Roseobacter ponti sp. nov., isolated from seawater

Roseobacter fucihabitans sp. nov., isolated from the brown alga Fucus spiralis

A Gram-negative, aerobic, pink-pigmented, and bacteriochlorophyll a-containing bacterial strain, designated B14T, was isolated from the macroalga Fucus spiralis sampled from the southern North Sea, Germany. Based on 16S rRNA gene sequences, species of the genera Roseobacter and Sulfitobacter were most closely related to strain B14T with sequence identities ranging from 98.15 % (Roseobacter denitrificans Och 114T) to 99.11 % (Roseobacter litoralis Och 149T), whereas Sulfitobacter mediterraneus CH-B427T exhibited 98.52 % sequence identity. Digital DNA-DNA hybridization and average nucleotide identity values between the genome of the novel strain and that of closely related Roseobacter and Sulfitobacter type strains were <20 % and <77 %, respectively. The novel strain contained ubiquinone-10 as the only respiratory quinone and C18 : 1 ω7c, C16 : 0, C18 : 0, C12 : 1 ω7c, C18 : 2 ω7,13c, and C10 : 0 3-OH as the major cellular fatty acids. The predominant polar lipids of strain B14T were phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. The genome of strain B14T comprises a chromosome with a size of 4.5 Mbp, one chromid, and four plasmids. The genome contains the complete gene cluster for aerobic anoxygenic photosynthesis required for a photoheterotrophic lifestyle. The results of this study indicate that strain B14T (=DSM 116946T=LMG 33352T) represents a novel species of the genus Roseobacter for which the name Roseobacter fucihabitans sp. nov. is proposed.

Roseobacter cerasinus sp. nov., isolated from a fish farm

An obligate aerobic and bacteriochlorophyll a-containing bacterium, designated strain AI77^T, was isolated from a fish farm in Uwa Sea, Japan. Cells were Gram-stain-negative, coccoid- to oval-shaped, and showed no motility. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain AI77^T is a member of the genus Roseobacter and closely related to Roseobacter ponti MM-7^T (97.8 %), Roseobacter denitrificans OCh 114^T (97.3 %) and Roseobacter litoralis OCh 149^T (97.3 %). The G+C content of strain AI77^T was 61.0 mol%. The average amino acid identity values of the genome in strain AI77^T with those in R. denitrificans OCh 114^T and R. litoralis OCh 149^T were 73.26 % (SD 16.46) and 72.63 % (SD 16.76), respectively. The digital DNA-DNA hybridization values of strain AI77^T with the type strains R. denitrificans OCh 114^T and R. litoralis OCh 149^T were 18.70 and 18.50 %, respectively. The dominant fatty acids (>10 % of total fatty acids) of AI77^T were summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1 ω6c) and saturated fatty acid C_16 : 0. The sole respiratory quinone was ubiquinone-10. The predominant polar lipids were phosphatidylcholine, phosphatidylglycerol and diphosphatidylglycerol. Based on the genetic and phenotypic data obtained herein, we conclude that strain AI77^T represents a new species of the genus Roseobacter, for which we propose the name Roseobacter cerasinus sp. nov.; the type strain is AI77^T (=DSM 110091^T=NBRC 114115^T).

Complete Genome of Roseobacter ponti DSM 106830T

Members of the Roseobacter group are known for their different ecologically relevant metabolic traits and high abundance in many marine environments. This includes traits like carbon monoxide oxidation, sulfur oxidation, nitrogen oxidation, DMSP demethylation, denitrification, and production of bioactive compounds. Nevertheless, their role in the marine biogeochemical cycles remains to be elucidated. Roseobacter ponti DSM 106830T, also designated strain MM-7T (=KCTC 52469T =NBRC 112431T), is a novel type strain of the Roseobacter group, which was proposed as new Roseobacter species. It was isolated from seawater of the Yellow Sea in South Korea. We report the complete genome sequence of R. ponti DSM 106830T, which belongs to the family Rhodobacteraceae. The genome of R. ponti DSM 106830T comprises a single circular chromosome (3,861,689 bp) with a GC content of 60.52% and an additional circular plasmid (p1) of 100,942 bp with a GC content of 61.51%. The genome encodes 3,812 putative genes, including 3 rRNA, 42 tRNA, 1 tmRNA, and 3 ncRNA. The genome information was used to perform a phylogenetic analysis, which confirmed that the strain represents a new species. Moreover, the genome sequence enabled the investigation of the metabolic capabilities and versatility of R. ponti DSM 106830T. Finally, it provided insight into the high niche adaptation potential of Roseobacter group members.