For the phylogenetic analysis, similarity searches for bacterial
16S rRNA gene partial sequences from the representative
OTUS (with relative abundance >0.1%) were performed
using the NCBI BLAST search program within the GenBank
database and within the SILVA databases. Recovered 16S rRNA
sequences were further aligned using the Clustal W tool and
used for the construction of a 16S rRNA gene-based phylogenetic
tree using the neighbor-joining (maximum composite
likelihood) method with the MEGA 6 package [21]. Bootstrapping
(1000 times) was performed to estimate the confidence
levels for the tree nodes. The tree was rooted using
Escherichia coli (accession number X80730).