Evaluation of the interspecific competitive ability of the bioincising fungus Physisporinus vitreus

A hierarchical set of assays were used to evaluate the interspecific competitive ability of the bioincising fungus Physiporinus vitreus (response species). The competitiveness and growth mode of P. vitreus against a range of blue stain fungi and Trichoderma species (challenge species) was investigated in dual culture tests (a) and a spatially heterogeneous system of tessellation agar (b) on different media. In addition, the robustness of the bioincising process against biotic influences was determined by controlled interaction tests with different inocula of the challenge species (colony-forming units: 10(2), 10(4), 10(6) ml(-1)) on Norway spruce (Picea abies Karst.) heartwood. The results of the dual culture and tessellation agar tests revealed a significant (P <= 0.001) antagonistic potential (lethal effect) of the T. atroviride strain (15603.1), whereas no or only a slight effect of the blue stain fungi on P. vitreus was detectable. The interaction tests on Norway spruce heartwood confirmed that an increase in inoculum size of the challenge fungi correlated with an increased negative effect (Spearman's rho coefficient (rho) = -0.521). Among the challenge species, T-15603.1 revealed the most negative effect on the homogeneous development of P. vitreus on wood and thus on the outcome of the bioincising process. To improve the uniformity of colonization and to reduce the rate of contamination, the incubation of wood in a sealed system (bioreactor) after sterilization is suggested.