Lee Jae Kyeong, Lee Min Woo, Moon Chae Yeong, Kim Jeong Min, Bayburt Hülya, Choi Byeong Jun, Jeon Che Ok
Department of Life Science, Chung-Ang University, Seoul 06974, Republic of Korea.
J Microbiol Biotechnol. 2025 Sep 16;35:e2507023. doi: 10.4014/jmb.2507.07023.
Two Gram-stain-negative, facultatively aerobic, non-motile, catalase- and oxidase-positive, rod-shaped bacteria, designated strains DGS2-2 (orange-pigmented) and DGS5-3 (yellow-pigmented), were isolated from marine red algae collected in Korea. Strain DGS2-2 grew at 20-40°C, pH 6.0-10.0, and in 1.0-6.0% (w/v) NaCl, while DGS5-3 grew at 15-40°C, pH 6.0-10.0, and in 2.0-6.0% NaCl. Ubiquinone-10 was the sole respiratory quinone. The G+C contents were 62.5% for DGS2-2 and 57.5% for DGS5-3. Both strains contained summed feature 8 (C7 and/or C6) and C as major fatty acids, and phosphatidylcholine, sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol as major polar lipids. The 16S rRNA gene similarity (97.3%), average nucleotide identity (ANI, 72.0%), and digital DNA-DNA hybridization (dDDH, 18.4%) values between the two strains were below the species delineation thresholds. Phylogenetic and phylogenomic analyses based on 16S rRNA gene and whole-genome sequences placed both strains in distinct lineages within the genus . ANI and dDDH values between each strain and type strains were below 74.5% and 19.5%, respectively, supporting their designation as novel species. Genomic analyses identified putative genes associated with potential algal symbiotic traits, including the biosynthesis of vitamins, siderophores, and hormone-like compounds. Carotenoid biosynthetic genes were also identified, and LC/MS confirmed astaxanthin (DGS2-2) and nostoxanthin (DGS5-3) production. Based on genomic, phylogenetic, phenotypic, and chemotaxonomic evidence, strains DGS2-2 and DGS5-3 represent two novel species of , for which the names sp. nov. (DGS2-2 =KACC 23855 =JCM 37496) and sp. nov. (DGS5-3 =KACC 23854 =JCM 37497) are proposed.
从韩国采集的海洋红藻中分离出两株革兰氏阴性、兼性需氧、无运动性、过氧化氢酶和氧化酶阳性的杆状细菌，分别命名为菌株DGS2-2（橙色色素）和DGS5-3（黄色色素）。菌株DGS2-2在20-40°C、pH 6.0-10.0和1.0-6.0%（w/v）NaCl条件下生长，而DGS5-3在15-40°C、pH 6.0-10.0和2.0-6.0% NaCl条件下生长。泛醌-10是唯一的呼吸醌。DGS2-2的G+C含量为62.5%，DGS5-3的为57.5%。两株菌均以特征性总和8（C7和/或C6）和C作为主要脂肪酸，以磷脂酰胆碱、鞘糖脂、磷脂酰乙醇胺、磷脂酰甘油和二磷脂酰甘油作为主要极性脂质。两株菌之间的16S rRNA基因相似性（97.3%）、平均核苷酸同一性（ANI，72.0%）和数字DNA-DNA杂交（dDDH，18.4%）值均低于种的界定阈值。基于16S rRNA基因和全基因组序列的系统发育和系统基因组分析将两株菌置于该属内不同的谱系中。各菌株与模式菌株之间的ANI和dDDH值分别低于74.5%和19.5%，支持将它们指定为新物种。基因组分析鉴定出与潜在藻类共生特性相关的推定基因，包括维生素、铁载体和类激素化合物的生物合成。还鉴定出类胡萝卜素生物合成基因，液相色谱/质谱法证实了虾青素（DGS2-2）和降红藻黄素（DGS5-3）的产生。基于基因组、系统发育、表型和化学分类学证据，菌株DGS2-2和DGS5-3代表该属的两个新物种，为此提出新物种名 sp. nov.（DGS2-2 =KACC 23855 =JCM 37496）和 sp. nov.（DGS5-3 =KACC 23854 =JCM 37497）。
