Degradation and detoxification of softwood extractives by sapstain fungi

Wood extractives (resin) cause pitch deposition problems and effluent toxic ity in pulp and papermaking. The ability of six sapstaining fungi to degrad e and detoxify extractive constituents in Scots pine sapwood was examined, and the results were compared with those obtained with the commercial depit ching fungus Cartapip (Ophiostoma piliferum). Pestalotiopsis crassiuscula a nd O. piliferum were the best strains and they provided high reductions of total resin (50-60% in 6 weeks). Both strains were highly effective in the degradation of individual extractive components including triglycerides, di glycerides and free fatty acids. Although all strains displayed moderate to high pitch degradation, their detoxifying capacity was limited. Two import ant exceptions were Ceratocystis deltoideospora and O. piliferum that cause d a 11-14-fold decrease in toxicity (Microtox bioassay). These results indi cate the potential of wood pretreatment with the selected sapstain fungi fo r minimizing pitch problems and decreasing effluent toxicity in pulping. (C ) 1999 Elsevier Science Ltd. All rights reserved.