Maribacter luteus sp. nov., a marine bacterium isolated from intertidal sand of the Yellow Sea

Maribacter halichondriae sp. nov., isolated from the marine sponge Halichondria panicea, displays features of a sponge-associated life style

A new member of the family Flavobacteriaceae (termed Hal144T) was isolated from the marine breadcrumb sponge Halichondria panicea. Sponge material was collected in 2018 at Schilksee which is located in the Kiel Fjord (Baltic Sea, Germany). Phylogenetic analysis of the full-length Hal144T 16S rRNA gene sequence revealed similarities from 94.3 to 96.6% to the nearest type strains of the genus Maribacter. The phylogenetic tree of the 16S rRNA gene sequences depicted a cluster of strain Hal144T with its closest relatives Maribacter aestuarii GY20T (96.6%) and Maribacter thermophilus HT7-2T (96.3%). Genome phylogeny showed that Maribacter halichondriae Hal144T branched from a cluster consisting of Maribacter arenosus, Maribacter luteus, and Maribacter polysiphoniae. Genome comparisons of strain Maribacter halichondriae Hal144T with Maribacter sp. type strains exhibited average nucleotide identities in the range of 75-76% and digital DNA-DNA hybridisation values in the range of 13.1-13.4%. Compared to the next related type strains, strain Hal144T revealed unique genomic features such as phosphoenolpyruvate-dependent phosphotransferase system pathway, serine-glyoxylate cycle, lipid A 3-O-deacylase, 3-hexulose-6-phosphate synthase, enrichment of pseudogenes and of genes involved in cell wall and envelope biogenesis, indicating an adaptation to the host. Strain Hal144T was determined to be Gram-negative, mesophilic, strictly aerobic, flexirubin positive, resistant to aminoglycoside antibiotics, and able to utilize N-acetyl-β-D-glucosamine. Optimal growth occurred at 25-30 °C, within a salinity range of 2-6% sea salt, and a pH range between 5 and 8. The major fatty acids identified were C17:0 3-OH, iso-C15:0, and iso-C15:1 G. The DNA G + C content of strain Hal144T was 41.4 mol%. Based on the polyphasic approach, strain Hal144T represents a novel species of the genus Maribacter, and we propose the name Maribacter halichondriae sp. nov. The type strain is Hal144T (= DSM 114563T = LMG 32744T).

Maribacter aquimaris sp. nov., isolated from seawater adjacent to Fildes Peninsula, Antarctica

A novel Gram-stain-negative, aerobic, and rod-shaped bacterium with gliding motility, named strain ANRC-HE7^T, was isolated from the seawater of Biological Bay adjacent to Fildes Peninsula, Antarctica. The optimal growth of this strain occurred at 28 °C, pH 7.5, and in the presence of 1.0% (w/v) NaCl. Strain ANRC-HE7^T can produce amylase and harbors gene clusters involved in cellulose degradation. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain ANRC-HE7^T formed a distinct lineage within the genus Maribacter and was closely related to Maribacter luteus RZ05^T (98.4% sequence similarity), Maribacter polysiphoniae LMG 23671^T (98.3%), and Maribacter arenosus CAU 1321^T (97.3%). However, digital DNA-DNA hybridization and average nucleotide identity values between strain ANRC-HE7^T and closely related strains were 17.4-49.1% and 70.9-92.7%, much lower than the cutoff values of 70% and 95%, respectively. On the other hand, strain ANRC-HE7^T shared characteristics with most type strains within the genus. Its respiratory quinone was MK-6. The major fatty acids were iso-C_15:0, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), and anteiso-C_15:0. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, four unidentified phospholipids, and five unidentified glycolipids. The DNA G + C content of strain ANRC-HE7^T was 40.1%. Based on the results of the biochemical, phylogenetic, and chemotaxonomic analyses, strain ANRC-HE7^T is suggested to represent a novel species of the genus Maribacter, for which the name Maribacter aquimaris sp. nov. is proposed. The type strain is ANRC-HE7^T (= MCCC 1K03787^T = KCTC 72532^T).