Anatomical characterization of wood decay patterns in Hevea brasiliensis and Pinus merkusii caused by white-rot fungi: Polyporus arcularius and Pycnoporus sanguineus

Biological pulping is an environmentally friendly process for making pulp and paper whereby the wood raw material is pre-treated with selective delignifying white-rot fungi. Therefore, the purpose of this study is to determine the decay patterns of white-rot fungi Polyporus arcularius and Pycnoporus sanguineus, as well as its ability to decay Hevea brasiliensis (as hardwood) and Pinus merkusii (as softwood) by observing the anatomical characteristics. Fungal attack testing on wood was carried out by the Kolle-flask method with a variation of 6, 9, and 12 weeks incubation time. The structure of wood cells was analyzed using wood incision method, followed by a combination of safranin-picro aniline blue and safranin-astra blue, and maceration method. The results showed that H. brasiliensis wood has a higher percentage of weight loss than P. merkusii wood. Wood attacked by P. sanguineus showed a higher weight loss compared to the P. arcularius. The decay pattern of P. sanguineus infected wood was concluded as selective delignification in P. merkusii and simultaneous delignification in H. brasiliensis while those infected with P. arcularius both performed simultaneous delignification. In the early stages of decay, selective delignification is characterized by the formation of intercellular space due to degradation of lignin in the middle lamella, while simultaneous delignification is characterized by cell wall thinning. The anatomical structure of H. brasiliensis attacked by the white-rot fungi showed differences with P.merkusii, whereby the ray cells of P.merkusii wood was more degraded than in H. brasiliensis.