Shamsuzzaman Md, Dahal Ram Hari, Choi Yoon-Jung, Kim Shukho, Kim Jungmin
Department of Biomedical Science, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
Antonie Van Leeuwenhoek. 2025 Aug 23;118(9):136. doi: 10.1007/s10482-025-02150-4.
Two bacterial strains, B2-R-102 and W1-Q-101, were isolated from the feces of a healthy Korean individual. These strains were Gram-stain negative, anaerobic, and non-motile, growing optimally between 20 and 40 °C and at pH 5.5-8.0. Importantly, they survived at pH 2.0 and tolerated 0.3% bile salts and pepsin after a 4 h exposure. The strains demonstrated in vitro antioxidant activity, inhibiting DPPH radicals by 48.12 ± 1.45 and 70.80 ± 12.8%, respectively. Furthermore, they inhibited α-amylase activity by 46.52 ± 4.42 to 60.84 ± 2.20%, compared to 74.82 ± 0.76% inhibition by sitagliptin. In vitro, anti-inflammatory assays revealed 57.77 ± 3.15 to 62.39 ± 2.23% inhibition of albumin protein denaturation, comparable to aspirin 72 ± 2.39% inhibition. The abundant cellular fatty acids were C C iso-C, Cω9c anteiso-C and iso-C 3-OH. Neither strain exhibited haemolytic activity, and genomic analysis revealed no acquired antibiotic resistance or virulence genes. Phylogenetic analysis showed that B2-R-102 and W1-Q-101 belonged to the genera Segatella and Parabacteroides, with 96.9 and 97.7% 16S rRNA gene sequence similarities to Segatella copri CB7 and Parabacteroides goldsteinii DSM 19448, respectively. Furthermore, biosynthetic gene cluster analysis revealed the potential for antimicrobial thiopeptides, lanthipeptides, and non-ribosomal peptides (NRPs). In silico average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were below the thresholds to distinguish novel species. Based on phenotypic, genomic, and phylogenetic analysis, we propose the names Segatella intestinalis sp. nov. (type strain B2-R-102 = CGMCC 1.17963 = KCTC 25417) and Parabacteroides caeci sp. nov. (type strain W1-Q-101 = KCTC 25456 = CGMCC 1.17991).
从一名健康韩国人的粪便中分离出两株细菌，分别为B2-R-102和W1-Q-101。这些菌株革兰氏染色阴性、厌氧且不运动，在20至40°C和pH 5.5 - 8.0条件下生长最佳。重要的是，它们在pH 2.0环境下存活，经4小时暴露后能耐受0.3%的胆汁盐和胃蛋白酶。这些菌株在体外具有抗氧化活性，分别能抑制48.12±1.45%和70.80±12.8%的DPPH自由基。此外，与西他列汀74.82±0.76%的抑制率相比，它们对α -淀粉酶活性的抑制率为46.52±4.42%至60.84±2.20%。体外抗炎试验显示，它们对白蛋白蛋白质变性的抑制率为57.77±3.15%至62.39±2.23%，与阿司匹林72±2.39%的抑制率相当。丰富的细胞脂肪酸为C C、异-C、Cω9c、anteiso-C和异-C 3-OH。两株菌均未表现出溶血活性，基因组分析未发现获得性抗生素耐药或毒力基因。系统发育分析表明，B2-R-102和W1-Q-101分别属于Segatella属和副拟杆菌属，其16S rRNA基因序列与Copri梭菌CB7和戈氏副拟杆菌DSM 19448的相似性分别为96.9%和97.7%。此外，生物合成基因簇分析揭示了产生抗微生物硫肽、羊毛硫肽和非核糖体肽（NRP）的潜力。计算机平均核苷酸同一性（ANI）和数字DNA - DNA杂交（dDDH）值低于区分新物种的阈值。基于表型、基因组和系统发育分析，我们提出新物种肠Segatella菌（Segatella intestinalis sp. nov.）（模式菌株B2-R-102 = CGMCC 1.17963 = KCTC 25417）和盲肠副拟杆菌（Parabacteroides caeci sp. nov.）（模式菌株W1-Q-101 = KCTC 25456 = CGMCC 1.17991）。
