A novel Gram-stain-negative, facultatively anaerobic, filamentous and rose-brown pigmented bacterium, designated strain HF401T, was isolated from marine sediment off the coast of Weihai, China. The isolate grew at temperatures between 4 and 45 °C (optimal growth at 33 °C), at pH 6.5-8.5 (optimal growth at pH 7.5) and with 0.5-6.0 % (w/v) NaCl (optimal growth at 3.0 %). The predominant menaquinone was menaquinone 7 (MK-7). The G+C content of the genomic DNA was 50.8 mol% (from high-performance liquid chromatography). The major fatty acids were iso-C15 : 0, C16:0, anteiso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2OH). The major polar lipids were phosphatidylethanolamine, phospholipid and an unidentified lipid. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain HF401T formed a distinct branch with Geofilum rubicundum JCM 15548T in the family Marinilabiliaceae. The most closely related strains of strain HF401T were Natronoflexuspectinivorans AP1T (96.2 % 16S rRNA gene sequence similarity), G. rubicundum JCM 15548T (96.2 %) and Alkalitaleasaponilacus SC/BZ-SP2T (96.0 %). Average nucleotide identity (ANI) values between strain HF401T and G. rubicundum JCM 15548T showed a relatedness of 71.3 % (ANIb) and 86.0 % (ANIm). The percentage of conserved proteins (POCP) value between strain HF401T and G. rubicundum JCM 15548T was 61.2 %. Based on polyphasic analysis, especially the phylogenetic relationships and the higher POCP value, strain HF401T is considered to represent a novel species in the genus Geofilum, for which the name Geofilum rhodophaeum sp. nov. is proposed. The type strain of Geofilum rhodophaeum is HF401T (KCTC 42595T=MCCC 1H00119T).
Keywords: 16S rRNA gene; Geofilum rhodophaeum sp. nov; marine sediment; polyphasic analysis.