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Functional guild classification predicts the enzymatic role of fungi in litter and soil biogeochemistry

Talbot, Jennifer M., Martin, Francis, Kohler, Annegret, Henrissat, Bernard, Peay, Kabir G.
Soil biology & biochemistry 2015 v.88 pp. 441-456
acid phosphatase, biogeochemical cycles, catechol oxidase, community structure, ecosystems, ectomycorrhizae, genes, microbial biomass, microbial communities, microbial culture, mycorrhizal fungi, peroxidase, phylogeny, plant litter, saprotrophs, white-rot fungi
Linking community composition to ecosystem function is a challenge in complex microbial communities. We tested the hypothesis that key biological features of fungi - evolutionary history, functional guild, and abundance of functional genes – can predict the biogeochemical activity of fungal species during decay. We measured the activity of 10 different enzymes produced by 48 model fungal species on leaf litter in laboratory microcosms. Taxa included closely related species with different ecologies (i.e. species in different “functional guilds”) and species with publicly available genomes. Decomposition capabilities differed less among phylogenetic lineages of fungi than among different functional guilds. Activity of carbohydrases and acid phosphatase was significantly higher in litter colonized by saprotrophs compared to ectomycorrhizal species. By contrast, oxidoreductase activities per unit fungal biomass were statistically similar across functional guilds, with white rot fungi having highest polyphenol oxidase activity and ectomycorrhizal fungi having highest peroxidase activity. On the ecosystem level, polyphenol oxidase activity in soil correlated with the abundance of white rot fungi, while soil peroxidase activity correlated with the abundance of ectomycorrhizal fungi in soil. Copy numbers of genes coding for different enzymes explained the activity of some carbohydrases and polyphenol oxidase produced by fungi in culture, but were not significantly better predictors of activity than specific functional guild. Collectively, our data suggest that quantifying the specific functional guilds of fungi in soil, potentially through environmental sequencing approaches, allows us to predict activity of enzymes that drive soil biogeochemical cycles.