Microbaculum mangrovi sp. nov., isolated from mangrove sediment

A Gram-stain-negative, strictly aerobic and motile bacterium, designated as FT89^T, was isolated from mangrove sediment in Shenzhen, China. Phylogenetic analysis of strain FT89^T was mostly related to Microbaculum marinisediminis, with 16S rRNA gene similarity of 99.66%. The genome size of strain FT89^T was 5,065,293 bp and the calculated G+C molar content was 65.90mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) value towards M. marinisediminis yielded 93.86% ANI and 53.2% dDDH. Although the 16S rRNA gene similarity is above 98.7%, the ANI and dDDH values are below the established species delineation thresholds (ANI <95% and dDDH <70%). Here, we confirm that strain FT89^T represents a novel species. Phenotypic characterization revealed that cells of strain FT89^T were ovoid to rod shaped, measuring 0.3-0.7 µm in width and 0.9-3.2 µm in length. Strain FT89^T grew at 20-40 °C (optimum 35 °C) at pH 5.5-9.0 (optimum pH 6.0-7.0) with 0-9% (w/v) NaCl (optimum 1-2%). The cells of strain FT89^T contained Q-10, and the major cellular fatty acids were composed of C_19:0 cyclo ω8c (41.7%) and summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c) (32.4%). Based on phylogenetic, phenotypic and chemotaxonomic analysis, strain FT89^T should represent a novel species of the genus Microbaculum, for which the proposed name is Microbaculum mangrovi FT89^T (=MCCC 1K08485^T=KCTC 8079^T).