Thermoprotei, 11a. Archaeoglobi, 11b. Halobacteria, 11c. Methanobacteria, 11d. Methanococci, 11e. Methanomicrobia,

11f. Methanopyri, 11g. Thermococci, 11h. Thermoplasmata, 12. Korarchaeota [phylum] and 13. Thaumarchaeota [phylum]. Phage (host): 14. Actinobacteria, 15. Bacilli, 16. Cyanobacteria, 17a. Alphaproteobacteria, 17b. Betaproteobacteria, 17c. Deltaproteobacteria, 17d. Gammaproteobacteria and 18. other classes each representing <1%. Groups (phylum): 3. Bacteroidetes, 7. and 17. Proteobacteria, 10. Crenarchaeota, 11. Euryarchaeota. Some annotated proteins CB-839 were associated with archaeal genes, and to a lesser extent to viral and eukaryotic genes (Table 1, Figure 1). Specifically, a total of 2,837 (TP) and 8,237 (BP) Archaea-related functions were identified using the SEED database.

The majority of the annotated sequences in both samples were related to proteins affiliated with archaea members of the class Methanomicrobia. Although, phages are extremely abundant and diverse in natural systems, we were able to identify only a low number of sequences (696), perhaps due to the loss of viruses during the sample concentration or DNA extraction steps [32]. Nonetheless, the results indicated that the community composition and structure of viruses parallels the distribution of Bacterial representatives [33]. Specifically, phages associated to the classes Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria were found to be the dominant phage sequences in our metagenomes

(Figure 1). Phages can potentially be used as biocontrol agents to specifically control some of selleckchem the bacteria implicated in corrosion. Future studies should focus on the use of viral concentration methods to further study the occurrence of phage TCL sequences that could be use as targets to monitor biocorrosion bacteria in wastewater concrete pipes. Comparative microbial community analysis In previous studies, biofilms were analyzed from the surface of primary settling tanks from a domestic wastewater treatment plant [7, 8] and from coupons placed in a collection system manhole [9], while our study focused on biofilms from top and bottom of a corroded pipe. In spite of the differences in sample matrix, some trends in the bacterial distribution between concrete wastewater biofilms were observed ( Additional file 1, Figure S3). For example, the bottom of the pipe (BP) is characterized by direct contact and long residence time with wastewater, which maintains an ideal anaerobic environment for SRB. In fact, obligate anaerobes of the class Deltaproteobacteria (16%) were the dominant cluster in BP biofilm (Figure 1). The BP harbored anaerobic bacteria normally found in the human gut such as members of the selleck screening library Bacteroidia (11%) and Clostridia (5.1%) classes (Figure 1 and Additional file 1, Figure S2). This was also supported by data from 16S rRNA gene clone libraries (Additional file 1, Figure S 4).