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

Two Gram-stain-negative, non-motile, rod-shaped bacterial strains, designated AW1-3^T (strictly aerobic) and AW1-7 ^T (facultatively aerobic), both catalase- and oxidase-positive, were isolated from a reed wetland in South Korea. Strain AW1-3^T grew at 15-35 °C, pH 6.0-7.0 and in 0.0-0.5% (w/v) NaCl, whereas strain AW1-7^T grew at 10-35 °C, pH 6.0-7.0 and in 0-0.5% NaCl. The major fatty acids (>10%) were iso-C_15:0 and summed feature 3 (C_16:1 <i> ω</i>7<i>c</i> and/or C_{16 :1} <i> </i>ω<i>6c</i>) in strain AW1-3^T and C_16:0, summed feature 3, C_18:0 and iso-C_15:0 in strain AW1-7^T. 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% (AW1-3^T) and 43.2 mol% (AW1-7^T). 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 AW1-3^T and AW1-7^T in close association with <i>Mucilaginibacter rivuli</i> HMF5004ᵀ and <i>Mucilaginibacter ginsenosidivorax</i> KHI28ᵀ, respectively. However, strain AW1-3^T shared 16S rRNA gene sequence similarity/ANI/dDDH values of 97.7%/73.7%/19.8% with <i>M. rivuli</i> HMF5004^T, and strain AW1-7ᵀ shared 98.5%/88.6%/36.6% with <i>M. ginsenosidivorax</i> KHI28ᵀ, all below the species delineation thresholds, supporting their recognition as novel species. Based on phenotypic, chemotaxonomic and genomic characteristics, the names <i>Mucilaginibacter aureus</i> sp. nov. (AW1-3^T=KACC 23848^T=JCM 37500^T) and <i>Mucilaginibacter sediminis</i> sp. nov. (AW1-7^T=KACC 23849^T=JCM 37501^T) are proposed.