Aurantiacibacter flavus sp. nov. and Aurantiacibacter gilvus sp. nov., isolated from the mudflat of Suaeda japonica colonies

Two novel strains were isolated from the mudflat of <i>Suaeda japonica</i> colonies in Incheon, Republic of Korea. Designated as DGU5^T and DGU6^T, these strains were Gram-stain-negative, facultatively anaerobic and rod-shaped and had yellowish colonies. Both strains were determined to belong to the genus <i>Aurantiacibacter</i> through phylogenetic analysis of their 16S rRNA sequences and draft genomes. The cells of strain DGU5^T were non-motile and grew at temperatures ranging between 7-45°C (optimum, 25-30°C), pH 6.0-10.0 (optimum, 7.0-8.0) and in the presence of 0-11.0% NaCl (optimum, 2.0%). The cells of strain DGU6T were non-motile and grew in temperatures ranging from 10-45 °C (optimum, 30-35°C), pH 3.0-10.0 (optimum, 7.0-8.0) and in the presence of 0-11.0% NaCl (optimum, 2.0%). Overall genome relatedness index calculations revealed average nucleotide identity values (72.3-88.6%) and digital DNA-DNA hybridization values (18.8-35.9%) aligning with those of the genus <i>Aurantiacibacter</i>. The major fatty acids in both strains were C_17:1 <i>ω</i>6<i>c</i> and summed feature 8 (C_18:1 <i>ω</i>6<i>c</i>/C_18:1 <i>ω</i>7<i>c</i>), while the predominant polar lipids were sphingoglycolipid, phosphatidylglycerol, and diphosphatidylglycerol. Phylogenetic, average nucleotide identity, digital DNA-DNA hybridization, physiological, and biochemical data collectively demonstrated the distinctiveness of the novel strains from other members within the family <i>Erythrobacteraceae</i>. We propose the names <i>A. flavus</i> sp. nov. (type strain DGU5^T = KACC 23720^T = TBRC 19015^T) and <i>A. gilvus</i> sp. nov. (type strain DGU6^T = KACC 23721^T = TBRC 19016^T) for the two strains.