Mesorhizobium microcysteis sp. nov., isolated from a culture of Microcystis aeruginosa

Strain MaA-C15 T , a Gram-stain-negative, non-spore-forming and strictly aerobic bacterium, was isolated from a xenic culture of Microcystis aeruginosa in the Republic of Korea. Cells were motile rods showing positive reactions in catalase and oxidase tests. Growth was observed between 15 and 37 °C (optimum, 30 °C), between pH 6.0 and pH 11.0 (optimum, pH 7.5) and in the presence of 0–2.0 % (w/v) NaCl (optimum, 0 %). Strain MaA-C15 T contained C 16 : 0 , 11-methyl-C 18 : 1 ω 7 c , cyclo-C 19 : 0 ω 8 c and summed feature 8 (C 18 : 1 ω 6 c and/or C 18 : 1 ω 7 c ) as the major cellular fatty acids and ubiquinone-10 as the sole respiratory quinone. Phosphatidylethanolamine, phosphatidylmonomethylethanolamine, an unidentified aminophospholipid, an unidentified glycolipid and three unidentified phospholipids were detected as the major polar lipids. The G+C content of the genomic DNA was 64.1 mol%. Phylogenetic and phylogenomic analyses based on 16S rRNA gene and genome sequences revealed that strain MaA-C15 T formed a phyletic lineage with Mesorhizobium sediminum YIM M12096 T within the family Phyllobacteriaceae . Strain MaA-C15 T was most closely related to Mesorhizobium albiziae DSM 21822 T with a 98.2 % 16S rRNA sequence similarity. Average nucleotide identity and in silico DNA–DNA hybridization values between strain MaA-C15 T and M. albiziae DSM 21822 T were 75.4 and 20.1 %, respectively. Based on the results of phenotypic, chemotaxonomic and molecular analyses, strain MaA-C15 T represents a novel species of the genus Mesorhizobium , for which the name Mesorhizobium microcysteis sp. nov. is proposed. The type strain is MaA-C15 T (=KACC 21226 T =JCM 33503 T ).