Fig. 3.

Phylogenetic trees of the CmpABCD proteins and NrtABCD proteins of the selected alkaliphilic cyanobacteria. The outgroup cyanobacteria includes Synechococcus sp. PCC 7942, which has an experimental study of HCO₃⁻ transporter BCT1 and nitrite/nitrate transport system, NRT [12]. (a) Phylogenetic tree based on the CmpA and NrtA protein sequences. (b) Phylogenetic tree based on the CmpB and NrtB protein sequences. (c) Phylogenetic tree based on the CmpC and NrtC protein sequences. (d) Phylogenetic tree based on the CmpD and NrtD protein sequences. The alkaliphilic cyanobacteria are identified by the blue diamond, respectively. Cmp and Nrt families are highlighted in orange and green, respectively. Bootstrap values with 3000 replicates are shown at the nodes of the tree. The scale bars indicate the number of nucleotide substitutions per site.