Mechanism of antibacterial activity of the white-rot fungus Hypholoma fasciculare colonizing wood

aNetherlands Institute of Ecology (NIOO-KNAW), Department of Microbial Ecology, Boterhoeksestraat 48, Heteren 6666 GA, Netherlands. bWater and Environmental Studies, Department of Thematic Studies, Linköping University, Linköping 58183, Sweden. cInstitute for Resources, Environment, and Sustainability (IRES) and Soil, Water, and Environmental Laboratory (SWEL), The University of British Columbia, 429-2202 Main Mall, Vancouver, BC V6T 1Z4, Canada. dInstituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, Seville 41080, Spain. eCardiff School of Biosciences, Cardiff University, Biomedical Building, Museum Avenue, Cardiff, Wales CF10 3AX, UK.

In a previous study it was shown that the number of wood-inhabiting bacteria was drastically reduced after colonization of beech (Fagus sylvatica) wood blocks by the white-rot fungus Hypholoma fasciculare, or sulfur tuft (Folman et al. 2008,). Here we report on the mechanisms of this fungal-induced antibacterial activity. Hypholoma fasciculare was allowed to invade beech and pine (Pinus sylvestris) wood blocks that had been precolonized by microorganisms from forest soil. The changes in the number of bacteria, fungal biomass, and fungal-related wood properties were followed for 23 weeks. Colonization by the fungus resulted in a rapid and large reduction in the number of bacteria (colony-forming units), which was already apparent after 4 weeks of incubation. The reduction in the number of bacteria coincided with fungal-induced acidification in both beech and pine wood blocks. No evidence was found for the involvement of toxic secondary metabolites or reactive oxygen species in the reduction of the number of bacteria. Additional experiments showed that the dominant bacteria present in the wood blocks were not able to grow under the acidic conditions (pH 3.5) created by the fungus. Hence our research pointed at rapid acidification as the major factor causing reduction of wood-inhabiting bacteria upon colonization of wood by H. fasciculare.

Peer reviewed