# Mucilaginibacter aureus sp. nov. and Mucilaginibacter sediminis sp. nov., isolated from wetland soil

## TL;DR

Two new bacterial species, Mucilaginibacter aureus and Mucilaginibacter sediminis, were discovered in wetland soil in South Korea.

## Contribution

The paper introduces two novel species within the genus Mucilaginibacter based on genomic and phenotypic analyses.

## Key findings

- Strains AW1-3T and AW1-7T show distinct growth conditions and fatty acid profiles.
- Genomic analysis confirms the two strains represent separate species with low ANI and dDDH values.
- Phylogenetic analysis places the strains close to known Mucilaginibacter species but below species delineation thresholds.

## Abstract

Two Gram-stain-negative, non-motile, rod-shaped bacterial strains, designated AW1-3T (strictly aerobic) and AW1-7 T (facultatively aerobic), both catalase- and oxidase-positive, were isolated from a reed wetland in South Korea. Strain AW1-3T grew at 15–35 °C, pH 6.0–7.0 and in 0.0–0.5% (w/v) NaCl, whereas strain AW1-7T grew at 10–35 °C, pH 6.0–7.0 and in 0–0.5% NaCl. The major fatty acids (>10%) were iso-C15:0 and summed feature 3 (C16:1 ω7c and/or C16 :1 ω6c) in strain AW1-3T and C16:0, summed feature 3, C18:0 and iso-C15:0 in strain AW1-7T. Phosphatidylethanolamine was the major polar lipid in both strains, and menaquinone-7 was the sole respiratory quinone. The genomic DNA G+C contents were 43.9 mol% (AW1-3T) and 43.2 mol% (AW1-7T). The two strains shared 94.9% 16S rRNA gene sequence similarity, with ANI and dDDH values of 70.9% and 20.0%, respectively, indicating they represent distinct species. Phylogenetic and phylogenomic analyses based on 16S rRNA gene and whole-genome sequences placed strains AW1-3T and AW1-7T in close association with Mucilaginibacter rivuli HMF5004ᵀ and Mucilaginibacter ginsenosidivorax KHI28ᵀ, respectively. However, strain AW1-3T shared 16S rRNA gene sequence similarity/ANI/dDDH values of 97.7%/73.7%/19.8% with M. rivuli HMF5004T, and strain AW1-7ᵀ shared 98.5%/88.6%/36.6% with M. ginsenosidivorax KHI28ᵀ, all below the species delineation thresholds, supporting their recognition as novel species. Based on phenotypic, chemotaxonomic and genomic characteristics, the names Mucilaginibacter aureus sp. nov. (AW1-3T=KACC 23848T=JCM 37500T) and Mucilaginibacter sediminis sp. nov. (AW1-7T=KACC 23849T=JCM 37501T) are proposed.