FIG. 1.

Neighbor-joining phylogeny inferred from partial 16S rRNA gene sequences rooted with Synechococcus strain PCC 7002 as the outgroup. Closed boxes indicate bootstrap values of >70 for both neighbor-joining and maximum parsimony analyses and a Bayesian posterior probability of >0.85. Open boxes designate support as described above but only for neighbor-joining and Bayesian analyses. Roman numerals indicate the 10 clades of Synechococcus subcluster 5.1 identified by Fuller and coworkers (8). Strains M11.1 and M16.17 are in bold.