Evenness and functional organization Figure 2 shows a Pareto-Lorenz evenness curve of the Archaea community based on the relative abundances of the 25 OTUs obtained by applying a 98.7% SB431542 mouse sequence similarity threshold. The functional organization (Fo) index, the combined relative abundance of 20% of the OTUs, is 56%, meaning that more than half of the observed LY3023414 mw sequences belong to only five of the observed OTUs. A high Fo index is an indication of a specialized community since it means that a big part of the population belongs to a small number of OTUs and performs a small number of ecological functions. In a completely
even community all OTUs would have the same number of individuals and it would be possible for a large number of different functions to be equally abundant. In the clone library, the five most abundant OTUs,
which include 56% of the sequences, all belong to Methanosaeta and presumably are all methanogens. Furthermore, the composition of the clone library indicates that the community includes a small number of ecological functions since 13 of 25 OTUs, including 77% of the sequences, were identified as Methanosaeta (Figure 3). Figure 2 Pareto-Lorenz evenness curve. 82 archaeal 16S rRNA gene sequences were divided in 25 OTUs based on a sequence similarity threshold of 98.7% and the OTUs were ranked from high to low, based on their abundance. The Pareto-Lorenz evenness curve is the plot of the cumulative proportion of OTU abundances (y-axis) against the cumulative proportion of OTUs (x-axis). The Fo index, i.e. the combined relative abundance of 20% of the OTUs, is shown. C646 supplier 4-Aminobutyrate aminotransferase The dotted straight line is the Pareto-Lorenz curve of a community with perfect evenness. Figure 3 Community composition. The 82 16S rRNA gene sequences were classified according to the phylogenetic tree analysis. The number of sequences within each group is given. Comparison with available sequences in GenBank and SILVA Searches in GenBank using BLAST  and in the SILVA rRNA database  found sequences with a sequence similarity of 98.7% or higher for 22
of 25 OTUs, including 78 of the 82 sequences (Table 2). With 100% coverage, 4 sequences could only be matched with sequence similarities lower than 98.7% and may therefore represent new species belonging to the genera Methanosaeta (OTU10 and OTU16) or the Thermoplasmatales, Cluster B (OTU20). The most similar sequences in the databases were from various types of soil environments, water environments and anaerobic bioreactors in North America, Europe and Asia. For 30 of the 82 sequences, the best match came from an anaerobic bioreactor. Table 2 Database comparisons Database matcha OTU Matching clones Acc. no. Identityb Taxonomy Source environment OTU1 1 CU917405 99.8 Methanosaeta Digester 6 CU917423 99.6-100 Methanosaeta Digester 6 CU917466 99.8-100 Methanosaeta Digester 2 JF280185 100.