Neighbor-joining phylogenetic tree of the Roseobacter clade in the α-Proteobacteria. Mn(II)-oxidizing isolates obtained in this study are indicated by boldface type. The relative levels of Mn(II) oxidation by the Elkhorn Slough isolates and reference Roseobacter-like species are indicated in the shaded boxes [−, weak to no Mn(II) oxidation; +++, strong Mn(II) oxidation on K medium plates containing 100 μM Mn(II), pH 7.5]. The tree is based on 1,182 nucleotide positions, and Hirschia baltica is the outgroup. Bootstrap values greater than 50% are indicated at nodes.