Truffle Brûlés Have an Impact on the Diversity of Soil Bacterial Communities

Background: The development of Tuber melanosporum mycorrhizal symbiosis is associated with the production of an area devoid of vegetation (commonly referred to by the French word ‘brûlé’) around the symbiotic plants and where the fruiting bodies of T. melanosporum are usually collected. The extent of the ecological impact of such an area is still being discovered. While the relationship between T. melanosporum and the other fungi present in the brûle ́ has been assessed, no data are available on the relationship between this fungus and the bacteria inhabiting the brûlé. Methodology/Principal Findings: We used DGGE and DNA microarrays of 16S rRNA gene fragments to compare the bacterial and archaeal communities inside and outside of truffle brûlés. Soil samples were collected in 2008 from four productive T. melanosporum/Quercus pubescens truffle-grounds located in Cahors, France, showing characteristic truffle brûlé. All the samples were analyzed by DGGE and one truffle-ground was analyzed also using phylogenetic microarrays. DGGE profiles showed differences in the bacterial community composition, and the microarrays revealed a few differences in relative richness between the brûle ́ interior and exterior zones, as well as differences in the relative abundance of several taxa. Conclusions/Significance: The different signal intensities we have measured for members of bacteria and archaea inside versus outside the brûle ́ are the first demonstration, to our knowledge, that not only fungal communities, but also othe