Fig. 3.

The most abundant bacterial and protist genus at three cooling towers. For each sampling site, the average relative abundance of the 20 most frequently observed bacteria and protist taxa are listed at the genus level. In total 79% of all bacterial OTUs and 59% of all protist OTUs could be classified at the genus level (Tables S3 and S4). For clarity, the phylum as well as the order level are also indicated (the Proteobacteria were split into its representative classes). The Sphingomonadales, Pseudomonadales, Rhizobiales, and Burkholderiales including many biofilm associated taxa are among the top bacterial groups.