Maribacter litoralis sp. nov. a marine bacterium isolated from seashore

Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity

Aromatic prenylated metabolites have important biological roles and activities in all living organisms. Compared to their importance in all domains of life, we know relatively little about their substrate scopes and metabolic functions. Here, we describe a new UbiA-like prenyltransferase (Ptase) Ubi-297 encoded in a conserved operon of several bacterial taxa, including marine Flavobacteria and the genus Sacchromonospora. In silico analysis of Ubi-297 homologs indicated that members of this Ptase group are composed of several transmembrane α-helices and carry a conserved and distinct aspartic-rich Mg²⁺-binding domain. We heterologously produced UbiA-like Ptases from the bacterial genera Maribacter, Zobellia, and Algoriphagus in Escherichia coli. Investigation of their substrate scope uncovered the preferential farnesylation of quinoline derivatives, such as 8-hydroxyquinoline-2-carboxylic acid (8-HQA) and quinaldic acid. The results of this study provide new insights into the abundance and diversity of Ptases in marine Flavobacteria and beyond.

Maribacter algicola sp. nov., isolated from a marine red alga, Porphyridium marinum, and transfer of Maripseudobacter aurantiacus Chen et al. 2017 to the genus Maribacter as Maribacter aurantiacus comb. nov

A Gram-stain-negative, strictly aerobic and moderately halophilic bacterial strain, designated strain PoM-212^T, was isolated from a marine alga, Porphyridium marinum, in the Republic of Korea. Cells were catalase- and oxidase-positive rods with gliding motility without flagellum. Growth was observed at 20-40 °C (optimum, 30 °C) and pH 5.0-8.5 (pH 5.0-5.5) and in the presence of 0.5-5 % (w/v) NaCl (2-3 %). Strain PoM-212^T contained iso-C_15 : 1, iso-C_15 : 0, iso-C_17 : 0 3-OH and summed feature 3 (comprising C_16 : 1ω7c and/or C_16 : 1ω6c) as major fatty acids and menaquinone-6 as the sole isoprenoid quinone. Phosphatidylethanolamine, three unidentified aminolipids and two unidentified polar lipids were detected as major polar lipids. The G+C content of the genomic DNA was 41.0 mol%. Strain PoM-212^T was most closely related to Maribacter lutimaris KJ4^T, Maripseudobacter aurantiacus CDA4^T and Maribacter flavus C3^T with 97.2, 97.2 and 97.0 % 16S rRNA gene sequence similarities, respectively, and it formed a distinct phylogenetic lineage from them within the genus Maribacter. Maripseudobacter aurantiacus formed a close phylogenetic lineage with Maribacter flavus with 99.7 % 16S rRNA gene sequence similarity, but their digital DNA-DNA hybridization value was 67.4 %. On the basis of its phenotypic, chemotaxonomic and molecular properties, strain PoM-212^T represents a novel species of the genus Maribacter, for which the name Maribacter algicola sp. nov. is proposed. The type strain is PoM-212^T (=KACC 19789^T=JCM 32941^T). The transfer of Maripseudobacter aurantiacus to the genus Maribacter as Maribacter aurantiacus comb. nov. is also proposed (type strain CDA4^T=KCTC 52409^T=MCCC 1K03210^T).