Gramella Forsetii Research Articles

Gramella sabulilitoris sp. nov., isolated from a marine sand.

A Gram-stain-negative, aerobic, non-spore-forming, motile by gliding and rod-shaped bacterial strain, designated HSMS-1T, was isolated from a marine sand collected from the Yellow Sea, Republic of Korea, and identified by a polyphasic taxonomic approach. The neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that HSMS-1T fell within the clade comprising the type strains of species of the genus Gramella. HSMS-1T exhibited 16S rRNA gene sequence similarity values of 99.0 and 98.7 % to the type strains of Gramella echinicola and Gramella sediminilitoris and of 93.3-98.5 % to the type strains of the other species of the genus Gramella. The ANI and dDDH values between HSMS-1T and the type strains of G. echinicola, Gramella gaetbulicola, Gramella forsetii, Gramella salexigens, Gramella portivictoriae and Gramella flava were 72.6-79.3 % and 17.4-22.2 %, respectively. Mean DNA-DNA relatedness value between HSMS-1T and the type strain of G. sediminilitoris was 18 %. HSMS-1T contained MK-6 as the predominant menaquinone and iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0 3-OH and iso-C16 : 0 as the major fatty acids. The major polar lipid of HSMS-1T was phosphatidylethanolamine. The DNA G+C content of HSMS-1T from genomic sequence data was 39.2 %. Distinguishing phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that HSMS-1T is separated from recognized species of the genus Gramella. On the basis of the data presented, strain HSMS-1T is considered to represent a novel species of the genus Gramella, for which the name Gramella sabulilitoris sp. nov. is proposed. The type strain is HSMS-1T(=KACC 19899T=NBRC 113648T).

Gramella antarctica sp. nov., isolated from marine surface sediment.

A Gram-stain-negative, aerobic, yellow-coloured, motile by gliding, rod-shaped bacterial strain, designated R17H11T, was isolated from surface sediment collected from the Ross Sea, Antarctica. Growth optimally occurred at 25-30 °C, at pH 7.0-7.5 and in the presence of 3 % NaCl (w/v). Phylogenetic trees based on 16S rRNA gene sequences indicated that strain R17H11T clustered together with Gramella flava JLT2011T and fell within the genus Gramella. Strain R17H11T shared the highest 16S rRNA gene similarities (96.1 and 96.0 %) with the type strains of Gramella forsetii and G. flava, and 92.6-95.5 % similarities with those of other known Gramella species. Strain R17H11T contained menaquinone-6 as the only isoprenoid quinone. The major fatty acids (>5 %) were summed feature 3 (17.5 %, comprising C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 (14.0 %), summed feature 9 (11.8 %, comprising 10-methyl C16 : 0 and/or iso-C17 : 1ω9c), iso-C17 : 0 3-OH (11.8 %), iso-C16 : 0 (7.4 %), C17 : 1ω6c (6.9 %) and anteiso-C15 : 0 (5.1 %). The major polar lipids were phosphatidylethanolamine, four unidentified lipids, an unidentified aminolipid, an unidentified aminophospholipid and an unidentified glycolipid. The DNA G+C content of strain R17H11T was 38.6 mol%. On the basis of the phylogenetic, physiological and chemotaxonomic characteristics, strain R17H11T represents a novel species in the genus Gramella, for which the name Gramellaantarctica sp. nov. is proposed. The type strain of the novel species is R17H11T (=GDMCC 1.1208T=KCTC 52925T).

An alternative polysaccharide uptake mechanism of marine bacteria

Heterotrophic microbial communities process much of the carbon fixed by phytoplankton in the ocean, thus having a critical role in the global carbon cycle. A major fraction of the phytoplankton-derived substrates are high-molecular-weight (HMW) polysaccharides. For bacterial uptake, these substrates must initially be hydrolysed to smaller sizes by extracellular enzymes. We investigated polysaccharide hydrolysis by microbial communities during a transect of the Atlantic Ocean, and serendipitously discovered—using super-resolution structured illumination microscopy—that up to 26% of total cells showed uptake of fluorescently labelled polysaccharides (FLA-PS). Fluorescence in situ hybridisation identified these organisms as members of the bacterial phyla Bacteroidetes and Planctomycetes and the gammaproteobacterial genus Catenovulum. Simultaneous membrane staining with nile red indicated that the FLA-PS labelling occurred in the cell but not in the cytoplasm. The dynamics of FLA-PS staining was further investigated in pure culture experiments using Gramella forsetii, a marine member of Bacteroidetes. The staining patterns observed in environmental samples and pure culture tests are consistent with a ‘selfish’ uptake mechanisms of larger oligosaccharides (>600 Da), as demonstrated for gut Bacteroidetes. Ecologically, this alternative polysaccharide uptake mechanism secures substantial quantities of substrate in the periplasmic space, where further processing can occur without diffusive loss. Such a mechanism challenges the paradigm that hydrolysis of HMW substrates inevitably yields low-molecular-weight fragments that are available to the surrounding community and demonstrates the importance of an alternative mechanism of polysaccharide uptake in marine bacteria.

Description of Gramella forsetii sp. nov., a marine Flavobacteriaceae isolated from North Sea water, and emended description of Gramella gaetbulicola Cho et al. 2011.

Strain KT0803T was isolated from coastal eutrophic surface waters of Helgoland Roads near the island of Helgoland, North Sea, Germany. The taxonomic position of the strain, previously known as 'Gramella forsetii' KT0803, was investigated by using a polyphasic approach. The strain was Gram-stain-negative, chemo-organotrophic, heterotrophic, strictly aerobic, oxidase- and catalase-positive, rod-shaped, motile by gliding and had orange-yellow carotenoid pigments, but was negative for flexirubin-type pigments. It grew optimally at 22-25 °C, at pH 7.5 and at a salinity between 2-3 %. Strain KT0803T hydrolysed the polysaccharides laminarin, alginate, pachyman and starch. The respiratory quinone was MK-6. Polar lipids comprised phosphatidylethanolamine, six unidentified lipids and two unidentified aminolipids. The predominant fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 1ω7c and iso-C17 : 1ω7c, with smaller amounts of iso-C15 : 0 2-OH, C15 : 0, anteiso-C15 : 0 and C17 : 1ω6c. The G+C content of the genomic DNA was 36.6 mol%. The 16S rRNA gene sequence identities were 98.6 % with Gramella echinicola DSM 19838T, 98.3 % with Gramella gaetbulicola DSM 23082T, 98.1 % with Gramella aestuariivivens BG-MY13T and Gramella aquimixticola HJM-19T, 98.0 % with Gramella lutea YJ019T, 97.9 % with Gramella portivictoriae DSM 23547T and 96.9 % with Gramella marina KMM 6048T. The DNA-DNA relatedness values were <35 % between strain KT0803T and type strains with >98.2 % 16S rRNA gene sequence identity. Based on the chemotaxonomic, phenotypic and genomic characteristics, strain KT0803T has been assigned to the genus Gramella, as Gramella forsetii sp. nov. The type strain is KT0803T (=DSM 17595T=CGMCC 1.15422T). An emended description of Gramella gaetbulicolaCho et al. 2011 is also proposed.

Functional characterization of polysaccharide utilization loci in the marine Bacteroidetes ‘Gramella forsetii’ KT0803

Members of the phylum Bacteroidetes are abundant in many marine ecosystems and are known to have a pivotal role in the mineralization of complex organic substrates such as polysaccharides and proteins. We studied the decomposition of the algal glycans laminarin and alginate by ‘Gramella forsetii' KT0803, a bacteroidetal isolate from North Sea surface waters. A combined application of isotope labeling, subcellular protein fractionation and quantitative proteomics revealed two large polysaccharide utilization loci (PULs) that were specifically induced, one by alginate and the other by laminarin. These regulons comprised genes of surface-exposed proteins such as oligomer transporters, substrate-binding proteins, carbohydrate-active enzymes and hypothetical proteins. Besides, several glycan-specific TonB-dependent receptors and SusD-like substrate-binding proteins were expressed also in the absence of polysaccharide substrates, suggesting an anticipatory sensing function. Genes for the utilization of the beta-1,3-glucan laminarin were found to be co-regulated with genes for glucose and alpha-1,4-glucan utilization, which was not the case for the non-glucan alginate. Strong syntenies of the PULs of ‘G. forsetii' with similar loci in other Bacteroidetes indicate that the specific response mechanisms of ‘G. forsetii' to changes in polysaccharide availability likely apply to other Bacteroidetes. Our results can thus contribute to an improved understanding of the ecological niches of marine Bacteroidetes and their roles in the polysaccharide decomposition part of carbon cycling in marine ecosystems.

Gliding Motility and Por Secretion System Genes Are Widespread among Members of the Phylum Bacteroidetes

The phylum Bacteroidetes is large and diverse, with rapid gliding motility and the ability to digest macromolecules associated with many genera and species. Recently, a novel protein secretion system, the Por secretion system (PorSS), was identified in two members of the phylum, the gliding bacterium Flavobacterium johnsoniae and the nonmotile oral pathogen Porphyromonas gingivalis. The components of the PorSS are not similar in sequence to those of other well-studied bacterial secretion systems. The F. johnsoniae PorSS genes are a subset of the gliding motility genes, suggesting a role for the secretion system in motility. The F. johnsoniae PorSS is needed for assembly of the gliding motility apparatus and for secretion of a chitinase, and the P. gingivalis PorSS is involved in secretion of gingipain protease virulence factors. Comparative analysis of 37 genomes of members of the phylum Bacteroidetes revealed the widespread occurrence of gliding motility genes and PorSS genes. Genes associated with other bacterial protein secretion systems were less common. The results suggest that gliding motility is more common than previously reported. Microscopic observations confirmed that organisms previously described as nonmotile, including Croceibacter atlanticus, "Gramella forsetii," Paludibacter propionicigenes, Riemerella anatipestifer, and Robiginitalea biformata, exhibit gliding motility. Three genes (gldA, gldF, and gldG) that encode an apparent ATP-binding cassette transporter required for F. johnsoniae gliding were absent from two related gliding bacteria, suggesting that the transporter may not be central to gliding motility.

The limitations of draft assemblies for understanding prokaryotic adaptation and evolution

The de novo assembly of next generation sequencing data is a daunting task made more difficult by the presence of genomic repeats or transposable elements, resulting in an increasing number of genomes designated as completed draft assemblies. We created and assembled idealized sequence data sets for Cupriavidus metallidurans CH34, Caulobacter sp. K31, Gramella forsetii KT0803, Rhodobacter sphaeroides 2.4.1 and Bordetella bronchiseptica RB50. In addition to confirming the role of transposable elements in interrupting the assemblies, an association was found between the most fragmented regions and known or predicted genomic islands in these strains. Assembly quality was more strongly related to putative genomic island content than to any other factor examined. We believe this association indicates that draft assemblies are limiting our ability to understand the genomic context of important bacterial adaptations and that the increased effort required for finishing genomes can provide a wealth of information for future studies.

Phylogeny and molecular signatures (conserved proteins and indels) that are specific for the Bacteroidetes and Chlorobi species

BackgroundThe Bacteroidetes and Chlorobi species constitute two main groups of the Bacteria that are closely related in phylogenetic trees. The Bacteroidetes species are widely distributed and include many important periodontal pathogens. In contrast, all Chlorobi are anoxygenic obligate photoautotrophs. Very few (or no) biochemical or molecular characteristics are known that are distinctive characteristics of these bacteria, or are commonly shared by them.ResultsSystematic blast searches were performed on each open reading frame in the genomes of Porphyromonas gingivalis W83, Bacteroides fragilis YCH46, B. thetaiotaomicron VPI-5482, Gramella forsetii KT0803, Chlorobium luteolum (formerly Pelodictyon luteolum) DSM 273 and Chlorobaculum tepidum (formerly Chlorobium tepidum) TLS to search for proteins that are uniquely present in either all or certain subgroups of Bacteroidetes and Chlorobi. These studies have identified > 600 proteins for which homologues are not found in other organisms. This includes 27 and 51 proteins that are specific for most of the sequenced Bacteroidetes and Chlorobi genomes, respectively; 52 and 38 proteins that are limited to species from the Bacteroidales and Flavobacteriales orders, respectively, and 5 proteins that are common to species from these two orders; 185 proteins that are specific for the Bacteroides genus. Additionally, 6 proteins that are uniquely shared by species from the Bacteroidetes and Chlorobi phyla (one of them also present in the Fibrobacteres) have also been identified. This work also describes two large conserved inserts in DNA polymerase III (DnaE) and alanyl-tRNA synthetase that are distinctive characteristics of the Chlorobi species and a 3 aa deletion in ClpB chaperone that is mainly found in various Bacteroidales, Flavobacteriales and Flexebacteraceae, but generally not found in the homologs from other organisms. Phylogenetic analyses of the Bacteroidetes and Chlorobi species is also reported based on concatenated sequences for 12 conserved proteins by different methods including the character compatibility (or clique) approach. The placement of Salinibacter ruber with other Bacteroidetes species was not resolved by other phylogenetic methods, but this affiliation was strongly supported by the character compatibility approach.ConclusionThe molecular signatures described here provide novel tools for identifying and circumscribing species from the Bacteroidetes and Chlorobi phyla as well as some of their main groups in clear terms. These results also provide strong evidence that species from these two phyla (and also possibly Fibrobacteres) are specifically related to each other and they form a single superphylum. Functional studies on these proteins and indels should aid in the discovery of novel biochemical and physiological characteristics that are unique to these groups of bacteria.

Whole genome analysis of the marine Bacteroidetes‘Gramella forsetii’ reveals adaptations to degradation of polymeric organic matter

Members of the Bacteroidetes, formerly known as the Cytophaga-Flavobacteria-Bacteroides (CFB) phylum, are among the major taxa of marine heterotrophic bacterioplankton frequently found on macroscopic organic matter particles (marine snow). In addition, they have been shown to also represent a significant part of free-living microbial assemblages in nutrient-rich microenvironments. Their abundance and distribution pattern in combination with enzymatic activity studies has led to the notion that organisms of this group are specialists for degradation of high molecular weight compounds in both the dissolved and particulate fraction of the marine organic matter pool, implying a major role of Bacteroidetes in the marine carbon cycle. Despite their ecological importance, comprehensive molecular data on organisms of this group have been scarce so far. Here we report on the first whole genome analysis of a marine Bacteroidetes representative, 'Gramella forsetii' KT0803. Functional analysis of the predicted proteome disclosed several traits which in joint consideration suggest a clear adaptation of this marine Bacteroidetes representative to the degradation of high molecular weight organic matter, such as a substantial suite of genes encoding hydrolytic enzymes, a predicted preference for polymeric carbon sources and a distinct capability for surface adhesion.