efficient degradation of soil HA under cellulolytic conditions;cellobiose dehydrogenase (CDH), an oxidative enzyme of the cellulolytic complex, was shown to play the keyrole in this process. Growth of a wood-decomposing fungus Cerrena unicolor on cellulose (CDH and laccaseproduction) and glucose (laccase production) resulted in HA decolorization by 60 and 20%, respectively. HAdepolymerization in the presence of CDH and its polymerization in the presence of laccase were shown bygel filtration experiments with the culture liquid and pure enzyme preparations. HA degradation in the presenceof CDH was inhibited by radical scavengers, indicating the radical nature of this process (probably theFenton’s reaction). HA depolymerization by CDH decreased in the presence of laccase, while HA polymerizationby laccase decreased in the presence of CDH. Thus, the interaction of these enzymes affects HAtransformation under cellulolytic conditions. These results improve our understanding of the mechanisms ofmicrobial degradation of the aromatic components of soil humus and of the ecological functions of wooddecomposingfungi grown under cellulolytic conditions.