AUTHOR=Yu Seung Yeob , Oh Byeong Seob , Ryu Seoung Woo , Bak Jeong Eun , Heo Eun Seo , Moon Jeong Chan , Jeong Jae-Ho , Lee Ju Huck 

TITLE=Novel microbiota Mesosutterella faecium sp. nov. has a protective effect against inflammatory bowel disease

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1342098

DOI=10.3389/fmicb.2024.1342098

ISSN=1664-302X

ABSTRACT=<p>A novel Gram-negative, obligate anaerobe, non-motile, flagella-lacking, catalase- and oxidase-negative, coccobacilli-shaped bacterial strain designated AGMB02718<sup>T</sup> was isolated from swine feces. The 16S rRNA gene analysis indicated that strain AGMB02718<sup>T</sup> belonged to the genus <italic>Mesosutterella</italic> with the highest similarity to <italic>M. multiformis</italic> 4NBBH2<sup>T</sup> (= DSM 106860<sup>T</sup>) (sequence similarity of 96.2%), forming a distinct phylogenetic lineage. Its growth occurred at 25–45°C (optimal 37°C) and in 0.5–1% NaCl (optimal 0.5%). Strain AGMB02718<sup>T</sup> was asaccharolytic and contained menaquinone 6 (MK-6) and methylmenaquinone 6 (MMK-6) as the predominant respiratory quinones. The major cellular fatty acids in the isolate were C<sub>18:1</sub><italic>ω</italic>9<italic>c</italic> and C<sub>16:0</sub>. Based on the whole-genome sequencing analysis, strain AGMB02718<sup>T</sup> had a 2,606,253 bp circular chromosome with a G + C content of 62.2%. The average nucleotide identity value between strain AGMB02718<sup>T</sup> and <italic>M. multiformis</italic> 4NBBH2<sup>T</sup> was 72.1%, while the digital DNA–DNA hybridization value was 20.9%. Interestingly, genome analysis suggested that strain AGMB02718<sup>T</sup> possessed a low-toxicity lipopolysaccharide (LPS) because the genome of the isolate does not include <italic>lpxJ</italic> and <italic>lpxM</italic> genes for Kdo<sub>2</sub>-Lipid A (KLA) assembly, which confers high toxicity to LPS. Moreover, <italic>in vitro</italic> macrophage stimulation assay confirmed that AGMB02718<sup>T</sup> produced LPS with low toxicity. Because the low-toxicity LPS produced by the <italic>Sutterellaceae</italic> family is involved in regulating host immunity and low-toxicity LPS-producing strains can help maintain host immune homeostasis, we evaluated the anti-inflammatory activity of strain AGMB02718<sup>T</sup> against inflammatory bowel disease (IBD). As a result, strain AGMB02718<sup>T</sup> was able to prevent the inflammatory response in a dextran sulfate sodium (DSS)-induced colitis model. Therefore, this strain represents a novel species of <italic>Mesosutterella</italic> that has a protective effect against DSS-induced colitis, and the proposed name is <italic>Mesosutterella faecium</italic> sp. nov. The type strain is AGMB02718<sup>T</sup> (=GDMCC 1.2717<sup>T</sup> = KCTC 25541<sup>T</sup>).</p>