Microchemical studies of wood degradation by brown rot and white rot fungi in two tropical timbers

Abstract

An observation that the growth of the brown rot fungus Gloeophyllum sepiarium and another species of the same genus isolated from decaying timbers-in-buildings, 'bleached' mahogany (Khaya ivorensis) timber, prompted a laboratory investigation of their pattern of wood degradation in obeche (Triplochiton scleroxylon) and mahogany. The white rot fungus Pleurotus ostreatus was studied for comparison. Microchemical and quantitative analyses indicated that the Gloeophyllum species degraded cellulose, but not lignin. P. ostreatus attacked lignin after substantially degrading cellulose. Spot tests indicated laccase production by all three species studied. Lignin peroxidase was detected only with P. ostreatus. It is hypothesized that laccase may be partly associated with breakdown of the decay-retarding pigmented extractives of the timbers. 'Bleaching' may have been due to lightening of timber colour caused by removal of these pigmented compounds. Copyright © 1996 Published by Elsevier Science Limited.