Characterisation of Aequorivita ciconiae sp. nov., isolated from oriental stork, Ciconia boyciana.

A single novel bacterial strain designated as H23M31 was isolated from the faecal sample of oriental stork (Ciconia boyciana) that inhabits the Republic of Korea. It was a rod-shaped, facultative anaerobic, Gram-negative, and non-motile strain. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that it branched from Aequorivita within Flavobacteriaceae. It was most closely related to A. capsosiphonis DSM 23843, which shared the sequence similarity of 96.36%. The strain exhibited optimal growth at pH 7.0 in a marine broth medium with 1% NaCl incubated at 30 °C. Chemotaxonomic characteristics indicated that the predominant cellular fatty acids were iso-C (24.4%), iso-C 3-OH (15.9%), and anteiso-C (13.9%). The polar lipid of the strain contained phosphatidylcholine (PC), phosphatidylglycerol (PG), and diphosphatidylglycerol (DPG). The major isoprenoid quinone was menaquinone 6 (MK-6), which was identical with that of a closely related Aequorivita species. The genomic G + C contents of the strain was 38.25 mol%. Average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA-DNA hybridization (dDDH) values between the novel isolate and A. viscosa CGMCC 1.11023 were 75.83%, 80.34% and 20.50%, respectively. Phylogenetic analyses revealed the evolutionary relationships of the strain, demonstrating that the strain clusters with other Aequorivita species. Pan-genome analyses and genome comparisons indicated that, unlike other environmentally isolated species, it possesses unique genes that enhance its ability to colonise the harsh animal gut environment. Taxonomic characterisation suggested that strain H23M31 represents a novel Aequorivita species, and the proposed name is Aequorivita ciconiae sp. nov. The type strain of A. ciconiae is H23M31 (= KCTC 62809 = JCM 33229).