Micromorfologia da degradação de madeira da espécie Amazônica Hura crepitans L. por fungos lignolíticos pertencentes a classe hymenomycetes

Abstract

Changes in wood microstructure and chemistry of "Açacu" Hura crepitans L. through progressive stages of decay by Pycnoporus sanguineus (L.: F.) Murr, Antrodia albida (F.) Donk and Tyromyces sp. collected around Manaus, AM, Brazil were studied. Scanning Electron Microscopy (SEM) was used for observation on degree of attack to various xylematic elements of Hura crepitans L. (Euphorbiaceae). Optimization of growth for fungi tested in relation to the effect of temperature and pH on micelial growth in different medium were also studied. The fungi prefer an environment with pH range 5.0-8.0 and pH 6.0 as optimum. Temperature optimum range 30-35 ºC. Occur progressive decrease on lignin content. Polysaccharides are degraded concurrently with lignin, which is degraded, in initial stage, on higher rate other than polysaccharide particularly to Pycnoporus sanguineus and Tyromyces sp. As lignin is removed the fibrillar structure of cellulose on cell wall become evident. Vessel elements are completely destroyed on initial stage of deterioration. Occur narrowing of fiber elements cell wall neighboring rays with atacck to primary and secondary wall. At advanced stage of deterioration occur the ray\'s destruction and formation of crystals (presumably calcium oxalate).