Fig. 3From: Trace element and temperature effects on microbial communities and links to biogas digester performance at high ammonia levelsMethanogenic community structure. Relative OTU distributions of mcrA genes retrieved in construction of clone libraries from digesters D37, DTE37, D42 and DTE42 at day 280 (period 3) based on 99 % identity threshold. Figures in the sectors represent OTU numbers. OTU1 and OTU19 had low identity (<79 %) to previously available mcrA genes. Nucleotide/amino acid sequence identity/similarity (%) to M. bourgensis OTU2: 92/89; OTUs 3–9: 97–99/≥89; OTU20: 92/89. Sectors with similar colour but different tunes are OTUs assembling based on 97 % identity threshold and referred to as assemblage A (blue), B (red) and C (green). Uncoloured sectors are OTUs and single mcrA genes with relatively low abundance. Frequencies and identities of the OTUs are listed in Additional file 1: Table S1Back to article page