Fungus-bacteria interactions in decomposing wood : unravelling community effects

• Main Author: Johnston, Sarah R.
• Published: Cardiff University 2017
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738344

Bacteria have long been known to inhabit decomposing wood, but much of their ecology remains unexplored. There are indications that bacterial communities are linked to interactions with fungi, which dominate the dead-wood environment. Manipulative field experiments were combined with meta-taxonomic DNA sequencing to examine fungal effects on bacterial communities, in wood precolonised by Vuilleminia comedens, Trametes versicolor or Hypholoma fasciculare. After one year in the field, H. fasciculare retained its territory in the wood and showed a significantly different bacterial community to the other treatments, where precolonisers did not retain territory. Bacterial communities were significantly correlated with developing fungal communities. Samples where cord-forming basidiomycetes were dominant showed a distinctive bacterial community. Bacterial community structure and richness was significantly associated with wood pH, but not with woodland site location. Over a shorter period of 12 weeks, fungal precolonisers significantly delayed bacterial colonisation. V. comedens and H. fasciculare were associated with distinct bacterial communities, but T. versicolor was not. In fungal-uncolonised wood, seasonal differences were apparent at 84 but not at 14 days. Bacterial communities were dominated by Proteobacteria, with Burkholderiaceae enriched in precolonised samples. Acidobacteria were a major component of the 1-yr samples, but not the earlier-stage samples. In contrast to previous studies, Actinobacteria were never abundant. Overall, there was strong evidence for fungal control of bacterial communities in decaying wood. Interactions between wood-decay fungi and three strains of fungal-migratory Paraburkholderia were examined in agar microcosms. Mycelial extension rates of eight fungi were unaffected by bacterial migration, but two strains of Phanerochaete were significantly inhibited. Bacteria were also introduced into pairwise competitive interactions between fungi. One Phanerochaete strain showed a significant reduction in competitive performance when inoculated with Paraburkholderia. The presence of bacteria made the outcomes of inter-fungal interactions more unpredictable, indicating bacteria can reciprocally influence fungal communities in decaying wood.