Aliikangiella litoralis sp. nov. and Aliikangiella aequoris sp. nov., isolated from coastal seawaters of the Yellow Sea.

Three Gram-stain-negative, strictly aerobic, motile bacterial strains, designated IMCC44359T, IMCC44632T, and IMCC44653, were isolated from coastal surface seawater collected near Jangbong Island in the Yellow Sea. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences assigned the isolates to the genus Aliikangiella. Strains IMCC44632T and IMCC44653 shared identical 16S rRNA gene sequences and exhibited high genomic relatedness (99.0% average nucleotide identity and 92.0% digital DNA-DNA hybridization), indicating that they represent a single species. In contrast, strain IMCC44359T showed low genomic relatedness to these strains and to previously validly published Aliikangiella species, supporting its recognition as a distinct species. The genome of IMCC44359T (5.95 Mbp; 36.5 mol% G + C) is substantially larger than those of IMCC44632T and IMCC44653 (~3.75 Mbp; 40.1-40.2 mol% G + C), and all genomes encode aerobic chemoorganotrophic metabolism and biochemical capacities consistent with adaptation to marine environments. The isolates grew under mesophilic and moderately halophilic conditions typical of coastal seawater bacteria, with growth occurring at ranges at 10-40℃, pH 6.0-9.0, and 0.5-7.5% NaCl (optimum, 30℃, pH 7.0-8.0, and 2.0-3.0% NaCl). All strains contained ubiquinone-8 (Q-8) as the sole respiratory quinone, and phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were the major polar lipids. The dominant cellular fatty acids were iso-C15:0 and summed feature 9 (iso-C17:1 ω9c and/or C16:0 10-methyl). Integrated phylogenetic, genomic, phenotypic evidence supported the recognition of two novel species within the genus Aliikangiella, for which the names Aliikangiella litoralis sp. nov. (type strain IMCC44359T = KCTC 18089T = JCM 37879T = HNIBRBA19635T) and Aliikangiella aequoris sp. nov. (type strain IMCC44632T = KCTC 18090T = JCM 37880T = HNIBRBA19636T) are proposed.