Capillimicrobium parvum gen. nov., sp. nov., a novel representative of Capillimicrobiaceae fam. nov. within the order Solirubrobacterales, isolated from a grassland soil.

The order Solirubrobacterales is a deep-branching lineage within the phylum Actinomycetota. Most representatives have been isolated from terrestrial environments. A strain isolated from a grassland soil was found to be affiliated with this order and therefore characterized by a polyphasic approach. Cells of strain 0166_1T are Gram-positive, short rods, non-motile, non-spore-forming and divide by binary fission. A surface layer with protrusions covers the majority of the cells. Strain 0166_1T grows optimally around neutral to slightly alkaline pH (pH 7.1-7.9) and at temperatures between 24-36 °C in SSE/HD 1 : 10 medium. It grows optimally with 0-0.5% NaCl (w/v) but can withstand concentrations up to 5 %. The major fatty acids are C18 : 1 ω9c, C16 : 1 ω7c, C17 : 0 cyclo ω7c, C18 : 1 ω7c methyl and C19 : 0 cyclo ω9c. The major polar lipids are diphosphatidylglycerol, two unidentified phospholipids and one unidentified glycolipid. MK-7(H4) and MK-7(H2) are the predominant respiratory quinones. meso-2,6-Diaminopimelic acid is the diagnostic diamino acid in the cell-wall peptidoglycan. The G+C content for strain 0166_1T is 72.8 mol%. 16S rRNA gene sequence analysis indicated that this bacterium was related to Conexibacter arvalis KV-962T and Conexibacter stalactiti YC2-25T with 95.5 and 95.2 % sequence similarity, respectively. Based on the phenotypic, genomic and phylogenetic data, we propose the novel species Capillimicrobium parvum sp. nov. (type strain 0166_1T=DSM 104329T=LMG 29999T=CECT 9240T) of the novel genus Capillimicrobium gen. nov. within the novel family Capillimicrobiaceae fam. nov.

Changes in Envelope Structure and Cell-Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium Trichormus variabilis ATCC 29413.

Planktonic freshwater filamentous cyanobacterium Trichormus variabilis ATCC 29413 (previously known as Anabaena variabilis) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, akinetes are spore-like resting cells that make the survival of the species possible under adverse growth conditions. Under suitable environmental conditions, they germinate to produce new vegetative filaments. Several morphological and physiological changes occur during akinete formation and germination. Here, using scanning electron microscopy (SEM), we found that the mature akinetes had a wrinkled envelope, and the surface of the envelope smoothened as the cell size increased during germination. Thereupon, the akinete envelope ruptured to release the short emerging filament. Focused ion beam-scanning electron microscopy (FIB/SEM) tomography of immature akinetes revealed the presence of cytoplasmic granules, presumably consisting of cyanophycin or glycogen. In addition, the akinete envelope architecture of different layers, the exopolysaccharide and glycolipid layers, could be visualized. We found that this multilayered envelope helped to withstand osmotic stress and to maintain the structural integrity. Furthermore, by fluorescence recovery after photobleaching (FRAP) measurements, using the fluorescent tracer calcein, we found that intercellular communication decreased during akinete formation as compared with the vegetative cells. In contrast, freshly germinating filaments restored cell communication.

Usitatibacter rugosus gen. nov., sp. nov. and Usitatibacter palustris sp. nov., novel members of Usitatibacteraceae fam. nov. within the order Nitrosomonadales isolated from soil.

Members of the metabolically diverse order Nitrosomonadales inhabit a wide range of environments. Two strains affiliated with this order were isolated from soils in Germany and characterized by a polyphasic approach. Cells of strains 0125_3T and Swamp67T are Gram-negative rods, non-motile, non-spore-forming, non-capsulated and divide by binary fission. They tested catalase-negative, but positive for cytochrome c-oxidase. Both strains form small white colonies on agar plates and grow aerobically and chemoorganotrophically on SSE/HD 1 : 10 medium, preferably utilizing organic acids and proteinaceous substrates. Strains 0125_3T and Swamp67T are mesophilic and grow optimally without NaCl addition at slightly alkaline conditions. Major fatty acids are C16 : 1 ω7c, C16 : 0 and C14 : 0. The major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidyglycerol. The predominant respiratory quinone is Q-8. The G+C content for 0125_3T and Swamp67T was 67 and 66.1 %, respectively. The 16S rRNA gene analysis indicated that the closest relatives (<91 % sequence similarity) of strain 0125_3T were Nitrosospira multiformis ATCC 25196T, Methyloversatilis universalis FAM5T and Denitratisoma oestradiolicum AcBE2-1T, while Nitrosospira multiformis ATCC 25196T, Nitrosospira tenuis Nv1T and Nitrosospira lacus APG3T were closest to strain Swamp67T. The two novel strains shared 97.4 % 16S rRNA gene sequence similarity with one another and show low average nucleotide identity of their genomes (83.8 %). Based on the phenotypic, chemotaxonomic, genomic and phylogenetic analysis, we propose the two novel species Usitatibacter rugosus sp. nov (type strain 0125_3T=DSM 104443T=LMG 29998T=CECT 9241T) and Usitatibacter palustris sp. nov. (type strain Swamp67T=DSM 104440T=LMG 29997T=CECT 9242T) of the novel genus Usitatibacter gen. nov., within the novel family Usitatibacteraceae fam. nov.

FIB-SEM-based analysis of Borrelia intracellular processing by human macrophages.

Borrelia burgdorferi is the causative agent of Lyme disease, a multisystemic disorder affecting primarily skin, joints and nervous system. Successful internalization and intracellular processing of borreliae by immune cells, like macrophages, is decisive for the outcome of a respective infection. Here, we use, for the first time, focused ion beam scanning electron microscopy tomography (FIB-SEM tomography) to visualize the interaction of borreliae with primary human macrophages with high resolution. We report that interaction between macrophages and the elongated and highly motile borreliae can lead to formation of membrane tunnels that extend deeper into the host cytoplasm than the actual phagosome, most probably as a result of partial extrication of captured borreliae. We also show that membrane tubulation at borreliae-containing phagosomes, a process suggested earlier as a mechanism leading to phagosome compaction but hard to visualize in live-cell imaging, is apparently a frequent phenomenon. Finally, we demonstrate that the endoplasmic reticulum (ER) forms multiple STIM1-positive contact sites with both membrane tunnels and phagosome tubulations, confirming the important role of the ER during uptake and intracellular processing of borreliae.

Lack of FIBRILLIN6 in Arabidopsis thaliana affects light acclimation and sulfate metabolism.

Arabidopsis thaliana contains 13 fibrillins (FBNs), which are all localized to chloroplasts. FBN1 and FBN2 are involved in photoprotection of photosystem II, and FBN4 and FBN5 are thought to be involved in plastoquinone transport and biosynthesis, respectively. The functions of the other FBNs remain largely unknown. To gain insight into the function of FBN6, we performed coexpression and Western analyses, conducted fluorescence and transmission electron microscopy, stained reactive oxygen species (ROS), measured photosynthetic parameters and glutathione levels, and applied transcriptomics and metabolomics. Using coexpression analyses, FBN6 was identified as a photosynthesis-associated gene. FBN6 is localized to thylakoid and envelope membranes, and its knockout results in stunted plants. The delayed-growth phenotype cannot be attributed to altered basic photosynthesis parameters or a reduced CO2 assimilation rate. Under moderate light stress, primary leaves of fbn6 plants begin to bleach and contain enlarged plastoglobules. RNA sequencing and metabolomics analyses point to an alteration in sulfate reduction in fbn6. Indeed, glutathione content is higher in fbn6, which in turn confers cadmium tolerance of fbn6 seedlings. We conclude that loss of FBN6 leads to perturbation of ROS homeostasis. FBN6 enables plants to cope with moderate light stress and affects cadmium tolerance.

Insights into replicative senescence of human testicular peritubular cells.

There is evidence for an age-related decline in male reproductive functions, yet how the human testis may age is not understood. Human testicular peritubular cells (HTPCs) transport sperm, contribute to the spermatogonial stem cell (SSC) niche and immune surveillance, and can be isolated and studied in vitro. Consequences of replicative senescence of HTPCs were evaluated to gain partial insights into human testicular aging. To this end, early and advanced HTPC passages, in which replicative senescence was indicated by increased cell size, altered nuclear morphology, enhanced ß-galactosidase activity, telomere attrition and reduced mitochondrial DNA (mtDNA), were compared. These alterations are typical for senescent cells, in general. To examine HTPC-specific changes, focused ion beam scanning electron microscopy (FIB/SEM) tomography was employed, which revealed a reduced mitochondrial network and an increased lysosome population. The results coincide with the data of a parallel proteomic analysis and indicate deranged proteostasis. The mRNA levels of typical contractility markers and growth factors, important for the SSC niche, were not significantly altered. A secretome analysis identified, however, elevated levels of macrophage migration inhibitory factor (MIF) and dipeptidyl peptidase 4 (DPP4), which may play a role in spermatogenesis. Testicular DPP4 may further represent a possible drug target.

Two adhesive systems cooperatively regulate axon ensheathment and myelin growth in the CNS.

Central nervous system myelin is a multilayered membrane produced by oligodendrocytes to increase neural processing speed and efficiency, but the molecular mechanisms underlying axonal selection and myelin wrapping are unknown. Here, using combined morphological and molecular analyses in mice and zebrafish, we show that adhesion molecules of the paranodal and the internodal segment work synergistically using overlapping functions to regulate axonal interaction and myelin wrapping. In the absence of these adhesive systems, axonal recognition by myelin is impaired with myelin growing on top of previously myelinated fibers, around neuronal cell bodies and above nodes of Ranvier. In addition, myelin wrapping is disturbed with the leading edge moving away from the axon and in between previously formed layers. These data show how two adhesive systems function together to guide axonal ensheathment and myelin wrapping, and provide a mechanistic understanding of how the spatial organization of myelin is achieved.

Early defects in translation elongation factor 1α levels at excitatory synapses in α-synucleinopathy.

Cognitive decline and dementia in neurodegenerative diseases are associated with synapse dysfunction and loss, which may precede neuron loss by several years. While misfolded and aggregated α-synuclein is recognized in the disease progression of synucleinopathies, the nature of glutamatergic synapse dysfunction and loss remains incompletely understood. Using fluorescence-activated synaptosome sorting (FASS), we enriched excitatory glutamatergic synaptosomes from mice overexpressing human alpha-synuclein (h-αS) and wild-type littermates to unprecedented purity. Subsequent label-free proteomic quantification revealed a set of proteins differentially expressed upon human alpha-synuclein overexpression. These include overrepresented proteins involved in the synaptic vesicle cycle, ER-Golgi trafficking, metabolism and cytoskeleton. Unexpectedly, we found and validated a steep reduction of eukaryotic translation elongation factor 1 alpha (eEF1A1) levels in excitatory synapses at early stages of h-αS mouse model pathology. While eEF1A1 reduction correlated with the loss of postsynapses, its immunoreactivity was found on both sides of excitatory synapses. Moreover, we observed a reduction in eEF1A1 immunoreactivity in the cingulate gyrus neuropil of patients with Lewy body disease along with a reduction in PSD95 levels. Altogether, our results suggest a link between structural impairments underlying cognitive decline in neurodegenerative disorders and local synaptic defects. eEF1A1 may therefore represent a limiting factor to synapse maintenance.

Engineering extracellular vesicles as novel treatment options: exploiting herpesviral immunity in CLL.

Extracellular vesicles (EVs) are important mediators of cell-cell communication. Intriguingly, EVs can be engineered and thus exploited for the targeted transfer of functional proteins of interest. Thus, engineered EVs may constitute attractive tools for the development of novel therapeutic interventions, like cancer immunotherapies, vaccinations or targeted drug delivery. Here, we describe a novel experimental immunotherapeutic approach for the adjuvant treatment of chronic lymphocytic leukaemia (CLL) based on engineered EVs carrying gp350, the major glycoprotein of Epstein-Barr virus (EBV), CD40L, a central immune accessory molecule and pp65, an immunodominant antigen of the human cytomegalovirus (CMV). We show that these engineered EVs specifically interact with malignant B cells from CLL patients and render these cells immunogenic to allogeneic and autologous EBV- and CMV-specific CD4+ and CD8+ T cells. Collectively, co-opting engineered EVs to re-target the strong herpesviral immunity in CLL patients to malignant cells constitutes an attractive strategy for the adjuvant treatment of a still incurable disease. Abbreviations: CLL: chronic lymphocytic leukaemia; EBV: Epstein-Barr virus; CMV: cytomegalovirus.

In vivo Ca2+ imaging of astrocytic microdomains reveals a critical role of the amyloid precursor protein for mitochondria.

The investigation of amyloid precursor protein (APP) has been mainly confined to its neuronal functions, whereas very little is known about its physiological role in astrocytes. Astrocytes exhibit a particular morphology with slender extensions protruding from somata and primary branches. Along these fine extensions, spontaneous calcium transients occur in spatially restricted microdomains. Within these microdomains mitochondria are responsible for local energy supply and Ca2+ buffering. Using two-photon in vivo Ca2+ imaging, we report a significant decrease in the density of active microdomains, frequency of spontaneous Ca2+ transients and slower Ca2+ kinetics in mice lacking APP. Mechanistically, these changes could be potentially linked to mitochondrial malfunction as our in vivo and in vitro data revealed severe, APP-dependent structural mitochondrial fragmentation in astrocytes. Functionally, such mitochondria exhibited prolonged kinetics and morphology dependent signal size of ATP-induced Ca2+ transients. Our results highlight a prominent role of APP in the modulation of Ca2+ activity in astrocytic microdomains whose precise functioning is crucial for the reinforcement and modulation of synaptic function. This study provides novel insights in APP physiological functions which are important for the understanding of the effects of drugs validated in Alzheimer's disease treatment that affect the function of APP.

From Light Microscopy to Analytical Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB)/SEM in Biology: Fixed Coordinates, Flat Embedding, Absolute References.

Correlative light and electron microscopy (CLEM) has been in use for several years, however it has remained a costly method with difficult sample preparation. Here, we report a series of technical improvements developed for precise and cost-effective correlative light and scanning electron microscopy (SEM) and focused ion beam (FIB)/SEM microscopy of single cells, as well as large tissue sections. Customized coordinate systems for both slides and coverslips were established for thin and ultra-thin embedding of a wide range of biological specimens. Immobilization of biological samples was examined with a variety of adhesives. For histological sections, a filter system for flat embedding was developed. We validated ultra-thin embedding on laser marked slides for efficient, high-resolution CLEM. Target cells can be re-located within minutes in SEM without protracted searching and correlative investigations were reduced to a minimum of preparation steps, while still reaching highest resolution. The FIB/SEM milling procedure is facilitated and significantly accelerated as: (i) milling a ramp becomes needless, (ii) significant re-deposition of milled material does not occur; and (iii) charging effects are markedly reduced. By optimizing all technical parameters FIB/SEM stacks with 2 nm iso-voxels were achieved over thousands of sections, in a wide range of biological samples.

Label-free 3D-CLEM Using Endogenous Tissue Landmarks.

Emerging 3D correlative light and electron microscopy approaches enable studying neuronal structure-function relations at unprecedented depth and precision. However, established protocols for the correlation of light and electron micrographs rely on the introduction of artificial fiducial markers, such as polymer beads or near-infrared brandings, which might obscure or even damage the structure under investigation. Here, we report a general applicable "flat embedding" preparation, enabling high-precision overlay of light and scanning electron micrographs, using exclusively endogenous landmarks in the brain: blood vessels, nuclei, and myelinated axons. Furthermore, we demonstrate feasibility of the workflow by combining in vivo 2-photon microscopy and focused ion beam scanning electron microscopy to dissect the role of astrocytic coverage in the persistence of dendritic spines.

Correction to: Precise and economic FIB/SEM for CLEM: with 2 nm voxels through mitosis.

Unfortunately, part of the legend to Fig. 6 has been incorrectly published.

Ionic stress induces fusion of mitochondria to 3-D networks: An electron tomography study.

Mitochondria are central organelles for energy supply of cells and play an important role in maintenance of ionic balance. Consequently mitochondria are highly sensitive to any kind of stress to which they mainly response by disturbance of respiration, ROS production and release of cytochrome c into the cytoplasm. Many of the physiological and molecular stress reactions of mitochondria are well known, yet there is a lack of information on corresponding stress induced structural changes. 3-D visualization of high-pressure frozen cells by FIB-SEM tomography and TEM tomography as used for the present investigation provide an excellent tool for studying structure related mitochondrial stress reactions. In the present study it is shown that mitochondria in the unicellular fresh-water algal model system Micrasterias as well as in the closely related aquatic higher plant Lemna fuse to local networks as a consequence of exposure to ionic stress induced by addition of KCl, NaCl and CoCl2. In dependence on concentration and duration of the treatment, fusion of mitochondria occurs either by formation of protuberances arising from the outer mitochondrial membrane, or by direct contact of the surface of elongated mitochondria. As our results show that respiration is maintained in both model systems during ionic stress and mitochondrial fusion, as well as formation of protuberances are reversible, we assume that mitochondrial fusion is a ubiquitous process that may help the cells to cope with stress. This may occur by interconnecting the respiratory chains of the individual mitochondria and by enhancing the buffer capacity against stress induced ionic imbalance.

Precise and economic FIB/SEM for CLEM: with 2 nm voxels through mitosis.

A portfolio is presented documenting economic, high-resolution correlative focused ion beam scanning electron microscopy (FIB/SEM) in routine, comprising: (i) the use of custom-labeled slides and coverslips, (ii) embedding of cells in thin, or ultra-thin resin layers for correlative light and electron microscopy (CLEM) and (iii) the claim to reach the highest resolution possible with FIB/SEM in xyz. Regions of interest (ROIs) defined in light microscope (LM), can be relocated quickly and precisely in SEM. As proof of principle, HeLa cells were investigated in 3D context at all stages of the cell cycle, documenting ultrastructural changes during mitosis: nuclear envelope breakdown and reassembly, Golgi degradation and reconstitution and the formation of the midzone and midbody.

Validation of a Hypothesis: Colonization of Black Smokers by Hyperthermophilic Microorganisms.

Newly erupted black smokers (hydrothermal vent chimneys) are sterile during their formation, but house hyperthermophilic microorganisms in substantial amounts in later stages. No direct experimental data exist by which mechanisms hyperthermophiles colonize newly erupted black smokers, but a scenario was proposed recently how this might happen. Here we combine high temperature light microscopy with electron microscopy to show that two hyperthermophilic Archaea, namely Pyrococcus furiosus and Methanocaldococcus villosus are able to adhere onto authentic black smoker material (BSM). We especially are able to directly observe the adhesion process via video recordings taken at high temperatures. These data validate the hypothesis that hyperthermophiles are transferred by serendipitous water currents to the outside of newly formed black smokers and react within seconds to the there prevailing high temperatures by very fast movements. They scan the surface of the hydrothermal chimneys via a much slower zigzag seek-movement and adhere via their flagella at a suitable place, building up biofilms.

Roseisolibacter agri gen. nov., sp. nov., a novel slow-growing member of the under-represented phylum Gemmatimonadetes.

A novel slow-growing bacterium, designated strain AW1220T, was isolated from agricultural floodplain soil sampled at Mashare (Kavango region, Namibia) by using a high-throughput cultivation approach. Strain AW1220T was characterized as a Gram-negative, non-motile, rod-shaped bacterium. Occasionally, some cells attained an unusual length of up to 35 µm. The strain showed positive responses for catalase and cytochrome-c oxidase and divided by binary fission and/or budding. The strain had an aerobic chemoorganoheterotrophic metabolism and was also able to grow under micro-oxic conditions. Colonies were small and pink pigmented. Strain AW1220T was found to be a mesophilic, neutrophilic and non-halophilic bacterium. Cells accumulated polyphosphate intracellularly and mainly utilized complex protein substrates for growth. 16S rRNA gene sequence comparisons revealed that strain AW1220T belonged to the class Gemmatimonadetes (=group 1). Its closest relatives were found to be Gemmatimonas aurantiaca T-27T (90.9 % gene sequence similarity), Gemmatimonas phototrophica AP64T (90.8 %) and Longimicrobiumterrae CB-286315T (84.2 %). The genomic G+C content was 73.3 mol%. The major fatty acids were iso-C15 : 0, C16 : 1ω7c and/or iso-C15 : 0 2-OH, iso-C17 : 1ω9c, iso-C15 : 0 3-OH and C16 : 0. The predominant respiratory quinone was MK-9, albeit minor amounts of MK-8 and MK-10 are also present. The polar lipids comprised major amounts of phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol and one unidentified phosphoglycolipid. On the basis of its polyphasic characterization, strain AW1220T represents a novel genus and species of the class Gemmatimonadetes for which the name Roseisolibacter agri gen. nov., sp. nov. is proposed, with the type strain AW1220T (=DSM 104292T=LMG 29977T).

Migrating Platelets Are Mechano-scavengers that Collect and Bundle Bacteria.

Blood platelets are critical for hemostasis and thrombosis and play diverse roles during immune responses. Despite these versatile tasks in mammalian biology, their skills on a cellular level are deemed limited, mainly consisting in rolling, adhesion, and aggregate formation. Here, we identify an unappreciated asset of platelets and show that adherent platelets use adhesion receptors to mechanically probe the adhesive substrate in their local microenvironment. When actomyosin-dependent traction forces overcome substrate resistance, platelets migrate and pile up the adhesive substrate together with any bound particulate material. They use this ability to act as cellular scavengers, scanning the vascular surface for potential invaders and collecting deposited bacteria. Microbe collection by migrating platelets boosts the activity of professional phagocytes, exacerbating inflammatory tissue injury in sepsis. This assigns platelets a central role in innate immune responses and identifies them as potential targets to dampen inflammatory tissue damage in clinical scenarios of severe systemic infection.

Aridibacter nitratireducens sp. nov., a member of the family Blastocatellaceae, class Blastocatellia, isolated from an African soil.

Members of the class Blastocatellia are frequently found in soils with a neutral and (slightly) basic pH where they constitute an important fraction of the microbial community. A novel representative of the class Blastocatellia was isolated from a Ghanaian soil and was characterized in detail. Cells of strain A24_SHP_-5_238T were non-motile rods that divided by binary fission and formed orange to salmon-coloured colonies on agar plates. Strain A24_SHP_-5_238T tolerated pH values of pH 6.0-9.0 (best growth at pH 7.0-8.5) and temperature values of 8-45 °C (best growth at 33-40 °C). It grew chemo-organoheterotrophically on several sugars, a few amino acids, organic acids and different complex protein substrates. In addition, strain A24_SHP_-5_238T was able to use nitrate as an alternative electron acceptor in the absence of oxygen. Major fatty acids of A24_SHP_-5_238T were iso-C15 : 0, summed feature 1 (C13 : 0 3-OH/iso-C15 : 1 H), summed feature 3 (C16 : 1ω7c/C16 : 1ω6c), anteiso-C17 : 0 and anteiso-C15 : 0. The major quinone was MK-8, and the DNA G+C content was 53.5 mol%. The closest described phylogenetic relatives were Aridibacter famidurans A22_HD_4HT and Aridibacter kavangonensis Ac_23_E3T with a 16S rRNA gene sequence identity of 97.6 and 97.2 %, respectively. The DNA-DNA hybridization values (<28.5 %) confirmed that A24_SHP_-5_238T represents a novel species within the genus Aridibacter. Based on its morphological, physiological and molecular characteristics, we propose the novel species Aridibacter nitratireducens sp. nov. (type strain A24_SHP_-5_238T = DSM 102177T = CECT 9235T).

Luteitalea pratensis gen. nov., sp. nov. a new member of subdivision 6 Acidobacteria isolated from temperate grassland soil.

Albeit being widespread and abundant in soils worldwide, bacteria of the phylum Acidobacteria have remained grossly understudied due to difficulties in their cultivation and isolation. To date, only 48 species have been validly described, including a single member of the phylogenetically diverse Acidobacteria subdivision 6. Here, we report the polyphasic characterization of strain HEG_-6_39T, a novel representative of Acidobacteria subdivision 6 isolated from a grassland soil in Thuringia, Germany. Cells of HEG_-6_39T are Gram-stain-negative, non-motile, non-spore-forming, non-capsulated short rods that form small dark yellow colonies. This slow growing bacterium is psychrotolerant and grows between 0 and 36 °C. It displays a narrower pH tolerance (5.3-8.3) than most acidobacteria. The strain is an aerobe that grows chemo-organotrophically utilizing mostly sugars and proteinaceous substrates such as peptone, yeast extract, casein hydrolysate and casamino acids as substrates. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol and two unknown phospholipids are identified as polar lipids. Major fatty acids are iso-C15 : 0, summed feature 3 (C16 : 1ω6c/C16 : 1ω7c), C18 : 1ω9c and iso-C17 : 1ω9c. The major respiratory quinone is MK-8. The G+C content of the genomic DNA is 64.7 mol%. 16S rRNA gene sequence analysis indicated that this bacterium was related to Vicinamibacter silvestris Ac_5_C6T with 93.6 % sequence similarity. Based on the present taxonomic characterization, strain HEG_-6_39T represents a new species of a novel genus for which the name Luteitalea pratensis gen. nov., sp. nov., is proposed. The type strain of the type species is HEG_-6_39T (=DSM 100886T=KCTC 52215T).