Fig. 1

Distribution of identity percentage to closest published relative for environmental sequences. For each of the 131,162 environmental sequence retrieved by our protocol, the closest published relative is identified as the best BLAST hit against July 2013 release of nr NCBI database. Identity percentage between the two sequences, shown in abscissa, is computed as the hit coverage relatively to the smallest sequence multiplied by the BLAST identity percentage. The proportion of environmental sequences showing a given identity percentage is given in ordinate, in blue for sequences from human gut microbiome and in red for others. a) Class1 (direct link to cultivated hosts sequences) and class2 (indirect link) are cumulated. b) Class1 and Class2 are separated on top and bottom, respectively