Fig. 4

Neighbor-joining phylogenetic tree of bacterial amoA gene sequences in all sampling sites in Yangtze River Estuary, where the white up-pointing triangle represents the sampling sites in S1, the black up-pointing triangle represents the sampling sites in S2, the white down-pointing triangle represents the sampling sites in S3, the black down-pointing triangle represents the sampling sites in S4, and next to these symbols are the numbers of sampling sites; the black circle represents the reference sequences gained from GenBank, and the two capital letters and six numbers in brackets are the accession numbers of the reference sequences. Bootstrap values close to the nodes are greater than 50% of 1000 replicates. The scale indicates 0.05 nucleotide substitutions per site