• Planctopirus ephydatiae, a novel Planctomycete isolated from a freshwater sponge.

      Kohn, T; Wiegand, S; Boedeker, C; Rast, P; Heuer, A; Jetten, M S M; Schüler, M; Becker, S; Rohde, C; Müller, R-W; et al. (2019-10-11)
      The microbiome of freshwater sponges is rarely studied, and not a single novel bacterial species has been isolated and subsequently characterized from a freshwater sponge to date. A previous study showed that 14.4% of the microbiome from Ephydatia fluviatilis belong to the phylum Planctomycetes. Therefore, we sampled an Ephydatia sponge from a freshwater lake and employed enrichment techniques targeting bacteria from the phylum Planctomycetes. The obtained strain spb1T was subject to genomic and phenomic characterization and found to represent a novel planctomycetal species proposed as Planctopirus ephydatiae sp. nov. (DSM 106606 = CECT 9866). In the process of differentiating spb1T from its next relative Planctopirus limnophila DSM 3776T, we identified and characterized the first phage - Planctopirus phage vB_PlimS_J1 - infecting planctomycetes that was only mentioned anecdotally before. Interestingly, classical chemotaxonomic methods would have failed to distinguish Planctopirus ephydatiae strain spb1T from Planctopirus limnophila DSM 3776T. Our findings demonstrate and underpin the need for whole genome-based taxonomy to detect and differentiate planctomycetal species.
    • Cultivation and functional characterization of 79 planctomycetes uncovers their unique biology.

      Wiegand, Sandra; Jogler, Mareike; Boedeker, Christian; Pinto, Daniela; Vollmers, John; Rivas-Marín, Elena; Kohn, Timo; Peeters, Stijn H; Heuer, Anja; Rast, Patrick; et al. (2019-11-18)
    • From the Cradle to the Grave of an Infection: Host-Pathogen Interaction Visualized by Intravital Microscopy.

      Handschuh, Juliane; Amore, Jonas; Müller, Andreas J (Wiley, 2019-11-27)
      During infections, interactions between host immune cells and the pathogen occur in distinct anatomical locations and along defined time scales. This can best be assessed in the physiological context of an infection in the living tissue. Consequently, intravital imaging has enabled us to dissect the critical phases and events throughout an infection in real time in living tissues. Specifically, advances in visualizing specific cell types and individual pathogens permitted tracking the early events of tissue invasion of the pathogen, cellular interactions involved in the induction of the immune response as well the events implicated in clearance of the infection. In this respect, two vantage points have evolved since the initial employment of this technique in the field of infection biology. On the one hand, strategies acquired by the pathogen to establish within the host and circumvent or evade the immune defenses have been elucidated. On the other hand, analyzing infections from the immune system’s perspective has led to insights into the dynamic cellular interactions that are involved in the initial recognition of the pathogen, immune induction as well as effector function delivery and immunopathology. Furthermore, an increasing interest in probing functional parameters in vivo has emerged, such as the analysis of pathogen reactivity to stress conditions imposed by the host organism in order to mediate clearance upon pathogen encounter. Here, we give an overview on recent intravital microscopy findings of hostpathogen interactions along the course of an infection, from both the immune system’s and pathogen’s perspectives. We also discuss recent developments and future perspectives in extracting intravital information beyond the localization of pathogens and their interaction with immune cells. Such reporter systems on the pathogen’s physiological state and immune cell functions may prove useful in dissecting the functional dynamics of hostpathogen interactions.
    • The Microbiome of Seagrass Leaves Can Be Dominated by Planctomycetes.

      Kohn, Timo; Rast, Patrick; Kallscheuer, Nicolai; Wiegand, Sandra; Boedeker, Christian; Jetten, Mike S M; Jeske, Olga; Vollmers, John; Kaster, Anne-Kristin; Rohde, Manfred; et al. (Frontiers, 2020-07-10)
      Seagrass meadows are ubiquitous, fragile and endangered marine habitats, which serve as fish breeding grounds, stabilize ocean floor substrates, retain nutrients and serve as important carbon sinks, counteracting climate change. In the Mediterranean Sea, seagrass meadows are mostly formed by the slow-growing endemic plant Posidonia oceanica (Neptune grass), which is endangered by global warming and recreational motorboating. Despite its importance, surprisingly little is known about the leaf surface microbiome of P. oceanica. Using amplicon sequencing, we here show that species belonging to the phylum Planctomycetes can dominate the biofilms of young and aged P. oceanica leaves. Application of selective cultivation techniques allowed for the isolation of two novel planctomycetal strains belonging to two yet uncharacterized genera.
    • Three novel Rubripirellula species isolated from plastic particles submerged in the Baltic Sea and the estuary of the river Warnow in northern Germany.

      Kallscheuer, Nicolai; Jogler, Mareike; Wiegand, Sandra; Peeters, Stijn H; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-05)
      Planctomycetes are a unique and important phylum containing mostly aquatic bacteria, which are often associated with phototrophic surfaces. A complex lifestyle, their potential for the production of bioactive small molecules, their unusual cell biology and a large number of giant and hypothetical genes in their genomes make these microorganisms a fascinating topic for further research. Here, we characterise three novel planctomycetal strains isolated from polystyrene and polyethylene particles that were submerged in the German part of the Baltic Sea and the estuary of the river Warnow. All three strains showed typical planctomycetal traits such as division by polar budding and formation of rosettes. The isolated strains were mesophilic and neutrophilic chemoheterotrophs and reached generation times of 10-25 h during laboratory-scale cultivation. Taxonomically, the three strains belong to the genus Rubripirellula. Based on our analyses all three strains represent novel species, for which we propose the names Rubripirellula amarantea sp. nov., Rubripirellula tenax sp. nov. and Rubripirellula reticaptiva sp. nov. The here characterised strains Pla22T (DSM 102267T = LMG 29691T), Poly51T (DSM 103356T = VKM B-3438T) and Poly59T (DSM 103767T = LMG 29696T) are the respective type strains of these novel species. We also emend the description of the genus Rubripirellula.
    • Description of three bacterial strains belonging to the new genus Novipirellula gen. nov., reclassificiation of Rhodopirellula rosea and Rhodopirellula caenicola and readjustment of the genus threshold of the phylogenetic marker rpoB for Planctomycetaceae.

      Kallscheuer, Nicolai; Wiegand, Sandra; Peeters, Stijn H; Jogler, Mareike; Boedeker, Christian; Heuer, Anja; Rast, Patrick; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-19)
      Access to axenic cultures of Planctomycetes is crucial for further investigating their complex lifestyle, uncommon cell biology and primary and secondary metabolism. As a contribution to achieve this goal in the future, we here describe three strains belonging to the novel genus Novipirellula gen. nov. The strains were isolated from biotic and abiotic surfaces in the Baltic Sea and from the island Heligoland in the North Sea. Colony colours range from white to light pink. Cells are acorn-shaped and grew optimally at neutral pH and temperatures between 27 and 30 °C. Phylogenetic analyses revealed that the isolated strains represent three novel species belonging to a new genus, Novipirellula gen. nov. Beyond that, our analysis suggests that Rhodopirellula rosea LHWP3T, Rhodopirellula caenicola YM26-125T and Rhodopirellula maiorica SM1 are also members of this novel genus. Splitting the current genus Rhodopirellula into a more strictly defined genus Rhodopirellula and Novipirellula also allowed readjusting the genus threshold value for the gene rpoB, encoding the RNA polymerase β-subunit, which is used as phylogenetic marker for Planctomycetales. A threshold range of 75.5-78% identity of the analysed partial rpoB sequence turned out to be reliable for differentiation of genera within the family Planctomycetaceae.
    • Alienimonas californiensis gen. nov. sp. nov., a novel Planctomycete isolated from the kelp forest in Monterey Bay.

      Boersma, Alje S; Kallscheuer, Nicolai; Wiegand, Sandra; Rast, Patrick; Peeters, Stijn H; Mesman, Rob J; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; et al. (2019-12-04)
      Planctomycetes are environmentally and biotechnologically important bacteria and are often found in association with nutrient-rich (marine) surfaces. To allow a more comprehensive understanding of planctomycetal lifestyle and physiology we aimed at expanding the collection of axenic cultures with new isolates. Here, we describe the isolation and genomic and physiological characterisation of strain CA12T obtained from giant bladder kelp (Macrocystis pyrifera) in Monterey Bay, California, USA. 16S rRNA gene sequence and whole genome-based phylogenetic analysis showed that strain CA12T clusters within the family Planctomycetaceae and that it has a high 16S rRNA sequence similarity (82.3%) to Planctomicrobium piriforme DSM 26348T. The genome of strain CA12T has a length of 5,475,215 bp and a G+C content of 70.1%. The highest growth rates were observed at 27 °C and pH 7.5. Using different microscopic methods, we could show that CA12T is able to divide by consecutive polar budding, without completing a characteristic planctomycetal lifestyle switch. Based on our data, we suggest that the isolated strain represents a novel species within a novel genus. We thus propose the name Alienimonas gen. nov. with Alienimonas californiensis sp. nov. as type species of the novel genus and CA12T as type strain of the novel species.
    • Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. isolated from natural or artificial marine surfaces in Northern Germany and California, USA, and emended description of the genus Rhodopirellula.

      Kallscheuer, Nicolai; Wiegand, Sandra; Jogler, Mareike; Boedeker, Christian; Peeters, Stijn H; Rast, Patrick; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-04)
      Expanding the collection of Planctomycetes by characterisation of novel species is key to better understanding of their complex lifestyles, uncommon cell biology and unexplored metabolism. Here, we isolated three novel planctomycetal strains from a kelp forest on the California Coastline at Monterey Bay or from plastic surfaces submerged in the Baltic Sea and the estuary of the river Warnow in the northeast of Germany. According to our phylogenetic analysis, the isolated strains Poly21T, Pla100T and CA85T represent three novel species within the genus Rhodopirellula. All three show typical planctomycetal traits such as division by budding. All are aerobic, mesophilic chemoheterotrophs and show genomic features comparable to other described Rhodopirellula species. However, strain CA85T is exceptional as it forms cream colonies, but no aggregates, which is a notable deviation from the pink- to red-pigmented and aggregate-forming Rhodopirellula species known thus far. We propose the names Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. for the novel strains Poly21T (DSM 102266T = LMG 29467T = CECT 9847T = VKM B-3435T), Pla100T (DSM 102937T = LMG 29465T) and CA85T (DSM 109595T = LMG 29699T = VKM B-3451T), respectively, which we present as the respective type strains of these novel species.
    • Three marine strains constitute the novel genus and species Crateriforma conspicua in the phylum Planctomycetes.

      Peeters, Stijn H; Wiegand, Sandra; Kallscheuer, Nicolai; Jogler, Mareike; Heuer, Anja; Jetten, Mike S M; Rast, Patrick; Boedeker, Christian; Rohde, Manfred; Jogler, Christian (2020-01-01)
      Planctomycetes is a ubiquitous phylum of mostly aquatic bacteria that have a complex lifestyle and an unusual cell biology. Here, we describe three strains of the same novel genus and species isolated from three different environments; from a red biofilm at a hydrothermal vent in the Mediterranean Sea, from sediment in a salt-water fish tank, and from the surface of algae at the coast of the Balearic island Mallorca. The three strains Mal65T (DSM 100706T = LMG 29792T, Pan14r (DSM 29351 = LMG 29012), and V7 (DSM 29812 = CECT 9853 = VKM B-3427) show typical characteristics of the Planctomycetaceae family, such as cell division by budding, crateriform structures and growth in aggregates or rosettes.  The strains are mesophilic, neutrophilic to alkaliphilic as well as chemoheterotrophic and exhibit doubling times between 12 and 35 h. Based on our phylogenetic analysis, the three strains represent a single novel species of a new genus, for which we propose the name Crateriforma conspicua gen. nov. sp. nov.
    • Description of the novel planctomycetal genus Bremerella, containing Bremerella volcania sp. nov., isolated from an active volcanic site, and reclassification of Blastopirellula cremea as Bremerella cremea comb. nov.

      Rensink, Stephanie; Wiegand, Sandra; Kallscheuer, Nicolai; Rast, Patrick; Peeters, Stijn H; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; Jogler, Mareike; et al. (2020-01-01)
      Planctomycetes are part of the PVC superphylum together with Verrucomicrobia, Chlamydiae and others. They are budding bacteria with very distinctive characteristics, such as a remarkable morphology and cell biology. Planctomycetes can be found in almost all habitats, and seem to have a preference for marine biotic and abiotic surfaces, on which they frequently occur in biofilm-forming communities. To extend the number of axenic cultures of planctomycetal strains, we isolated Pan97T from a biofilm in a volcanic site close to the Italian island Panarea in the Thyrrhenian Sea. The physiology, genome and morphology of the novel strain were characterised revealing typical planctomycetal characteristics, such as, division by polar budding and presence of crateriform structures. The strain shows pear-shaped cells of 1.5 ± 0.3 µm × 0.8 ± 0.2 µm and forms white- to cream-coloured colonies on solid medium. Strain Pan97T is mesophilic and neutrophilic, since growth was observed  at a pH range of 5.5-9.5 with optimal growth at pH 7.0 and at a temperature range of 15-40 °C with a maximal growth rate at 36 °C. Pan97T has a genome size of 6,496,182 bp with a G + C content of 56.2%. 5264 protein-coding genes were identified, of which 2141 genes (41%) encode hypothetical proteins. Based on the phylogenetic analysis, we suggest that Pan97T (DSM 101992T = LMG 29460T) represents a novel species of a novel genus within the family Planctomycetaceae, for which we propose the name Bremerella gen. nov., with strain Pan97T classified as Bremerella volcania sp. nov. Based on our analysis, we also propose the reclassification of Blastopirellula cremea Lee et al. 2013 as Bremerella cremea comb. nov., as this species is considered to be the type species of the novel genus Bremerella.
    • Blastopirellula retiformator sp. nov. isolated from the shallow-sea hydrothermal vent system close to Panarea Island.

      Kallscheuer, Nicolai; Wiegand, Sandra; Heuer, Anja; Rensink, Stephanie; Boersma, Alje S; Jogler, Mareike; Boedeker, Christian; Peeters, Stijn H; Rast, Patrick; Jetten, Mike S M; et al. (2020-01-01)
      Aquatic bacteria belonging to the deep-branching phylum Planctomycetes play a major role in global carbon and nitrogen cycles. However, their uncommon morphology and physiology, and their roles and survival on biotic surfaces in marine environments, are only partially understood. Access to axenic cultures of different planctomycetal genera is key to study their complex lifestyles, uncommon cell biology and primary and secondary metabolism in more detail. Here, we describe the characterisation of strain Enr8T isolated from a marine biotic surface in the seawater close to the shallow-sea hydrothermal vent system off Panarea Island, an area with high temperature and pH gradients, and high availability of different sulphur and nitrogen sources resulting in a great microbial diversity. Strain Enr8T showed typical planctomycetal traits such as division by polar budding, aggregate formation and presence of fimbriae and crateriform structures. Growth was observed at ranges of 15-33 °C (optimum 30 °C), pH 6.0-8.0 (optimum 7.0) and at NaCl concentrations from 100 to 1200 mM (optimum 350-700 mM). Strain Enr8T forms white colonies on solid medium and white flakes in liquid culture. Its genome has a size of 6.20 Mb and a G + C content of 59.2%. Phylogenetically, the strain belongs to the genus Blastopirellula. We propose the name Blastopirellula retiformator sp. nov. for the novel species, represented by the type strain Enr8T (DSM 100415T = LMG 29081T).
    • Calycomorphotria hydatis gen. nov., sp. nov., a novel species in the family Planctomycetaceae with conspicuous subcellular structures.

      Schubert, Torsten; Kallscheuer, Nicolai; Wiegand, Sandra; Boedeker, Christian; Peeters, Stijn H; Jogler, Mareike; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2020-05-12)
      A novel strain belonging to the family Planctomycetaceae, designated V22T, was isolated from sediment of a seawater fish tank in Braunschweig, Germany. The isolate forms pink colonies on solid medium and displays common characteristics of planctomycetal strains, such as division by budding, formation of rosettes, a condensed nucleoid and presence of crateriform structures and fimbriae. Unusual invaginations of the cytoplasmic membrane and filamentous putative cytoskeletal elements were observed in thin sections analysed by transmission electron microscopy. Strain V22T is an aerobic heterotroph showing optimal growth at 30 °C and pH 8.5. During laboratory cultivations, strain V22T reached generation times of 10 h (maximal growth rate of 0.069 h-1). Its genome has a size of 5.2 Mb and a G + C content of 54.9%. Phylogenetically, the strain represents a novel genus and species in the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. We propose the name Calycomorphotria hydatis gen. nov., sp. nov. for the novel taxon, represented by the type strain V22T (DSM 29767T = LMG 29080T).
    • Preclinical Assessment of Bacteriophage Therapy against Experimental Lung Infection.

      Wienhold, Sandra-Maria; Brack, Markus C; Nouailles, Geraldine; Krishnamoorthy, Gopinath; Korf, Imke H E; Seitz, Claudius; Wienecke, Sarah; Dietert, Kristina; Gurtner, Corinne; Kershaw, Olivia; et al. (MDPI, 2021-12-24)
      Respiratory infections caused by multidrug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality among critically ill hospitalized patients. Bacteriophages (phages) eliminate pathogens with high host specificity and efficacy. However, the lack of appropriate preclinical experimental models hampers the progress of clinical development of phages as therapeutic agents. Therefore, we tested the efficacy of a purified lytic phage, vB_AbaM_Acibel004, against multidrug-resistant A. baumannii clinical isolate RUH 2037 infection in immunocompetent mice and a human lung tissue model. Sham- and A. baumannii-infected mice received a single-dose of phage or buffer via intratracheal aerosolization. Group-specific differences in bacterial burden, immune and clinical responses were compared. Phage-treated mice not only recovered faster from infection-associated hypothermia but also had lower pulmonary bacterial burden, lower lung permeability, and cytokine release. Histopathological examination revealed less inflammation with unaffected inflammatory cellular recruitment. No phage-specific adverse events were noted. Additionally, the bactericidal effect of the purified phage on A. baumannii was confirmed after single-dose treatment in an ex vivo human lung infection model. Taken together, our data suggest that the investigated phage has significant potential to treat multidrug-resistant A. baumannii infections and further support the development of appropriate methods for preclinical evaluation of antibacterial efficacy of phages.
    • Interaction of myxobacteria-derived outer membrane vesicles with biofilms: antiadhesive and antibacterial effects.

      Goes, Adriely; Vidakovic, Lucia; Drescher, Knut; Fuhrmann, Gregor; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany.; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Royal Society of Chemistry, 2021-08-02)
      Bacterial biofilms are widespread in nature and in medical settings and display a high tolerance to antibiotics and disinfectants. Extracellular vesicles have been increasingly studied to characterise their origins and assess their potential for use as a versatile drug delivery system; however, it remains unclear whether they also have antibiofilm effects. Outer membrane vesicles are lipid vesicles shed by Gram-negative bacteria and, in the case of myxobacteria, carry natural antimicrobial compounds produced by these microorganisms. In this study, we demonstrate that vesicles derived from the myxobacteria Cystobacter velatus Cbv34 and Cystobacter ferrugineus Cbfe23 are highly effective at inhibiting the formation and disrupting biofilms by different bacterial species.
    • Congenital deficiency reveals critical role of ISG15 in skin homeostasis.

      Malik, Muhammad Nasir Hayat; Waqas, Syed F Hassnain; Zeitvogel, Jana; Cheng, Jingyuan; Geffers, Robert; Gouda, Zeinab Abu-Elbaha; Elsaman, Ahmed Mahrous; Radwan, Ahmed R; Schefzyk, Matthias; Braubach, Peter; et al. (Society of clinical investigation, 2021-11-30)
      Ulcerating skin lesions are manifestations of human ISG15 deficiency, a type I interferonopathy. However, chronic inflammation may not be their exclusive cause. We describe two siblings with recurrent skin ulcers that healed with scar formation upon corticosteroid treatment. Both had a homozygous nonsense mutation in the ISG15 gene, leading to unstable ISG15 protein lacking the functional domain. We characterized ISG15-/- dermal fibroblasts, HaCaT keratinocytes, and human induced pluripotent stem cell-derived vascular endothelial cells. ISG15-deficient cells exhibited the expected hyperinflammatory phenotype, but also dysregulated expression of molecules critical for connective tissue and epidermis integrity, including reduced collagens and adhesion molecules, but increased matrix metalloproteases. ISG15-/- fibroblasts exhibited elevated ROS levels and reduced ROS scavenger expression. As opposed to hyperinflammation, defective collagen and integrin synthesis was not rescued by conjugation-deficient ISG15. Cell migration was retarded in ISG15-/- fibroblasts and HaCaT keratinocytes, but normalized under ruxolitinib treatment. Desmosome density was reduced in an ISG15-/- 3D epidermis model. Additionally, there were loose architecture and reduced collagen and desmoglein expression, which could be reversed by treatment with ruxolitinib/doxycycline/TGF-β1. These results reveal critical roles of ISG15 in maintaining cell migration and epidermis and connective tissue homeostasis, whereby the latter likely requires its conjugation to yet unidentified targets.
    • Cortactin Is Required for Efficient FAK, Src and Abl Tyrosine Kinase Activation and Phosphorylation of CagA.

      Knorr, Jakob; Sharafutdinov, Irshad; Fiedler, Florian; Soltan Esmaeili, Delara; Rohde, Manfred; Rottner, Klemens; Backert, Steffen; Tegtmeyer, Nicole; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-06-03)
      Cortactin is a well-known regulatory protein of the host actin cytoskeleton and represents an attractive target of microbial pathogens like Helicobacter pylori. H. pylori manipulates cortactin's phosphorylation status by type-IV secretion-dependent injection of its virulence protein CagA. Multiple host tyrosine kinases, like FAK, Src, and Abl, are activated during infection, but the pathway(s) involved is (are) not yet fully established. Among them, Src and Abl target CagA and stimulate tyrosine phosphorylation of the latter at its EPIYA-motifs. To investigate the role of cortactin in more detail, we generated a CRISPR/Cas9 knockout of cortactin in AGS gastric epithelial cells. Surprisingly, we found that FAK, Src, and Abl kinase activities were dramatically downregulated associated with widely diminished CagA phosphorylation in cortactin knockout cells compared to the parental control. Together, we report here a yet unrecognized cortactin-dependent signaling pathway involving FAK, Src, and Abl activation, and controlling efficient phosphorylation of injected CagA during infection. Thus, the cortactin status could serve as a potential new biomarker of gastric cancer development.
    • Analysis of Bacterial Communities on North Sea Macroalgae and Characterization of the Isolated Planctomycetes gen. nov., sp. nov., sp. nov., sp. nov. and sp. nov.

      Wiegand, Sandra; Rast, Patrick; Kallscheuer, Nicolai; Jogler, Mareike; Heuer, Anja; Boedeker, Christian; Jeske, Olga; Kohn, Timo; Vollmers, John; Kaster, Anne-Kristin; et al. (MDPI, 2021-07-13)
      Planctomycetes are bacteria that were long thought to be unculturable, of low abundance, and therefore neglectable in the environment. This view changed in recent years, after it was shown that members of the phylum Planctomycetes can be abundant in many aquatic environments, e.g., in the epiphytic communities on macroalgae surfaces. Here, we analyzed three different macroalgae from the North Sea and show that Planctomycetes is the most abundant bacterial phylum on the alga Fucus sp., while it represents a minor fraction of the surface-associated bacterial community of Ulva sp. and Laminaria sp. Especially dominant within the phylum Planctomycetes were Blastopirellula sp., followed by Rhodopirellula sp., Rubripirellula sp., as well as other Pirellulaceae and Lacipirellulaceae, but also members of the OM190 lineage. Motivated by the observed abundance, we isolated four novel planctomycetal strains to expand the collection of species available as axenic cultures since access to different strains is a prerequisite to investigate the success of planctomycetes in marine environments. The isolated strains constitute four novel species belonging to one novel and three previously described genera in the order Pirellulales, class Planctomycetia, phylum Planctomycetes.
    • Cortactin Is Required for Efficient FAK, Src and Abl Tyrosine Kinase Activation and Phosphorylation of CagA.

      Knorr, Jakob; Sharafutdinov, Irshad; Fiedler, Florian; Soltan Esmaeili, Delara; Rohde, Manfred; Rottner, Klemens; Backert, Steffen; Tegtmeyer, Nicole; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-06-03)
      Cortactin is a well-known regulatory protein of the host actin cytoskeleton and represents an attractive target of microbial pathogens like Helicobacter pylori. H. pylori manipulates cortactin's phosphorylation status by type-IV secretion-dependent injection of its virulence protein CagA. Multiple host tyrosine kinases, like FAK, Src, and Abl, are activated during infection, but the pathway(s) involved is (are) not yet fully established. Among them, Src and Abl target CagA and stimulate tyrosine phosphorylation of the latter at its EPIYA-motifs. To investigate the role of cortactin in more detail, we generated a CRISPR/Cas9 knockout of cortactin in AGS gastric epithelial cells. Surprisingly, we found that FAK, Src, and Abl kinase activities were dramatically downregulated associated with widely diminished CagA phosphorylation in cortactin knockout cells compared to the parental control. Together, we report here a yet unrecognized cortactin-dependent signaling pathway involving FAK, Src, and Abl activation, and controlling efficient phosphorylation of injected CagA during infection. Thus, the cortactin status could serve as a potential new biomarker of gastric cancer development.
    • Genome analyses of the carboxydotrophic sulfate-reducers Desulfotomaculum nigrificans and Desulfotomaculum carboxydivorans and reclassification of Desulfotomaculum caboxydivorans as a later synonym of Desulfotomaculum nigrificans.

      Visser, Michael; Parshina, Sofiya N; Alves, Joana I; Sousa, Diana Z; Pereira, Inês A C; Muyzer, Gerard; Kuever, Jan; Lebedinsky, Alexander V; Koehorst, Jasper J; Worm, Petra; et al. (BioMedCentral (BMC), 2014-06-15)
      Desulfotomaculum nigrificans and D. carboxydivorans are moderately thermophilic members of the polyphyletic spore-forming genus Desulfotomaculum in the family Peptococcaceae. They are phylogenetically very closely related and belong to 'subgroup a' of the Desulfotomaculum cluster 1. D. nigrificans and D. carboxydivorans have a similar growth substrate spectrum; they can grow with glucose and fructose as electron donors in the presence of sulfate. Additionally, both species are able to ferment fructose, although fermentation of glucose is only reported for D. carboxydivorans. D. nigrificans is able to grow with 20% carbon monoxide (CO) coupled to sulfate reduction, while D. carboxydivorans can grow at 100% CO with and without sulfate. Hydrogen is produced during growth with CO by D. carboxydivorans. Here we present a summary of the features of D. nigrificans and D. carboxydivorans together with the description of the complete genome sequencing and annotation of both strains. Moreover, we compared the genomes of both strains to reveal their differences. This comparison led us to propose a reclassification of D. carboxydivorans as a later heterotypic synonym of D. nigrificans.
    • Loss of Hem1 disrupts macrophage function and impacts migration, phagocytosis, and integrin-mediated adhesion.

      Stahnke, Stephanie; Döring, Hermann; Kusch, Charly; de Gorter, David J J; Dütting, Sebastian; Guledani, Aleks; Pleines, Irina; Schnoor, Michael; Sixt, Michael; Geffers, Robert; et al. (Wiley-VCH, 2021-03-11)
      Hematopoietic-specific protein 1 (Hem1) is an essential subunit of the WAVE regulatory complex (WRC) in immune cells. WRC is crucial for Arp2/3 complex activation and the protrusion of branched actin filament networks. Moreover, Hem1 loss of function in immune cells causes autoimmune diseases in humans. Here, we show that genetic removal of Hem1 in macrophages diminishes frequency and efficacy of phagocytosis as well as phagocytic cup formation in addition to defects in lamellipodial protrusion and migration. Moreover, Hem1-null macrophages displayed strong defects in cell adhesion despite unaltered podosome formation and concomitant extracellular matrix degradation. Specifically, dynamics of both adhesion and de-adhesion as well as concomitant phosphorylation of paxillin and focal adhesion kinase (FAK) were significantly compromised. Accordingly, disruption of WRC function in non-hematopoietic cells coincided with both defects in adhesion turnover and altered FAK and paxillin phosphorylation. Consistently, platelets exhibited reduced adhesion and diminished integrin αIIbβ3 activation upon WRC removal. Interestingly, adhesion phenotypes, but not lamellipodia formation, were partially rescued by small molecule activation of FAK. A full rescue of the phenotype, including lamellipodia formation, required not only the presence of WRCs but also their binding to and activation by Rac. Collectively, our results uncover that WRC impacts on integrin-dependent processes in a FAK-dependent manner, controlling formation and dismantling of adhesions, relevant for properly grabbing onto extracellular surfaces and particles during cell edge expansion, like in migration or phagocytosis.