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 degrees 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 SHETT (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 omega 7c and/or C-18:1 omega 6c) and summed feature 3 (C-16:1 omega 6c/C-16:1 omega 7c). 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.