Inhibition of decay fungi using cotton cellulose hydrolysis as a model forwood decay

Environmental pressures to replace chromium and arsenic in fixed waterborne preservatives have been increasing. Potential inhibitors of brown-, white- and soft-rot fungi need to be evaluated as alternative preservatives by sc reening and testing in, in vitro, model systems. This paper reports the inh ibition of cellulose depolymerization and weight loss of selected decay fun gi by 11 chemical compounds. The ability to depolymerize carbohydrate polym ers is analogous to strength loss of wood which can occur independently of utilization (weight loss). Cotton cellulose was pretreated with 10% solutio ns of compounds selected for their unique ability to stain wood components, dye cellulose or to act as a scavenger of active oxygen species. Cotton ce llulose was exposed to three brown-rot fungi (Gloeophyllum, trabeum MAD-617 ; Postia placenta MAD-698 and Tyromyces palustris TYP-6137) and the white-r ot fungus Trametes versicolor MAD-697. After 12 weeks exposure to the fungi in modified soil-block tests. cotton samples were removed and tested for w eight loss: reduction in degree of polymerization (DP) and elemental analys is by inductive coupled plasma (ICP) spectroscopy. Only two compounds teste d (NHA and ruthenium red) inhibited weight loss for all fungi tested. The r emaining compounds were selective in their ability to prevent weight loss o r inhibit reduction in DP. In general, antioxidants were only effective aga inst blown-rot fungi. Independent mechanisms of cellulose hydrolysis by bro wn- and white-rot fungi demonstrates one problem inherent in development of target specific wood preservatives not evident in preservatives containing broad-spectrum biocides, i.e. different mechanisms require different inhib itors. Published by Elsevier Science Ltd.