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<p>Two bacterial strains, B2-R-102<sup>T</sup> and W1-Q-101<sup>T</sup>, 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&#xa0;°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&#xa0;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 <i>α</i>-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<sub>15:0,</sub> C<sub>16:0,</sub> iso-C<sub>15:0</sub>, C<sub>18:1</sub><i>ω</i>9<i>c</i><sub>,</sub> anteiso-C<sub>15:0</sub> and iso-C<sub>17:0</sub> 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<sup>T</sup> and W1-Q-101<sup>T</sup> belonged to the genera <i>Segatella</i> and <i>Parabacteroides</i>, with 96.9 and 97.7% 16S rRNA gene sequence similarities to <i>Segatella copri</i> CB7<sup>T</sup> and <i>Parabacteroides goldsteinii</i> DSM 19448<sup>T</sup>, 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 <i>Segatella intestinalis</i> sp. nov. (type strain B2-R-102<sup>T</sup> = CGMCC 1.17963<sup>T</sup> = KCTC 25417<sup>T</sup>) and <i>Parabacteroides caeci</i>&#xa0;sp<i>.</i> nov. (type strain W1-Q-101<sup>T</sup> = KCTC 25456<sup>T</sup> = CGMCC 1.17991<sup>T</sup>).</p>

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Segatella intestinalis sp. nov., and Parabacteroides caeci sp. nov., novel potential probiotics from the human gut microbiome

  • 期刊论文

  • 发表日期：

    2025年8月23日

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  • Md Shamsuzzaman,
  • Ram Hari Dahal,
  • Yoon-Jung Choi,
  • Shukho Kim,
  • Jungmin Kim

摘要

Two bacterial strains, B2-R-102T and W1-Q-101T, 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 C15:0, C16:0, iso-C15:0, C18:1ω9c, anteiso-C15:0 and iso-C17:0 3-OH. Neither strain exhibited haemolytic activity, and genomic analysis revealed no acquired antibiotic resistance or virulence genes. Phylogenetic analysis showed that B2-R-102T and W1-Q-101T belonged to the genera Segatella and Parabacteroides, with 96.9 and 97.7% 16S rRNA gene sequence similarities to Segatella copri CB7T and Parabacteroides goldsteinii DSM 19448T, 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-102T = CGMCC 1.17963T = KCTC 25417T) and Parabacteroides caeci sp. nov. (type strain W1-Q-101T = KCTC 25456T = CGMCC 1.17991T).