Sandarakinorhabdus cyanobacteriorum sp. nov., a novel bacterium isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, designated TH057, was isolated from cyanobacterial aggregates in a eutrophic lake in China. Cells were observed to be slightly curved, rod-shaped, capsule-forming and stained Gram-negative. Optimal growth was obtained at pH 7.0 (range: pH 5-9) and 30 °C (range: 20-37 °C) in R2A broth. According to the absorption spectrum, carotenoids (455 and 490 nm) and light-harvesting complex LHI (857 nm) were present in the cells. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was ubiquinone Q-10. The major fatty acids were identified as C17 : 1ω6c, C16 : 1ω7c/C16 : 1ω6c, C18 : 1ω6c/C18 : 1ω7c and C16 : 0. The major polar lipids were found to consist of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, unidentified glycolipid and two sphingoglycolipids. Strain TH057 shared highest 16S rRNA gene sequence similarity to Sandarakinorhabdus limnophila so42 (96.8 %), followed by Polymorphobacter fuscus D40P (95.8 %). The genomic G+C content of strain TH057 was 66.1 mol% based on total genome calculations. The average nucleotide identity and the digital DNA-DNA hybridization value for the complete genomes were 81.0 and 23.0 % between strain TH057 and Sandarakinorhabdus limnophila so42. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH057 represents a novel species within the genus Sandarakinorhabdus, for which the name Sandarakinorhabduscyanobacteriorum sp. nov. is proposed. The type strain is TH057 (=CGMCC 1.15803=LMG 30294).