6 Wood Discoloration

3.8 Competition and Interactions Between Organisms 81
Murmanis et al. 1988; Morris et al. 1992; Doi and Yamada 1992; Bruce 1998;
Phillips-Laing et al. 2003). Culture filtrates of Chaetomium globosum, Penicillium
sp., Sporotrichum pulverulentum and Trichoderma viride decreased wood
degradation by T. versicolor (Ananthapadmanabha et al. 1992).
Current attempts for biological wood protection use a colorless mutant
of the blue-stain fungus Ophiostoma piliferum. Round wood and cut timber
is treated with a spore suspension of the mutant to reduce or even prevent
subsequent natural colonization of the wood by blue-stain fungi (Blanchette
et al. 1994; Behrendt et al. 1995; Schmidt and Müller 1996; White-McDougall
et al. 1998; Ernst et al. 2004). Corresponding experiments used Gliocladium
roseum to protect green lumber from molds, stain, and decay (Yang et al.
2004a). Figure 3.4 demonstrates the inhibiting effect of O. piliferum against
two blue-stain fungi in the laboratory.
Synergism (mutualistic reciprocal effect) means the mutual promotion and
inthebroadersensethepromotionofoneorganismbyothers.Topreparethe
substrate, the pH value can be changed, vitamins can be excreted (Henningsson
1967), and inhibiting heartwood compounds can be degraded. The nitrogen
content may be increased by N-fixing soil bacteria (Baines and Millbank 1976),
and nutrients can become more available (also Levy 1975a; Hulme and Shields
1975). Neutralistic reciprocal effects, neither inhibition nor promotion, occur
more rarely.
Fig.3.4. Inhibition by a colorless mutant of Ophiostoma piliferum of blue-staining of wood
samples by Phoma exigua and Aureobasidium pullulans. Wood samples A were previously
dipped in a spore solution of O. piliferum and then all four samples were inoculated with
the blue-stain fungi (from Müller and Schmidt 1995)
www.taq.ir