Institute of Jeju Microbial Resources, BioPS Co., Ltd, Jeju, 63243, Republic of Korea.
Korean Collection for Type Cultures, Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup, 56212, Republic of Korea.
Arch Microbiol. 2024 Feb 14;206(3):100. doi: 10.1007/s00203-023-03804-5.
Three Gram-reaction-positive bacterial strains, designated KSW-18, KSW2-22, and KSW4-11, were isolated from seawater, and two dried seaweed samples collected at Gwakji Beach in Jeju, Republic of Korea, respectively, and their taxonomic positions were examined by a polyphasic approach. The 16S rRNA gene phylogeny showed that strain KSW4-11 was tightly associated with Microbacterium oleivorans NBRC 103075, while strains KSW-18 and KSW2-22 formed a distinctive subline at the base of a clade including the above two strains. The three isolates showed high sequence similarity with one another (99.7-99.9%; 1-4 nt differences) and Microbacterium oleivorans (99.8-99.9%; 1-3 nt differences). The chemotaxonomic features were typical for the genus Microbacterium; Lysine as the diagnostic diamino acid and N-glycolylated muramic acid of the peptidoglycans, the predominant menaquinones of MK-11, MK-10 and MK-12, the major fatty acids of anteiso-C and anteiso-C, and the major polar lipids including diphosphatidylglycerol, phosphatidylglycerol, and two or three unidentified glycolipids. In core genome-based phylogenetic tree, strains KSW-18 and KSW2-22 were closely associated with Microbacterium oleivorans NBRC 103075, while strain KSW4-11 formed a distinctive subline at the base of a clade including the above three strains, in contrast to the 16S rRNA gene tree. Strains KSW-18 and KSW2-22 shared an OrthoANIu of 98.6% and a digital DNA-DNA hybridization of 87.6% with each other, representing that they were strains of a species, while the OrthoANIu and digital DNA-DNA hybridization values between strains KSW-18 and KSW4-11, and between both of these isolates and all members of the genus Microbacterium were ≤86.5% and ≤30.7%, respectively. The analyses of overall genomic relatedness indices and phenotypic distinctness support that the three isolates represent two new species of the genus Microbacterium. Based on the results obtained here, Microbacterium aquilitoris sp. nov. (type strain KSW-18 = KCTC 49623 = NBRC 115222) and Microbacterium gwkjiense sp. nov. (type strain KSW4-11 = KACC 23321 = DSM 116380) are proposed.
从海水和韩国济州岛 Gwakji 海滩采集的两份干海藻样本中分离到三株革兰氏反应阳性细菌菌株，分别命名为 KSW-18、KSW2-22 和 KSW4-11。通过多相分类法研究了它们的分类地位。16S rRNA 基因系统发育分析表明，菌株 KSW4-11 与 Microbacterium oleivorans NBRC 103075 密切相关，而菌株 KSW-18 和 KSW2-22 则在包括上述两株菌的一个分支的基部形成了一个独特的亚群。这三个分离株彼此之间具有很高的序列相似性（99.7-99.9%；1-4 个核苷酸差异），与 Microbacterium oleivorans 的序列相似性也很高（99.8-99.9%；1-3 个核苷酸差异）。化学分类特征典型地属于 Microbacterium 属；赖氨酸是诊断二氨基酸，肽聚糖中的 N-糖基化 muramic 酸，主要的menaquinones 为 MK-11、MK-10 和 MK-12，主要的脂肪酸为 anteiso-C 和 anteiso-C，主要的极性脂包括双磷脂酰甘油、磷脂酰甘油和两到三种未鉴定的糖脂。在基于核心基因组的系统发育树中，菌株 KSW-18 和 KSW2-22 与 Microbacterium oleivorans NBRC 103075 密切相关，而菌株 KSW4-11 则在包括上述三株菌的一个分支的基部形成了一个独特的亚群，与 16S rRNA 基因树相反。菌株 KSW-18 和 KSW2-22 之间的 OrthoANIu 为 98.6%，数字 DNA-DNA 杂交率为 87.6%，表明它们是同种的菌株，而菌株 KSW-18 和 KSW4-11 之间以及这两个分离株与所有 Microbacterium 属成员之间的 OrthoANIu 和数字 DNA-DNA 杂交值分别为≤86.5%和≤30.7%。整体基因组相关性指数和表型差异分析支持这三个分离株代表了 Microbacterium 属的两个新种。基于这里获得的结果，提出了 Aquilitoris 属的新种 Microbacterium aquilitoris sp. nov.（模式菌株 KSW-18=KCTC 49623=NBRC 115222）和 Gwkajiense 属的新种 Microbacterium gwkjiense sp. nov.（模式菌株 KSW4-11=KACC 23321=DSM 116380）。
