DEVELOPMETNT OF A NEW SCREENIG SYSTEM FOR WOOD PRSERVATIVES BY USE OF THE INHIBITION FOR WOOD ROTTING FUNGI

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The primary objective of this research project is to develop a new screening system for wood preservatives on the basis of biochemical analysis of the inhibitors blocking the key enzymes of the copper-tolerant wood rotting fungi. First we investigated metabolic mechanism for biosynthesis of oxalic acid which causes detoxification of copper preservatives, and finally, attempted to test many compounds if they inhibit potently the key enzyme isocitrate lyase in the in vitro inhibitor screening system.The following important findings obtained have been published in the international journals listed at the end of this abstract.1) The brown-rot fungus Fomitopsis palustris contains constitutively the glyoxylate cycle in contrast with the normal microorganisms grown on glucose and the cycle linked with the TCA cycle was also found to couple with the oxalic acid biosynthesis.2) Through these metabolic cycles coupling with the oxalate biosynthesis, the wood-rotting fungi seem to gain the energy for their growth and one of the key enzymes was found to be isocitrate lyase (ICL) which plays a pivotal role for biosynthesis of oxalic acid.3) Both ICL and malate synthase (MS) which are key enzymes of the glyoxylate cycle were found to distribute widely among the both white-rot and brown-rot fungi.4) We have successfully purified these key enzymes (ICL and MS) for the first time from the wood-rotting fungi and characterized for comparison with the enzymes from other sources.5) We also succeeded in making fruit bodies of the F.palustris in the liquid culture for the first time.