Open access publications in the SLU publication database

Abstract

Soft rot decay of treated wood in ground contact and loss of service life is an important economic issue worldwide. One of the most important and cosmopolitan fungal groups causing soft rot belong to the imperfect fungal anamorph genus Phialophora. An aim of this study was therefore to determine the molecular identity and phylogeny of several economically important Phialophora species isolated from copper-treated and untreated wood using PCR combined with sequencing. Strain compatibility and copper detoxification of Phialophora species/strains were also assessed in-vitro from both liquid and solid cultures. The identity of a number of so far unclassified Phialophora spp. A strains isolated from treated wood in-service were found as Phialocephala dimorphospora.

The ability of strongly (P. malorum, P. mutabilis) and weakly (Chaetomium globosum) copper tolerant soft rot fungi to degrade CuSO4 and micronized-Cu (MC) treated wood (birch/pine) was assessed using a modified ENV 807 decay test with vermiculate and sterile soil. A direct relationship between Cu-tolerance in-vitro and soft rot decay of Cu-treated wood was not found. Rather, the additive effect of copper binding to the wood and the chemical nature of the wood material (lignin type/level) appeared more important with the less Cu-tolerant fungi causing similar/greater mass losses than Cu-tolerant strains.

LC-MS/MS and MALDI-TOF MS/MS allowed characterization of total and extracellular (wall-bound) upregulated proteins produced by P. malorum while growing in Cu-supplemented growth medium. Despite P. malorum lacking a sequenced genome, it was possible using modern proteomics to characterize changes in global proteins and detect a number of unique as well as up-regulated and down-regulated proteins when grown in Cu-supplemented liquid media. Using MALDI-TOF MS/MS a number of cell wall/slime bound proteins were also shown up-regulated in response to growth in copper media and thereby likely involved in Cu-tolerance.