Effect of nutrients on interactions between two decay fungi and Trichoderma harzianum Rifai on ponderosa pine sapwood wafers

Graduation date: 1996Small size wood assays were utilized to study the\ud effect of added nutrients to the wood on the interactions\ud of Trichoderma harzianum Rifai and two wood decay fungi,\ud Trametes versicolor (white rot) and Gloeophyllum trabeum\ud (brown rot). Weight losses related to time of exposure\ud were monitored as a measure of decay. Total protein\ud content from extracts obtained from ponderosa pine sapwood\ud wafers treated with different levels of carbon or nitrogen\ud compounds served as an indicator of biomass. The\ud activities of selected wood degrading enzymes were studied\ud in pure and mixed cultures of T. harzianum and the two\ud decay fungi growing on the wood wafers.\ud Weight losses for mixed cultures of T. harzianum and\ud decay fungi indicated that the bioprotectant can delay the\ud decay process. The results also suggested that T.\ud harzianum was more active against brown rot fungi than the\ud white rot fungi although completely inhibition did not\ud occur with either decay fungus. The addition of carbon or\ud nitrogen to the wood had a positive effect on T. harzianum\ud performance against the two decay fungi studied but these\ud nutrients also generally enhanced the growth of both decay fungi. The exception was glucose which had a negative\ud effect on cellulase activity of Trametes versicolor.\ud Trichoderma harzianum showed low hemicellulase and\ud cellulase activity which is a desirable feature in a\ud bioprotectant against wood decay but it stimulated laccase\ud activity in the white rot Trametes versicolor. The reasons\ud for this behavior are unknown and merit further study.\ud The overall effect of Trichoderma harzianum on the\ud decay fungi studied was reflected in decreased weight\ud loss, total protein content and enzymatic activity except\ud for laccase activity which was stimulated. Addition of\ud sources of carbon or nitrogen to the wood enhanced the\ud effect in most cases.\ud The results indicate that the use of nutrients to\ud enhance bioprotectant capabilities has potential although\ud care must be taken to ensure that the nutrient do not\ud stimulate the target organism