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.

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.

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