Diversity and structure of bacterial communities associated with Phanerochaete chrysosporium during wood decay

Wood recycling is key to forest biogeochemical cycles, largely driven by microorganisms such as white-rot fungi which naturally coexist with bacteria in the environment. We have tested whether and to what extent the diversity of the bacterial community associated with wood decay is determined by wood and/or by white-rot fungus Phanerochaete chrysosporium. We combined a microcosm approach with an enrichment procedure, using beech sawdust inoculated with or without P.chrysosporium. During 18 weeks, we used 16S rRNA gene-based pyrosequencing to monitor the forest bacterial community inoculated into these microcosms. We found bacterial communities associated with wood to be substantially less diverse than the initial forest soil inoculum. The presence of most bacterial operational taxonomic units (OTUs) varied over time and between replicates, regardless of their treatment, suggestive of the stochastic processes. However, we observed two OTUs belonging to Xanthomonadaceae and Rhizobium, together representing 50% of the relative bacterial abundance, as consistently associated with the wood substrate, regardless of fungal presence. Moreover, after 12 weeks, the bacterial community composition based on relative abundance was significantly modified by the presence of the white-rot fungus. Effectively, members of the Burkholderia genus were always associated with P.chrysosporium, representing potential taxonomic bioindicators of the white-rot mycosphere.