Roseococcus microcysteis sp. Nov., isolated from a microcystis aeruginosa culture sample

Strain NIBR12^T (=KACC 22094^T=HAMBI 3739^T), a novel Gram-stain-negative, obligate aerobic, non-spore-forming, nonmotile and coccobacillus-shaped bacterium, was isolated from a cyanobacterial sample culture (Microcysitis aeruginosa NIBRCYC000000452). The newly identified bacterial strain grew optimally in modified Reasoner's 2A medium under the following conditions: 0% (w/v) NaCl, pH 7.5 and 35 °C. Phylogenetic analysis using the 16S rRNA gene sequence confirmed that strain NIBR12^T belongs to the genus Roseococcus, with its closest neighbours being Roseococcus suduntuyensis SHET^T (98.8%), Roseococcus thiosulfatophilus RB-3^T (97.7%), “Sediminicoccus rosea” R-30^T (95.7%) and Rubritepida flocculans H-8^T (95.0%). Genomic comparison of strain NIBR12^T with type species in the genus Roseococcus was conducted using digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity analyses, resulting in values of ≤53.7, ≤93.7 and ≤96.1%, respectively. The genomic DNA G+C content of strain NIBR12^T was 70.9 mol%. The major fatty acids of strain NIBR12^T were summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c) and summed feature 3 (C_{16: 1} ω6c/C_{16: 1} ω7c). Q-9 was its major respiratory quinone. Moreover, the major polar lipids of strain NIBR12^T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. Based on our chemotaxonomic, genotypic and phenotype analyses, strain NIBR12^T is identified as represeting a novel species of the genus Roseococcus, for which the name Roseococcus microcysteis sp. nov. is proposed.