A novel bacterial strain, designated as HN-E44T, was isolated from marine sponge collected from Yangpu Bay, Hainan, PR China. Strain HN-E44T was Gram-stain-negative, non-motile, catalase-positive, oxidase-negative, rod-shaped and yellow-pigmented. Growth occurred at 4-37 °C (optimum, 28 °C), at pH 6-8 (pH 7) and in 0.5-14 % (w/v) NaCl (3-5 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HN-E44T formed an independent cluster with Marixanthomonas ophiurae JCM 14121T within the family Flavobacteriaceae and had the highest sequence similarity of 93.6 % to the closest type strain M. ophiurae JCM 14121T. The major fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0 3-OH, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C15 : 1 G. The polar lipids comprised phosphatidylethanolamine, sphingolipid, four unidentified phospholipids, an unidentified aminophospholipid and an unidentified lipid. The respiratory quinone was identified as MK-6. The genomic DNA G+C content was determined to be 40.6 mol%. The average nucleotide identity (ANI) and average amino acid identity (AAI) values between strain HN-E44T and closest type strain M. ophiurae JCM 14121T were, respectively, 79.6 and 85.2 %, both of which were below thresholds for species delineation (95-96 % ANI and 95-96 % AAI), but were over thresholds for genus delineation (73.98 % ANI and 70-76 % AAI). The combined genotypic and phenotypic distinctiveness demonstrated that strain HN-E44T could be differentiated from closely related genera. Therefore, it is proposed that strain HN-E44T represents a novel species of the genus Marixanthomonas, for which the name Marixanthomonas spongiae sp. nov. is proposed, with the type strain HN-E44T (=MCCC 1K03332T=LMG 30459T).
Keywords: Marixanthomonas spongiae sp. nov.; polyphasic taxonomy; sponge.