PNNL

The Science

Earth’s largest pool of aboveground biotic carbon and an important natural resource is lignocellulose in wood. White and brown rot fungi both degrade lignocellulose but do that in different ways.  This study deployed mass spectrometry-based metabolomics techniques in thin wood wafers to compare the degradation mechanisms of two different groups of fungi. Two decay stages, earlier and later, were measured. Distinct metabolome profiles were captured from the two different wood rot decaying types, and each showed a strong dependency with type of wood rot decay and stage of decay. This likely reflects different life history strategies that are tailored for different environments with competition for resources.

The Impact

Despite the ecological and economic importance of wood-degrading fungi, little is known about the array of metabolites that fungi produce during wood decomposition. This provides an in-depth insight into the wood decomposition process by comparing the metabolome of fungi with two distinct nutritional modes. We found a unique pattern of metabolites that correlated with brown rot in later decay. These compounds were in line with some of the physiochemical and genetic features previously seen in these fungi. This study provides insight into decay mechanisms and establishes critical groundwork for studies in basic biology and ecology.

Summary

This is the first in planta (in solid wood wafers in this case) extracellular metabolomics study of wood-degrading fungi comparing brown and white rot fungal species on this wood wafer system. The metabolite patterns showed a dependency with the type of wood rot and the stage of decay; late brown rot decay produced the most identifiable signature. Globally, white rot fungi showed a higher capacity to release sugars early. However, this capacity did not increase at later decay stages. In contrast, brown rot fungi were not able to release a lot of sugars from the wood substrate early during decay, but at later stages showed a very sharp increase in the amount of released sugars. This likely reflects different life history strategies tailored for different environments. Dissimilar strategies for resource competition in the same environment is expected. The metabolome profiles of two different modes of fungal wood degradation were characterized by mass spectrometry-based metabolomics capability available at Environmental Molecular Sciences Laboratory, a DOE National User Facility, located at Pacific Northwest National Laboratory, Richland, WA.

PNNL Contact

Young-Mo Kim, Pacific Northwest National Laboratory, young-mo.kim@pnnl.gov

Funding

Department of Energy, Office of Science, Biological and Environmental Research Biosystems Science Program.