Phenotypic and genotypic characterization of Marinobacterium weihaiense sp. nov. and Marinobacterium marinum sp. nov., isolated from marine sediment, and genomic properties of the genus Marinobacterium.

In this study, two novel bacterial strains were isolated from coastal sediment of Weihai, China. The two strains were Gram-stain-negative and facultatively aerobic, designated 3-1745T and A346T. Based on phenotypic, genetic and phylogenetic properties, strains 3-1745T and A346T represent two novel species of the genus Marinobacterium. The results of genome analysis revealed many central carbohydrate metabolism pathways such as gluconeogenesis, pyruvate oxidation, tricyclic acid cycle, pentose phosphate pathway and PRPP biosynthesis in the genus Marinobacterium. The ability of strains 3-1745T and A346T to utilize volatile fatty acids was experimentally confirmed. Polyhydroxyalkanoate synthases (PhaA, PhaB and PhaC) for the synthesis of polyhydroxyalkanoates were prevalent in the genus Marinobacterium. Multiple BGCs (biosynthetic gene clusters) including betalactone, ectoine, ranthipeptide, redox-cofactor, RiPPs (ribosomally synthesized post-translationally modified peptides) and T3PKS (polyketide synthases) in the genome of the genus Marinobacterium were found. Additional genome analyses suggested that the genus Marinobacterium contained diverse potential mechanisms of salt tolerance and mainly utilized oligosaccharides. This is the first report on broad genomic analyses of the genus Marinobacterium with the description of two novel species and potential ecological and biotechnological implications.

Maribellus maritimus sp. nov., isolated from marine sediment.

A novel facultatively anaerobic and Gram-stain-negative bacterial strain, designated 5E3T, was isolated from intertidal sediments of Xiaoshi Island of Weihai, People's Republic of China. Cells of strain 5E3T were long rod-shaped with widths of 0.3-0.5 µm and lengths of 4.0-6.0 µm. Optimum growth of strain 5E3T occurred at 33 °C, pH 6.5-7.0 and with 3% (w/v) NaCl. Oxidase activity was negative but catalase activity was weakly positive. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain 5E3T was most closely related to 'Maribellus comscasis' WC007 (99.5%), followed by M. sediminis MCCC 1K04285T (95.9%) and M. luteus XSD2T (95.6%). Genome comparisons between strain 5E3T and strain 'M. comscasis' WC007, using average nucleotide identity (ANI) value (93.0%) and DNA-DNA hybridization (DDH) value (50.1%), confirmed low genome relatedness. The major cellular fatty acids (≥ 10%) were iso-C15:0 and iso-C17:0 3-OH. The sole respiratory quinone was MK-7. The polar lipids consisted of phosphatidylethanolamine (PE), one unidentified aminolipid (AL) and three unidentified lipids (L1, L2, L3). The DNA G + C content was 37.9 mol%. According to the integrated results of phylogenetic, physiological, biochemical and chemotaxonomic characteristics, we propose that strain 5E3T represents a novel species of the genus Maribellus, for which the name Maribellus maritimus sp. nov. is proposed. The type strain is 5E3T (= KCTC 82744T = MCCC 1H00473T).