Bacterial "social" network in french soils : a Metagenomics insight
Résumé
New generation sequencing evidenced that soil houses a huge microbial biodiversity. Based on these observations, it is now possible to better describe the spatial distribution of soil microbial communities, to study the ecological processes lying behind (environmental selection, dispersal limitations), and to mine the data to define the ecological attributes of soil microbial taxa. These huge datasets also offer the opportunity to study how soil microbial populations are interrelated. The objective of this study was to design the first bacterial "social" network in french soils to characterize how bacterial taxa are related to one-another. To do so, the bacterial community composition was characterized for the 2,200 soils of the French Soil Quality Monitoring Network using 454-pyrosequencing based on 16S rRNA genes directly amplified from soil DNA and bacterial taxa were identified based on SILVA database. Then, the bacterial social network was designed by means of a network analysis. First results at the phylum level demonstrate that the soil bacterial social network is highly complex with different relationships between bacterial phyla (positive/negative, strong/weak). This complexity is determined both by biotic relationships between bacterial phyla and by environmental conditions. Indeed, the soil bacterial social networks in different ecosystem types (forests, grasslands, croplands and vineyards) did not have the same complexity. Understanding these relationships represents a cornerstone of soil microbial ecology to go further in understanding ecological processes shaping soil microbial communities; and to identify land-use practices preserving soil bacterial social network complexity.
