Niveispirillum lacus sp. nov., isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, 1-14, was isolated from cyanobacterial aggregates in a eutrophic lake, Taihu Lake, China. Cells were observed to be slightly curved, rod-shaped, aerobic and Gram-stain-negative. Optimal growth occurred at pH 7.0 (range: 5.0-9.0), 28 °C (range: 20-32 °C) and 0 % (w/v) NaCl (range: 0-1.0 %) in R2A broth. No growth is observed at 37 °C. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was ubiquinone Q-10. The major fatty acids (>10 %) were identified as C18 : 1ω6c/C18 : 1ω7c, C16 : 0 3-OH and C18 : 1 2-OH. The major polar lipids were found to consist of phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and phosphatidylcholine. Within the genus Niveispirillum, strain 1-14 was most closely related to Niveispirillum cyanobacteriorum TH16 (98.3 % 16S rRNA gene sequence similarity), followed by Niveispirillum irakense DSM 11586 (97.8 %) and Niveispirillum fermenti CC-LY736 (97.0 %). The genomic G+C content of strain 1-14 was 62.2 mol% based on total genome calculations. Genes coding for light-harvesting complexes LHI and LHII, and a photosynthetic reaction centre were detected in the genome. Average nucleotide identities and digital DNA-DNA hybridizations for complete genomes ranged from 76.4 to 83.5 and from 21.5 to 27.4 % between strain 1-14 and strains within the genus Niveispirillum. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain 1-14 represents a novel species within the genus Niveispirillum, for which the name Niveispirillum lacus sp. nov. is proposed. The type strain is 1-14 (=CGMCC 1.12980=LMG 28363).