Micromorphological Characteristics of Degradation in Bamboo Attacked by White Rot Fungus Lentinus edodes
Chang Hyun Cho, Kwang Ho Lee, Yoon Soo Kim
In comparison with micromorphological works for wood decay, little known is about the decay pattern of bamboos by wood decay fungi. The present work was undertaken to understand the general degradation pattern of bamboo and the influence of polylaminate layers in bamboo fiber walls on the restriction of fungal decay. The weight loss of bamboo species Phyllostachys puberscens against the white rot fungus Lentinus edodes after 16 weeks incubation was around 13%. Degradation was restricted to the parenchyma cells while degradation of fiber and vessel walls was limited. Degradation of bamboo fiber cell wall by L. edodes showed two different decay patterns. At the beginning stage of decay, middle lamellae including cell corner middle lamellae were selectively degraded, leaving the fiber secondary walls. In a certain stage of decay, the secondary wall in bamboo fibers was eroded outward from the cell lumen. Lamellation of bamboo fiber cells restricted the movement of fungal hyphse into next lamellae. Narrow layers in bamboo fiber appeared to influence the direct penetration of fungal hyphae into next layer. Cytochemical examinations exhibited that narrow layers were rich both in lignin and in polysaccharides. Chemical composition and microfibril orientation in narrow layers might influence on the movement of fungal hyphae in the bamboo fibers.