Lee Soon Dong, Yang Hong Lim, Kim In Seop
Institute of Jeju Microbial Resources, BioPS Co., Ltd, Jeju, 63243, Republic of Korea.
Department of Biological Sciences and Biotechnology, Hannam University, Daejeon, 34054, Republic of Korea.
Curr Microbiol. 2025 Aug 14;82(10):452. doi: 10.1007/s00284-025-04352-5.
Three actinobacterial strains, designated as KSW-48, KSWW-56 and SSW1-59, were isolated from seawater, rock-attached living and dried seaweeds collected at Gwakji Beach in Jeju, Republic of Korea. All the isolates showed growth at 15-42 °C and pH 5-10, and tolerated NaCl for growth up to 10%. The 16S rRNA gene-based phylogeny showed that the novel strains were closely related with the type strains of Microbacterium aquimaris and Microbacterium luteum, with the 16S rRNA gene sequence similarity of 99.93-100% (0-1 nt differences) with one another and of 99.86-99.93% (1-2 nt differences) with Microbacterium aquimaris KCTC 19124, followed by (98.98-99.04%; 14-15 nt differences) with Microbacterium luteum A18JL200. The core genome-based phylogenomic tree reflected the tree topologies of the 16S rRNA gene-based phylogeny. The chemotaxonomic features were in agreement with the classification in the genus Microbacterium as follow. The cell wall diamino acid and the whole-cell sugars were ornithine. The muramic acid of the cell-wall peptidoglycan was of the N-glycolyl form. The predominant menaquinones were MK-10, MK-11 and MK-12. The polar lipids in common consisted of phosphatidylglycerol and an unidentified glycolipid. The presence of diphosphatidylglycerol and an additional unidentified glycolipid were variable depending on isolated strains. The major fatty acids were anteiso-C, anteiso-C and iso-C. Average nucleotide identity and digital DNA-DNA hybridisation values showed that strain KSW-48 and SSW1-59 represented a new species of the genus Microbacterium, while KSWW-56 was a strain of Microbacterium aquimaris. Based on the results obtained here, Microbacterium xanthum sp. nov. (type strain, SSW1-59 = KCTC 49622 = KACC 23361 = DSM 116382 = MCCC 1K08947) are proposed. Also, it is proposed that Microbacterium ihumii Yacouba et al. 2023 be reclassified as a later heterotypic synonym of Microbacterium tenebrionis Lee and Kim 2023 by high genomic similarity.
从韩国济州岛格瓦吉海滩采集的海水、附着在岩石上的活体和干燥海藻中分离出三株放线菌，分别命名为KSW-48、KSWW-56和SSW1-59。所有分离株在15-42℃和pH 5-10条件下均能生长，并且耐受高达10%的NaCl用于生长。基于16S rRNA基因的系统发育分析表明，这些新菌株与海栖微杆菌（Microbacterium aquimaris）和黄色微杆菌（Microbacterium luteum）的模式菌株密切相关，它们彼此之间的16S rRNA基因序列相似性为99.93-100%（0-1个核苷酸差异），与海栖微杆菌KCTC 19124的相似性为99.86-99.93%（1-2个核苷酸差异），其次与黄色微杆菌A18JL200的相似性为98.98-99.04%（14-15个核苷酸差异）。基于核心基因组的系统发育树反映了基于16S rRNA基因的系统发育树的拓扑结构。化学分类学特征与微杆菌属的分类一致，如下所示。细胞壁二氨基酸和全细胞糖为鸟氨酸。细胞壁肽聚糖的胞壁酸为N-糖基化形式。主要的甲基萘醌为MK-10、MK-11和MK-12。常见的极性脂质由磷脂酰甘油和一种未鉴定的糖脂组成。二磷脂酰甘油和另一种未鉴定的糖脂的存在因分离菌株而异。主要脂肪酸为anteiso-C、anteiso-C和iso-C。平均核苷酸同一性和数字DNA-DNA杂交值表明，菌株KSW-48和SSW1-59代表微杆菌属的一个新物种，而KSWW-56是海栖微杆菌的一个菌株。基于此处获得的结果，提出了新种黄色微杆菌（Microbacterium xanthum sp. nov.）（模式菌株，SSW1-59 = KCTC 49622 = KACC 23361 = DSM 116382 = MCCC 1K08947）。此外，由于基因组高度相似，建议将2023年Yacouba等人报道的ihumii微杆菌重新分类为2023年Lee和Kim报道的暗黑微杆菌的晚出异名。
