A NEWLY DESIGNED PHOTOMETRY APPARATUS FOR THE ESTIMATION OF WOOD COMPONENT DEGRADATION BY WHITE-ROT FUNGI

Biodegradation of lignin by white rot fungi is accompanied by a bleach ing of the substrate. A correlation was found between the increase of light transmission measured through the sample and the loss of lignin. An apparatus named a ''degradophotometer'' has been developed to quan tify light transmission through samples composed of sawdust included i n an agar matrix. The apparatus consists of a 12 volt tungsten filamen t lamp supplied with an adjustable direct current, a device to hold th e sample included in a Petri dish and a photocell connected to a photo meter. By reference to a standard curve, the degradophotometer allows determining amounts of lignin, and also of several components of the w ood, such as cellulose and polyphenols whose concentration changes whe n samples are subjected to degradation by wood decay fungi. The photom etric method proved to be; as accurate and sensitive as gravimetric an d spectrometric procedures to measure wood component degradation and t o estimate the protection of wood linked to a quaternary ammonium salt .