Roseibacterium beibuensis sp. nov., a Novel Member of Roseobacter Clade Isolated from Beibu Gulf in the South China Sea

Roseicyclus sediminis sp. nov. and Roseicyclus salinarum sp. nov., isolated from marine environment, and reclassification of two species of the genus Roseibacterium as species of the genus Roseicyclus

Two Gram-stain-negative, facultatively anaerobic, rod-shaped bacteria were isolated from coastal sediments and salt marshes in Weihai, China, and designated as SDUM158017T and SDUM158016T, respectively. Both grew at temperatures ranging from 20 to 43°C and within a pH range of 6.0 to 9.0. However, strain SDUM158016T grew in the presence of 1.0-7.0% (w/v) NaCl, whereas strain SDUM158017T was able to grow in the presence of 1.0-10.0% (w/v) NaCl. Strains SDUM158016T and SDUM158017T contain major fatty acids of C18 : 1 ω7ϲ and C16 : 0 and contain Q10 as the sole quinone. Based on 16S rRNA gene sequence analysis, the closest relatives of strains SDUM158016T and SDUM158017T are 'Roseibacterium beibuensis' MCCC 1F00103T, followed by Roseibacterium elongatum JCM 11220T, with the highest similarities 97.1 and 97.3 %, respectively. The average nucleotide identity values between strain SDUM158016T and species of the genera Roseibacterium and Roseicyclus ranged from 76.0 to 78.9 %, while they ranged from 75.9 to 78.6% for strain SDUM158017T. These values are below the species delineation threshold of 98.6%, suggesting that both strains represent novel species. Phylogenetic analysis of the 16S rRNA genes and genome sequences further indicates that Roseibacterium species within the genus Roseicyclus and these isolates represent two potentially novel species within the genus Roseicyclus. Taken together, strains SDUM158017T and SDUM158016T represent two novel species of the genus Roseicyclus, for which the names Roseicyclus sediminis and Roseicyclus salinarum are proposed with the type strains SDUM158016T (=KCTC 92632T =MCCC 1H01367T) and SDUM158017T (=KCTC 92633T =MCCC 1H01363T), respectively. Based on phylogenetic and genomic analyses, we also propose the reclassification of Roseibacterium elongatum as Roseicyclus elongatus comb. nov. and Roseibacterium persicicum as Roseicyclus persicicus comb. nov.

Fontisubflavum oceani gen. nov., sp. nov., isolated from the deep-sea cold seep water of South China Sea

In this study, we report a Gram-stain-negative, rod-shaped, atrichous and aerobic bacterial strain named CSW1921T, which was isolated from the deep-sea water of a cold seep in South China Sea. Growth of strain CSW1921T occurred at 10.0-35.0 °C (optimum, 30 °C), pH 5.0-10.0 (optimum, pH 8.0-9.0) and with 0-9.0 % (w/v) NaCl (optimum, 1.0-2.0 %). Phylogenetic tree analysis based on 16S rRNA gene sequence or the genomic sequence indicated that strain CSW1921T belonged to the family Rhodobacteraceae and was closely related to Rhodophyticola porphyridii MA-7-27T (97.5 % sequence similarity). Genomic analysis indicated that strain CSW1921T contains a circular chromosome of 3 592 879 bp with G+C content of 60.5 mol%. The predominant respiratory quinone of CSW1921T was ubiquinone-10. The polar lipids of CSW1921T contained phosphatidylglycerol, three unidentified aminolipids, two unidentified phospholipids and two unidentified lipids. The major fatty acids of strain CSW1921T contained C16 : 0, C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c). The average nucleotide identity, DNA-DNA hybridization and average amino acid identity values between strain CSW1921T and members of its related species were 68.02-69.08 %, 12.7-12.9 % and 46.87-48.08 %, respectively, which were lower than the recommended threshold values for bacterial species or genus delineation. Phylogenetic, physiological, biochemical and morphological analyses suggested that strain CSW1921T represents a novel genus and a novel species of the family Rhodobacteraceae, and the name Fontisubflavum oceani gen. nov., sp. nov. is proposed with the type strain CSW1921T (=MCCC 1K08371T=KCTC 92834T).

Purification, characterization and immunostimulatory activity of a novel exopolysaccharide from Bacillus sp. H5

Crude exopolysaccharides from extracellular polymeric substances produced by the marine bacterium Bacillus sp. H5 were fractionated using DEAE-Sepharose FF and Sephadex G-75 chromatography. The high molecular weight fraction (89.0 kD) from the neutral fraction was designated EPS5SH; it contained mannose, glucosamine, glucose, and galactose in a molar ratio of 1.00: 0.02: 0.07: 0.02. Infra-red, gas chromatography-mass spectrometry, electrospray ionisation-tandem mass spectrometry analysis and nuclear magnetic resonance revealed EPS5SH was a mannan with α-(1 → 4)-Manp, α-(1 → 2)-Manp, α-(1 → 4, 6)-Manp and β-terminal-Manp. Preliminary in vitro experiments revealed that EPS5SH significantly upregulated nitric oxide synthesis and release of pro-inflammatory factors in murine macrophage RAW264.7 cells. Western blot experiments verified the immunostimulatory effects of EPS5SH through the modulation of the NF-κB and MAPK signalling pathways. In conclusion, EPS5SH was a novel immunostimulatory mannan.

Characterization of Roseibacterium persicicum sp. nov., and emended description of the genus Roseibacterium

A novel alphaproteobacterium, designated as KMU-115T, was isolated from seawater collected on the coast of Chuam Beach, Republic of Korea, and subjected to a polyphasic characterization. The cells were pale apricot-colored, strictly aerobic, Gram-staining-negative, rod-shaped, non-motile and chemoorganoheterotrophic. The novel isolate grew at NaCl concentrations of 0–7%, pH 6.0–9.5 and 10–45°C. A phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain KMU-115T belongs to the family ‘Rhodobacteraceae’, and that it had the greatest sequence similarity (96.8%) with ‘Roseibacterium beibuensis’ JLT1202rT. The major respiratory quinone system of the novel isolate was ubiquinone-10 (Q-10) and the main (>10%) cellular fatty acid was C18:1 ω7c. The assembled draft genome size of strain KMU-115T was 3.71 Mbp. The genomic DNA G + C content was 70.8 mol%. Strain KMU-115T had phosphatidylglycerol, four unidentified aminolipids, an unidentified aminophospholipid and seven unidentified lipids as polar lipids. From the distinct polyphasic taxonomic characteristics, the strain is considered to represent a novel species of the genus Roseibacterium for which the name Roseibacterium persicicum sp. nov. is proposed. The type strain of R. persicicum sp. nov. is KMU-115T (= KCCM 90339T = NBRC 114190T). An emended description of the genus Roseibacterium is also provided.

Influence of Environmental Drivers and Potential Interactions on the Distribution of Microbial Communities From Three Permanently Stratified Antarctic Lakes

The McMurdo Dry Valley (MDV) lakes represent unique habitats in the microbial world. Perennial ice covers protect liquid water columns from either significant allochthonous inputs or seasonal mixing, resulting in centuries of stable biogeochemistry. Extreme environmental conditions including low seasonal photosynthetically active radiation (PAR), near freezing temperatures, and oligotrophy have precluded higher trophic levels from the food webs. Despite these limitations, diverse microbial life flourishes in the stratified water columns, including Archaea, bacteria, fungi, protists, and viruses. While a few recent studies have applied next generation sequencing, a thorough understanding of the MDV lake microbial diversity and community structure is currently lacking. Here we used Illumina MiSeq sequencing of the 16S and 18S rRNA genes combined with a microscopic survey of key eukaryotes to compare the community structure and potential interactions among the bacterial and eukaryal communities within the water columns of Lakes Bonney (east and west lobes, ELB, and WLB, respectively) and Fryxell (FRX). Communities were distinct between the upper, oxic layers and the dark, anoxic waters, particularly among the bacterial communities residing in WLB and FRX. Both eukaryal and bacterial community structure was influenced by different biogeochemical parameters in the oxic and anoxic zones. Bacteria formed complex interaction networks which were lake-specific. Several eukaryotes exhibit potential interactions with bacteria in ELB and WLB, while interactions between these groups in the more productive FRX were relatively rare.

Binariimonas pacifica gen. nov., sp. nov., a Novel Marine Bacterium of Family Sphingomonadaceae Isolated from East Pacific Ocean Surface Seawater

A novel rod-shaped binary fission, and yellow-pigmented bacterial strain, JLT 2480(T), was isolated from surface seawater in the East Pacific Ocean. The strain is Gram negative and oxidase negative. Phylogenetic analyses based on 16S rRNA gene sequence indicate that strain JLT 2480(T) falls in the family Sphingomonadaceae, sharing highest similarity (95.6 %) with the species Blastomonas ursincola. The DNA G+C content of JLT 2480(T) is 65.5 mol%, and the sole respiratory quinone is coenzyme Q10. The predominant polar lipids are sphingoglycolipids (SGL1 and SGL2), phosphatidylglycerols, phosphatidylethanolamines, phospholipids, glycolipids, and phosphatidylcholines. The predominant cellular fatty acids are C16:0, C18:0, C18:1ω7c, C12:0, and C16:1ω7c. Strain JLT 2480(T) is distinct from the B. ursincola type strain DSM 9006(T) as reflected by major chemotaxonomic distinctions between the two. Furthermore, two notable characteristics of the genus Blastomonas, that is, the presence of bacteriochlorophyll a and the puf genes, are not detected in JLT 2480(T). On the basis of present evidence, we consider JLT 2480(T) to be a novel species in a new genus of the family Sphingomonadaceae, and propose the name Binariimonas pacifica gen. nov., sp. nov., with strain JLT 2480(T) (=CGMCC 1.12850(T) = DSM 28646(T)) to be the type strain for genus Binariimonas.

Maritimibacter lacisalsi sp. nov., isolated from a salt lake, and emended description of the genus Maritimibacter Lee et al. 2007

A Gram-staining-negative, non-motile, strictly aerobic bacterium, strain X12M-4T, was isolated from Xiaochaidan Lake, a salt lake (salinity 9.9 %, w/w) in Qaidam basin, Qinghai Province, China. Its taxonomic position was determined by using a polyphasic approach. Strain X12M-4T was catalase- and oxidase-positive. Cells were rod-shaped, 0.5–0.8 μm wide and 1.1–1.6 μm long. Growth was observed in the presence of 0–11.0 % (w/v) NaCl (optimum, 5.0–6.0 %) and at 15–40 °C (optimum, 25 °C) and pH 6.5–9.5 (optimum, pH 7.0). No growth occurred at 10 °C or 45 °C. Strain X12M-4T contained C18 : 1ω7c, C19 : 0 cyclo ω8c and C16 : 0 as the major fatty acids (>10.0 %). The predominant respiratory quinone was Q-10.The major polar lipids were phosphatidylcholine, phosphatidylglycerol, diphosphatidglycerol, an unknown aminolipid and an unidentified lipid. The DNA G+C content was 65.7 mol% (determined using T m). Strain X12M-4T showed highest 16S rRNA gene sequence similarities to Maritimibacter alkaliphilus HTCC2654T (96.7 %), Roseibacterium elongatum DSM 19469T (96.4 %), Tropicimonas aquimaris DPG-21T (95.6 %), ‘Roseibacterium beibuensis’ JLT1202r (95.6 %) and Tropicimonas sediminicola M97T (95.5 %) and < 95.5 % to others. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain X12M-4T formed a robust cluster with M. alkaliphilus HTCC2654T. On the basis of the data, it is concluded that strain X12M-4T represents a novel species of the genus Maritimibacter, for which the name Maritimibacter lacisalsi sp. nov. is proposed. The type strain is X12M-4T ( = CGMCC 1.12922T = JCM 30555T). To accommodate the novel species, the description of the genus Maritimibacter was emended.

Complete genome sequence of the bacteriochlorophyll a-containing Roseibacterium elongatum type strain (DSM 19469(T)), a representative of the Roseobacter group isolated from Australian coast sand

Roseibacterium elongatum Suzuki et al. 2006 is a pink-pigmented and bacteriochlorophyll a-producing representative of the Roseobacter group within the alphaproteobacterial family Rhodobacteraceae. Representatives of the marine 'Roseobacter group' were found to be abundant in the ocean and play an important role in global and biogeochemical processes. In the present study we describe the features of R. elongatum strain OCh 323(T) together with its genome sequence and annotation. The 3,555,102 bp long genome consists of one circular chromosome with no extrachromosomal elements and is one of the smallest known Roseobacter genomes. It contains 3,540 protein-coding genes and 59 RNA genes. Genome analysis revealed the presence of a photosynthetic gene cluster, which putatively enables a photoheterotrophic lifestyle. Gene sequences associated with quorum sensing, motility, surface attachment, and thiosulfate and carbon monoxide oxidation could be detected. The genome was sequenced as part of the activities of the Transregional Collaborative Research Centre 51 (TRR51) funded by the German Research Foundation (DFG).