Flavobacterium cyanobacteriorum sp. nov., isolated from cyanobacterial aggregates in a eutrophic lake.

ABSTRACT

A Gram-reaction-negative, aerobic, non-flagellated, non-gliding, rod-shaped and yellow-pigmented bacterium, designated strain TH021T, was isolated from cyanobacterial aggregates in a eutrophic lake, Taihu Lake, China. Optimal growth occurred at pH 7.0 (range 5.0-10.0), 28 °C (range, 4-32 °C) and 0 % (w/v) NaCl (range, 0-1.0 %) in Reasoner's 2A broth. No growth was observed at 37 °C. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was menaquinone-6. The major fatty acids (>10 %) were identified as iso-C15  0 and C16  1ω7c/C16  1ω6c. The major polar lipid was phosphatidylethanolamine. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was affiliated with the genus Flavobacterium, with the highest sequence similarity found to Flavobacterium hauense BX12T (94.92 %), followed by Flavobacterium suzhouense XIN-1T (94.85 %), Flavobacterium arcticum SM1502T (94.79 %) and Flavobacterium beibuense F44-8T (94.30 %). The genomic G+C content of strain TH021T was 41.9 mol% based on total genome calculations. Average nucleotide identities and digital DNA-DNA hybridizations values for complete genomes ranged from 69.4 to 72.8 and 18.0 to 23.8 % between strain TH021T and strains within the genus Flavobacterium. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH021T represents a novel species within the genus Flavobacterium, for which the name Flavobacterium cyanobacteriorum sp. nov. is proposed. The type strain is TH021T (=LMG 29720T=CGMCC 1.16325T).