Blanchette [86] has described two kinds of soft-rot: type I consisting of biconical or cylindrical cavities that are formed within secondary walls and type II refers to an erosion form of degradation. For example, Daldinia concentrica is the most efficient fungus of type II group, which primarily affect hardwood. Nilsson et al. [94] found 53% weight loss in birch wood within 2 months. During early stage of classification of different wood-rotting fungi, Xylariaceous ascomycetes from genera such as Daldinia, Hypoxylon, and Xylaria have often been regarded as white — rot fungi, but today these fungi are categorized to soft-rot fungi as they cause typical type II soft-rot in wood. In coniferous wood (e. g., pine wood), the weight loss was very low and it has been thought that these type of woods have more guaiacyl units in middle lamella, which inhibit the growth of soft-rot fungi [49].

Some microfungi (Penicillium chrysogenum, Fusarium oxysporum, and Fusarium solani) identified in a forest soil sample are able to mineralize grass lignins upto 27 % [49]. However, most of the soft-rot and microfungi consume readily economically important carbohydrates during invading and have very less applications in biological pretreatment.