The genus Pseudooceanicola from the alphaproteobacterial Roseobacter group currently includes ten validated species. We herein describe strain Lw-13e^T, the first Pseudooceanicola species from marine macroalgae, isolated from the brown alga Fucus spiralis abundant at European and North American coasts. Physiological and pangenome analyses of Lw-13e^T showed corresponding adaptive features. Adaptations to the tidal environment include a broad salinity tolerance, degradation of macroalgae-derived substrates (mannitol, mannose, proline), and resistance to several antibiotics and heavy metals. Notably, Lw-13e^T can degrade oligomeric alginate via PL15 alginate lyase encoded in a polysaccharide utilization locus (PUL), rarely described for roseobacters to date. Plasmid localization of the PUL strengthens the importance of mobile genetic elements for evolutionary adaptations within the Roseobacter group. PL15 homologs were primarily detected in marine plant-associated metagenomes from coastal environments but not in the open ocean, corroborating its adaptive role in algae-rich habitats. Exceptional is the tolerance of Lw-13e^T against the broad-spectrum antibiotic tropodithietic acid, produced by Phaeobacter spp. co-occurring in coastal habitats. Furthermore, Lw-13e^T exhibits features resembling terrestrial plant-bacteria associations, i.e. biosynthesis of siderophores, terpenes and volatiles, which may contribute to mutual bacteria-algae interactions. Closest described relative of Lw-13e^T is Pseudopuniceibacterium sediminis CY03^T with 98.4% 16S rRNA gene sequence similarity. However, protein sequence-based core genome phylogeny and average nucleotide identity indicate affiliation of Lw-13e^T with the genus Pseudooceanicola. Based on phylogenetic, physiological and (chemo)taxonomic distinctions, we propose strain Lw-13e^T (=DSM 29013^T = LMG 30557^T) as a novel species with the name Pseudooceanicola algae.

来自 alphaproteobacterial Roseobacter群的Pseudooceanicola属目前包括 10 个经过验证的物种。我们在此描述了 Lw-13e ^T菌株，这是第一个来自海洋大型藻类的拟海洋藻物种，从欧洲和北美海岸丰富的褐藻墨角藻中分离出来。 Lw-13e ^T的生理和全基因组分析显示出相应的适应性特征。对潮汐环境的适应包括广泛的盐度耐受性、大型藻类底物（甘露醇、甘露糖、脯氨酸）的降解以及对多种抗生素和重金属的抵抗力。值得注意的是，Lw-13e ^T可以通过多糖利用位点 (PUL) 中编码的 PL15 海藻酸盐裂解酶降解低聚海藻酸盐，迄今为止很少对玫瑰杆菌进行描述。 PUL 的质粒定位增强了移动遗传元件对于玫瑰杆菌属群内进化适应的重要性。 PL15 同源物主要在沿海环境的海洋植物相关宏基因组中检测到，但在公海中未检测到，这证实了其在藻类丰富的栖息地中的适应作用。 Lw-13e ^T对由褐杆菌属产生的广谱抗生素原二硫酸具有特殊的耐受性。在沿海生境中同时发生。此外，Lw-13e ^T表现出类似于陆地植物-细菌关联的特征，即铁载体、萜烯和挥发物的生物合成，这可能有助于细菌-藻类的相互作用。 Lw-13e ^T最接近的亲缘关系是Pseudopuniceibacter sediminis CY03 ^T （编号为 98）。4% 16S rRNA 基因序列相似性。然而，基于蛋白质序列的核心基因组系统发育和平均核苷酸同一性表明 Lw-13e ^T与Pseudooceanicola属有联系。基于系统发育、生理和（化学）分类学的区别，我们提出菌株 Lw-13e ^T (=DSM 29013 ^T = LMG 30557 ^T ) 作为一个新物种，命名为Pseudooceanicola algae 。