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Targeted inhibition of wood decay fungi: degradation of cotton cellulose
1999 - IRG/WP 99-10321
Brown-rot decay is responsible for 80% of the damage and replacement of wood in service. For nearly thirty years, researchers have postulated a one-electron oxidase system combining Fe+2 oxalic acid, and H2O2 in the production of hydroxy radicals which ultimately oxidize cellulose in situ. Recently, researchers have been investigating antioxicants, in combination with biocides (Schultz, et al.,1998), as targeted inhibitors of the decay process and potential wood preservatives. In order to target the cellulolytic mechanisms of brown-rot and white-rot decay fungi, cotton cellulose was treated with free radical scavengers, antioxidants, dyes and hydroxy-radical detectors 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) in order to assess their ability to retard cellulose hydrolysis. Weight loss of cotton cellulose is the most reliable and accurate measure of exoglucanase activity. Cotton cellulose was exposed to G. trabeum MAD 617, T. palustris 6137 and T. versicolor MAD 697 in soil-block tests. After 12 weeks exposure, cotton was evaluated for weight loss, change in DP, and elemental analysis by ICP spectroscopy. Only 2 out of 11 compounds tested (NHA and ruthenium red) showed less than 1% weight loss for all three fungi tested. All other compounds were selective, underscoring difficulties in sharply targeting decay mechanisms. Weight loss and DP of cellulose are analogous to degradation and strength loss of wood caused by decay fungi.
F Green III, T A Kuster