Roseococcus microcysteis sp. nov., isolated from a Microcystis aeruginosa culture sample

Abstract

Strain NIBR12 T (=KACC 22094 T =HAMBI 3739 T ), a novel Gram-stain-negative, obligate aerobic, non-spore-forming, non-motile 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 ω 7 c and/or C 18:1 ω 6 c ) and summed feature 3 (C 16 : 1 ω 6 c /C 16 : 1 ω 7 c ). 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.

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