Studies on preservative tolerant Phialophora species

Phialophora species are shown to possess a variable capacity for growth on either copper, arsenic or copper-chrome-arsenic (CCA) supplemented laboratory media. The most copper tolerant species. Phialophora sp. A, P. malorum and P. mutabilis, were also the most arsenic resistant. Fine structural studies have shown intra- and to a lesser extent extracellular localization of copper which may provide a means of tolerating high external copper levels under culture conditions. Wood decay experiments have shown Phialophora spp. to have a good capacity to degrade K33 treated birch after 7·5 months but not pine, despite colonization. The most important wood degrading Phialophora were also the more copper/arsenic resistant species although non-tolerant species were also able to degrade treated birch. A comparison between the extreme copper levels tolerated by selected species with the amount of copper in treated wood may suggest that only sub-toxic levels may be obtained, levels which may not require special detoxification mechanisms for either colonization or decay in wood. In this respect, factors other than toxicity, particularly the nature of the substrate (e.g. lignin type and level) and reaction with CCA and ammoniacal-copper during treatment may be of greater significance.