Recent Submissions

  • Microbiome yarns: microbiome basis of memory,,.

    Timmis, Kenneth; Jebok, Franziska; Molinari, Gabriella; Rohde, Manfred; Timmis, James Kenneth; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-01-01)
  • Lipoteichoic acid deficiency permits normal growth but impairs virulence of Streptococcus pneumoniae.

    Heß, Nathalie; Waldow, Franziska; Kohler, Thomas P; Rohde, Manfred; Kreikemeyer, Bernd; Gómez-Mejia, Alejandro; Hain, Torsten; Schwudke, Dominik; Vollmer, Waldemar; Hammerschmidt, Sven; Gisch, Nicolas; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-12-12)
    Teichoic acid (TA), a crucial cell wall constituent of the pathobiont Streptococcus pneumoniae, is bound to peptidoglycan (wall teichoic acid, WTA) or to membrane glycolipids (lipoteichoic acid, LTA). Both TA polymers share a common precursor synthesis pathway, but differ in the final transfer of the TA chain to either peptidoglycan or a glycolipid. Here, we show that LTA exhibits a different linkage conformation compared to WTA, and identify TacL (previously known as RafX) as a putative lipoteichoic acid ligase required for LTA assembly. Pneumococcal mutants deficient in TacL lack LTA and show attenuated virulence in mouse models of acute pneumonia and systemic infections, although they grow normally in culture. Hence, LTA is important for S. pneumoniae to establish systemic infections, and TacL represents a potential target for antimicrobial drug development.
  • Metatranscriptome Analysis of the Vaginal Microbiota Reveals Potential Mechanisms for Protection against Metronidazole in Bacterial Vaginosis.

    Deng, Zhi-Luo; Gottschick, Cornelia; Bhuju, Sabin; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-06-27)
    Bacterial vaginosis (BV) is a prevalent multifactorial disease of women in their reproductive years characterized by a shift from the
  • Tracking gene expression and oxidative damage of O-stressed Clostridioides difficile by a multi-omics approach.

    Neumann-Schaal, Meina; Metzendorf, Nicole G; Troitzsch, Daniel; Nuss, Aaron Mischa; Hofmann, Julia Danielle; Beckstette, Michael; Dersch, Petra; Otto, Andreas; Sievers, Susanne; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-05-31)
    Clostridioides difficile is the major pathogen causing diarrhea following antibiotic treatment. It is considered to be a strictly anaerobic bacterium, however, previous studies have shown a certain and strain-dependent oxygen tolerance. In this study, the model strain C. difficile 630Δerm was shifted to micro-aerobiosis and was found to stay growing to the same extent as anaerobically growing cells with only few changes in the metabolite pattern. However, an extensive change in gene expression was determined by RNA-Seq. The most striking adaptation strategies involve a change in the reductive fermentation pathways of the amino acids proline, glycine and leucine. But also a far-reaching restructuring in the carbohydrate metabolism was detected with changes in the phosphotransferase system (PTS) facilitated uptake of sugars and a repression of enzymes of glycolysis and butyrate fermentation. Furthermore, a temporary induction in the synthesis of cofactor riboflavin was detected possibly due to an increased demand for flavin mononucleotid (FMN) and flavin adenine dinucleotide (FAD) in redox reactions. However, biosynthesis of the cofactors thiamin pyrophosphate and cobalamin were repressed deducing oxidation-prone enzymes and intermediates in these pathways. Micro-aerobically shocked cells were characterized by an increased demand for cysteine and a thiol redox proteomics approach revealed a dramatic increase in the oxidative state of cysteine in more than 800 peptides after 15 min of micro-aerobic shock. This provides not only a catalogue of oxidation-prone cysteine residues in the C. difficile proteome but also puts the amino acid cysteine into a key position in the oxidative stress response. Our study suggests that tolerance of C. difficile towards O
  • Chronic rhinosinusitis with nasal polyps is characterized by dysbacteriosis of the nasal microbiota.

    Chalermwatanachai, Thanit; Vilchez-Vargas, Ramiro; Holtappels, Gabriele; Lacoere, Tim; Jáuregui, Ruy; Kerckhof, Frederiek-Maarten; Pieper, Dietmar H; Van de Wiele, Tom; Vaneechoutte, Mario; Van Zele, Thibaut; Bachert, Claus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-05-21)
    Chronic rhinosinusitis with nasal polyp (CRSwNP) patients are often characterized by asthma comorbidity and a type-2 inflammation of the sinonasal mucosa. The mucosal microbiota has been suggested to be implicated in the persistence of inflammation, but associations have not been well defined. To compare the bacterial communities of healthy subjects with CRSwNP patients, we collected nasal swabs from 17 healthy subjects, 21 CRSwNP patients without asthma (CRSwNP-A), and 20 CRSwNP patients with co-morbid asthma (CRSwNP+A). We analysed the microbiota using high-throughput sequencing of the bacterial 16S rRNA. Bacterial communities were different between the three groups. Haemophilus influenzae was significantly enriched in CRSwNP patients, Propionibacterium acnes in the healthy group; Staphylococcus aureus was abundant in the CRSwNP-A group, even though present in 57% of patients. Escherichia coli was found in high amounts in CRSwNP+A patients. Nasal tissues of CRSwNP+A patients expressed significantly higher concentrations of IgE, SE-IgE, and IL-5 compared to those of CRSwNP-A patients. Co-cultivation demonstrated that P. acnes growth was inhibited by H. influenzae, E. coli and S. aureus. The nasal microbiota of healthy subjects are different from those of CRSwNP-A and CRSwNP+A patients. However, the most abundant species in healthy status could not inhibit those in CRSwNP disease.
  • Horizontal operon transfer, plasmids, and the evolution of photosynthesis in Rhodobacteraceae

    Brinkmann, Henner; Göker, Markus; Koblížek, Michal; Wagner-Döbler, Irene; Petersen, Jörn; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany.
  • Microbiome Yarns: microbiome of the built environment, paranormal microbiology, and the power of single cell genomics1,2,3,4.

    Timmis, Kenneth; Jebok, Franziska; Rohde, Manfred; Molinari, Gabriella; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-05-16)
  • Regulation of Flagellum Biosynthesis in Response to Cell Envelope Stress in Serovar Typhimurium.

    Spöring, Imke; Felgner, Sebastian; Preuße, Matthias; Eckweiler, Denitsa; Rohde, Manfred; Häussler, Susanne; Weiss, Siegfried; Erhardt, Marc (2018-05-01)
    Flagellum-driven motility of serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of , resulting in flagellated and nonflagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhDC with respect to proteolytic degradation. Information concerning the environmental cues controlling expression of and thus about the bistable flagellar biosynthesis remains ambiguous. Here, we demonstrated that RflP responds to cell envelope stress and alterations of outer membrane integrity. Lipopolysaccharide (LPS) truncation mutants of Typhimurium exhibited increasing motility defects due to downregulation of flagellar gene expression. Transposon mutagenesis and genetic profiling revealed that σ (RpoE) and Rcs phosphorelay-dependent cell envelope stress response systems sense modifications of the lipopolysaccaride, low pH, and activity of the complement system. This subsequently results in activation of RflP expression and degradation of FlhDC via ClpXP. We speculate that the presence of diverse hostile environments inside the host might result in cell envelope damage and would thus trigger the repression of resource-costly and immunogenic flagellum biosynthesis via activation of the cell envelope stress response. Pathogenic bacteria such as Typhimurium sense and adapt to a multitude of changing and stressful environments during host infection. At the initial stage of gastrointestinal colonization, uses flagellum-mediated motility to reach preferred sites of infection. However, the flagellum also constitutes a prime target for the host's immune response. Accordingly, the pathogen needs to determine the spatiotemporal stage of infection and control flagellar biosynthesis in a robust manner. We found that uses signals from cell envelope stress-sensing systems to turn off production of flagella. We speculate that downregulation of flagellum synthesis after cell envelope damage in hostile environments aids survival of during late stages of infection and provides a means to escape recognition by the immune system.
  • Genome biology of a novel lineage of planctomycetes widespread in anoxic aquatic environments.

    Spring, Stefan; Bunk, Boyke; Spröer, Cathrin; Rohde, Manfred; Klenk, Hans-Peter; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-04-26)
    Anaerobic strains affiliated with a novel order-level lineage of the Phycisphaerae class were retrieved from the suboxic zone of a hypersaline cyanobacterial mat and anoxic sediments of solar salterns. Genome sequences of five isolates were obtained and compared with metagenome-assembled genomes representing related uncultured bacteria from various anoxic aquatic environments. Gene content surveys suggest a strictly fermentative saccharolytic metabolism for members of this lineage, which could be confirmed by the phenotypic characterization of isolates. Genetic analyses indicate that the retrieved isolates do not have a canonical origin of DNA replication, but initiate chromosome replication at alternative sites possibly leading to an accelerated evolution. Further potential factors driving evolution and speciation within this clade include genome reduction by metabolic specialization and rearrangements of the genome by mobile genetic elements, which have a high prevalence in strains from hypersaline sediments and mats. Based on genetic and phenotypic data a distinct group of strictly anaerobic heterotrophic planctomycetes within the Phycisphaerae class could be assigned to a novel order that is represented by the proposed genus Sedimentisphaera gen. nov. comprising two novel species, S. salicampi gen. nov., sp. nov. and S. cyanobacteriorum gen. nov., sp. nov. This article is protected by copyright. All rights reserved.
  • Extracellular Actin Is a Receptor for Mycoplasma hyopneumoniae.

    Raymond, Benjamin B A; Madhkoor, Ranya; Schleicher, Ina; Uphoff, Cord C; Turnbull, Lynne; Whitchurch, Cynthia B; Rohde, Manfred; Padula, Matthew P; Djordjevic, Steven P; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018)
    Mycoplasma hyopneumoniae, an agriculturally important porcine pathogen, disrupts the mucociliary escalator causing ciliostasis, loss of cilial function, and epithelial cell death within the porcine lung. Losses to swine production due to growth rate retardation and reduced feed conversion efficiency are severe, and antibiotics are used heavily to control mycoplasmal pneumonia. Notably, little is known about the repertoire of host receptors that M. hyopneumoniae targets to facilitate colonization. Here we show, for the first time, that actin exists extracellularly on porcine epithelial monolayers (PK-15) using surface biotinylation and 3D-Structured Illumination Microscopy (3D-SIM), and that M. hyopneumoniae binds to the extracellular β-actin exposed on the surface of these cells. Consistent with this hypothesis we show: (i) monoclonal antibodies that target β-actin significantly block the ability of M. hyopneumoniae to adhere and colonize PK-15 cells; (ii) microtiter plate binding assays show that M. hyopneumoniae cells bind to monomeric G-actin in a dose dependent manner; (iii) more than 100 M. hyopneumoniae proteins were recovered from affinity-chromatography experiments using immobilized actin as bait; and (iv) biotinylated monomeric actin binds directly to M. hyopneumoniae proteins in ligand blotting studies. Specifically, we show that the P97 cilium adhesin possesses at least two distinct actin-binding regions, and binds monomeric actin with nanomolar affinity. Taken together, these observations suggest that actin may be an important receptor for M. hyopneumoniae within the swine lung and will aid in the future development of intervention strategies against this devastating pathogen. Furthermore, our observations have wider implications for extracellular actin as an important bacterial receptor.
  • Phenotypic heterogeneity: a bacterial virulence strategy.

    Weigel, W A; Dersch, P; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-02-01)
    Growing knowledge of the complexity of the host-pathogen interactions during the course of an infection revealed an amazing variability of bacterial pathogens within the same host tissue site. This heterogeneity in bacterial populations is either the result of a different bacterial response to a slightly divergent tissue microenvironment or is caused by a genetic circuit in which small endogenous fluctuations in a small number of transcription factors drive gene expression in combination with a positive feedback loop. As a result host-pathogen encounters can have different outcomes in individual cells, which enables bet-hedging and/or a co-operative behavior that enhance bacterial fitness and virulence, drive different host responses and promote resistance of small subpopulations to antibiotic treatment. This has a strong impact on the progression and control of the infection, which must be considered for the development of successful antimicrobial therapies.
  • Differential magnesium implant corrosion coat formation and contribution to bone bonding.

    Rahim, Muhammad Imran; Weizbauer, Andreas; Evertz, Florian; Hoffmann, Andrea; Rohde, Manfred; Glasmacher, Birgit; Windhagen, Henning; Gross, Gerhard; Seitz, Jan-Marten; Mueller, Peter P; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
    Magnesium alloys are presently under investigation as promising biodegradable implant materials with osteoconductive properties. To study the molecular mechanisms involved, the potential contribution of soluble magnesium corrosion products to the stimulation of osteoblastic cell differentiation was examined. However, no evidence for the stimulation of osteoblast differentiation could be obtained when cultured mesenchymal precursor cells were differentiated in the presence of metallic magnesium or in cell culture medium containing elevated magnesium ion levels. Similarly, in soft tissue no bone induction by metallic magnesium or by the corrosion product magnesium hydroxide could be observed in a mouse model. Motivated by the comparatively rapid accumulation solid corrosion products physicochemical processes were examined as an alternative mechanism to explain the stimulation of bone growth by magnesium-based implants. During exposure to physiological solutions a structured corrosion coat formed on magnesium whereby the elements calcium and phosphate were enriched in the outermost layer which could play a role in the established biocompatible behavior of magnesium implants. When magnesium pins were inserted into avital bones, corrosion lead to increases in the pull out force, suggesting that the expanding corrosion layer was interlocking with the surrounding bone. Since mechanical stress is a well-established inducer of bone growth, volume increases caused by the rapid accumulation of corrosion products and the resulting force development could be a key mechanism and provide an explanation for the observed stimulatory effects of magnesium-based implants in hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 697-709, 2017.
  • Detection of Streptococcus pyogenes virulence genes in Streptococcus dysgalactiae subsp. equisimilis from Vellore, India.

    Babbar, Anshu; Itzek, Andreas; Pieper, Dietmar H; Nitsche-Schmitz, D Patric; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-03-12)
    Streptococcus dysgalactiae subsp. equisimilis (SDSE), belonging to the group C and G streptococci, are human pathogens reported to cause clinical manifestations similar to infections caused by Streptococcus pyogenes. To scrutinize the distribution of gene coding for S. pyogenes virulence factors in SDSE, 255 isolates were collected from humans infected with SDSE in Vellore, a region in southern India, with high incidence of SDSE infections. Initial evaluation indicated SDSE isolates comprising of 82.35% group G and 17.64% group C. A multiplex PCR system was used to detect 21 gene encoding virulence-associated factors of S. pyogenes, like superantigens, DNases, proteinases, and other immune modulatory toxins. As validated by DNA sequencing of the PCR products, sequences homologous to speC, speG, speH, speI, speL, ssa and smeZ of the family of superantigen coding genes and for DNases like sdaD and sdc were detected in the SDSE collection. Furthermore, there was high abundance (48.12% in group G and 86.6% in group C SDSE) of scpA, the gene coding for C5a peptidase in these isolates. Higher abundance of S. pyogenes virulence factor genes was observed in SDSE of Lancefield group C as compared to group G, even though the incidence rates in former were lower. This study not only substantiates detection of S. pyogenes virulence factor genes in whole genome sequenced SDSE but also makes significant contribution towards the understanding of SDSE and its increasing virulence potential.
  • Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products.

    Sváb, Domonkos; Falgenhauer, Linda; Rohde, Manfred; Szabó, Judit; Chakraborty, Trinad; Tóth, István; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018)
    During recent years, interest in the use of bacteriophages as biocontrol agents against foodborne pathogens has increased, particularly for members of the family Enterobacteriaceae, with pathogenic Escherichia coli, Shigella, and Salmonella strains among them. Here, we report the isolation and characterisation of 12 novel T5-like bacteriophages from confiscated food samples. All bacterophages effectively lysed E. coli K-12 strains and were able to infect pathogenic E. coli strains representing enterohaemorrhagic (EHEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), and enteroinvasive (EIEC) pathotypes, Shigella dysenteriae, S. sonnei strains, as well as multidrug-resistant (MDR) E. coli and multiple strains representing different Salmonella enterica serovars. All the bacteriophages exhibited Siphoviridae morphology. Whole genome sequencing of the novel T5-like bacteriophages showed that they represent two distinct groups, with the genome-based grouping correlating to the different host spectra. As these bacteriophages are of food origin, their stability and lack of any virulence genes, as well as their broad and mutually complementary host spectrum makes these new T5-like bacteriophages valuable candidates for use as biocontrol agents against foodborne pathogenic enterobacteria.
  • Microbiome Yarns: human biome reproduction, evolution and visual acuity,,.

    Timmis, Kenneth; Jebok, Franziska; Molinari, Gabriella; Rohde, Manfred; Lahti, Leo; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-01)
  • Insights into Broilers' Gut Microbiota Fed with Phosphorus, Calcium, and Phytase Supplemented Diets.

    Borda-Molina, Daniel; Vital, Marius; Sommerfeld, Vera; Rodehutscord, Markus; Camarinha-Silva, Amélia; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
    Phytase supplementation in broiler diets is a common practice to improve phosphorus (P) availability and to reduce P loss by excretion. An enhanced P availability, and its concomitant supplementation with calcium (Ca), can affect the structure of the microbial community in the digestive tract of broiler chickens. Here, we aim to distinguish the effects of mineral P, Ca, and phytase on the composition of microbial communities present in the content and the mucosa layer of the gastrointestinal tract (GIT) of broiler chickens. Significant differences were observed between digesta and mucosa samples for the GIT sections studied (p= 0.001). The analyses of 56 individual birds showed a high microbial composition variability within the replicates of the same diet. The average similarity within replicates of digesta and mucosa samples across all diets ranged from 29 to 82% in crop, 19-49% in ileum, and 17-39% in caeca. Broilers fed with a diet only supplemented with Ca had the lowest body weight gain and feed conversion values while diets supplemented with P showed the best performance results. An effect of each diet on crop mucosa samples was observed, however, similar results were not obtained from digesta samples. Microbial communities colonizing the ileum mucosa samples were affected by P supplementation. Caeca-derived samples showed the highest microbial diversity when compared to the other GIT sections and the most prominent phylotypes were related to genusFaecalibacteriumandPseudoflavonifractor, known for their influence on gut health and as butyrate producers. Lower microbial diversity in crop digesta was linked to lower growth performance of birds fed with a diet only supplemented with Ca. Each diet affected microbial communities within individual sections, however, no diet showed a comprehensive effect across all GIT sections, which can primarily be attributed to the great variability among replicates. The substantial community differences between digesta and mucosa derived samples indicate that both habitats have to be considered when the influence of diet on the gut microbiota, broiler growth performance, and animal health is investigated.
  • The invasin D protein fromYersinia pseudotuberculosisselectively binds the Fab region of host antibodies and affects colonization of the intestine.

    Sadana, Pooja; Geyer, Rebecca; Pezoldt, Joern; Helmsing, Saskia; Huehn, Jochen; Hust, Michael; Dersch, Petra; Scrima, Andrea; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-03-13)
    Yersinia pseudotuberculosis is a Gram-negative bacterium and zoonotic pathogen responsible for a wide range of diseases, ranging from mild diarrhea, enterocolitis, lymphatic adenitis to persistent local inflammation. TheY. pseudotuberculosisinvasin D (InvD) molecule belongs to the invasin (InvA)-type autotransporter proteins, but its structure and function remain unknown. In this study, we present the first crystal structure of InvD, analyzed its expression and function in a murine infection model, and identified its target molecule in the host. We found that InvD is induced at 37°C and expressed in vivo2-4 days after infection, indicating that InvD is a virulence factor. During infection, InvD was expressed in all parts of the intestinal tract, but not in deeper lymphoid tissues. The crystal structure of the C-terminal adhesion domain of InvD revealed a distinct Ig-related fold, that, apart from the canonical β-sheets, comprises various modifications of and insertions into the Ig-core structure. We identified the Fab fragment of host-derived IgG/IgA antibodies as the target of the adhesion domain. Phage display panning and flow cytometry data further revealed that InvD exhibits a preferential binding specificity toward antibodies with VH3/VK1 variable domains and that it is specifically recruited to a subset of B cells. This finding suggests that InvD modulates Ig functions in the intestine and affects direct interactions with a subset of cell surface-exposed B-cell receptors. In summary, our results provide extensive insights into the structure of InvD and its specific interaction with the target molecule in the host.
  • Members of a new subgroup of Streptococcus anginosus harbor virulence related genes previously observed in Streptococcus pyogenes.

    Babbar, Anshu; Kumar, Venkatesan Naveen; Bergmann, René; Barrantes, Israel; Pieper, Dietmar H; Itzek, Andreas; Nitsche-Schmitz, D Patric; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-04)
    Conventionally categorized as commensals, the Streptococci of the species S. anginosus are facultative human pathogens that are difficult to diagnose and often overlooked. Furthermore, detailed investigation and diagnosis of S. anginosus infections is hampered by unexplored taxonomy and widely elusive molecular pathogenesis. To explore their pathogenic potential, S. anginosus isolates collected from patients of two geographical locations (Vellore, India and Leipzig, Germany) were subjected to multi-locus sequence analysis (MLSA). This analysis revealed the potential presence of a new distinct clade of the species S. anginosus, tentatively termed here as genomosubspecies vellorensis. A complementary PCR-based screening for S. pyogenes virulence factor as well as antibiotic resistance genes revealed not only the presence of superantigen- and extracellular DNase coding genes identical to corresponding genes of S. pyogenes, but also of erythromycin and tetracycline resistance genes in the genomes of the analyzed S. anginosus isolates, thus posing a matter of significant health concern. Identification of new pathogenic S. anginosus strains capable of causing difficult to treat infections may pose additional challenges to the diagnosis and treatment of Streptococcus based infections.
  • Initial evenness determines diversity and cell density dynamics in synthetic microbial ecosystems.

    Ehsani, Elham; Hernandez-Sanabria, Emma; Kerckhof, Frederiek-Maarten; Props, Ruben; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar Helmut; Boon, Nico; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-01-10)
    The effect of initial evenness on the temporal trajectory of synthetic communities in comprehensive, low-volume microcosm studies remains unknown. We used flow cytometric fingerprinting and 16S rRNA gene amplicon sequencing to assess the impact of time on community structure in one hundred synthetic ecosystems of fixed richness but varying initial evenness. Both methodologies uncovered a similar reduction in diversity within synthetic communities of medium and high initial evenness classes. However, the results of amplicon sequencing showed that there were no significant differences between and within the communities in all evenness groups at the end of the experiment. Nevertheless, initial evenness significantly impacted the cell density of the community after five medium transfers. Highly even communities retained the highest cell densities at the end of the experiment. The relative abundances of individual species could be associated to particular evenness groups, suggesting that their presence was dependent on the initial evenness of the synthetic community. Our results reveal that using synthetic communities for testing ecological hypotheses requires prior assessment of initial evenness, as it impacts temporal dynamics.
  • Labrenzia salina sp. nov., isolated from the rhizosphere of the halophyte Arthrocnemum macrostachyum.

    Camacho, Maria; Redondo-Gómez, Susana; Rodríguez-Llorente, Ignacio; Rohde, Manfred; Spröer, Cathrin; Schumann, Peter; Klenk, Hans-Peter; Montero-Calasanz, Maria Del Carmen; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-12)
    A novel, halophilic, motile, rod-shaped, Gram-staining-negative and non-endospore forming bacterium, designated Cs25T, was isolated from the rhizosphere of the halophyte Arthrocnemum macrostachyum growing in a tidal flat. Strain Cs25T was observed to be catalase-negative and oxidase-positive, and to hydrolyse hypoxanthine. Growth occurred from 15 to 40 °C, at pH 7.0-10.0 and with 1-11 % (w/v) NaCl. Q-10 was identified as the dominant ubiquinone, and the major cellular fatty acids were C18 : 1ω7c, 11-methyl C18 : 1ω7c, C20 : 1ω7c and C18 : 0. The polar lipids comprised phosphatidylmonomethylethanolamine, phosphatidylcholine, sulphoquinovosyldiacylglyceride, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The 16S rRNA gene showed 99.19, 98.6 and 98.59 % sequence identity with Labrenzia alba DSM 18320T, L. aggregata DSM 13394T and L. marina DSM 17023T, respectively. Based on the phenotypic and molecular features and DNA-DNA hybridization data, it is concluded that strain Cs25T represents a novel species for which the name Labrenzia salinasp. nov. is proposed. The type strain is Cs25T (=DSM 29163T=CECT 8816T).

View more