Representative sequences of abundant OTUs were assessed using the National Centre for Biotechnology Information (NCBI) nucleotide Basic Local Alignment Search Tool (BLAST) (Altschul et al., 1990) (available at http://blast.ncbi.nlm.nih.gov/Blast.cgi) searching within available 16S rRNA bacterial and archaeal sequences. BLAST searches were also undertaken using the Nucleotide Collection (nr/nt) database when required to compare sequences to those reported for uncultured bacteria