Genome sequence of strain HIMB30, a novel member of the marine Gammaproteobacteria

Strain HIMB30 was isolated from coastal Hawaii seawater by extinction culturing in seawater-based oligotrophic medium. It is a phylogenetically unique member of the class Gammaproteobacteria that is only distantly related to its closest cultured relatives. Here we present the genome sequence of strain HIMB30, including genes for proteorhodopsin-based phototrophy and the Calvin-Benson-Bassham cycle.     

Genome sequence of strain IMCC2047, a novel marine member of the Gammaproteobacteria

Strain IMCC2047 was isolated from the Yellow Sea using dilution-to-extinction culturing. The strain was shown to occupy a distinct phylogenetic position within the Gammaproteobacteria. Here we present the genome sequence of strain IMCC2047, which harbors genes for various metabolic pathways, including proteorhodopsin and ribulose bisphosphate carboxylase.     

Genome sequence of strain HTCC2083, a novel member of the marine clade Roseobacter

Strain HTCC2083 was isolated from Oregon seawater using dilution-to-extinction culturing and represents a novel member of the Roseobacter clade. The draft genome sequence of HTCC2083 is presented here. The genome is predicted to contain genes for aerobic anoxygenic phototrophy, sulfite-oxidizing chemolithotrophy, anapleurotic CO(2) fixation, carbon monoxide oxidation, and dimethylsulfoniopropionate (DMSP) utilization.     

Genome sequence of strain TW15, a novel member of the genus Ruegeria, belonging to the marine Roseobacter clade

Ruegeria sp. TW15, which belongs to the family Rhodobacteraceae, was isolated from an ark clam in the South Sea of Korea. Here is presented the draft genome sequence of Ruegeria sp. TW15 (4,490,771 bp with a G+C content of 55.7%), a member of the marine Roseobacter clade, which comprises up to 20% of the bacterioplankton in the coastal and oceanic mixed layer.     

Genome sequence of Phaeobacter caeruleus type strain (DSM 24564T), a surface-associated member of the marine Roseobacter clade

In 2009 Phaeobacter caeruleus was described as a novel species affiliated with the marine Roseobacter clade, which, in turn, belongs to the class Alphaproteobacteria. The genus Phaeobacter is well known for members that produce various secondary metabolites. Here we report of putative quorum sensing systems, based on the finding of six N-acyl-homoserine lactone synthetases, and show that the blue color of P. caeruleus is probably due to the production of the secondary metabolite indigoidine. Therefore, P. caeruleus might have inhibitory effects on other bacteria. In this study the genome of the type strain DSM 24564^T was sequenced, annotated and characterized. The 5,344,419 bp long genome with its seven plasmids contains 5,227 protein-coding genes (3,904 with a predicted function) and 108 RNA genes.     

Genome sequence of "Candidatus Aquiluna" sp. strain IMCC13023, a marine member of the Actinobacteria isolated from an arctic fjord

We report the genome sequence of actinobacterial strain IMCC13023, isolated from arctic fjord seawater. Phylogenetic analysis of 16S rRNA gene showed that the strain is related to "Candidatus Aquiluna rubra." The genome information suggests that strain IMCC13023 is a photoheterotroph carrying actinorhodopsin, with the smallest genome ever reported for a free-living member of the Actinobacteria.     

Growth phase‐dependent global protein and metabolite profiles of Phaeobacter gallaeciensis strain DSM 17395, a member of the marine Roseobacter‐clade

The marine heterotrophic roseobacter Phaeobacter gallaeciensis DSM 17395 was grown with glucose in defined mineral medium. Relative abundance changes of global protein (2‐D DIGE) and metabolite (GC‐MS) profiles were determined across five different time points of growth. In total, 215 proteins were identified and 147 metabolites detected (101 structurally identified), among which 60 proteins and 87 metabolites displayed changed abundances upon entry into stationary growth phase. Glucose breakdown to pyruvate apparently proceeds via the Entner–Doudoroff (ED) pathway, since phosphofructokinase of the Embden–Meyerhof–Parnas pathway is missing and the key metabolite of the ED‐pathway, 2‐keto‐3‐desoxygluconate, was detected. The absence of pfk in other genome‐sequenced roseobacters suggests that the use of the ED pathway is an important physiological property among these heterotrophic marine bacteria. Upon entry into stationary growth phase (due to glucose starvation), sulfur assimilation (including cysteine biosynthesis) and parts of cell envelope synthesis (e.g. the lipid precursor 1‐monooleoylglycerol) were down‐regulated and cadaverine formation up‐regulated. In contrast, central carbon catabolism remained essentially unchanged, pointing to a metabolic “stand‐by” modus as an ecophysiological adaptation strategy. Stationary phase response of P. gallaeciensis differs markedly from that of standard organisms such as Escherichia coli, as evident e.g. by the absence of an rpoS gene.     

Genome sequence of the Leisingera aquimarina type strain (DSM 24565T), a member of the marine Roseobacter clade rich in extrachromosomal elements

Leisingera aquimarina Vandecandelaere et al. 2008 is a member of the genomically well characterized Roseobacter clade within the family Rhodobacteraceae. Representatives of the marine Roseobacter clade are metabolically versatile and involved in carbon fixation and biogeochemical processes. They form a physiologically heterogeneous group, found predominantly in coastal or polar waters, especially in symbiosis with algae, in microbial mats, in sediments or associated with invertebrates. Here we describe the features of L. aquimarina DSM 24565^T together with the permanent-draft genome sequence and annotation. The 5,344,253 bp long genome consists of one chromosome and an unusually high number of seven extrachromosomal elements and contains 5,129 protein-coding and 89 RNA genes. It was sequenced as part of the DOE Joint Genome Institute Community Sequencing Program 2010 and of the activities of the Transregional Collaborative Research Centre 51 funded by the German Research Foundation (DFG).     

Genome sequence of strain IMCC1989, a novel member of the marine gammaproteobacteria

Strain IMCC1989 is a novel member of the oligotrophic marine Gammaproteobacteria (OMG) group and is closely related with a symbiont group of the genera Teredinibacter and "Candidatus Endobugula." Here we present the genome sequence of strain IMCC1989, which was isolated from the Yellow Sea by using dilution-to-extinction culturing.     

Comparative genomics and mutagenesis analyses of choline metabolism in the marine Roseobacter clade

Choline is ubiquitous in marine eukaryotes and appears to be widely distributed in surface marine waters; however, its metabolism by marine bacteria is poorly understood. Here, using comparative genomics and molecular genetic approaches, we reveal that the capacity for choline catabolism is widespread in marine heterotrophs of the marine Roseobacter clade (MRC). Using the model bacterium Ruegeria pomeroyi, we confirm that the betA, betB and betC genes, encoding choline dehydrogenase, betaine aldehyde dehydrogenase and choline sulfatase, respectively, are involved in choline metabolism. The betT gene, encoding an organic solute transporter, was essential for the rapid uptake of choline but not glycine betaine (GBT). Growth of choline and GBT as a sole carbon source resulted in the re‐mineralization of these nitrogen‐rich compounds into ammonium. Oxidation of the methyl groups from choline requires formyltetrahydrofolate synthetase encoded by fhs in R. pomeroyi, deletion of which resulted in incomplete degradation of GBT. We demonstrate that this was due to an imbalance in the supply of reducing equivalents required for choline catabolism, which can be alleviated by the addition of formate. Together, our results demonstrate that choline metabolism is ubiquitous in the MRC and reveal the role of Fhs in methyl group oxidation in R. pomeroyi.     

Candidatus Prosiliicoccus vernus,a spring phytoplankton bloom associated member of the Flavobacteriaceae

Microbial degradation of algal biomass following spring phytoplankton blooms has been characterised as a concerted effort among multiple clades of heterotrophic bacteria. Despite their significance to overall carbon turnover, many of these clades have resisted cultivation. One clade known from 16S rRNA gene sequencing surveys at Helgoland in the North Sea, was formerly identified as belonging to the genus Ulvibacter. This clade rapidly responds to algal blooms, transiently making up as much as 20% of the free-living bacterioplankton. Sequence similarity below 95% between the 16S rRNA genes of described Ulvibacter species and those from Helgoland suggest this is a novel genus. Analysis of 40 metagenome assembled genomes (MAGs) derived from samples collected during spring blooms at Helgoland support this conclusion. These MAGs represent three species, only one of which appears to bloom in response to phytoplankton. MAGs with estimated completeness greater than 90% could only be recovered for this abundant species. Additional, less complete, MAGs belonging to all three species were recovered from a mini-metagenome of cells sorted via flow cytometry using the genus specific ULV995 fluorescent rRNA probe. Metabolic reconstruction indicates this highly abundant species most likely degrades proteins and the polysaccharide laminarin. Fluorescence in situ hybridisation showed coccoid cells, with a mean diameter of 0.78 mm, with standard deviation of 0.12 μm. Based on the phylogenetic and genomic characteristics of this clade, we propose the novel candidate genus Candidatus Prosiliicoccus, and for the most abundant and well characterised of the three species the name Candidatus Prosiliicoccus vernus.     

Draft genome sequence of strain HIMB100, a cultured representative of the SAR116 clade of marine Alphaproteobacteria

Strain HIMB100 is a planktonic marine bacterium in the class Alphaproteobacteria. This strain is of interest because it is one of the first known isolates from a globally ubiquitous clade of marine bacteria known as SAR116 within the family Rhodospirillaceae. Here we describe preliminary features of the organism, together with the draft genome sequence and annotation. This is the second genome sequence of a member of the SAR116 clade. The 2,458,945 bp genome contains 2,334 protein-coding and 42 RNA genes.     

Genome sequence of strain HIMB55, a novel marine gammaproteobacterium of the OM60/NOR5 clade

Strain HIMB55 is a phylogenetically unique member of the OM60/NOR5 clade of the Gammaproteobacteria isolated from coastal seawater of Kaneohe Bay on the northeastern shore of Oahu, Hawaii, by extinction culturing in seawater-based oligotrophic medium. Here we present the genome sequence of strain HIMB55, including genes for bacteriochlorophyll-based phototrophy.     

The enzyme of carbon metabolism in the thermotolerant sulfobacillus strain K1

To determine enzymatic activities in the thermotolerant strain K1 (formerly "Sulfobacillus thermosulfidooxidans subsp. thermotolerans"), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions). Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle. Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. An increased content of carbon dioxide (up to 5 vol%) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway. Carbon dioxide was fixed in the Calvin cycle. The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase decreased with the increasing content of CO2 in the medium.     

Metabolic fluxes in the central carbon metabolism of Dinoroseobacter shibae and Phaeobacter gallaeciensis, two members of the marine Roseobacter clade

Background  

In the present work the central carbon metabolism of Dinoroseobacter shibae and Phaeobacter gallaeciensis was studied at the level of metabolic fluxes. These two strains belong to the marine Roseobacter clade, a dominant bacterial group in various marine habitats, and represent surface-associated, biofilm-forming growth (P. gallaeciensis) and symbiotic growth with eukaryotic algae (D. shibae). Based on information from recently sequenced genomes, a rich repertoire of pathways has been identified in the carbon core metabolism of these organisms, but little is known about the actual contribution of the various reactions in vivo.     

Analysis of N-acetylglucosamine metabolism in the marine bacterium Pirellula sp. strain 1 by a proteomic approach

Pirellula sp. strain 1 is a marine bacterium that can grow with the chitin monomer N-acetylglucosamine as sole source of carbon and nitrogen under aerobic conditions, and that is a member of the bacterial phylum Planctomycetes. As a basis for the proteomic studies we quantified growth of strain 1 with N-acetylglucosamine and glucose, revealing doubling times of 14 and 10 h, respectively. Studies with dense cell suspensions indicated that the capacity to degrade N-acetylglucosamine and glucose may not be tightly regulated. Proteins from soluble extracts prepared from exponential cultures grown either with N-acetylglucosamine or glucose were separated by two-dimensional gel electrophoresis and visualized by fluorescence staining (Sypro Ruby). Analysis of the protein patterns revealed the presence of several protein spots only detectable in soluble extracts of N-acetylglucosamine grown cells. Determination of amino acid sequences and peptide mass fingerprints from tryptic fragments of the most abundant one of these spots allowed the identification of the coding gene on the genomic sequence of Pirellula sp. strain 1. This gene showed similarities to a dehydrogenase from Bacillus subtilis, and is closely located to a gene similar to glucosamine-6-phosphate isomerase from B. subtilis. Genes of two other proteins expressed during growth on N-acetylglucosamine as well as on glucose were also identified and found to be similar to a glyceraldehyde-3-phosphate-dehydrogenase and a NADH-dehydrogenase, respectively. Thus the coding genes of three proteins expressed during growth of Pirellula sp. strain 1 on carbohydrates were identified and related by sequence similarity to carbohydrate metabolism.     

Genome sequence of strain IMCC3088, a proteorhodopsin-containing marine bacterium belonging to the OM60/NOR5 clade

Strain IMCC3088, cultivated from the Yellow Sea, is a novel isolate belonging to the OM60/NOR5 clade and is closely related to clone OM241, Congregibacter litoralis, and strain HTCC2080. Here, the genome sequence of strain IMCC3088 is presented, showing the absence of photosynthetic gene clusters and the presence of proteorhodopsin.     

Genome sequence of the reddish-pigmented Rubellimicrobium thermophilum type strain (DSM 16684T), a member of the Roseobacter clade

Rubellimicrobium thermophilum Denner et al. 2006 is the type species of the genus Rubellimicrobium, a representative of the Roseobacter clade within the Rhodobacteraceae. Members of this clade were shown to be abundant especially in coastal and polar waters, but were also found in microbial mats and sediments. They are metabolically versatile and form a physiologically heterogeneous group within the Alphaproteobacteria. Strain C-Ivk-R2A-2^T was isolated from colored deposits in a pulp dryer; however, its natural habitat is so far unknown. Here we describe the features of this organism, together with the draft genome sequence and annotation and novel aspects of its phenotype. The 3,161,245 bp long genome contains 3,243 protein-coding and 45 RNA genes.     

Novel groups of Gammaproteobacteria catalyse sulfur oxidation and carbon fixation in a coastal, intertidal sediment

The oxidation of hydrogen sulfide is essential to sulfur cycling in marine habitats. However, the role of microbial sulfur oxidation in marine sediments and the microorganisms involved are largely unknown, except for the filamentous, mat‐forming bacteria. In this study we explored the diversity, abundance and activity of sulfur‐oxidizing prokaryotes (SOP) in sulfidic intertidal sediments using 16S rRNA and functional gene sequence analyses, fluorescence in situ hybridization (FISH) and microautoradiography. The 16S rRNA gene analysis revealed that distinct clades of uncultured Gammaproteobacteria are important SOP in the tidal sediments. This was supported by the dominance of gammaproteobacterial sequences in clone libraries of genes encoding the reverse dissimilatory sulfite reductase (rDSR) and the adenosine phosphosulfate reductase (APR). Numerous sequences of all three genes grouped with uncultured autotrophic SOP. Accordingly, Gammaproteobacteria accounted for 40–70% of all ¹⁴CO₂‐incorporating cells in surface sediments as shown by microautoradiography. Furthermore, phylogenetic analysis of all three genes consistently suggested a discrete population of SOP that was most closely related to the sulfur‐oxidizing endosymbionts of the tubeworm Oligobrachia spp. FISH showed that members of this population (WS‐Gam209 group) were abundant, reaching up to 1.3 × 10⁸ cells ml^?1 (4.6% of all cells). Approximately 25% of this population incorporated CO₂, consistent with a chemolithoautotrophic metabolism most likely based on sulfur oxidation. Thus, we hypothesize that novel, gammaproteobacterial SOP attached to sediment particles may play a more important role for sulfide removal and primary production in marine sediments than previously assumed.