Conclusions And Future Perspectives In The Enzymology Of Decomposer Basidiomycetes

In the past the potential use of ligninolytic enzymes in biotechnology led to the accumulation of greater knowledge of many basic and applied aspects of the enzymology of lignin decomposition (Hatakka, 2001; Martinez et al., 2005). Nonetheless some areas are only just beginning to be studied, e.g. role of esterases cleaving the bonds between lignin and hemicelluloses. Other aspects of the enzymology of saprotrophic basidiomycetes have attracted only scattered attention without even a recent review of cellulose decomposition by these species.

Many questions on both the physiology and ecology of enzyme production remain to be answered. For brown-rot fungi we do not know how most of them degrade crystalline cellulose. What is the relative importance of the none-nzymatic versus enzymatic depolymerization of polysaccharides? What none-nzymatic systems are used by different species? Are there as yet undiscovered systems? Even less is known of the enzymology of litter-decomposing fungi. Several species seem to have a physiology similar to white-rot fungi, but what is the difference in metabolism in nutrient-rich soil patches compared to soil devoid of resources? Can we expect some nonligninolytic decomposers in soils equivalent to "brown-rotters"? What is the exact difference in enzyme production between saprotrophic and mycorrhizal basidiomycetes inhabiting the same habitat?

Many unresolved questions remain concerning the ecology of enzyme production and substrate transformation in natural conditions, in wood and even more in soil and litter. Owing to the complexity of the microbial communities in nature it is not yet possible to make a clear link between expressed genes (i.e. from individual species) and enzyme activities or to relate individual catalyzed reactions to complex environmental processes and to nutrient flow. The solution of these problems and the struggle for understanding of how the complex processes of substrate transformation are regulated in nature represent perhaps one of the greatest challenges for microbial ecologists. This may be aided by the developing abilities to link genes to individual species.

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