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 Suaeda japonica 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 Aurantiacibacter 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 Aurantiacibacter. The major fatty acids in both strains were C_17:1 ω6c and summed feature 8 (C_18:1 ω6c/C_18:1 ω7c), 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 Erythrobacteraceae. We propose the names A. flavus sp. nov. (type strain DGU5^T = KACC 23720^T = TBRC 19015^T) and A. gilvus sp. nov. (type strain DGU6^T = KACC 23721^T = TBRC 19016^T) for the two strains.