FIG 3.

(a) Phylogenetic affiliations of bacterial 16S rRNA and dsrAB genes at the leak site, the bottom, and a weld of the tube. Shades of blue and green denote gammaproteobacterial and deltaproteobacterial lineages, respectively. (b) Phylogenetic affiliations of archaeal 16S rRNA and mcrA genes at the leak site, the bottom, and a weld of the tube section. Shades of orange denote lineages from the order Methanosarcinales. Blank represents sequences amplified from the DNA extraction and purification negative control. The amount of PCR product obtained from mcrA gene amplification of material from the leak site sample was too small for sequencing.