Interactions of wood-decay Agaricomycetes affect hyphal growth, enzyme activity profiles and decomposition events

Fungal communities are dynamic in nature. Fungal species and isolates may be tolerant and mutualistic, or antagonists upon interactions. Fomitopsis pinicola is a common brown rot Basidiomycota species of Polyporales encountered in boreal and temperate forests. The influence of F. pinicola on hyphal growth and enzyme production of five white rot fungal species, including the Polyporales species Phlebia radiata and Trichaptum abietinum, was studied as species combinations on e.g. wood-supplemented cultures. Production profiles of activities of CAZymes and lignin-modifying oxidoreductases (xylanase, beta-glucosidase, laccase, manganese peroxidase) were followed for eight weeks, together with activities involved in recycling of organic nitrogen and hyphal decomposition, along with oxalic acid production and Fenton chemistry indicating iron reduction capability. In fungal co-cultures on agar media, F. pinicola was a supreme colonizer quickly advancing over hyphae of the white rot species. Other white rot species were confronted by P. radiata with dense mycelial front formation. In liquid cultures, as well as in solid-state cultures, fungal produced oxalic acid was the main component that acidified the medium, and marked changes in enzyme activity patterns over time were directed by the fungal combinations. In solid-state cultures on spruce wood sawdust, apparent wood carbohydrate consumption and mass loss occurred early on in co-cultures with the brown rot species F. pinicola. Aggressive decomposition of wood cellulose by F. pinicola resulted in release of increasing amounts of reducing sugars in the spruce-wood cultures. Our results indicate that fungal species-species interactions have an outstanding role in wood-decomposition processes and carbon cycling in the forest ecosystems.

Mali T, Kuuskeri J, Shah F, Lundell TK. 2017. Interactions affect hyphal growth and enzyme profiles in combinations of coniferous wood-decaying fungi of Agaricomycetes. PLoS ONE 12(9): e0185171. DOI: http://dx.doi.org/10.1371/journal.pone.0185171