Most of the differences were attributed to the enrichment of specific gene families within metabolic pathways, some of which may indicate functional niches corresponding to varying microenvironments in the sewer pipes. Sulfur metabolism
Analysis of metagenome libraries identified key genes implicated in the sulfur pathway (Figure 2). Combretastatin A4 datasheet These functions were found to be abundant in the metagenomes, although we observed differences in the enrichment of specific gene families within the sulfur pathway. For example, in both metagenomes enzymes of three pathways involved in sulfur oxidation were detected: the Adenosine-5’-Phosphosulfate (EC 188.8.131.52, EC 184.108.40.206), the Sulfite:Cytochrome C oxidoreductase (EC 220.127.116.11) and the Sox enzyme complex (Figure 2). However, we found a relatively low odds ratio for the first pathway (<1.5), while the enzymes of
the Sox complex that convert thiosulfate to sulfate were more statistically abundant and enriched (odds ratio >9) in the TP biofilm (Fisher’s exact test, q < 0.05) (Table 2, Figure 2). Approximately 66% of the genomes in TP metagenome contained the soxB gene, a key gene of the periplasmic JNJ-26481585 manufacturer Sox enzyme complex  (Table 2). The widespread distribution of the Sox-complex among various phylogenetic groups of SOB was confirmed , specifically soxB-sequences affiliated with T. intermedia T. denitrificans T. thioparus Acidiphilium cryptum, and MRT67307 cost species of Burkholderia among others ( Additional file 1, Figure S7). The relative similar level of enrichment of the Adenosine-5’-Phosphosulfate pathway may be explained by the fact that key enzymes can be
found in species of SRB and SOB, in which the latter can operate in the reverse direction [51, 52]. In addition, ADP ribosylation factor the composition of species carrying the dsrB gene (sulfite reductase; EC 18.104.22.168) is noteworthy (Fisher’s exact test, q < 0.05) (Figure 2 and Table 2). Retrieved dsrB-sequences for the TP biofilm show 80% of genes were closely related to T. denitrificans (SOB), while 78% in the BP were represented by SRB: Desulfobacter postgatei Desulfomicrobium baculatum, and species of Desulfovibrio among others ( Additional file 1, Figure S7). Figure 2 Enrichment of enzymes in the sulfur metabolic pathway. Diagram with the enzyme classification (identified by their Enzyme Commission number; EC number) for each step in the sulfur pathway. Asterik (*) indicate components that are significantly different between the two samples (q < 0.05) based on the Fisher’s exact test using corrected q-values (Storey’s FDR multiple test correction approach) (Table 2). Bar chart shows the odds ratio values for each function. An odds ratio of 1 indicates that the community DNA has the same proportion of hits to a given category as the comparison data set . Housekeeping genes: gyrA gyrB recA rpoA and rpoB. Error bars represent the standard error of the mean.