H+ and Na+ are involved in flagellar rotation of the spirochete Leptospira

International Nuclear Information System (INIS)

Islam, Md. Shafiqul; Morimoto, Yusuke V.; Kudo, Seishi; Nakamura, Shuichi

2015-01-01

Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H + is used in Escherichia coli, and Na + is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the coupling ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H + is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na + , though it vigorously moved even under Na + -free conditions. These results suggest that H + is preferentially used and that Na + is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. - Highlights: • This is a study on input energy for motility in the spirochete Leptospira. • Leptospira biflexa exhibited active motility in acidic to alkaline pH. • Both H + and Na + are involved in flagellar rotation in Leptospira. • H + is a primary energy source, but Na + can secondarily enhance motility.

Flagellar Synchronization Is a Simple Alternative to Cell Cycle Synchronization for Ciliary and Flagellar Studies.

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Dutta, Soumita; Avasthi, Prachee

2017-01-01

The unicellular green alga Chlamydomonas reinhardtii is an ideal model organism for studies of ciliary function and assembly. In assays for biological and biochemical effects of various factors on flagellar structure and function, synchronous culture is advantageous for minimizing variability. Here, we have characterized a method in which 100% synchronization is achieved with respect to flagellar length but not with respect to the cell cycle. The method requires inducing flagellar regeneration by amputation of the entire cell population and limiting regeneration time. This results in a maximally homogeneous distribution of flagellar lengths at 3 h postamputation. We found that time-limiting new protein synthesis during flagellar synchronization limits variability in the unassembled pool of limiting flagellar protein and variability in flagellar length without affecting the range of cell volumes. We also found that long- and short-flagella mutants that regenerate normally require longer and shorter synchronization times, respectively. By minimizing flagellar length variability using a simple method requiring only hours and no changes in media, flagellar synchronization facilitates the detection of small changes in flagellar length resulting from both chemical and genetic perturbations in Chlamydomonas . This method increases our ability to probe the basic biology of ciliary size regulation and related disease etiologies. IMPORTANCE Cilia and flagella are highly conserved antenna-like organelles that found in nearly all mammalian cell types. They perform sensory and motile functions contributing to numerous physiological and developmental processes. Defects in their assembly and function are implicated in a wide range of human diseases ranging from retinal degeneration to cancer. Chlamydomonas reinhardtii is an algal model system for studying mammalian cilium formation and function. Here, we report a simple synchronization method that allows detection of small

H{sup +} and Na{sup +} are involved in flagellar rotation of the spirochete Leptospira

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Islam, Md. Shafiqul [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Morimoto, Yusuke V. [Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka 565-0874 (Japan); Graduate School of Frontier BioSciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kudo, Seishi [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Nakamura, Shuichi, E-mail: naka@bp.apph.tohoku.ac.jp [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Graduate School of Frontier BioSciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2015-10-16

Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H{sup +} is used in Escherichia coli, and Na{sup +} is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the coupling ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H{sup +} is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na{sup +}, though it vigorously moved even under Na{sup +}-free conditions. These results suggest that H{sup +} is preferentially used and that Na{sup +} is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. - Highlights: • This is a study on input energy for motility in the spirochete Leptospira. • Leptospira biflexa exhibited active motility in acidic to alkaline pH. • Both H{sup +} and Na{sup +} are involved in flagellar rotation in Leptospira. • H{sup +} is a primary energy source, but Na{sup +} can secondarily enhance motility.

In Vitro Reconstitution of Functional Type III Protein Export and Insights into Flagellar Assembly.

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Terashima, Hiroyuki; Kawamoto, Akihiro; Tatsumi, Chinatsu; Namba, Keiichi; Minamino, Tohru; Imada, Katsumi

2018-06-26

The type III secretion system (T3SS) forms the functional core of injectisomes, protein transporters that allow bacteria to deliver virulence factors into their hosts for infection, and flagella, which are critical for many pathogens to reach the site of infection. In spite of intensive genetic and biochemical studies, the T3SS protein export mechanism remains unclear due to the difficulty of accurate measurement of protein export in vivo Here, we developed an in vitro flagellar T3S protein transport assay system using an inverted cytoplasmic membrane vesicle (IMV) for accurate and controlled measurements of flagellar protein export. We show that the flagellar T3SS in the IMV fully retains export activity. The flagellar hook was constructed inside the lumen of the IMV by adding purified component proteins externally to the IMV solution. We reproduced the hook length control and export specificity switch in the IMV consistent with that seen in the native cell. Previous in vivo analyses showed that flagellar protein export is driven by proton motive force (PMF) and facilitated by ATP hydrolysis by FliI, a T3SS-specific ATPase. Our in vitro assay recapitulated these previous in vivo observations but furthermore clearly demonstrated that even ATP hydrolysis by FliI alone can drive flagellar protein export. Moreover, this assay showed that addition of the FliH 2 /FliI complex to the assay solution at a concentration similar to that in the cell dramatically enhanced protein export, confirming that the FliH 2 /FliI complex in the cytoplasm is important for effective protein transport. IMPORTANCE The type III secretion system (T3SS) is the functional core of the injectisome, a bacterial protein transporter used to deliver virulence proteins into host cells, and bacterial flagella, critical for many pathogens. The molecular mechanism of protein transport is still unclear due to difficulties in accurate measurements of protein transport under well-controlled conditions in

Kinematics of flagellar swimming in Euglena gracilis: Helical trajectories and flagellar shapes.

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Rossi, Massimiliano; Cicconofri, Giancarlo; Beran, Alfred; Noselli, Giovanni; DeSimone, Antonio

2017-12-12

The flagellar swimming of euglenids, which are propelled by a single anterior flagellum, is characterized by a generalized helical motion. The 3D nature of this swimming motion, which lacks some of the symmetries enjoyed by more common model systems, and the complex flagellar beating shapes that power it make its quantitative description challenging. In this work, we provide a quantitative, 3D, highly resolved reconstruction of the swimming trajectories and flagellar shapes of specimens of Euglena gracilis We achieved this task by using high-speed 2D image recordings taken with a conventional inverted microscope combined with a precise characterization of the helical motion of the cell body to lift the 2D data to 3D trajectories. The propulsion mechanism is discussed. Our results constitute a basis for future biophysical research on a relatively unexplored type of eukaryotic flagellar movement. Copyright © 2017 the Author(s). Published by PNAS.

Tetrameric structure of the flagellar cap protein FliD from Serratia marcescens.

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Cho, So Yeon; Song, Wan Seok; Hong, Ho Jeong; Lee, Geun-Shik; Kang, Seung Goo; Ko, Hyun-Jeong; Kim, Pyeung-Hyeun; Yoon, Sung-Il

2017-07-15

Bacterial motility is provided by the flagellum. FliD is located at the distal end of the flagellum and plays a key role in the insertion of each flagellin protein at the growing tip of the flagellar filament. Because FliD functions as an oligomer, the determination of the oligomeric state of FliD is critical to understanding the molecular mechanism of FliD-mediated flagellar growth. FliD has been shown to adopt a pentameric or a hexameric structure depending on the bacterial species. Here, we report another distinct oligomeric form of FliD based on structural and biochemical studies. The crystal structures of the D2 and D3 domains of Serratia marcescens FliD (smFliD) were determined in two crystal forms and together revealed that smFliD assembles into a tetrameric architecture that resembles a four-pointed star plate. smFliD tetramerization was also confirmed in solution by cross-linking experiments. Although smFliD oligomerizes in a head-to-tail orientation using a common primary binding interface between the D2 and D3' domains (the prime denotes the second subunit in the oligomer) similarly to other FliD orthologs, the smFliD tetramer diverges to present a unique secondary D2-D2' binding interface. Our structure-based comparative analysis of FliD suggests that bacteria have developed diverse species-specific oligomeric forms of FliD that range from tetramers to hexamers for flagellar growth. Copyright © 2017 Elsevier Inc. All rights reserved.

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps.

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Kühn, Marco J; Schmidt, Felix K; Eckhardt, Bruno; Thormann, Kai M

2017-06-13

Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.

Bio-hybrid micro/nanodevices powered by flagellar motor: challenges and strategies

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Jin-Woo eKim

2015-07-01

Full Text Available Molecular motors, which are precision-engineered by nature, offer exciting possibilities for bio-hybrid engineered systems. They could enable real applications ranging from micro/nano fluidics, to biosensing, to medical diagnoses. This review describes the fundamental biological insights and fascinating potentials of these remarkable sensing and actuation machines, in particular bacterial flagellar motors, as well as their engineering perspectives with regard to applications in bio-engineered hybrid systems and nanobiotechnology.

The Flagellar Regulon of Legionella—A Review

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Appelt, Sandra; Heuner, Klaus

2017-01-01

The Legionella genus comprises more than 60 species. In particular, Legionella pneumophila is known to cause severe illnesses in humans. Legionellaceae are ubiquitous inhabitants of aquatic environments. Some Legionellaceae are motile and their motility is important to move around in habitats. Motility can be considered as a potential virulence factor as already shown for various human pathogens. The genes of the flagellar system, regulator and structural genes, are structured in hierarchical levels described as the flagellar regulon. Their expression is modulated by various environmental factors. For L. pneumophila it was shown that the expression of genes of the flagellar regulon is modulated by the actual growth phase and temperature. Especially, flagellated Legionella are known to express genes during the transmissive phase of growth that are involved in the expression of virulence traits. It has been demonstrated that the alternative sigma-28 factor is part of the link between virulence expression and motility. In the following review, the structure of the flagellar regulon of L. pneumophila is discussed and compared to other flagellar systems of different Legionella species. Recently, it has been described that Legionella micdadei and Legionella fallonii contain a second putative partial flagellar system. Hence, the report will focus on flagellated and non-flagellated Legionella strains, phylogenetic relationships, the role and function of the alternative sigma factor (FliA) and its anti-sigma-28 factor (FlgM). PMID:29104863

The MogR Transcriptional Repressor Regulates Nonhierarchal Expression of Flagellar Motility Genes and Virulence in Listeria monocytogenes.

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2006-04-01

Full Text Available Flagella are surface structures critical for motility and virulence of many bacterial species. In Listeria monocytogenes, MogR tightly represses expression of flagellin (FlaA during extracellular growth at 37 degrees C and during intracellular infection. MogR is also required for full virulence in a murine model of infection. Using in vitro and in vivo infection models, we determined that the severe virulence defect of MogR-negative bacteria is due to overexpression of FlaA. Specifically, overproduction of FlaA in MogR-negative bacteria caused pleiotropic defects in bacterial division (chaining phenotype, intracellular spread, and virulence in mice. DNA binding and microarray analyses revealed that MogR represses transcription of all known flagellar motility genes by binding directly to a minimum of two TTTT-N(5-AAAA recognition sites positioned within promoter regions such that RNA polymerase binding is occluded. Analysis of MogR protein levels demonstrated that modulation of MogR repression activity confers the temperature-specificity to flagellar motility gene expression. Epistasis analysis revealed that MogR repression of transcription is antagonized in a temperature-dependent manner by the DegU response regulator and that DegU further regulates FlaA levels through a posttranscriptional mechanism. These studies provide the first known example to our knowledge of a transcriptional repressor functioning as a master regulator controlling nonhierarchal expression of flagellar motility genes.

Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

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van Oene, Maarten M.; Dickinson, Laura E.; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H.

2017-01-01

The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor’s response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor’s performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level. PMID:28266562

Speed of the bacterial flagellar motor near zero load depends on the number of stator units.

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Nord, Ashley L; Sowa, Yoshiyuki; Steel, Bradley C; Lo, Chien-Jung; Berry, Richard M

2017-10-31

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque-speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na + - and H + -driven motors. We measure the full torque-speed relationship of one and two H + units in Escherichia coli by selecting the number of H + units and controlling the number of Na + units in hybrid motors. These experiments confirm that speed near zero torque in H + -driven motors increases with the stator number. We also measured 75 torque-speed curves for Na + -driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque-speed curves to be collapsed onto a single curve by simple rescaling. Published under the PNAS license.

Flagellar Motility of Trypanosoma cruzi Epimastigotes

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G. Ballesteros-Rodea

2012-01-01

Full Text Available The hemoflagellate Trypanosoma cruzi is the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known about T. cruzi motility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths.

Microscopic Analysis of Bacterial Motility at High Pressure

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Nishiyama, Masayoshi; Sowa, Yoshiyuki

2012-01-01

The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

Design of a Comprehensive Biochemistry and Molecular Biology Experiment: Phase Variation Caused by Recombinational Regulation of Bacterial Gene Expression

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Sheng, Xiumei; Xu, Shungao; Lu, Renyun; Isaac, Dadzie; Zhang, Xueyi; Zhang, Haifang; Wang, Huifang; Qiao, Zheng; Huang, Xinxiang

2014-01-01

Scientific experiments are indispensable parts of Biochemistry and Molecular Biology. In this study, a comprehensive Biochemistry and Molecular Biology experiment about "Salmonella enterica" serovar Typhi Flagellar phase variation has been designed. It consisted of three parts, namely, inducement of bacterial Flagellar phase variation,…

Flagellar motility confers epiphytic fitness advantages upon Pseudomonas syringae

International Nuclear Information System (INIS)

Haefele, D.M.; Lindow, S.E.

1987-01-01

The role of flagellar motility in determining the epiphytic fitness of an ice-nucleation-active strain of Pseudomonas syringae was examined. The loss of flagellar motility reduced the epiphytic fitness of a normally motile P. syringae strain as measured by its growth, survival, and competitive ability on bean leaf surfaces. Equal population sizes of motile parental or nonmotile mutant P. syringae strains were maintained on bean plants for at least 5 days following the inoculation of fully expanded primary leaves. However, when bean seedlings were inoculated before the primary leaves had expanded and bacterial populations on these leaves were quantified at full expansion, the population size of the nonmotile derivative strain reached only 0.9% that of either the motile parental or revertant strain. When fully expanded bean primary leaves were coinoculated with equal numbers of motile and nonmotile cells, the population size of a nonmotile derivative strain was one-third of that of the motile parental or revertant strain after 8 days. Motile and nonmotile cells were exposed in vitro and on plants to UV radiation and desiccating conditions. The motile and nonmotile strains exhibited equal resistance to both stresses in vitro. However, the population size of a nonmotile strain on leaves was less than 20% that of a motile revertant strain when sampled immediately after UV irradiation. Epiphytic populations of both motile and nonmotile P. syringae declined under desiccating conditions on plants, and after 8 days, the population size of a nonmotile strain was less than one-third that of the motile parental or revertant strain

Flagellar region 3b supports strong expression of integrated DNA and the highest chromosomal integration efficiency of the Escherichia coli flagellar regions.

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Juhas, Mario; Ajioka, James W

2015-07-01

The Gram-negative bacterium Escherichia coli is routinely used as the chassis for a variety of biotechnology and synthetic biology applications. Identification and analysis of reliable chromosomal integration and expression target loci is crucial for E. coli engineering. Chromosomal loci differ significantly in their ability to support integration and expression of the integrated genetic circuits. In this study, we investigate E. coli K12 MG1655 flagellar regions 2 and 3b. Integration of the genetic circuit into seven and nine highly conserved genes of the flagellar regions 2 (motA, motB, flhD, flhE, cheW, cheY and cheZ) and 3b (fliE, F, G, J, K, L, M, P, R), respectively, showed significant variation in their ability to support chromosomal integration and expression of the integrated genetic circuit. While not reducing the growth of the engineered strains, the integrations into all 16 target sites led to the loss of motility. In addition to high expression, the flagellar region 3b supports the highest efficiency of integration of all E. coli K12 MG1655 flagellar regions and is therefore potentially the most suitable for the integration of synthetic genetic circuits. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Identification and characterization of a stage specific membrane protein involved in flagellar attachment in Trypanosoma brucei.

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Katherine Woods

Full Text Available Flagellar attachment is a visibly striking morphological feature of African trypanosomes but little is known about the requirements for attachment at a molecular level. This study characterizes a previously undescribed membrane protein, FLA3, which plays an essential role in flagellar attachment in Trypanosoma brucei. FLA3 is heavily N-glycosylated, locates to the flagellar attachment zone and appears to be a bloodstream stage specific protein. Ablation of the FLA3 mRNA rapidly led to flagellar detachment and a concomitant failure of cytokinesis in the long slender bloodstream form but had no effect on the procyclic form. Flagellar detachment was obvious shortly after induction of the dsRNA and the newly synthesized flagellum was often completely detached after it emerged from the flagellar pocket. Within 12 h most cells possessed detached flagella alongside the existing attached flagellum. These results suggest that proteins involved in attachment are not shared between the new and old attachment zones. In other respects the detached flagella appear normal, they beat rapidly although directional motion was lost, and they possess an apparently normal axoneme and paraflagellar rod structure. The flagellar attachment zone appeared to be disrupted when FLA3 was depleted. Thus, while flagellar attachment is a constitutive feature of the life cycle of trypanosomes, attachment requires stage specific elements at the protein level.

Self-Sustained Oscillatory Sliding Movement of Doublet Microtubules and Flagellar Bend Formation.

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Sumio Ishijima

Full Text Available It is well established that the basis for flagellar and ciliary movements is ATP-dependent sliding between adjacent doublet microtubules. However, the mechanism for converting microtubule sliding into flagellar and ciliary movements has long remained unresolved. The author has developed new sperm models that use bull spermatozoa divested of their plasma membrane and midpiece mitochondrial sheath by Triton X-100 and dithiothreitol. These models enable the observation of both the oscillatory sliding movement of activated doublet microtubules and flagellar bend formation in the presence of ATP. A long fiber of doublet microtubules extruded by synchronous sliding of the sperm flagella and a short fiber of doublet microtubules extruded by metachronal sliding exhibited spontaneous oscillatory movements and constructed a one beat cycle of flagellar bending by alternately actuating. The small sliding displacement generated by metachronal sliding formed helical bends, whereas the large displacement by synchronous sliding formed planar bends. Therefore, the resultant waveform is a half-funnel shape, which is similar to ciliary movements.

Slipping slender bodies and enhanced flagellar locomotion

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Man, Yi; Lauga, Eric

2017-11-01

In the biological world, many cells exploit slender appendages to swim, include numerous species of bacteria, algae and spermatozoa. A classical method to describe the flow field around such appendages is slender-body theory (SBT), which is often used to study flagellar motility in Newtonian fluids. However, biology environments are often rheologically complex due to the presence of polymers. These polymers generically phase-separate near rigid boundaries where low-viscosity fluid layers lead to effective slip on the surface. In this talk, we present an analytical derivation of SBT in the case where the no-slip boundary condition on the appendage is replaced by a Navier slip boundary condition. Our results demonstrate in particular a systematic reduction of the resistance coefficient of the slender filaments in their tangential direction, which leads to enhanced flagellar locomotion.

Coevolved Mutations Reveal Distinct Architectures for Two Core Proteins in the Bacterial Flagellar Motor.

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Alessandro Pandini

Full Text Available Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC "torque" helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM domains (amino-terminal (FliGN, middle (FliGM and FliGC as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6. FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM

In situ ellipsometric study of surface immobilization of flagellar filaments

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Kurunczi, S., E-mail: kurunczi@mfa.kfki.hu [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Nemeth, A.; Huelber, T. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Kozma, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Petrik, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Jankovics, H. [Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Sebestyen, A. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Vonderviszt, F. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Institute of Enzymology, Karolina ut 29-33, Budapest, H-1113 (Hungary); and others

2010-10-15

Protein filaments composed of thousands of subunits are promising candidates as sensing elements in biosensors. In this work in situ spectroscopic ellipsometry is applied to monitor the surface immobilization of flagellar filaments. This study is the first step towards the development of layers of filamentous receptors for sensor applications. Surface activation is performed using silanization and a subsequent glutaraldehyde crosslinking. Structure of the flagellar filament layers immobilized on activated and non-activated Si wafer substrates is determined using a two-layer effective medium model that accounted for the vertical density distribution of flagellar filaments with lengths of 300-1500 nm bound to the surface. The formation of the first interface layer can be explained by the multipoint covalent attachment of the filaments, while the second layer is mainly composed of tail pinned filaments floating upwards with the free parts. As confirmed by atomic force microscopy, covalent immobilization resulted in an increased surface density compared to absorption.

Intraflagellar transport particle size scales inversely with flagellar length: revisiting the balance-point length control model.

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Engel, Benjamin D; Ludington, William B; Marshall, Wallace F

2009-10-05

The assembly and maintenance of eukaryotic flagella are regulated by intraflagellar transport (IFT), the bidirectional traffic of IFT particles (recently renamed IFT trains) within the flagellum. We previously proposed the balance-point length control model, which predicted that the frequency of train transport should decrease as a function of flagellar length, thus modulating the length-dependent flagellar assembly rate. However, this model was challenged by the differential interference contrast microscopy observation that IFT frequency is length independent. Using total internal reflection fluorescence microscopy to quantify protein traffic during the regeneration of Chlamydomonas reinhardtii flagella, we determined that anterograde IFT trains in short flagella are composed of more kinesin-associated protein and IFT27 proteins than trains in long flagella. This length-dependent remodeling of train size is consistent with the kinetics of flagellar regeneration and supports a revised balance-point model of flagellar length control in which the size of anterograde IFT trains tunes the rate of flagellar assembly.

The dynamic instability in the hook/flagellum system that triggers bacterial flicks

Science.gov (United States)

Jabbarzadeh, Mehdi; Fu, Henry

2017-11-01

Dynamical bending, buckling, and polymorphic transformations of the flagellum are known to affect bacterial motility, but run-reverse-flick motility of monotrichous bacteria also involves the even more flexible hook, which connects the flagellum to the cell body. Here, we identify the dynamic buckling mechanism that produces flicks in Vibrio alginolyticus. Estimates of forces and torques on the hook from experimental observations suggest that flicks are triggered at stresses below the hook's static Euler buckling criterion. Using an accurate linearization of the Kirchoff rod model for the hook in a model of a swimming bacterium with rigid flagellum, we show that as hook stiffness decreases there is a transition from on-axis flagellar rotation with small hook deflections to flagellar precession with large deflections. When flagellum flexibility is incorporated, the precession is disrupted by significant flagellar bending - i.e., incipient flicks. The predicted onset of dynamic instabilities corresponds well with experimentally observed flick events.

Bacterial flagella and Type III secretion: case studies in the evolution of complexity.

Science.gov (United States)

Pallen, M J; Gophna, U

2007-01-01

Bacterial flagella at first sight appear uniquely sophisticated in structure, so much so that they have even been considered 'irreducibly complex' by the intelligent design movement. However, a more detailed analysis reveals that these remarkable pieces of molecular machinery are the product of processes that are fully compatible with Darwinian evolution. In this chapter we present evidence for such processes, based on a review of experimental studies, molecular phylogeny and microbial genomics. Several processes have played important roles in flagellar evolution: self-assembly of simple repeating subunits, gene duplication with subsequent divergence, recruitment of elements from other systems ('molecular bricolage'), and recombination. We also discuss additional tentative new assignments of homology (FliG with MgtE, FliO with YscJ). In conclusion, rather than providing evidence of intelligent design, flagellar and non-flagellar Type III secretion systems instead provide excellent case studies in the evolution of complex systems from simpler components.

Minimum Information Loss Based Multi-kernel Learning for Flagellar Protein Recognition in Trypanosoma Brucei

KAUST Repository

Wang, Jim Jing-Yan

2014-12-01

Trypanosma brucei (T. Brucei) is an important pathogen agent of African trypanosomiasis. The flagellum is an essential and multifunctional organelle of T. Brucei, thus it is very important to recognize the flagellar proteins from T. Brucei proteins for the purposes of both biological research and drug design. In this paper, we investigate computationally recognizing flagellar proteins in T. Brucei by pattern recognition methods. It is argued that an optimal decision function can be obtained as the difference of probability functions of flagella protein and the non-flagellar protein for the purpose of flagella protein recognition. We propose to learn a multi-kernel classification function to approximate this optimal decision function, by minimizing the information loss of such approximation which is measured by the Kull back-Leibler (KL) divergence. An iterative multi-kernel classifier learning algorithm is developed to minimize the KL divergence for the problem of T. Brucei flagella protein recognition, experiments show its advantage over other T. Brucei flagellar protein recognition and multi-kernel learning methods. © 2014 IEEE.

Role of calmodulin and calcineurin in regulating flagellar motility and wave polarity in Leishmania.

Science.gov (United States)

Mukhopadhyay, Aakash Gautam; Dey, Chinmoy Sankar

2017-11-01

We have previously reported the involvement of cyclic AMP in regulating flagellar waveforms in Leishmania. Here, we investigated the roles of calcium, calmodulin, and calcineurin in flagellar motility regulation in L. donovani. Using high-speed videomicroscopy, we show that calcium-independent calmodulin and calcineurin activity is necessary for motility in Leishmania. Inhibition of calmodulin and calcineurin induced ciliary beats interrupting flagellar beating in both live (in vivo) and ATP-reactivated (in vitro) parasites. Our results indicate that signaling mediated by calmodulin and calcineurin operates antagonistically to cAMP signaling in regulating the waveforms of Leishmania flagellum. These two pathways are possibly involved in maintaining the balance between the two waveforms, essential for responding to environmental cues, survival, and infectivity.

Chlamydomonas IFT25 is dispensable for flagellar assembly but required to export the BBSome from flagella

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Bin Dong

2017-11-01

Full Text Available Intraflagellar transport (IFT particles are composed of polyprotein complexes IFT-A and IFT-B as well as cargo adaptors such as the BBSome. Two IFT-B subunits, IFT25 and IFT27 were found to form a heterodimer, which is essential in exporting the BBSome out of the cilium but not involved in flagellar assembly and cytokinesis in vertebrates. Controversial results were, however, recorded to show that defects in IFT, flagellar assembly and even cytokinesis were caused by IFT27 knockdown in Chlamydomonas reinhardtii. Using C. reinhardtii as a model organism, we report that depletion of IFT25 has no effect on flagellar assembly and does not affect the entry of the BBSome into the flagellum, but IFT25 depletion did impair BBSome movement out of the flagellum, clarifying the evolutionally conserved role of IFT25 in regulating the exit of the BBSome from the flagellum cross species. Interestingly, depletion of IFT25 causes dramatic reduction of IFT27 as expected, which does not cause defects in flagellar assembly and cytokinesis in C. reinhardtii. Our data thus support that Chlamydomonas IFT27, like its vertebrate homologues, is not involved in flagellar assembly and cytokinesis.

Tuning bacterial hydrodynamics with magnetic fields

Science.gov (United States)

Pierce, C. J.; Mumper, E.; Brown, E. E.; Brangham, J. T.; Lower, B. H.; Lower, S. K.; Yang, F. Y.; Sooryakumar, R.

2017-06-01

Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.

Flagellar glycosylation in Clostridium botulinum.

Science.gov (United States)

Twine, Susan M; Paul, Catherine J; Vinogradov, Evgeny; McNally, David J; Brisson, Jean-Robert; Mullen, James A; McMullin, David R; Jarrell, Harold C; Austin, John W; Kelly, John F; Logan, Susan M

2008-09-01

Flagellins from Clostridium botulinum were shown to be post-translationally modified with novel glycan moieties by top-down MS analysis of purified flagellin protein from strains of various toxin serotypes. Detailed analyses of flagellin from two strains of C. botulinum demonstrated that the protein is modified by a novel glycan moiety of mass 417 Da in O-linkage. Bioinformatic analysis of available C. botulinum genomes identified a flagellar glycosylation island containing homologs of genes recently identified in Campylobacter coli that have been shown to be responsible for the biosynthesis of legionaminic acid derivatives. Structural characterization of the carbohydrate moiety was completed utilizing both MS and NMR spectroscopy, and it was shown to be a novel legionaminic acid derivative, 7-acetamido-5-(N-methyl-glutam-4-yl)-amino-3,5,7,9-tetradeoxy-D-glycero-alpha-D-galacto-nonulosonic acid, (alphaLeg5GluNMe7Ac). Electron transfer dissociation MS with and without collision-activated dissociation was utilized to map seven sites of O-linked glycosylation, eliminating the need for chemical derivatization of tryptic peptides prior to analysis. Marker ions for novel glycans, as well as a unique C-terminal flagellin peptide marker ion, were identified in a top-down analysis of the intact protein. These ions have the potential for use in for rapid detection and discrimination of C. botulinum cells, indicating botulinum neurotoxin contamination. This is the first report of glycosylation of Gram-positive flagellar proteins by the 'sialic acid-like' nonulosonate sugar, legionaminic acid.

Architecture of the flagellar apparatus and related structures in the type species of Peridinium, P. cinctum (Dinophyceae)

DEFF Research Database (Denmark)

Calado, A.C.; Hansen, Gert; Moestrup, Øjvind

1999-01-01

The ultrastructure of Peridinium cinctum, was examined by serial sectioning with particular emphasis on the detailed construction of the flagellar apparatus. The pusular system of P. cinctum included two sac pusules in open connection with the flagellar canals; disorganized material was found ins...

Temperature Dependences of Torque Generation and Membrane Voltage in the Bacterial Flagellar Motor

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Inoue, Yuichi; Baker, Matthew A.B.; Fukuoka, Hajime; Takahashi, Hiroto; Berry, Richard M.; Ishijima, Akihiko

2013-01-01

In their natural habitats bacteria are frequently exposed to sudden changes in temperature that have been shown to affect their swimming. With our believed to be new methods of rapid temperature control for single-molecule microscopy, we measured here the thermal response of the Na+-driven chimeric motor expressed in Escherichia coli cells. Motor torque at low load (0.35 μm bead) increased linearly with temperature, twofold between 15°C and 40°C, and torque at high load (1.0 μm bead) was independent of temperature, as reported for the H+-driven motor. Single cell membrane voltages were measured by fluorescence imaging and these were almost constant (∼120 mV) over the same temperature range. When the motor was heated above 40°C for 1–2 min the torque at high load dropped reversibly, recovering upon cooling below 40°C. This response was repeatable over as many as 10 heating cycles. Both increases and decreases in torque showed stepwise torque changes with unitary size ∼150 pN nm, close to the torque of a single stator at room temperature (∼180 pN nm), indicating that dynamic stator dissociation occurs at high temperature, with rebinding upon cooling. Our results suggest that the temperature-dependent assembly of stators is a general feature of flagellar motors. PMID:24359752

Molecular automata assembly: principles and simulation of bacterial membrane construction.

Science.gov (United States)

Lahoz-Beltra, R

1997-01-01

The motivation to understand the basic rules and principles governing molecular self-assembly may be relevant to explain in the context of molecular biology the self-organization and biological functions exhibited within cells. This paper presents a molecular automata model to simulate molecular self-assembly introducing the concept of molecular programming to simulate the biological function or operation performed by an assembled molecular state machine. The method is illustrated modelling Escherichia coli membrane construction including the assembly and operation of ATP synthase as well as the assembly of the bacterial flagellar motor. Flagellar motor operation was simulated using a different approach based on state machine definition used in virtual reality systems. The proposed methodology provides a modelling framework for simulation of biological functions performed by cellular components and other biological systems suitable to be modelled as molecular state machines.

Flagellar apparatus and nuclear chambers of the green dinoflagellate Gymnodinium chlorophorum

DEFF Research Database (Denmark)

Hansen, Gert; Moestrup, Øjvind

2005-01-01

The green dinoflagellate Gymnodinium chlorophorum (BAH ME 100, the type culture) was reexamined with emphasis on the structure of the flagellar apparatus and nuclear envelope. Like other Gymnodinium species, G. chlorophorum possessed a nuclear fibrous connective linking the flagellar apparatus...... present in G. chlorophorum similar to those reported in Gymnodinium aureolum and Gymnodinium nolleri. In contrast to the type species of Gymnodinium, Gymnodinium fuscum, only one nuclear pore was present per chamber. The presence of a feeding tube (peduncle) suggests that G. chlorophorum is mixotrophic....... Although the fine structure of G. chlorophorum revealed its affiliation to the Gymnodinium group the above discrepancies set it apart, indicating that it might belong in a different genus....

Second-chance signal transduction explains cooperative flagellar switching.

Science.gov (United States)

Zot, Henry G; Hasbun, Javier E; Minh, Nguyen Van

2012-01-01

The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).

Impaired competence in flagellar mutants of Bacillus subtilis is connected to the regulatory network governed by DegU

DEFF Research Database (Denmark)

Hölscher, Theresa; Schiklang, Tina; Dragos, Anna

2018-01-01

The competent state is a developmentally distinct phase, in which bacteria are able to take up and integrate exogenous DNA into their genome. Bacillus subtilis is one of the naturally competent bacterial species and the domesticated laboratory strain 168 is easily transformable. In this study, we...... report a reduced transformation frequency of B. subtilis mutants lacking functional and structural flagellar components. This includes hag, the gene encoding the flagellin protein forming the filament of the flagellum. We confirm that the observed decrease of the transformation frequency is due...... a close link between motility and natural competence in B. subtilis suggesting that hindrance in motility has great impact on differentiation of this bacterium not restricted only to the transition towards sessile growth stage....

Human sperm steer with second harmonics of the flagellar beat.

Science.gov (United States)

Saggiorato, Guglielmo; Alvarez, Luis; Jikeli, Jan F; Kaupp, U Benjamin; Gompper, Gerhard; Elgeti, Jens

2017-11-10

Sperm are propelled by bending waves traveling along their flagellum. For steering in gradients of sensory cues, sperm adjust the flagellar waveform. Symmetric and asymmetric waveforms result in straight and curved swimming paths, respectively. Two mechanisms causing spatially asymmetric waveforms have been proposed: an average flagellar curvature and buckling. We image flagella of human sperm tethered with the head to a surface. The waveform is characterized by a fundamental beat frequency and its second harmonic. The superposition of harmonics breaks the beat symmetry temporally rather than spatially. As a result, sperm rotate around the tethering point. The rotation velocity is determined by the second-harmonic amplitude and phase. Stimulation with the female sex hormone progesterone enhances the second-harmonic contribution and, thereby, modulates sperm rotation. Higher beat frequency components exist in other flagellated cells; therefore, this steering mechanism might be widespread and could inspire the design of synthetic microswimmers.

The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems.

Directory of Open Access Journals (Sweden)

Sophie S Abby

2012-09-01

Full Text Available Type 3 secretion systems (T3SSs are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS, which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems.

Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

KAUST Repository

Gadelha, H.; Gaffney, E. A.; Smith, D. J.; Kirkman-Brown, J. C.

2010-01-01

. We study the effect of geometrical nonlinearity, focusing on the spermatozoon flagellum. For a wide range of physiologically relevant parameters, the nonlinear model predicts that flagellar compression by the internal forces initiates an effective

Identification of flagellar motility genes in Yersinia ruckeri by transposon mutagenesis

DEFF Research Database (Denmark)

Evenhuis, Jason P:; LaPatra, Scott E.; Verner-Jeffreys, David W.

2009-01-01

Here we demonstrate that flagellar secretion is required for production of secreted lipase activity in the fish pathogen Yersinia ruckeri and that neither of these activities is necessary for virulence in rainbow trout. Our results suggest a possible mechanism for the emergence of nonmotile biotype...

Genetical and functional investigation of fliC genes encoding flagellar serotype H4 in wildtype strains of Escherichia coli and in a laboratory E. coli K-12 strain expressing flagellar antigen type H48

Directory of Open Access Journals (Sweden)

Schaudinn Christoph

2005-01-01

Full Text Available Abstract Background Serotyping of O-(lipopolysaccharide and H-(flagellar antigens is a wideley used method for identification of pathogenic strains and clones of Escherichia coli. At present, 176 O- and 53 H-antigens are described for E. coli which occur in different combinations in the strains. The flagellar antigen H4 is widely present in E. coli strains of different O-serotypes and pathotypes and we have investigated the genetic relationship between H4 encoding fliC genes by PCR, nucleotide sequencing and expression studies. Results The complete nucleotide sequence of fliC genes present in E. coli reference strains U9-41 (O2:K1:H4 and P12b (O15:H17 was determined and both were found 99.3% (1043 of 1050 nucleotides identical in their coding sequence. A PCR/RFLP protocol was developed for typing of fliC-H4 strains and 88 E. coli strains reacting with H4 antiserum were investigated. Nucleotide sequencing of complete fliC genes of six E. coli strains which were selected based on serum agglutination titers, fliC-PCR genotyping and reference data revealed 96.6 to 100% identity on the amino acid level. The functional expression of flagellin encoded by fliC-H4 from strain U9-41 and from our strain P12b which is an H4 expressing variant type was investigated in the E. coli K-12 strain JM109 which encodes flagellar type H48. The fliC recombinant plasmid carrying JM109 strains reacted with both H4 and H48 specific antisera whereas JM109 reacted only with the H48 antiserum. By immunoelectron microscopy, we could show that the flagella made by the fliC-H4 recombinant plasmid carrying strain are constituted of H48 and H4 flagellins which are co-assembled into functional flagella. Conclusion The flagellar serotype H4 is encoded by closely related fliC genes present in serologically different types of E. coli strainswhich were isolated at different time periods and geographical locations. Our expression studies show for the first time, that flagellins of

Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and Flagellar apparatus.

Science.gov (United States)

Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind; Matsuoka, Kazumi

2010-01-01

The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior sulcal extension on the dorsal side of the epicone. The eyespot is located dorsally and composed of two layers of globules situated within the chloroplast. A narrow invagination of the plasma membrane is associated with the eyespot. The nuclear envelope has normal nuclear pores similar to other eukaryotes but different from the Gymnodinium group with diagnostic nuclear chambers. The longitudinal and transverse basal bodies are separated by approximately 0.5-1.0 microm and interconnected directly by a striated basal body connective and indirectly by microtubular and fibrous structures. Characteristic features of the flagellar apparatus are as follows: (1) a nuclear extension projects to the R1 (longitudinal microtubular root) and is connected to the root by thin fibrous material; (2) fibrillar structures are associated with the longitudinal and transverse flagellar canal; and (3) a striated ventral connective extends toward the posterior end of the cell along the longitudinal flagellar canal. We conclude, based on both morphological and molecular evidence, that Cochlodinium is only distantly related to Gymnodinium.

Induction of phospholipase- and flagellar synthesis in Serratia liquefaciens is controlled by expression of the flagellar master operon flhD

DEFF Research Database (Denmark)

Givskov, M; Eberl, L; Christiansen, Gunna

1995-01-01

When a liquid culture of Serratia spp. reaches the last part of the logarithmic phase of growth it induces the synthesis of several extracellular hydrolytic enzymes. In this communication we show that synthesis and secretion of the extracellular phospholipase is coupled to expression of flagella....... Expression of flagella is demonstrated to follow a growth-phase-dependent pattern. Cloning, complementation studies and DNA-sequencing analysis has identified a genetic region in Serratia liquefaciens which exhibits extensive homology to the Escherichia coli flhD flagellar master operon. Interruption...

Induction of phospholipase- and flagellar synthesis in Serratia liquefaciens is controlled by expression of the flagellar master operon flhD

DEFF Research Database (Denmark)

Givskov, M; Eberl, L; Christiansen, Gunna

1995-01-01

. Expression of flagella is demonstrated to follow a growth-phase-dependent pattern. Cloning, complementation studies and DNA-sequencing analysis has identified a genetic region in Serratia liquefaciens which exhibits extensive homology to the Escherichia coli flhD flagellar master operon. Interruption...... of the chromosomal flhD operon in S. liquefaciens results in non-flagellated and phospholipase-negative cells, but the synthesis of other exoenzymes is not affected. By placing the flhD operon under the control of a foreign inducible promoter we have shown that increased transcription through the flhD operon leads...

An Element of Determinism in a Stochastic Flagellar Motor Switch.

Science.gov (United States)

Xie, Li; Altindal, Tuba; Wu, Xiao-Lun

2015-01-01

Marine bacterium Vibrio alginolyticus uses a single polar flagellum to navigate in an aqueous environment. Similar to Escherichia coli cells, the polar flagellar motor has two states; when the motor is counter-clockwise, the cell swims forward and when the motor is clockwise, the cell swims backward. V. alginolyticus also incorporates a direction randomization step at the start of the forward swimming interval by flicking its flagellum. To gain an understanding on how the polar flagellar motor switch is regulated, distributions of the forward Δf and backward Δb intervals are investigated herein. We found that the steady-state probability density functions, P(Δf) and P(Δb), of freely swimming bacteria are strongly peaked at a finite time, suggesting that the motor switch is not Poissonian. The short-time inhibition is sufficiently strong and long lasting, i.e., several hundred milliseconds for both intervals, which is readily observed and characterized. Treating motor reversal dynamics as a first-passage problem, which results from conformation fluctuations of the motor switch, we calculated P(Δf) and P(Δb) and found good agreement with the measurements.

Emergence of flagellar beating from the collective behavior of individual ATP-powered dyneins

Science.gov (United States)

Namdeo, S.; Onck, P. R.

2016-10-01

Flagella are hair-like projections from the surface of eukaryotic cells, and they play an important role in many cellular functions, such as cell-motility. The beating of flagella is enabled by their internal architecture, the axoneme, and is powered by a dense distribution of motor proteins, dyneins. The dyneins deliver the required mechanical work through the hydrolysis of ATP. Although the dynein-ATP cycle, the axoneme microstructure, and the flagellar-beating kinematics are well studied, their integration into a coherent picture of ATP-powered flagellar beating is still lacking. Here we show that a time-delayed negative-work-based switching mechanism is able to convert the individual sliding action of hundreds of dyneins into a regular overall beating pattern leading to propulsion. We developed a computational model based on a minimal representation of the axoneme consisting of two representative doublet microtubules connected by nexin links. The relative sliding of the microtubules is incorporated by modeling two groups of ATP-powered dyneins, each responsible for sliding in opposite directions. A time-delayed switching mechanism is postulated, which is key in converting the local individual sliding action of multiple dyneins into global beating. Our results demonstrate that an overall nonreciprocal beating pattern can emerge with time due to the spatial and temporal coordination of the individual dyneins. These findings provide insights in the fundamental working mechanism of axonemal dyneins and could possibly open new research directions in the field of flagellar motility.

Polymorphism in Bacterial Flagella Suspensions

Science.gov (United States)

Schwenger, Walter J.

Bacterial flagella are a type of biological polymer studied for its role in bacterial motility and the polymorphic transitions undertaken to facilitate the run and tumble behavior. The naturally rigid, helical shape of flagella gives rise to novel colloidal dynamics and material properties. This thesis studies methods in which the shape of bacterial flagella can be controlled using in vitro methods and the changes the shape of the flagella have on both single particle dynamics and bulk material properties. We observe individual flagellum in both the dilute and semidilute regimes to observe the effects of solvent condition on the shape of the filament as well as the effect the filament morphology has on reptation through a network of flagella. In addition, we present rheological measurements showing how the shape of filaments effects the bulk material properties of flagellar suspensions. We find that the individual particle dynamics in suspensions of flagella can vary with geometry from needing to reptate linearly via rotation for helical filaments to the prevention of long range diffusion for block copolymer filaments. Similarly, for bulk material properties of flagella suspensions, helical geometries show a dramatic enhancement in elasticity over straight filaments while block copolymers form an elastic gel without the aid of crosslinking agents.

Flagellar-phase variation: isolation of the rh1 gene

International Nuclear Information System (INIS)

Silverman, M.; Zieg, J.; Simon, M.

1979-01-01

In Salmonella, expression of flagellar antigen alternates between two serotypes (phases) encoded by two genes, H1 and H2. The mechanism which controls the alternative expression of the H1 and H2 genes was examined by cloning these genes and the genetic elements which control their activity on hybrid vehicles in Escherichia coli. H2 gene activity was shown to be controlled by a recombinational switch located adjacent to the H2 gene. Activity of the H1 gene is thought to be repressed, when the H2 gene is expressed, by the product of another gene, rhl (repressor of H1), which is controlled coordinately with the H2 gene. In this report, we describe the construction of hybrid lambda vehicles which contain, in addition to the H2 gene, a genetic activity corresponding to rhl. Variation of flagellar antigens analogous to that observed in Salmonella was observed when E. coli strains were transduced with the hybrid lambda. By using the lambda H2rhl hybrid to program protein syntheis in uv-irradiated cells, the synthesis of a polypeptide was correlated with rhl gene product activity. We conclude that the H2 region consists of two cotranscribed genes, H2 and rhl. The expression of both gene products is regulated by the same recombinational event

Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode.

Science.gov (United States)

Beznosov, Sergei N; Veluri, Pavan S; Pyatibratov, Mikhail G; Chatterjee, Abhijit; MacFarlane, Douglas R; Fedorov, Oleg V; Mitra, Sagar

2015-01-13

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g(-1) after 50 cycles and with high rate capability, delivering 770 mAh g(-1) at 5 A g(-1) (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

The phylogeny of swimming kinematics: The environment controls flagellar waveforms in sperm motility

Science.gov (United States)

Guasto, Jeffrey; Burton, Lisa; Zimmer, Richard; Hosoi, Anette; Stocker, Roman

2013-11-01

In recent years, phylogenetic and molecular analyses have dominated the study of ecology and evolution. However, physical interactions between organisms and their environment, a fundamental determinant of organism ecology and evolution, are mediated by organism form and function, highlighting the need to understand the mechanics of basic survival strategies, including locomotion. Focusing on spermatozoa, we combined high-speed video microscopy and singular value decomposition analysis to quantitatively compare the flagellar waveforms of eight species, ranging from marine invertebrates to humans. We found striking similarities in sperm swimming kinematics between genetically dissimilar organisms, which could not be uncovered by phylogenetic analysis. The emergence of dominant waveform patterns across species are suggestive of biological optimization for flagellar locomotion and point toward environmental cues as drivers of this convergence. These results reinforce the power of quantitative kinematic analysis to understand the physical drivers of evolution and as an approach to uncover new solutions for engineering applications, such as micro-robotics.

Deduction of upstream sequences of Xanthomonas campestris flagellar genes responding to transcription activation by FleQ

International Nuclear Information System (INIS)

Hu, R.-M.; Yang, T.-C.; Yang, S.-H.; Tseng, Y.-H.

2005-01-01

Xanthomonas campestris pv. campestris (Xcc), a close relative to Pseudomonas aeruginosa, is the pathogen causing black rot in cruciferous plants. In P. aeruginosa, FleQ serves as a cognate activator of σ 54 in transcription from several σ 54 -dependent promoters of flagellar genes. These P. aeruginosa promoters have been analyzed for FleQ-binding sequences; however, no consensus was deduced. Xcc, although lacks fleSR, has a fleQ homologue residing among over 40 contiguously clustered flagellar genes. A fleQ mutant, Xc17fleQ, constructed by insertional mutation is deficient in FleQ protein, non-flagellated, and immobile. Transcriptional fusion assays on six putative σ 54 -dependent promoters of the flagellar genes, fliE, fliQ, fliL, flgG, flgB, and flhF, indicated that each of them is also FleQ dependent. Each of these promoters has a sequence with weak consensus to 5'-gaaacCCgccgCcgctTt-3', immediately upstream of the predicted σ 54 -binding site, with an imperfect inverted repeat containing a GC-rich center flanked by several A and T at 5'- and 3'-ends, respectively. Replacing this region in fliE promoter with a HindIII recognition sequence abolished the transcription, indicating that this region responds to transcription activation by FleQ

Minimum Information Loss Based Multi-kernel Learning for Flagellar Protein Recognition in Trypanosoma Brucei

KAUST Repository

Wang, Jim Jing-Yan; Gao, Xin

2014-01-01

for the purposes of both biological research and drug design. In this paper, we investigate computationally recognizing flagellar proteins in T. Brucei by pattern recognition methods. It is argued that an optimal decision function can be obtained as the difference

Flagellar filament bio-templated inorganic oxide materials – towards an efficient lithium battery anode

Science.gov (United States)

Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; MacFarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

2015-01-01

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g−1 after 50 cycles and with high rate capability, delivering 770 mAh g−1 at 5 A g−1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future. PMID:25583370

Crystallization and preliminary X-ray analysis of the flagellar motor `brake' molecule YcgR with c-di-GMP from Escherichia coli.

Science.gov (United States)

Hou, Yanjie; Li, De Feng; Wang, Da Cheng

2013-06-01

In Escherichia coli and Salmonella enterica, bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP), a ubiquitous bacterial second-messenger molecule that participates in many cellular processes, can regulate flagellar motor speed and reduce cell swimming velocity by binding to the PilZ-containing protein YcgR. Here, the crystallization and preliminary X-ray crystallographic analysis of YcgR with c-di-GMP are reported. The crystals diffracted to 2.3 Å resolution and belonged to space group R3:H, with unit-cell parameters a = b = 93.96, c = 109.61 Å. The asymmetric unit appeared to contain one subunit with a Matthews coefficient of 3.21 Å(3) Da(-1). The results reported here provide a sound basis for solving the crystal structure of YcgR with c-di-GMP and revealing its structure-function relationship based on the three-dimensional structure.

CRIS-a novel cAMP-binding protein controlling spermiogenesis and the development of flagellar bending.

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Anke Miriam Krähling

Full Text Available The second messengers cAMP and cGMP activate their target proteins by binding to a conserved cyclic nucleotide-binding domain (CNBD. Here, we identify and characterize an entirely novel CNBD-containing protein called CRIS (cyclic nucleotide receptor involved in sperm function that is unrelated to any of the other members of this protein family. CRIS is exclusively expressed in sperm precursor cells. Cris-deficient male mice are either infertile due to a lack of sperm resulting from spermatogenic arrest, or subfertile due to impaired sperm motility. The motility defect is caused by altered Ca(2+ regulation of flagellar beat asymmetry, leading to a beating pattern that is reminiscent of sperm hyperactivation. Our results suggest that CRIS interacts during spermiogenesis with Ca(2+-regulated proteins that--in mature sperm--are involved in flagellar bending.

Association of Lis1 with outer arm dynein is modulated in response to alterations in flagellar motility

Science.gov (United States)

Rompolas, Panteleimon; Patel-King, Ramila S.; King, Stephen M.

2012-01-01

The cytoplasmic dynein regulatory factor Lis1, which induces a persistent tight binding to microtubules and allows for transport of cargoes under high-load conditions, is also present in motile cilia/flagella. We observed that Lis1 levels in flagella of Chlamydomonas strains that exhibit defective motility due to mutation of various axonemal substructures were greatly enhanced compared with wild type; this increase was absolutely dependent on the presence within the flagellum of the outer arm dynein α heavy chain/light chain 5 thioredoxin unit. To assess whether cells might interpret defective motility as a “high-load environment,” we reduced the flagellar beat frequency of wild-type cells through enhanced viscous load and by reductive stress; both treatments resulted in increased levels of flagellar Lis1, which altered the intrinsic beat frequency of the trans flagellum. Differential extraction of Lis1 from wild-type and mutant axonemes suggests that the affinity of outer arm dynein for Lis1 is directly modulated. In cytoplasm, Lis1 localized to two punctate structures, one of which was located near the base of the flagella. These data reveal that the cell actively monitors motility and dynamically modulates flagellar levels of the dynein regulatory factor Lis1 in response to imposed alterations in beat parameters. PMID:22855525

Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

KAUST Repository

Gadelha, H.

2010-05-12

Throughout biology, cells and organisms use flagella and cilia to propel fluid and achieve motility. The beating of these organelles, and the corresponding ability to sense, respond to and modulate this beat is central to many processes in health and disease. While the mechanics of flagellum-fluid interaction has been the subject of extensive mathematical studies, these models have been restricted to being geometrically linear or weakly nonlinear, despite the high curvatures observed physiologically. We study the effect of geometrical nonlinearity, focusing on the spermatozoon flagellum. For a wide range of physiologically relevant parameters, the nonlinear model predicts that flagellar compression by the internal forces initiates an effective buckling behaviour, leading to a symmetry-breaking bifurcation that causes profound and complicated changes in the waveform and swimming trajectory, as well as the breakdown of the linear theory. The emergent waveform also induces curved swimming in an otherwise symmetric system, with the swimming trajectory being sensitive to head shape-no signalling or asymmetric forces are required. We conclude that nonlinear models are essential in understanding the flagellar waveform in migratory human sperm; these models will also be invaluable in understanding motile flagella and cilia in other systems.

Testing the time-of-flight model for flagellar length sensing.

Science.gov (United States)

Ishikawa, Hiroaki; Marshall, Wallace F

2017-11-07

Cilia and flagella are microtubule-based organelles that protrude from the surface of most cells, are important to the sensing of extracellular signals, and make a driving force for fluid flow. Maintenance of flagellar length requires an active transport process known as intraflagellar transport (IFT). Recent studies reveal that the amount of IFT injection negatively correlates with the length of flagella. These observations suggest that a length-dependent feedback regulates IFT. However, it is unknown how cells recognize the length of flagella and control IFT. Several theoretical models try to explain this feedback system. We focused on one of the models, the "time-of-flight" model, which measures the length of flagella on the basis of the travel time of IFT protein in the flagellar compartment. We tested the time-of-flight model using Chlamydomonas dynein mutant cells, which show slower retrograde transport speed. The amount of IFT injection in dynein mutant cells was higher than that in control cells. This observation does not support the prediction of the time-of-flight model and suggests that Chlamydomonas uses another length-control feedback system rather than that described by the time-of-flight model. © 2017 Ishikawa and Marshall. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Trypanin, a component of the flagellar Dynein regulatory complex, is essential in bloodstream form African trypanosomes.

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Katherine S Ralston

2006-09-01

Full Text Available The Trypanosoma brucei flagellum is a multifunctional organelle with critical roles in motility, cellular morphogenesis, and cell division. Although motility is thought to be important throughout the trypanosome lifecycle, most studies of flagellum structure and function have been restricted to the procyclic lifecycle stage, and our knowledge of the bloodstream form flagellum is limited. We have previously shown that trypanin functions as part of a flagellar dynein regulatory system that transmits regulatory signals from the central pair apparatus and radial spokes to axonemal dyneins. Here we investigate the requirement for this dynein regulatory system in bloodstream form trypanosomes. We demonstrate that trypanin is localized to the flagellum of bloodstream form trypanosomes, in a pattern identical to that seen in procyclic cells. Surprisingly, trypanin RNA interference is lethal in the bloodstream form. These knockdown mutants fail to initiate cytokinesis, but undergo multiple rounds of organelle replication, accumulating multiple flagella, nuclei, kinetoplasts, mitochondria, and flagellum attachment zone structures. These findings suggest that normal flagellar beat is essential in bloodstream form trypanosomes and underscore the emerging concept that there is a dichotomy between trypanosome lifecycle stages with respect to factors that contribute to cell division and cell morphogenesis. This is the first time that a defined dynein regulatory complex has been shown to be essential in any organism and implicates the dynein regulatory complex and other enzymatic regulators of flagellar motility as candidate drug targets for the treatment of African sleeping sickness.

Rab23 is a flagellar protein in Trypanosoma brucei

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Field Mark C

2011-06-01

Full Text Available Abstract Background Rab small GTPases are important mediators of membrane transport, and orthologues frequently retain similar locations and functions, even between highly divergent taxa. In metazoan organisms Rab23 is an important negative regulator of Sonic hedgehog signaling and is crucial for correct development and differentiation of cellular lineages by virtue of an involvement in ciliary recycling. Previously, we reported that Trypanosoma brucei Rab23 localized to the nuclear envelope 1, which is clearly inconsistent with the mammalian location and function. As T. brucei is unicellular the potential that Rab23 has no role in cell signaling was possible. Here we sought to further investigate the role(s of Rab23 in T. brucei to determine if Rab23 was an example of a Rab protein with divergent function in distinct taxa. Methods/major findings The taxonomic distribution of Rab23 was examined and compared with the presence of flagella/cilia in representative taxa. Despite evidence for considerable secondary loss, we found a clear correlation between a conventional flagellar structure and the presence of a Rab23 orthologue in the genome. By epitope-tagging, Rab23 was localized and found to be present at the flagellum throughout the cell cycle. However, RNAi knockdown did not result in a flagellar defect, suggesting that Rab23 is not required for construction or maintenance of the flagellum. Conclusions The location of Rab23 at the flagellum is conserved between mammals and trypanosomes and the Rab23 gene is restricted to flagellated organisms. These data may suggest the presence of a Rab23-mediated signaling mechanism in trypanosomes.

Tuning Bacterial Hydrodynamics with Magnetic Fields: A Path to Bacterial Robotics

Science.gov (United States)

Pierce, Christopher; Mumper, Eric; Brangham, Jack; Wijesinghe, Hiran; Lower, Stephen; Lower, Brian; Yang, Fengyuan; Sooryakumar, Ratnasingham

Magnetotactic Bacteria (MTB) are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nano-particles. In this study, the innate magnetism of these flagellated swimmers is exploited to explore their hydrodynamics near confining surfaces, using the magnetic field as a tuning parameter. With weak (Gauss), uniform, external, magnetic ?elds and the field gradients arising from micro-magnetic surface patterns, the relative strength of hydrodynamic, magnetic and ?agellar force components is tuned through magnetic control of the bacteria's orientation and position. In addition to direct measurement of several hydrodynamic quantities related to the motility of individual cells, their tunable dynamics reveal a number of novel, highly controllable swimming behaviors with potential value in micro-robotics applications. Specifically, the experiments permit the MTB cells to be directed along parallel or divergent trajectories, suppress their flagellar forces through magnetic means, and induce transitions between planar, circulating trajectories and drifting, vertically oriented ``top-like'' motion. The implications of the work for fundamental hydrodynamics research as well as bacterially driven robotics applications will be discussed.

Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

Science.gov (United States)

Balakrishnan, Arjun; Negi, Vidya Devi; Sakorey, Deepika; Chandra, Nagasuma

2016-01-01

ABSTRACT One of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility of Salmonella, a foodborne pathogen. It reduced the motility of Salmonella enterica serovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175. IMPORTANCE This work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important

Emergence of flagellar beating from the collective behavior of individual ATP-powered dyneins

OpenAIRE

Namdeo, S.; Onck, P. R.

2016-01-01

Flagella are hair-like projections from the surface of eukaryotic cells, and they play an important role in many cellular functions, such as cell-motility. The beating of flagella is enabled by their internal architecture, the axoneme, and is powered by a dense distribution of motor proteins, dyneins. The dyneins deliver the required mechanical work through the hydrolysis of ATP. Although the dynein-ATP cycle, the axoneme microstructure, and the flagellar-beating kinematics are well studied, ...

Unique ATPase site architecture triggers cis-mediated synchronized ATP binding in heptameric AAA+-ATPase domain of flagellar regulatory protein FlrC.

Science.gov (United States)

Dey, Sanjay; Biswas, Maitree; Sen, Udayaditya; Dasgupta, Jhimli

2015-04-03

Bacterial enhancer-binding proteins (bEBPs) oligomerize through AAA(+) domains and use ATP hydrolysis-driven energy to isomerize the RNA polymerase-σ(54) complex during transcriptional initiation. Here, we describe the first structure of the central AAA(+) domain of the flagellar regulatory protein FlrC (FlrC(C)), a bEBP that controls flagellar synthesis in Vibrio cholerae. Our results showed that FlrC(C) forms heptamer both in nucleotide (Nt)-free and -bound states without ATP-dependent subunit remodeling. Unlike the bEBPs such as NtrC1 or PspF, a novel cis-mediated "all or none" ATP binding occurs in the heptameric FlrC(C), because constriction at the ATPase site, caused by loop L3 and helix α7, restricts the proximity of the trans-protomer required for Nt binding. A unique "closed to open" movement of Walker A, assisted by trans-acting "Glu switch" Glu-286, facilitates ATP binding and hydrolysis. Fluorescence quenching and ATPase assays on FlrC(C) and mutants revealed that although Arg-349 of sensor II, positioned by trans-acting Glu-286 and Tyr-290, acts as a key residue to bind and hydrolyze ATP, Arg-319 of α7 anchors ribose and controls the rate of ATP hydrolysis by retarding the expulsion of ADP. Heptameric state of FlrC(C) is restored in solution even with the transition state mimicking ADP·AlF3. Structural results and pulldown assays indicated that L3 renders an in-built geometry to L1 and L2 causing σ(54)-FlrC(C) interaction independent of Nt binding. Collectively, our results underscore a novel mechanism of ATP binding and σ(54) interaction that strives to understand the transcriptional mechanism of the bEBPs, which probably interact directly with the RNA polymerase-σ(54) complex without DNA looping. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis.

Science.gov (United States)

Corkidi, G; Montoya, F; Hernández-Herrera, P; Ríos-Herrera, W A; Müller, M F; Treviño, C L; Darszon, A

2017-09-01

Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm? The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D). Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella. Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed. Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D. We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non

A novel flagellar sheath protein, FcpA, determines filament coiling, translational motility and virulence for the Leptospira spirochete.

Science.gov (United States)

Wunder, Elsio A; Figueira, Cláudio P; Benaroudj, Nadia; Hu, Bo; Tong, Brian A; Trajtenberg, Felipe; Liu, Jun; Reis, Mitermayer G; Charon, Nyles W; Buschiazzo, Alejandro; Picardeau, Mathieu; Ko, Albert I

2016-08-01

Leptospira are unique among bacteria based on their helical cell morphology with hook-shaped ends and the presence of periplasmic flagella (PF) with pronounced spontaneous supercoiling. The factors that provoke such supercoiling, as well as the role that PF coiling plays in generating the characteristic hook-end cell morphology and motility, have not been elucidated. We have now identified an abundant protein from the pathogen L. interrogans, exposed on the PF surface, and named it Flagellar-coiling protein A (FcpA). The gene encoding FcpA is highly conserved among Leptospira and was not found in other bacteria. fcpA(-) mutants, obtained from clinical isolates or by allelic exchange, had relatively straight, smaller-diameter PF, and were not able to produce translational motility. These mutants lost their ability to cause disease in the standard hamster model of leptospirosis. Complementation of fcpA restored the wild-type morphology, motility and virulence phenotypes. In summary, we identified a novel Leptospira 36-kDa protein, the main component of the spirochete's PF sheath, and a key determinant of the flagella's coiled structure. FcpA is essential for bacterial translational motility and to enable the spirochete to penetrate the host, traverse tissue barriers, disseminate to cause systemic infection and reach target organs. © 2016 John Wiley & Sons Ltd.

Extensive flagellar remodeling during the complex life cycle of &ITParatrypanosoma&IT, an early-branching trypanosomatid

Czech Academy of Sciences Publication Activity Database

Skalický, Tomáš; Dobáková, Eva; Wheeler, R. J.; Tesařová, Martina; Flegontov, P.; Jirsová, Dagmar; Votýpka, Jan; Yurchenko, V.; Ayala, F. J.; Lukeš, Julius

2017-01-01

Roč. 114, č. 44 (2017), s. 11757-11762 ISSN 0027-8424 R&D Projects: GA ČR(CZ) GA14-23986S; GA MŠk LL1601; GA MŠk(CZ) LM2015062 Institutional support: RVO:60077344 Keywords : trypanosomatid * evolution * flagellar remodeling * haptomonads * cytostome Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 9.661, year: 2016

Nonlinear amplitude dynamics in flagellar beating.

Science.gov (United States)

Oriola, David; Gadêlha, Hermes; Casademunt, Jaume

2017-03-01

The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive cross-linkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatio-temporal dynamics of dynein populations and flagellum shape for different regimes of motor activity, medium viscosity and flagellum elasticity. Unstable modes saturate via the coupling of dynein kinetics and flagellum shape without the need of invoking a nonlinear axonemal response. Hence, our work reveals a novel mechanism for the saturation of unstable modes in axonemal beating.

The Lipid Raft Proteome of African Trypanosomes Contains Many Flagellar Proteins.

Science.gov (United States)

Sharma, Aabha I; Olson, Cheryl L; Engman, David M

2017-08-24

Lipid rafts are liquid-ordered membrane microdomains that form by preferential association of 3-β-hydroxysterols, sphingolipids and raft-associated proteins often having acyl modifications. We isolated lipid rafts of the protozoan parasite Trypanosoma brucei and determined the protein composition of lipid rafts in the cell. This analysis revealed a striking enrichment of flagellar proteins and several putative signaling proteins in the lipid raft proteome. Calpains and intraflagellar transport proteins, in particular, were found to be abundant in the lipid raft proteome. These findings provide additional evidence supporting the notion that the eukaryotic cilium/flagellum is a lipid raft-enriched specialized structure with high concentrations of sterols, sphingolipids and palmitoylated proteins involved in environmental sensing and cell signaling.

Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and flagellar apparatus

DEFF Research Database (Denmark)

Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind

2010-01-01

The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior...

Evidence for loss of a partial flagellar glycolytic pathway during trypanosomatid evolution.

Directory of Open Access Journals (Sweden)

Robert W B Brown

Full Text Available Classically viewed as a cytosolic pathway, glycolysis is increasingly recognized as a metabolic pathway exhibiting surprisingly wide-ranging variations in compartmentalization within eukaryotic cells. Trypanosomatid parasites provide an extreme view of glycolytic enzyme compartmentalization as several glycolytic enzymes are found exclusively in peroxisomes. Here, we characterize Trypanosoma brucei flagellar proteins resembling glyceraldehyde-3-phosphate dehydrogenase (GAPDH and phosphoglycerate kinase (PGK: we show the latter associates with the axoneme and the former is a novel paraflagellar rod component. The paraflagellar rod is an essential extra-axonemal structure in trypanosomes and related protists, providing a platform into which metabolic activities can be built. Yet, bioinformatics interrogation and structural modelling indicate neither the trypanosome PGK-like nor the GAPDH-like protein is catalytically active. Orthologs are present in a free-living ancestor of the trypanosomatids, Bodo saltans: the PGK-like protein from B. saltans also lacks key catalytic residues, but its GAPDH-like protein is predicted to be catalytically competent. We discuss the likelihood that the trypanosome GAPDH-like and PGK-like proteins constitute molecular evidence for evolutionary loss of a flagellar glycolytic pathway, either as a consequence of niche adaptation or the re-localization of glycolytic enzymes to peroxisomes and the extensive changes to glycolytic flux regulation that accompanied this re-localization. Evidence indicating loss of localized ATP provision via glycolytic enzymes therefore provides a novel contribution to an emerging theme of hidden diversity with respect to compartmentalization of the ubiquitous glycolytic pathway in eukaryotes. A possibility that trypanosome GAPDH-like protein additionally represents a degenerate example of a moonlighting protein is also discussed.

Characterization of a subunit of the outer dynein arm docking complex necessary for correct flagellar assembly in Leishmania donovani.

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Simone Harder

Full Text Available BACKGROUND: In order to proceed through their life cycle, Leishmania parasites switch between sandflies and mammals. The flagellated promastigote cells transmitted by the insect vector are phagocytized by macrophages within the mammalian host and convert into the amastigote stage, which possesses a rudimentary flagellum only. During an earlier proteomic study of the stage differentiation of the parasite we identified a component of the outer dynein arm docking complex, a structure of the flagellar axoneme. The 70 kDa subunit of the outer dynein arm docking complex consists of three subunits altogether and is essential for the assembly of the outer dynein arm onto the doublet microtubule of the flagella. According to the nomenclature of the well-studied Chlamydomonas reinhardtii complex we named the Leishmania protein LdDC2. METHODOLOGY/PRINCIPAL FINDINGS: This study features a characterization of the protein over the life cycle of the parasite. It is synthesized exclusively in the promastigote stage and localizes to the flagellum. Gene replacement mutants of lddc2 show reduced growth rates and diminished flagellar length. Additionally, the normally spindle-shaped promastigote parasites reveal a more spherical cell shape giving them an amastigote-like appearance. The mutants lose their motility and wiggle in place. Ultrastructural analyses reveal that the outer dynein arm is missing. Furthermore, expression of the amastigote-specific A2 gene family was detected in the deletion mutants in the absence of a stage conversion stimulus. In vitro infectivity is slightly increased in the mutant cell line compared to wild-type Leishmania donovani parasites. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the correct assembly of the flagellum has a great influence on the investigated characteristics of Leishmania parasites. The lack of a single flagellar protein causes an aberrant morphology, impaired growth and altered infectiousness of the parasite.

Complex Interplay between FleQ, Cyclic Diguanylate and Multiple σ Factors Coordinately Regulates Flagellar Motility and Biofilm Development in Pseudomonas putida.

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Alicia Jiménez-Fernández

Full Text Available Most bacteria alternate between a free living planktonic lifestyle and the formation of structured surface-associated communities named biofilms. The transition between these two lifestyles requires a precise and timely regulation of the factors involved in each of the stages that has been likened to a developmental process. Here we characterize the involvement of the transcriptional regulator FleQ and the second messenger cyclic diguanylate in the coordinate regulation of multiple functions related to motility and surface colonization in Pseudomonas putida. Disruption of fleQ caused strong defects in flagellar motility, biofilm formation and surface attachment, and the ability of this mutation to suppress multiple biofilm-related phenotypes associated to cyclic diguanylate overproduction suggests that FleQ mediates cyclic diguanylate signaling critical to biofilm growth. We have constructed a library containing 94 promoters potentially involved in motility and biofilm development fused to gfp and lacZ, screened this library for FleQ and cyclic diguanylate regulation, and assessed the involvement of alternative σ factors σN and FliA in the transcription of FleQ-regulated promoters. Our results suggest a dual mode of action for FleQ. Low cyclic diguanylate levels favor FleQ interaction with σN-dependent promoters to activate the flagellar cascade, encompassing the flagellar cluster and additional genes involved in cyclic diguanylate metabolism, signal transduction and gene regulation. On the other hand, characterization of the FleQ-regulated σN- and FliA-independent PlapA and PbcsD promoters revealed two disparate regulatory mechanisms leading to a similar outcome: the synthesis of biofilm matrix components in response to increased cyclic diguanylate levels.

Proteomic Analysis of Intact Flagella of Procyclic Trypanosoma brucei Cells Identifies Novel Flagellar Proteins with Unique Sub-localization and Dynamics*

Science.gov (United States)

Subota, Ines; Julkowska, Daria; Vincensini, Laetitia; Reeg, Nele; Buisson, Johanna; Blisnick, Thierry; Huet, Diego; Perrot, Sylvie; Santi-Rocca, Julien; Duchateau, Magalie; Hourdel, Véronique; Rousselle, Jean-Claude; Cayet, Nadège; Namane, Abdelkader; Chamot-Rooke, Julia; Bastin, Philippe

2014-01-01

Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity. PMID:24741115

Proteomic analysis of intact flagella of procyclic Trypanosoma brucei cells identifies novel flagellar proteins with unique sub-localization and dynamics.

Science.gov (United States)

Subota, Ines; Julkowska, Daria; Vincensini, Laetitia; Reeg, Nele; Buisson, Johanna; Blisnick, Thierry; Huet, Diego; Perrot, Sylvie; Santi-Rocca, Julien; Duchateau, Magalie; Hourdel, Véronique; Rousselle, Jean-Claude; Cayet, Nadège; Namane, Abdelkader; Chamot-Rooke, Julia; Bastin, Philippe

2014-07-01

Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity. © 2014 by The

The flagellar master operon flhDC is a pleiotropic regulator involved in motility and virulence of the fish pathogen Yersinia ruckeri

Science.gov (United States)

Aims: To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of flhD mutation to a naturally occurring mutation causing loss-of-motility in emergent biotype 2 (BT2) strains. Methods and Results: In this study isogenic Y. ruckeri ...

Crystallization and preliminary X-ray analysis of a C-terminal fragment of FlgJ, a putative flagellar rod cap protein from Salmonella

International Nuclear Information System (INIS)

Kikuchi, Yuki; Matsunami, Hideyuki; Yamane, Midori; Imada, Katsumi; Namba, Keiichi

2008-01-01

A C-terminal fragment of Salmonella FlgJ, FlgJ 120–316 , which has peptidoglycan-hydrolysing activity, has been overproduced, purified and crystallized and the crystals have been characterized by X-ray diffraction. The formation of the bacterial flagellar axial structure, including the filament, the hook and the rod, requires the attachment of a cap complex to the distal end of the growing structure. Because the rod penetrates the peptidoglycan (PG) layer, the rod cap complex is thought to have PG-hydrolyzing activity. FlgJ is a putative rod cap protein whose C-terminal region shows sequence similarity to known muramidases. In this study, FlgJ 120–316 , a C-terminal fragment of FlgJ which contains the muramidase region, was overproduced, purified and crystallized. Crystals were obtained by the sitting-drop vapour-diffusion technique using PEG 3350 as a crystallizing agent and belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 38.8, b = 43.9, c = 108.5 Å. Anomalous difference Patterson maps calculated from the diffraction data set of a selenomethionine-labelled crystal showed significant peaks in the Harker sections, indicating that the data were suitable for structure determination

Changes in the flagellar bundling time account for variations in swimming behavior of flagellated bacteria in viscous media

Science.gov (United States)

Qu, Zijie; Temel, Fatma; Henderikx, Rene; Breuer, Kenneth

2017-11-01

The motility of bacteria E.coli in viscous fluids has been widely studied, although conflicting results on the effect of viscosity on swimming speed abound. The swimming mode of wild-type E.coli is idealized as a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended time and find that the swimming behavior of a single cell can exhibit a variety of behaviors including run-and-tumble and ``slow-random-walk'' in which the cells move at relatively low speed without the characteristic run. Although the characteristic swimming speed varies between individuals and in different polymer solutions, we find that the skewness of the speed distribution is solely a function of viscosity, and uniquely determines the ratio of the average speed to the characteristic run speed. Using Resistive Force Theory and the cell-specific measured characteristic run speed, we show that differences in the swimming behavior observed in solutions of different viscosity are due to changes in the flagellar bundling time, which increases as the viscosity rises, due to lower rotation rate of the flagellar motor. National Science Foundation.

The flagellar master operon flhDC is a pleiotropic regulator involved in motility and virulence of the fish pathogen Yersinia ruckeri.

Science.gov (United States)

Jozwick, A K S; Graf, J; Welch, T J

2017-03-01

To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of a constructed flhD mutation to a naturally occurring fliR mutation causing loss-of-motility in emergent biotype 2 (BT2) strains. Yersinia ruckeri flhD and fliR mutants were constructed in a motile strain. Both mutations caused loss-of-motility, ablation of flagellin synthesis and phospholipase secretion, similar to naturally occurring BT2 strains. Transcriptome analysis confirmed flhDC regulation of flagellar, chemotaxis and phospholipase loci as well as other genes of diverse function. The flhD mutation confers a competitive advantage within the fish host when compared with its parent strain, while this advantage was not seen with the naturally occurring fliR mutation. An intact flhD is necessary for expression of the flagellar secretion system as well as other diverse loci, consistent with a role for flhD as a pleiotropic regulator. The maintenance of the flhD locus in Y. ruckeri strains suggests its importance for aspects of Y. ruckeri biology other than virulence, since the flhD mutation conferred a competitive advantage during experimental challenge of rainbow trout. Yersinia ruckeri is the causative agent of enteric red mouth disease, an invasive septicaemia that affects farmed salmonid fish species. Disease outbreaks can cause severe economic losses in aquaculture. BT2 variants, which have independently emerged worldwide, are an increasing threat to farmed fish production. Knowledge of mechanisms involved in virulence, conserved functions and gene regulation among strains may be exploited for the development of novel disease control strategies to prevent pathogen growth or virulence phenotypes within aquaculture. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Cloning, overexpression, purification, crystallization and preliminary X-ray analysis of CheY3, a response regulator that directly interacts with the flagellar ‘switch complex’ in Vibrio cholerae

International Nuclear Information System (INIS)

Khamrui, Susmita; Biswas, Maitree; Sen, Udayaditya; Dasgupta, Jhimli

2010-01-01

A chemotaxis response regulator CheY3 from V. cholerae has been cloned, overexpressed, purified and crystallized. The crystals of CheY3 diffracted to 1.86 Å resolution. Vibrio cholerae is the aetiological agent of the severe diarrhoeal disease cholera. This highly motile organism uses the processes of motility and chemotaxis to travel and colonize the intestinal epithelium. Chemotaxis in V. cholerae is far more complex than that in Escherichia coli or Salmonella typhimurium, with multiple paralogues of various chemotaxis genes. In contrast to the single copy of the chemotaxis response-regulator protein CheY in E. coli, V. cholerae contains four CheYs (CheY1–CheY4), of which CheY3 is primarily responsible for interacting with the flagellar motor protein FliM, which is one of the major constituents of the ‘switch complex’ in the flagellar motor. This interaction is the key step that controls flagellar rotation in response to environmental stimuli. CheY3 has been cloned, overexpressed and purified by Ni–NTA affinity chromatography followed by gel filtration. Crystals of CheY3 were grown in space group R3, with a calculated Matthews coefficient of 2.33 Å 3 Da −1 (47% solvent content) assuming the presence of one molecule per asymmetric unit

Cloning, purification, crystallization and preliminary X-ray studies of flagellar hook scaffolding protein FlgD from Pseudomonas aeruginosa PAO1

International Nuclear Information System (INIS)

Luo, Miao; Niu, Siqiang; Yin, Yibing; Huang, Ailong; Wang, Deqiang

2009-01-01

In order to better elucidate the functions of FlgD in flagellar hook biosynthesis, the three-dimensional structure of FlgD is being determined by X-ray crystallography. Here, the expression, purification, crystallization and preliminary crystallographic analysis of FlgD from P. aeruginosa are reported. FlgD regulates the assembly of the hook cap structure to prevent leakage of hook monomers into the medium and hook monomer polymerization and also plays a role in determination of the correct hook length, with the help of the FliK protein. In order to better elucidate the functions of FlgD in flagellar hook biosynthesis, the three-dimensional structure of FlgD is being determined by X-ray crystallography. Here, the expression, purification, crystallization and preliminary crystallographic analysis of FlgD from P. aeruginosa are reported. The crystal belonged to space group I222 and diffracted to a resolution of 2.5 Å, with unit-cell parameters a = 116.47, b = 118.71, c = 118.85 Å. The crystals are most likely to contain three molecules in the asymmetric unit, with a V M value of 2.73 Å 3 Da −1

Igg Subclasses Targeting the Flagella of Salmonella enterica Serovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing

Science.gov (United States)

Goh, Yun Shan; Armour, Kathryn L; Clark, Michael R; Grant, Andrew J; Mastroeni, Pietro

2016-01-01

Invasive non-typhoidal Salmonella are a common cause of invasive disease in immuno-compromised individuals and in children. Multi-drug resistance poses challenges to disease control, with a critical need for effective vaccines. Flagellin is an attractive vaccine candidate due to surface exposure and high epitope copy number, but its potential as a target for opsonophacytic antibodies is unclear. We examined the effect of targeting flagella with different classes of IgG on the interaction between Salmonella Typhimurium and a human phagocyte-like cell line, THP-1. We tagged the FliC flagellar protein with a foreign CD52 mimotope (TSSPSAD) and bacteria were opsonized with a panel of humanised CD52 antibodies with the same antigen-binding V-region, but different constant regions. We found that IgG binding to flagella increases bacterial phagocytosis and reduces viable intracellular bacterial numbers. Opsonisation with IgG3, followed by IgG1, IgG4, and IgG2, resulted in the highest level of bacterial uptake and in the highest reduction in the intracellular load of viable bacteria. Taken together, our data provide proof-of-principle evidence that targeting flagella with antibodies can increase the antibacterial function of host cells, with IgG3 being the most potent subclass. These data will assist the rational design of urgently needed, optimised vaccines against iNTS disease. PMID:27366588

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial

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Gopinathan, Priya [Nanobiotechnology Laboratory, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India); Ashok, Anuradha M. [HRTEM facility, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India); Selvakumar, R., E-mail: selvabiotech@gmail.com [Nanobiotechnology Laboratory, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India)

2013-07-01

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV–vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3–11 nm. I–V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial

International Nuclear Information System (INIS)

Gopinathan, Priya; Ashok, Anuradha M.; Selvakumar, R.

2013-01-01

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV–vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3–11 nm. I–V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Hydration-controlled bacterial motility and dispersal on surfaces

DEFF Research Database (Denmark)

Dechesne, Arnaud; Wang, G.; Gulez, Gamze

2010-01-01

hydrated habitats, where water dynamics result in fragmented aquatic habitats connected by micrometric films, is debated. Here, we quantify the spatial dynamics of Pseudomonas putida KT2440 and its nonflagellated isogenic mutant as affected by the hydration status of a rough porous surface using......Flagellar motility, a mode of active motion shared by many prokaryotic species, is recognized as a key mechanism enabling population dispersal and resource acquisition in microbial communities living in marine, freshwater, and other liquid-replete habitats. By contrast, its role in variably...... an experimental system that mimics aquatic habitats found in unsaturated soils. The flagellar motility of the model soil bacterium decreased sharply within a small range of water potential (0 to −2 kPa) and nearly ceased in liquid films of effective thickness smaller than 1.5 μm. However, bacteria could rapidly...

Main: FBA1 [TP Atlas

Lifescience Database Archive (English)

Full Text Available n is homologous to bacterial flagellar basal body. It is like a molecular syringe through which a bacterium (e.g. certai...la, the causing agent of legionellosis (Legionnaires' disease) utilizes type IV s

Two Types of Genetic Interaction Implicate the Whirligig Gene of Drosophila Melanogaster in Microtubule Organization in the Flagellar Axoneme

Science.gov (United States)

Green, L. L.; Wolf, N.; McDonald, K. L.; Fuller, M. T.

1990-01-01

The mutant nc4 allele of whirligig (3-54.4) of Drosophila melanogaster fails to complement mutations in an α-tubulin locus, α1t, mutations in a β-tubulin locus, B2t, or a mutation in the haywire locus. However, wrl fails to map to any of the known α- or β-tubulin genes. The extragenic failure to complement could indicate that the wrl product participates in structural interactions with microtubule proteins. The whirligig locus appears to be haploinsufficient for male fertility. Both a deficiency of wrl and possible loss of function alleles obtained by reverting the failure to complement between wrl(nc4) and B2t(n) are dominant male sterile in a genetic background wild type for tubulin. The dominant male sterility of the revertant alleles is suppressed if the flies are also heterozygous for B2t(n), for a deficiency of α1t, or for the hay(nc2) allele. These results suggest that it is not the absolute level of wrl gene product but its level relative to tubulin or microtubule function that is important for normal spermatogenesis. The phenotype of homozygous wrl mutants suggests that the whirligig product plays a role in postmeiotic spermatid differentiation, possibly in organizing the microtubules of the sperm flagellar axoneme. Flies homozygous for either wrl(nc4) or revertant alleles are viable and female fertile but male sterile. Premeiotic and meiotic stages of spermatogenesis appear normal. However, in post-meiotic stages, flagellar axonemes show loss of the accessory microtubule on the B-subfiber of outer doublet microtubules, outer triplet instead of outer doublet microtubules, and missing central pair microtubules. PMID:2127579

Crystallographic and molecular dynamics analysis of loop motions unmasking the peptidoglycan-binding site in stator protein MotB of flagellar motor.

Directory of Open Access Journals (Sweden)

Cyril F Reboul

Full Text Available BACKGROUND: The C-terminal domain of MotB (MotB-C shows high sequence similarity to outer membrane protein A and related peptidoglycan (PG-binding proteins. It is believed to anchor the power-generating MotA/MotB stator unit of the bacterial flagellar motor to the peptidoglycan layer of the cell wall. We previously reported the first crystal structure of this domain and made a puzzling observation that all conserved residues that are thought to be essential for PG recognition are buried and inaccessible in the crystal structure. In this study, we tested a hypothesis that peptidoglycan binding is preceded by, or accompanied by, some structural reorganization that exposes the key conserved residues. METHODOLOGY/PRINCIPAL FINDINGS: We determined the structure of a new crystalline form (Form B of Helicobacter pylori MotB-C. Comparisons with the existing Form A revealed conformational variations in the petal-like loops around the carbohydrate binding site near one end of the β-sheet. These variations are thought to reflect natural flexibility at this site required for insertion into the peptidoglycan mesh. In order to understand the nature of this flexibility we have performed molecular dynamics simulations of the MotB-C dimer. The results are consistent with the crystallographic data and provide evidence that the three loops move in a concerted fashion, exposing conserved MotB residues that have previously been implicated in binding of the peptide moiety of peptidoglycan. CONCLUSION/SIGNIFICANCE: Our structural analysis provides a new insight into the mechanism by which MotB inserts into the peptidoglycan mesh, thus anchoring the power-generating complex to the cell wall.

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Indian Academy of Sciences (India)

Unknown

The bacterial flagellar motor is a rotary molecular engine ... the sodium ions of the medium (Aizawa 2001), trans- ... Video imaging was used for short dura- ... J. Biosci. 30(4), September 2005. Anindito Sen, Ranjan K Nandi and Amar N Ghosh.

Polymorphic transformation of helical flagella of bacteria

Science.gov (United States)

Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

2016-11-01

Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

Soluble components of the flagellar export apparatus, FliI, FliJ, and FliH, do not deliver flagellin, the major filament protein, from the cytosol to the export gate.

Science.gov (United States)

Sajó, Ráchel; Liliom, Károly; Muskotál, Adél; Klein, Agnes; Závodszky, Péter; Vonderviszt, Ferenc; Dobó, József

2014-11-01

Flagella, the locomotion organelles of bacteria, extend from the cytoplasm to the cell exterior. External flagellar proteins are synthesized in the cytoplasm and exported by the flagellar type III secretion system. Soluble components of the flagellar export apparatus, FliI, FliH, and FliJ, have been implicated to carry late export substrates in complex with their cognate chaperones from the cytoplasm to the export gate. The importance of the soluble components in the delivery of the three minor late substrates FlgK, FlgL (hook-filament junction) and FliD (filament-cap) has been convincingly demonstrated, but their role in the transport of the major filament component flagellin (FliC) is still unclear. We have used continuous ATPase activity measurements and quartz crystal microbalance (QCM) studies to characterize interactions between the soluble export components and flagellin or the FliC:FliS substrate-chaperone complex. As controls, interactions between soluble export component pairs were characterized providing Kd values. FliC or FliC:FliS did not influence the ATPase activity of FliI alone or in complex with FliH and/or FliJ suggesting lack of interaction in solution. Immobilized FliI, FliH, or FliJ did not interact with FliC or FliC:FliS detected by QCM. The lack of interaction in the fluid phase between FliC or FliC:FliS and the soluble export components, in particular with the ATPase FliI, suggests that cells use different mechanisms for the export of late minor substrates, and the major substrate, FliC. It seems that the abundantly produced flagellin does not require the assistance of the soluble export components to efficiently reach the export gate. Copyright © 2014 Elsevier B.V. All rights reserved.

A Xanthomonas citri subsp citri hypothetical protein related to virulence contains a non-functional HD domain and is implicated in flagellar motility.

Science.gov (United States)

Vieira, F C F; Gonçalves, A M; Mendoza, E F R; Ferreira, R M; Costa, M L M; Balbuena, T S; Sebinelli, H G; Ciancaglini, P; Pizauro Junior, J M; Ferro, J A

2017-08-31

Citrus canker, caused by the Gram-negative bacterium Xanthomonas citri subsp citri (Xac), severely affects most economically important citrus varieties worldwide. A previous study showed that disruption of the ORF XAC1201 from the Xac 306 strain by transposon Tn5 decreased bacterium virulence in the Rangpur lime host (Citrus limonia L. Osbeck). However, little is known regarding the possible function of the hypothetical protein XAC1201 and how it affects the virulence of Xac 306. Here, we confirmed that disruption of ORF XAC1201 reduces Xac 306 virulence in two different hosts, delaying the onset of typical symptoms. In silico analysis suggested that XAC1201 interacts with the flagellar proteins FliM and FliL, known to be an important factor for virulence. In fact, motility assays revealed that the XAC1201 mutant has a significant difference in motility compared to the wild-type Xac 306. Also, a 3-D structure model revealed modified cofactor binding sites and suggested that XAC1201 has a non-functional HD domain. This hypothesis was confirmed by enzymatic assays performed in purified, XAC1201 recombinant protein expressed in Escherichia coli, which revealed no significant activities previously associated with HD domains for the tested substrates. Thus, the role of the XAC1201 protein in Xac 306 virulence seems to be related to flagellar motility, although a non-classic role for the HD domain cannot be dismissed.

Flagellar membrane fusion and protein exchange in trypanosomes; a new form of cell-cell communication? [version 1; referees: 2 approved

Directory of Open Access Journals (Sweden)

Simon Imhof

2016-04-01

Full Text Available Diverse structures facilitate direct exchange of proteins between cells, including plasmadesmata in plants and tunnelling nanotubes in bacteria and higher eukaryotes.  Here we describe a new mechanism of protein transfer, flagellar membrane fusion, in the unicellular parasite Trypanosoma brucei. When fluorescently tagged trypanosomes were co-cultured, a small proportion of double-positive cells were observed. The formation of double-positive cells was dependent on the presence of extracellular calcium and was enhanced by placing cells in medium supplemented with fresh bovine serum. Time-lapse microscopy revealed that double-positive cells arose by bidirectional protein exchange in the absence of nuclear transfer.  Furthermore, super-resolution microscopy showed that this process occurred in ≤1 minute, the limit of temporal resolution in these experiments. Both cytoplasmic and membrane proteins could be transferred provided they gained access to the flagellum. Intriguingly, a component of the RNAi machinery (Argonaute was able to move between cells, raising the possibility that small interfering RNAs are transported as cargo. Transmission electron microscopy showed that shared flagella contained two axonemes and two paraflagellar rods bounded by a single membrane. In some cases flagellar fusion was partial and interactions between cells were transient. In other cases fusion occurred along the entire length of the flagellum, was stable for several hours and might be irreversible. Fusion did not appear to be deleterious for cell function: paired cells were motile and could give rise to progeny while fused. The motile flagella of unicellular organisms are related to the sensory cilia of higher eukaryotes, raising the possibility that protein transfer between cells via cilia or flagella occurs more widely in nature.

Swimming Motility Mediates the Formation of Neutrophil Extracellular Traps Induced by Flagellated Pseudomonas aeruginosa.

Directory of Open Access Journals (Sweden)

Madison Floyd

2016-11-01

Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections often characterized by robust neutrophilic infiltration. Neutrophils provide the first line of defense against P. aeruginosa. Aside from their defense conferred by phagocytic activity, neutrophils also release neutrophil extracellular traps (NETs to immobilize bacteria. Although NET formation is an important antimicrobial process, the details of its mechanism are largely unknown. The identity of the main components of P. aeruginosa responsible for triggering NET formation is unclear. In this study, our focus was to identify the main bacterial factors mediating NET formation and to gain insight into the underlying mechanism. We found that P. aeruginosa in its exponential growth phase promoted strong NET formation in human neutrophils while its NET-inducing ability dramatically decreased at later stages of bacterial growth. We identified the flagellum as the primary component of P. aeruginosa responsible for inducing NET extrusion as flagellum-deficient bacteria remained seriously impaired in triggering NET formation. Purified P. aeruginosa flagellin, the monomeric component of the flagellum, does not stimulate NET formation in human neutrophils. P. aeruginosa-induced NET formation is independent of the flagellum-sensing receptors TLR5 and NLRC4 in both human and mouse neutrophils. Interestingly, we found that flagellar motility, not flagellum binding to neutrophils per se, mediates NET release induced by flagellated bacteria. Immotile, flagellar motor-deficient bacterial strains producing paralyzed flagella did not induce NET formation. Forced contact between immotile P. aeruginosa and neutrophils restored their NET-inducing ability. Both the motAB and motCD genetic loci encoding flagellar motor genes contribute to maximal NET release; however the motCD genes play a more important role. Phagocytosis of P. aeruginosa and superoxide production by neutrophils were also

Transcriptional analysis of the MrpJ network: modulation of diverse virulence-associated genes and direct regulation of mrp fimbrial and flhDC flagellar operons in Proteus mirabilis.

Science.gov (United States)

Bode, Nadine J; Debnath, Irina; Kuan, Lisa; Schulfer, Anjelique; Ty, Maureen; Pearson, Melanie M

2015-06-01

The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections (UTIs). Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects an array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking levels observed during UTIs leads to differential expression of 217 genes related to, among other functions, bacterial virulence, type VI secretion, and metabolism. We probed the molecular mechanism of transcriptional regulation by MrpJ using transcriptional reporters and chromatin immunoprecipitation (ChIP). Binding of MrpJ to two virulence-associated target gene promoters, the promoters of the flagellar master regulator flhDC and mrp itself, appears to be affected by the condensation state of the native chromosome, although both targets share a direct MrpJ binding site proximal to the transcriptional start. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observed that mrpJ is widely conserved in a collection of recent clinical isolates. Altogether, these findings support a role of MrpJ as a global regulator of P. mirabilis virulence. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Transcriptional Analysis of the MrpJ Network: Modulation of Diverse Virulence-Associated Genes and Direct Regulation of mrp Fimbrial and flhDC Flagellar Operons in Proteus mirabilis

Science.gov (United States)

Bode, Nadine J.; Debnath, Irina; Kuan, Lisa; Schulfer, Anjelique; Ty, Maureen

2015-01-01

The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections (UTIs). Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects an array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking levels observed during UTIs leads to differential expression of 217 genes related to, among other functions, bacterial virulence, type VI secretion, and metabolism. We probed the molecular mechanism of transcriptional regulation by MrpJ using transcriptional reporters and chromatin immunoprecipitation (ChIP). Binding of MrpJ to two virulence-associated target gene promoters, the promoters of the flagellar master regulator flhDC and mrp itself, appears to be affected by the condensation state of the native chromosome, although both targets share a direct MrpJ binding site proximal to the transcriptional start. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observed that mrpJ is widely conserved in a collection of recent clinical isolates. Altogether, these findings support a role of MrpJ as a global regulator of P. mirabilis virulence. PMID:25847961

Microhydrodynamics and complex fluids

CERN Document Server

Barthès-Biesel, Dominique

2012-01-01

""In view of the good choice of highly topical subject matter, the book will be of interest to a wide readership, not only among pure scientists. It will be useful to technicians, medical scientists and pharmaceutical chemists as a source of detailed information on advanced flow processes. ... [The chapters] are written in such a way that the reader can quickly absorb the essential information. The articles are of a high scientific standard and include interesting examples from many different areas of rheology."" -Prof. Dr. Heinz Rehage, Institute of Physical Chemistry, Technische Universität

First genomic insights into members of a candidate bacterial phylum responsible for wastewater bulking

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Yuji Sekiguchi

2015-01-01

Full Text Available Filamentous cells belonging to the candidate bacterial phylum KSB3 were previously identified as the causative agent of fatal filament overgrowth (bulking in a high-rate industrial anaerobic wastewater treatment bioreactor. Here, we obtained near complete genomes from two KSB3 populations in the bioreactor, including the dominant bulking filament, using differential coverage binning of metagenomic data. Fluorescence in situ hybridization with 16S rRNA-targeted probes specific for the two populations confirmed that both are filamentous organisms. Genome-based metabolic reconstruction and microscopic observation of the KSB3 filaments in the presence of sugar gradients indicate that both filament types are Gram-negative, strictly anaerobic fermenters capable of non-flagellar based gliding motility, and have a strikingly large number of sensory and response regulator genes. We propose that the KSB3 filaments are highly sensitive to their surroundings and that cellular processes, including those causing bulking, are controlled by external stimuli. The obtained genomes lay the foundation for a more detailed understanding of environmental cues used by KSB3 filaments, which may lead to more robust treatment options to prevent bulking.

Cationic amino acid uptake constitutes a metabolic regulation mechanism and occurs in the flagellar pocket of Trypanosoma cruzi.

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Mariana R Miranda

Full Text Available Trypanosomatids' amino acid permeases are key proteins in parasite metabolism since they participate in the adaptation of parasites to different environments. Here, we report that TcAAP3, a member of a Trypanosoma cruzi multigene family of permeases, is a bona fide arginine transporter. Most higher eukaryotic cells incorporate cationic amino acids through a single transporter. In contrast, T. cruzi can recognize and transport cationic amino acids by mono-specific permeases since a 100-fold molar excess of lysine could not affect the arginine transport in parasites that over-express the arginine permease (TcAAP3 epimastigotes. In order to test if the permease activity regulates downstream processes of the arginine metabolism, the expression of the single T. cruzi enzyme that uses arginine as substrate, arginine kinase, was evaluated in TcAAP3 epimastigotes. In this parasite model, intracellular arginine concentration increases 4-folds and ATP level remains constant until cultures reach the stationary phase of growth, with decreases of about 6-folds in respect to the controls. Interestingly, Western Blot analysis demonstrated that arginine kinase is significantly down-regulated during the stationary phase of growth in TcAAP3 epimastigotes. This decrease could represent a compensatory mechanism for the increase in ATP consumption as a consequence of the displacement of the reaction equilibrium of arginine kinase, when the intracellular arginine concentration augments and the glucose from the medium is exhausted. Using immunofluorescence techniques we also determined that TcAAP3 and the specific lysine transporter TcAAP7 co-localize in a specialized region of the plasma membrane named flagellar pocket, staining a single locus close to the flagellar pocket collar. Taken together these data suggest that arginine transport is closely related to arginine metabolism and cell energy balance. The clinical relevance of studying trypanosomatids' permeases

Flagellar coordination in Chlamydomonas cells held on micropipettes.

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Rüffer, U; Nultsch, W

1998-01-01

The two flagella of Chlamydomonas are known to beat synchronously: During breaststroke beating they are generally coordinated in a bilateral way while in shock responses during undulatory beating coordination is mostly parallel [Rüffer and Nultsch, 1995: Botanica Acta 108:169-276]. Analysis of a great number of shock responses revealed that in undulatory beats also periods of bilateral coordination are found and that the coordination type may change several times during a shock response, without concomitant changes of the beat envelope and the beat period. In normal wt cells no coordination changes are found during breaststroke beating, but only short temporary asynchronies: During 2 or 3 normal beats of the cis flagellum, the trans flagellum performs 3 or 4 flat beats with a reduced beat envelope and a smaller beat period, resulting in one additional trans beat. Long periods with flat beats of the same shape and beat period are found in both flagella of the non-phototactic mutant ptx1 and in defective wt 622E cells. During these periods, the coordination is parallel, the two flagella beat alternately. A correlation between normal asynchronous trans beats and the parallel-coordinated beats in the presumably cis defective cells and also the undulatory beats is discussed. In the cis defective cells, a perpetual spontaneous change between parallel beats with small beat periods (higher beat frequency) and bilateral beats with greater beat periods (lower beat frequency) are observed and render questionable the existence of two different intrinsic beat frequencies of the two flagella cis and trans. Asynchronies occur spontaneously but may also be induced by light changes, either step-up or step-down, but not by both stimuli in turn as breaststroke flagellar photoresponses (BFPRs). Asynchronies are not involved in phototaxis. They are independent of the BFPRs, which are supposed to be the basis of phototaxis. Both types of coordination must be assumed to be regulated

Two new species of Piaroa (Arachnida: Schizomida, Hubbardiidae) from Colombia, with comments on the genus taxonomy and the flagellar setae pattern of Hubbardiinae.

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Moreno-González, Jairo A; Delgado-Santa, Leonardo; De Armas, Luis F

2014-08-14

Two new species of the genus Piaroa Villarreal, Tourinho & Giupponi, 2008, P. escalerete sp. nov. and P. bacata sp. nov. are described from Valle del Cauca, and Cundinamarca departments, Colombia, respectively. The female flagellum is fully illustrated for a Piaroa species for the first time; the generic diagnosis is also emended and the relationships of the new species with those previously described are discussed. New characters for Piaroa species, a new nomenclature for the chitinized arch and a reinterpretation of the Hubbardiinae flagellar setae pattern are proposed. A distribution map of the known species of Piaroa is provided. 

Crystallization of FcpA from Leptospira, a novel flagellar protein that is essential for pathogenesis.

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San Martin, Fabiana; Mechaly, Ariel E; Larrieux, Nicole; Wunder, Elsio A; Ko, Albert I; Picardeau, Mathieu; Trajtenberg, Felipe; Buschiazzo, Alejandro

2017-03-01

The protein FcpA is a unique component of the flagellar filament of spirochete bacteria belonging to the genus Leptospira. Although it plays an essential role in translational motility and pathogenicity, no structures of FcpA homologues are currently available in the PDB. Its three-dimensional structure will unveil the novel motility mechanisms that render pathogenic Leptospira particularly efficient at invading and disseminating within their hosts, causing leptospirosis in humans and animals. FcpA from L. interrogans was purified and crystallized, but despite laborious attempts no useful X ray diffraction data could be obtained. This challenge was solved by expressing a close orthologue from the related saprophytic species L. biflexa. Three different crystal forms were obtained: a primitive and a centred monoclinic form, as well as a hexagonal variant. All forms diffracted X-rays to suitable resolutions for crystallographic analyses, with the hexagonal type typically reaching the highest limits of 2.0 Å and better. A variation of the quick-soaking procedure resulted in an iodide derivative that was instrumental for single-wavelength anomalous diffraction methods.

Imaging of the 3D dynamics of flagellar beating in human sperm.

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Silva-Villalobos, F; Pimentel, J A; Darszon, A; Corkidi, G

2014-01-01

The study of the mechanical and environmental factors that regulate a fundamental event such as fertilization have been subject of multiple studies. Nevertheless, the microscopical size of the spermatozoa and the high beating frequency of their flagella (up to 20 Hz) impose a series of technological challenges for the study of the mechanical factors implicated. Traditionally, due to the inherent characteristics of the rapid sperm movement, and to the technological limitations of microscopes (optical or confocal) to follow in three dimensions (3D) their movement, the analysis of their dynamics has been studied in two dimensions, when the head is confined to a surface. Flagella propel sperm and while their head can be confined to a surface, flagellar movement is not restricted to 2D, always displaying 3D components. In this work, we present a highly novel and useful tool to analyze sperm flagella dynamics in 3D. The basis of the method is a 100 Hz oscillating objective mounted on a bright field optical microscope covering a 16 microns depth space at a rate of ~ 5000 images per second. The best flagellum focused subregions were associated to their respective Z real 3D position. Unprecedented graphical results making evident the 3D movement of the flagella are shown in this work and supplemental material illustrating a 3D animation using the obtained experimental results is also included.

Interaction between the flagellar pocket collar and the hook complex via a novel microtubule-binding protein in Trypanosoma brucei.

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Anna Albisetti

2017-11-01

Full Text Available Trypanosoma brucei belongs to a group of unicellular, flagellated parasites that are responsible for human African trypanosomiasis. An essential aspect of parasite pathogenicity is cytoskeleton remodelling, which occurs during the life cycle of the parasite and is accompanied by major changes in morphology and organelle positioning. The flagellum originates from the basal bodies and exits the cell body through the flagellar pocket (FP but remains attached to the cell body via the flagellum attachment zone (FAZ. The FP is an invagination of the pellicular membrane and is the sole site for endo- and exocytosis. The FAZ is a large complex of cytoskeletal proteins, plus an intracellular set of four specialised microtubules (MtQ that elongate from the basal bodies to the anterior end of the cell. At the distal end of the FP, an essential, intracellular, cytoskeletal structure called the flagellar pocket collar (FPC circumvents the flagellum. Overlapping the FPC is the hook complex (HC (a sub-structure of the previously named bilobe that is also essential and is thought to be involved in protein FP entry. BILBO1 is the only functionally characterised FPC protein and is necessary for FPC and FP biogenesis. Here, we used a combination of in vitro and in vivo approaches to identify and characterize a new BILBO1 partner protein-FPC4. We demonstrate that FPC4 localises to the FPC, the HC, and possibly to a proximal portion of the MtQ. We found that the C-terminal domain of FPC4 interacts with the BILBO1 N-terminal domain, and we identified the key amino acids required for this interaction. Interestingly, the FPC4 N-terminal domain was found to bind microtubules. Over-expression studies highlight the role of FPC4 in its association with the FPC, HC and FPC segregation. Our data suggest a tripartite association between the FPC, the HC and the MtQ.

Zernike phase contrast cryo-electron tomography of sodium-driven flagellar hook-basal bodies from Vibrio alginolyticus.

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Hosogi, Naoki; Shigematsu, Hideki; Terashima, Hiroyuki; Homma, Michio; Nagayama, Kuniaki

2011-01-01

Vibrio alginolyticus use flagella to swim. A flagellum consists of a filament, hook and basal body. The basal body is made up of a rod and several ring structures. This study investigates the structure of the T ring which is a unique component of the V. alginolyticus sodium ion-driven flagellar basal body. Using Zernike phase contrast (ZPC) cryo-electron tomography, we compared the 3D structures of purified hook-basal bodies (HBB) from a wild-type strain (KK148) and a deletion mutant lacking MotX and MotY (TH3), which are thought to form the T ring. ZPC images of HBBs had highly improved signal-to-noise ratio compared to conventional phase contrast images. We observed the outline of the HBBs from strains KK148 and TH3, and the TH3 mutant was missing its T ring. In the wild-type strain, the T ring was beneath the LP ring and seemed to form a ring shape with diameter of 32 nm. Copyright © 2010 Elsevier Inc. All rights reserved.

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

Science.gov (United States)

2012-01-01

Summary: Flagellar and translocation-associated type III secretion (T3S) systems are present in most Gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria. PMID:22688814

CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas

Science.gov (United States)

Tam, Lai-Wa; Ranum, Paul T.; Lefebvre, Paul A.

2013-01-01

The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC. PMID:23283985

A phylogenomic analysis of the bacterial phylum Fibrobacteres

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Nurdyana eAbdul Rahman

2016-01-01

Full Text Available The Fibrobacteres has been recognized as a bacterial phylum for over a decade, but little is known about the group beyond its environmental distribution, and characterization of its sole cultured representative genus, Fibrobacter, after which the phylum was named. Based on these incomplete data, it is thought that cellulose hydrolysis, anaerobic metabolism, and lack of motility are unifying features of the phylum. There are also contradicting views as to whether an uncultured sister lineage, candidate phylum TG3, should be included in the Fibrobacteres. Recently, chitin-degrading cultured representatives of TG3 were obtained isolated from a hypersaline soda lake, and the genome of one species, Chitinivibrio alkaliphilus, sequenced and described in detail. Here, we performed a comparative analysis of Fibrobacter succinogenes, C. alkaliphilus and eight near or substantially complete Fibrobacteres/TG3 genomes of environmental populations recovered from termite gut, anaerobic digester, and sheep rumen metagenomes. We propose that TG3 should be amalgamated with the Fibrobacteres phylum based on robust monophyly of the two lineages and shared character traits. Polymer hydrolysis, using a distinctive set of glycoside hydrolases and binding domains, appears to be a prominent feature of members of the Fibrobacteres. Not all members of this phylum are strictly anaerobic as some termite gut Fibrobacteres have respiratory chains adapted to the microaerophilic conditions found in this habitat. Contrary to expectations, motility is is predicted to be an ancestral and common trait in this phylum and has only recently been lost in F. succinogenes and its relatives based on phylogenetic distribution of flagellar genes. Our findings extend current understanding of the Fibrobacteres and provide an improved basis for further investigation of this phylum.

Impact of fluorescent protein fusions on the bacterial flagellar motor

NARCIS (Netherlands)

Heo, M.; Nord, A. L.; Chamousset, D.; van Rijn, E.; Beaumont, H.J.E.; Pedaci, F.

2017-01-01

Fluorescent fusion proteins open a direct and unique window onto protein function. However, they also introduce the risk of perturbation of the function of the native protein. Successful applications of fluorescent fusions therefore rely on a careful assessment and minimization of the side

Immunological reactions to Salmonella FlgK and FliD flagellar proteins by broiler sera

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Background: Salmonella is the leading foodborne pathogen that causes human acute bacterial gastroenteritis worldwide. Chickens are considered as one of major reservoirs of this bacterium. Because the bacterial flagellum is involved in motility, adhesion, quorum sensing and other virulence activit...

Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum.

Science.gov (United States)

Carter, Andrew T; Paul, Catherine J; Mason, David R; Twine, Susan M; Alston, Mark J; Logan, Susan M; Austin, John W; Peck, Michael W

2009-03-19

Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray. Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs) present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes), and the flagellar glycosylation island (FGI). These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5) has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI. Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism outbreaks.

Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum

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Twine Susan M

2009-03-01

Full Text Available Abstract Background Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray. Results Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes, and the flagellar glycosylation island (FGI. These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5 has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI. Conclusion Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism

Bacterial prostatitis.

Science.gov (United States)

Gill, Bradley C; Shoskes, Daniel A

2016-02-01

The review provides the infectious disease community with a urologic perspective on bacterial prostatitis. Specifically, the article briefly reviews the categorization of prostatitis by type and provides a distillation of new findings published on bacterial prostatitis over the past year. It also highlights key points from the established literature. Cross-sectional prostate imaging is becoming more common and may lead to more incidental diagnoses of acute bacterial prostatitis. As drug resistance remains problematic in this condition, the reemergence of older antibiotics such as fosfomycin, has proven beneficial. With regard to chronic bacterial prostatitis, no clear clinical risk factors emerged in a large epidemiological study. However, bacterial biofilm formation has been associated with more severe cases. Surgery has a limited role in bacterial prostatitis and should be reserved for draining of a prostatic abscess or the removal of infected prostatic stones. Prostatitis remains a common and bothersome clinical condition. Antibiotic therapy remains the basis of treatment for both acute and chronic bacterial prostatitis. Further research into improving prostatitis treatment is indicated.

Magnetic Actuation of Self-assembled Bacteria Inspired Nanoswimmers

Science.gov (United States)

Ali, Jamel; Cheang, U. Kei; Martindale, James D.; Jabbarzadeh, Mehdi; Fu, Henry C.; Kim, Min Jun

2017-11-01

Currently, there is growing interest in developing nanoscale swimmers for biological and biomedical tasks. Of particular interest is the development of soft stimuli-responsive nanorobots to probe cellular and sub-cellular environments. While there have been a few reports of nanoscale robotic swimmers, which have shown potential to be used for these tasks, they often lack multifuctionality. In particular, no man-made soft nanoscale material has been able to match the ability of natural bacterial flagella to undergo rapid and reversible morphological changes in response to multiple forms of environmental stimuli. Towards this end, we report self-assembled stimuli-responsive nanoscale robotic swimmers composed of single or multiple bacterial flagella and attached to magnetic nanoparticles. We visualize the movement of flagella using high resolution fluorescence microscopy while controlling these swimmers via a magnetic control system. Differences in in propulsion before and after the change in flagellar form are observed. Furthermore, we demonstrate the ability to induce flagellar bundling in multiflagellated nanoswimmers. This work was funded by the National Science Foundation (DMR 1712061 and CMMI 1737682 to M.J.K. and DMR 1650970 and CBET 1651031 to H.C.F.), and the Korea Evaluation Institute of Industrial Technology (MOTIE) (NO. 10052980) award to M.J.K.

Role of Glycosyltransferases Modifying Type B Flagellin of Emerging Hypervirulent Clostridium difficile Lineages and Their Impact on Motility and Biofilm Formation*

Science.gov (United States)

Valiente, Esmeralda; Bouché, Laura; Hitchen, Paul; Faulds-Pain, Alexandra; Songane, Mario; Dawson, Lisa F.; Donahue, Elizabeth; Stabler, Richard A.; Panico, Maria; Morris, Howard R.; Bajaj-Elliott, Mona; Logan, Susan M.; Dell, Anne; Wren, Brendan W.

2016-01-01

Clostridium difficile is the principal cause of nosocomial infectious diarrhea worldwide. The pathogen modifies its flagellin with either a type A or type B O-linked glycosylation system, which has a contributory role in pathogenesis. We study the functional role of glycosyltransferases modifying type B flagellin in the 023 and 027 hypervirulent C. difficile lineages by mutagenesis of five putative glycosyltransferases and biosynthetic genes. We reveal their roles in the biosynthesis of the flagellin glycan chain and demonstrate that flagellar post-translational modification affects motility and adhesion-related bacterial properties of these strains. We show that the glycosyltransferases 1 and 2 (GT1 and GT2) are responsible for the sequential addition of a GlcNAc and two rhamnoses, respectively, and that GT3 is associated with the incorporation of a novel sulfonated peptidyl-amido sugar moiety whose structure is reported in our accompanying paper (Bouché, L., Panico, M., Hitchen, P., Binet, D., Sastre, F., Faulds-Pain, A., Valiente, E., Vinogradov, E., Aubry, A., Fulton, K., Twine, S., Logan, S. M., Wren, B. W., Dell, A., and Morris, H. R. (2016) J. Biol. Chem. 291, 25439–25449). GT2 is also responsible for methylation of the rhamnoses. Whereas type B modification is not required for flagellar assembly, some mutations that result in truncation or abolition of the glycan reduce bacterial motility and promote autoaggregation and biofilm formation. The complete lack of flagellin modification also significantly reduces adhesion of C. difficile to Caco-2 intestinal epithelial cells but does not affect activation of human TLR5. Our study advances our understanding of the genes involved in flagellar glycosylation and their biological roles in emerging hypervirulent C. difficile strains. PMID:27703012

Bacterial Adhesion & Blocking Bacterial Adhesion

DEFF Research Database (Denmark)

Vejborg, Rebecca Munk

2008-01-01

, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...... tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters...

Plasmid AZOBR_p1-borne fabG gene for putative 3-oxoacyl-[acyl-carrier protein] reductase is essential for proper assembly and work of the dual flagellar system in the alphaproteobacterium Azospirillum brasilense Sp245.

Science.gov (United States)

Filip'echeva, Yulia A; Shelud'ko, Andrei V; Prilipov, Alexei G; Burygin, Gennady L; Telesheva, Elizaveta M; Yevstigneyeva, Stella S; Chernyshova, Marina P; Petrova, Lilia P; Katsy, Elena I

2018-02-01

Azospirillum brasilense can swim and swarm owing to the activity of a constitutive polar flagellum (Fla) and inducible lateral flagella (Laf), respectively. Experimental data on the regulation of the Fla and Laf assembly in azospirilla are scarce. Here, the coding sequence (CDS) AZOBR_p1160043 (fabG1) for a putative 3-oxoacyl-[acyl-carrier protein (ACP)] reductase was found essential for the construction of both types of flagella. In an immotile leaky Fla - Laf - fabG1::Omegon-Km mutant, Sp245.1610, defects in flagellation and motility were fully complemented by expressing the CDS AZOBR_p1160043 from plasmid pRK415. When pRK415 with the cloned CDS AZOBR_p1160045 (fliC) for a putative 65.2 kDa Sp245 Fla flagellin was transferred into the Sp245.1610 cells, the bacteria also became able to assemble a motile single flagellum. Some cells, however, had unusual swimming behavior, probably because of the side location of the organelle. Although the assembly of Laf was not restored in Sp245.1610 (pRK415-p1160045), this strain was somewhat capable of swarming motility. We propose that the putative 3-oxoacyl-[ACP] reductase encoded by the CDS AZOBR_p1160043 plays a role in correct flagellar location in the cell envelope and (or) in flagellar modification(s), which are also required for the inducible construction of Laf and for proper swimming and swarming motility of A. brasilense Sp245.

Detecting Lyme disease using antibody-functionalized carbon nanotubes

Science.gov (United States)

Dailey, Jennifer; Lerner, Mitchell; Goldsmith, Brett; Brisson, Dustin; Johnson, A. T. Charlie

2011-03-01

We combine antibodies for Lyme flagellar protein with carbon nanotube transistors to create an electronic sensor capable of definitive detection of Lyme disease. Over 35,000 cases of Lyme disease are reported in the United States each year, of which more than 23 percent are originally misdiagnosed. Rational design of the coupling of the biological system to the electronic system gives us a flexible sensor platform which we can apply to several biological systems. By coupling these antibodies to carbon nanotubes in particular, we allow for fast, sensitive, highly selective, electronic detection. Unlike antibody or biomarker detection, bacterial protein detection leads to positive identification of both early and late stage bacterial infections, and is easily expandable to environmental monitoring.

The Sensor Kinase GacS Negatively Regulates Flagellar Formation and Motility in a Biocontrol Bacterium, Pseudomonas chlororaphis O6

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Ji Soo Kim

2014-06-01

Full Text Available The GacS/GacA two component system regulates various traits related to the biocontrol potential of plant-associated pseudomonads. The role of the sensor kinase, GacS, differs between strains in regulation of motility. In this study, we determined how a gacS mutation changed cell morphology and motility in Pseudomonas chlororaphis O6. The gacS mutant cells were elongated in stationary-phase compared to the wild type and the complemented gacS mutant, but cells did not differ in length in logarithmic phase. The gacS mutant had a two-fold increase in the number of flagella compared with the wild type strain; flagella number was restored to that of the wild type in the complemented gacS mutant. The more highly flagellated gacS mutant cells had greater swimming motilities than that of the wild type strain. Enhanced flagella formation in the gacS mutant correlated with increased expression of three genes, fleQ, fliQ and flhF, involved in flagellar formation. Expression of these genes in the complemented gacS mutant was similar to that of the wild type. These findings show that this root-colonizing pseudomonad adjusts flagella formation and cell morphology in stationary-phase using GacS as a major regulator.

Bacterial mycophagy: definition and diagnosis of a unique bacterial-fungal interaction

NARCIS (Netherlands)

Leveau, J.H.J.; Preston, G.M.

2008-01-01

This review analyses the phenomenon of bacterial mycophagy, which we define as a set of phenotypic behaviours that enable bacteria to obtain nutrients from living fungi and thus allow the conversion of fungal into bacterial biomass. We recognize three types of bacterial strategies to derive

Noncontact Cohesive Swimming of Bacteria in Two-Dimensional Liquid Films.

Science.gov (United States)

Li, Ye; Zhai, He; Sanchez, Sandra; Kearns, Daniel B; Wu, Yilin

2017-07-07

Bacterial swimming in confined two-dimensional environments is ubiquitous in nature and in clinical settings. Characterizing individual interactions between swimming bacteria in 2D confinement will help to understand diverse microbial processes, such as bacterial swarming and biofilm formation. Here we report a novel motion pattern displayed by flagellated bacteria in 2D confinement: When two nearby cells align their moving directions, they tend to engage in cohesive swimming without direct cell body contact, as a result of hydrodynamic interaction but not flagellar intertwining. We further found that cells in cohesive swimming move with higher directional persistence, which can increase the effective diffusivity of cells by ∼3 times as predicted by computational modeling. As a conserved behavior for peritrichously flagellated bacteria, cohesive swimming in 2D confinement may be key to collective motion and self-organization in bacterial swarms; it may also promote bacterial dispersal in unsaturated soils and in interstitial space during infections.

The gram-negative bacterial periplasm: Size matters.

Directory of Open Access Journals (Sweden)

Samuel I Miller

2018-01-01

Full Text Available Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control. The periplasm also contains structural elements and important environmental sensing modules, and it allows complex nanomachines to span the cell envelope. Recent work indicates that the size or intermembrane distance of the periplasm is controlled by periplasmic lipoproteins that anchor the outer membrane to the periplasmic peptidoglycan polymer. This periplasm intermembrane distance is critical for sensing outer membrane damage and dictates length of the flagellar periplasmic rotor, which controls motility. These exciting results resolve longstanding debates about whether the periplasmic distance has a biological function and raise the possibility that the mechanisms for maintenance of periplasmic size could be exploited for antibiotic development.

Chagas' disease: IgG isotypes against cytoplasmic (CRA) and flagellar (FRA) recombinant repetitive antigens of Trypanosoma cruzi in chronic Chagasic patients.

Science.gov (United States)

Verçosa, A F A; Lorena, V M B; Carvalho, C L; Melo, M F A D; Cavalcanti, M G A; Silva, E D; Ferreira, A G P; Pereira, V R A; Souza, W V; Gomes, Y M

2007-01-01

The wide range of clinical Chagas' disease manifestations, of which heart involvement is the most significant, because of its characteristics, frequency and consequences, and lack of treatment and cure, justify research in this area. Specific immunoglobulin G (IgG) antibody subclasses have been associated with human Chagas' disease. Thus, in this study, the profile of IgG subclasses against cytoplasmic (CRA) and flagellar (FRA) recombinant repetitive T. cruzi-specific antigens was correlated with cardiac (CARD, n=33), cardiodigestive (CD, n=7), and indeterminate (IND, n=20) forms of Chagas' disease by indirect enzyme-linked immunosorbent assay (ELISA). IgG subclasses were detected in almost all Chagas patients studied. Nevertheless, only specific IgG2 isotype FRA was found with a significant statistical difference in CARD patients when compared to IND patients. This result suggests the potential use of this isotype for prognostic purposes, for monitoring the progression of chronic Chagas' disease, and for predicting the risk of CARD damage. This is important information, as it could help physicians to evaluate and manage the treatment of their patients. However, a follow-up study is necessary to confirm our result. (c) 2007 Wiley-Liss, Inc.

Bacterial meningitis

NARCIS (Netherlands)

Roos, Karen L.; van de Beek, Diederik

2010-01-01

Bacterial meningitis is a neurological emergency. Empiric antimicrobial and adjunctive therapy should be initiated as soon as a single set of blood cultures has been obtained. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, vomiting, photophobia, and an

Bacterial lung abscess

International Nuclear Information System (INIS)

Groskin, S.A.; Panicek, D.M.; Ewing, D.K.; Rivera, F.; Math, K.; Teixeira, J.; Heitzman, E.R.

1987-01-01

A retrospective review of patients with bacterial lung abscess was carried out. Demographic, clinical, and radiographical features of this patient group are compared with similar data from patients with empyema and/or cavitated lung carcinoma; differential diagnostic points are stressed. The entity of radiographically occult lung abscess is discussed. Complications associated with bacterial lung abscess are discussed. Current therapeutic options and treatment philosophy for patients with bacterial lung abscess are noted

Bacterial growth on macrophyte leachate and fate of bacterial production

International Nuclear Information System (INIS)

Findlay, S.; Carlough, L.; Crocker, M.T.; Gill, H.K.; Meyer, J.L.; Smith, P.J.

1986-01-01

The role bacteria play in transferring organic carbon to other trophic levels in aquatic ecosystems depends on the efficiency with which they convert dissolved organic [ 14 C]-labelled carbon into bacterial biomass and on the ability of consumers to graze bacteria. The authors have measured the conversion efficiency for bacteria growing on macrophyte-derived dissolved organic carbon and estimated the amount of bacterial production removed by grazing. Bacteria converted this DOC into new tissue with an efficiency of 53%, substantially higher than the apparent conversion efficiency of macrophyte-derived particulate organic carbon or other types of DOC. Two estimates of grazing indicate that the decline in bacterial numbers after the bloom was probably due to grazing by flagellates. These results show the significance of the bacterial link between DOC and other trophic levels

Selective proteomic analysis of antibiotic-tolerant cellular subpopulations in pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Babin, Brett M.; Atangcho, Lydia; van Eldijk, Mark B.

2017-01-01

involved in central carbon metabolism. We differentiated the immediate proteomic response, characterized by an increase in flagellar motility, from the long-term adaptive strategy, which included the upregulation of purine synthesis. This targeted, selective analysis of a bacterial subpopulation...... amino acid tagging (BONCAT) method to enable selective proteomic analysis of a Pseudomonas aeruginosa biofilm subpopulation. Through controlled expression of a mutant methionyl-tRNA synthetase, we targeted BONCAT labeling to cells in the regions of biofilm microcolonies that showed increased tolerance...... demonstrates how the study of proteome dynamics can enhance our understanding of biofilm heterogeneity and antibiotic tolerance. IMPORTANCE Bacterial growth is frequently characterized by behavioral heterogeneity at the single-cell level. Heterogeneity is especially evident in the physiology of biofilms...

FliD. : Exploring the flagellar tip protein as a target against Campylobacter jejuni

NARCIS (Netherlands)

Freitag, C.M.|info:eu-repo/dai/nl/412516802

2017-01-01

Campylobacter jejuni is most common bacterial agent causing human diarrhea. Symptoms can range from mild colitis to severe bloody enteritis with abdominal cramping. Chickens represent the main reservoir of C. jejuni and contaminated meat products are an important source of human infection. In order

BACTERIAL CONSORTIUM

Directory of Open Access Journals (Sweden)

Payel Sarkar

2013-01-01

Full Text Available Petroleum aromatic hydrocarbons like benzen e, toluene, ethyl benzene and xylene, together known as BTEX, has almost the same chemical structure. These aromatic hydrocarbons are released as pollutants in th e environment. This work was taken up to develop a solvent tolerant bacterial cons ortium that could degrade BTEX compounds as they all share a common chemical structure. We have isolated almost 60 different types of bacterial strains from different petroleum contaminated sites. Of these 60 bacterial strains almost 20 microorganisms were screene d on the basis of capability to tolerate high concentration of BTEX. Ten differe nt consortia were prepared and the compatibility of the bacterial strains within the consortia was checked by gram staining and BTEX tolerance level. Four successful mi crobial consortia were selected in which all the bacterial strains concomitantly grew in presence of high concentration of BTEX (10% of toluene, 10% of benzene 5% ethyl benzene and 1% xylene. Consortium #2 showed the highest growth rate in pr esence of BTEX. Degradation of BTEX by consortium #2 was monitored for 5 days by gradual decrease in the volume of the solvents. The maximum reduction observed wa s 85% in 5 days. Gas chromatography results also reveal that could completely degrade benzene and ethyl benzene within 48 hours. Almost 90% degradation of toluene and xylene in 48 hours was exhibited by consortium #2. It could also tolerate and degrade many industrial solvents such as chloroform, DMSO, acetonitrile having a wide range of log P values (0.03–3.1. Degradation of aromatic hydrocarbon like BTEX by a solvent tolerant bacterial consortium is greatly significant as it could degrade high concentration of pollutants compared to a bacterium and also reduces the time span of degradation.

Bacterial surface adaptation

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Utada, Andrew

2014-03-01

Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

Bacterial Protein-Tyrosine Kinases

DEFF Research Database (Denmark)

Shi, Lei; Kobir, Ahasanul; Jers, Carsten

2010-01-01

in exopolysaccharide production, virulence, DNA metabolism, stress response and other key functions of the bacterial cell. BY-kinases act through autophosphorylation (mainly in exopolysaccharide production) and phosphorylation of other proteins, which have in most cases been shown to be activated by tyrosine......Bacteria and Eukarya share essentially the same family of protein-serine/threonine kinases, also known as the Hanks-type kinases. However, when it comes to protein-tyrosine phosphorylation, bacteria seem to have gone their own way. Bacterial protein-tyrosine kinases (BY-kinases) are bacterial...... and highlighted their importance in bacterial physiology. Having no orthologues in Eukarya, BY-kinases are receiving a growing attention from the biomedical field, since they represent a particularly promising target for anti-bacterial drug design....

Differentiation of bacterial and non-bacterial community-acquired pneumonia by thin-section computed tomography

Energy Technology Data Exchange (ETDEWEB)

Ito, Isao [Department of Respiratory Medicine, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki 710-8602 (Japan); Department of Respiratory Medicine, Kyoto University, 54 Shogoin-kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan)], E-mail: isaoito@kuhp.kyoto-u.ac.jp; Ishida, Tadashi [Department of Respiratory Medicine, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki 710-8602 (Japan)], E-mail: ishidat@kchnet.or.jp; Togashi, Kaori [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, 54 Shogoin-kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan)], E-mail: ktogashi@kuhp.kyoto-u.ac.jp; Niimi, Akio [Department of Respiratory Medicine, Kyoto University, 54 Shogoin-kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan)], E-mail: niimi@kuhp.kyoto-u.ac.jp; Koyama, Hiroshi [General Internal Medicine, National Hospital Organization Kyoto Medical Center, 1-1 Fukakusa-Mukohatacho, Fushimi-ku, Kyoto 612-8555 (Japan)], E-mail: hkoyama-kyt@umin.ac.jp; Ishimori, Takayoshi [Department of Radiology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki 710-8602 (Japan)], E-mail: ti10794@kchnet.or.jp; Kobayashi, Hisataka [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, 54 Shogoin-kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Building 10, Room 1B40, MSC1088, 10 Center Drive, Bethesda, MD 20892-1088 (United States)], E-mail: kobayash@mail.nih.gov; Mishima, Michiaki [Department of Respiratory Medicine, Kyoto University, 54 Shogoin-kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan)], E-mail: mishima@kuhp.kyoto-u.ac.jp

2009-12-15

Background and objective: The management of community-acquired pneumonia (CAP) depends, in part, on the identification of the causative agents. The objective of this study was to determine the potential of thin-section computed tomography (CT) in differentiating bacterial and non-bacterial pneumonia. Patients and methods: Thin-section CT studies were prospectively examined in hospitalized CAP patients within 2 days of admission, followed by retrospective assessment by two pulmonary radiologists. Thin-section CT findings on the pneumonias caused by each pathogen were examined, and two types of pneumonias were compared. Using multivariate logistic regression analyses, receiver operating characteristic (ROC) curves were produced. Results: Among 183 CAP episodes (181 patients, 125 men and 56 women, mean age {+-} S.D.: 61.1 {+-} 19.7) examined by thin-section CT, the etiologies of 125 were confirmed (94 bacterial pneumonia and 31 non-bacterial pneumonia). Centrilobular nodules were specific for non-bacterial pneumonia and airspace nodules were specific for bacterial pneumonia (specificities of 89% and 94%, respectively) when located in the outer lung areas. When centrilobular nodules were the principal finding, they were specific but lacked sensitivity for non-bacterial pneumonia (specificity 98% and sensitivity 23%). To distinguish the two types of pneumonias, centrilobular nodules, airspace nodules and lobular shadows were found to be important by multivariate analyses. ROC curve analysis discriminated bacterial pneumonia from non-bacterial pneumonia among patients without underlying lung diseases, yielding an optimal point with sensitivity and specificity of 86% and 79%, respectively, but was less effective when all patients were analyzed together (70% and 84%, respectively). Conclusion: Thin-section CT examination was applied for the differentiation of bacterial and non-bacterial pneumonias. Though showing some potential, this examination at the present time would

Differentiation of bacterial and non-bacterial community-acquired pneumonia by thin-section computed tomography

International Nuclear Information System (INIS)

Ito, Isao; Ishida, Tadashi; Togashi, Kaori; Niimi, Akio; Koyama, Hiroshi; Ishimori, Takayoshi; Kobayashi, Hisataka; Mishima, Michiaki

2009-01-01

Background and objective: The management of community-acquired pneumonia (CAP) depends, in part, on the identification of the causative agents. The objective of this study was to determine the potential of thin-section computed tomography (CT) in differentiating bacterial and non-bacterial pneumonia. Patients and methods: Thin-section CT studies were prospectively examined in hospitalized CAP patients within 2 days of admission, followed by retrospective assessment by two pulmonary radiologists. Thin-section CT findings on the pneumonias caused by each pathogen were examined, and two types of pneumonias were compared. Using multivariate logistic regression analyses, receiver operating characteristic (ROC) curves were produced. Results: Among 183 CAP episodes (181 patients, 125 men and 56 women, mean age ± S.D.: 61.1 ± 19.7) examined by thin-section CT, the etiologies of 125 were confirmed (94 bacterial pneumonia and 31 non-bacterial pneumonia). Centrilobular nodules were specific for non-bacterial pneumonia and airspace nodules were specific for bacterial pneumonia (specificities of 89% and 94%, respectively) when located in the outer lung areas. When centrilobular nodules were the principal finding, they were specific but lacked sensitivity for non-bacterial pneumonia (specificity 98% and sensitivity 23%). To distinguish the two types of pneumonias, centrilobular nodules, airspace nodules and lobular shadows were found to be important by multivariate analyses. ROC curve analysis discriminated bacterial pneumonia from non-bacterial pneumonia among patients without underlying lung diseases, yielding an optimal point with sensitivity and specificity of 86% and 79%, respectively, but was less effective when all patients were analyzed together (70% and 84%, respectively). Conclusion: Thin-section CT examination was applied for the differentiation of bacterial and non-bacterial pneumonias. Though showing some potential, this examination at the present time would not

Bacterial Prostatitis: Bacterial Virulence, Clinical Outcomes, and New Directions.

Science.gov (United States)

Krieger, John N; Thumbikat, Praveen

2016-02-01

Four prostatitis syndromes are recognized clinically: acute bacterial prostatitis, chronic bacterial prostatitis, chronic prostatitis/chronic pelvic pain syndrome, and asymptomatic prostatitis. Because Escherichia coli represents the most common cause of bacterial prostatitis, we investigated the importance of bacterial virulence factors and antimicrobial resistance in E. coli strains causing prostatitis and the potential association of these characteristics with clinical outcomes. A structured literature review revealed that we have limited understanding of the virulence-associated characteristics of E. coli causing acute prostatitis. Therefore, we completed a comprehensive microbiological and molecular investigation of a unique strain collection isolated from healthy young men. We also considered new data from an animal model system suggesting certain E. coli might prove important in the etiology of chronic prostatitis/chronic pelvic pain syndrome. Our human data suggest that E. coli needs multiple pathogenicity-associated traits to overcome anatomic and immune responses in healthy young men without urological risk factors. The phylogenetic background and accumulation of an exceptional repertoire of extraintestinal pathogenic virulence-associated genes indicate that these E. coli strains belong to a highly virulent subset of uropathogenic variants. In contrast, antibiotic resistance confers little added advantage to E. coli strains in these healthy outpatients. Our animal model data also suggest that certain pathogenic E. coli may be important in the etiology of chronic prostatitis/chronic pelvic pain syndrome through mechanisms that are dependent on the host genetic background and the virulence of the bacterial strain.

Bacterial Cell Mechanics.

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Auer, George K; Weibel, Douglas B

2017-07-25

Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.

Bacterial vaginosis in pregnant adolescents: proinflammatory cytokine and bacterial sialidase profile. Cross-sectional study

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Carolina Sanitá Tafner Ferreira

Full Text Available ABSTRACT CONTEXT AND OBJECTIVE: Bacterial vaginosis occurs frequently in pregnancy and increases susceptibility to sexually transmitted infections (STI. Considering that adolescents are disproportionally affected by STI, the aim of this study was to evaluate the cervicovaginal levels of interleukin (IL-1 beta, IL-6, IL-8 and bacterial sialidase in pregnant adolescents with bacterial vaginosis. DESIGN AND SETTING: Cross-sectional study at mother and child referral units in Belém, Pará, Brazil. METHODS: Vaginal samples from 168 pregnant adolescents enrolled were tested for trichomoniasis and candidiasis. Their vaginal microbiota was classified according to the Nugent criteria (1991 as normal, intermediate or bacterial vaginosis. Cervical infection due to Chlamydia trachomatisand Neisseria gonorrhoeae was also assessed. Cytokine and sialidase levels were measured, respectively, using enzyme-linked immunosorbent assays and MUAN conversion in cervicovaginal lavages. Forty-eight adolescents (28.6% were excluded because they tested positive for some of the infections investigated. The remaining 120 adolescents were grouped according to vaginal flora type: normal (n = 68 or bacterial vaginosis (n = 52. Their cytokine and sialidase levels were compared between the groups using the Mann-Whitney test (P < 0.05. RESULTS: The pregnant adolescents with bacterial vaginosis had higher levels of IL-1 beta, IL-6 and IL-8 (P < 0.05. Sialidase was solely detected in 35 adolescents (67.2% with bacterial vaginosis. CONCLUSIONS: Not only IL-1 beta and sialidase levels, but also IL-6 and IL-8 levels are higher in pregnant adolescents with bacterial vaginosis, thus indicating that this condition elicits a more pronounced inflammatory response in this population, which potentially increases vulnerability to STI acquisition.

ATG24 Represses Autophagy and Differentiation and Is Essential for Homeostasy of the Flagellar Pocket in Trypanosoma brucei.

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Ana Brennand

Full Text Available We have previously identified homologs for nearly half of the approximately 30 known yeast Atg's in the genome database of the human sleeping sickness parasite Trypanosoma brucei. So far, only a few of these homologs have their role in autophagy experimentally confirmed. Among the candidates was the ortholog of Atg24 that is involved in pexophagy in yeast. In T. brucei, the peroxisome-like organelles named glycosomes harbor core metabolic processes, especially glycolysis. In the autotrophic yeast, autophagy is essential for adaptation to different nutritional environments by participating in the renewal of the peroxisome population. We hypothesized that autophagic turnover of the parasite's glycosomes plays a role in differentiation during its life cycle, which demands adaptation to different host environments and associated dramatic changes in nutritional conditions. We therefore characterized T. brucei ATG24, the T. brucei ortholog of yeast Atg24 and mammalian SNX4, and found it to have a regulatory role in autophagy and differentiation as well as endocytic trafficking. ATG24 partially localized on endocytic membranes where it was recruited via PI3-kinase III/VPS34. ATG24 silencing severely impaired receptor-mediated endocytosis of transferrin, but not adsorptive uptake of a lectin, and caused a major enlargement of the flagellar pocket. ATG24 silencing approximately doubled the number of autophagosomes, suggesting a role in repressing autophagy, and strongly accelerated differentiation, in accordance with a role of autophagy in parasite differentiation. Overexpression of the two isoforms of T. brucei ATG8 fused to GFP slowed down differentiation, possibly by a dominant-negative effect. This was overcome by ATG24 depletion, further supporting its regulatory role.

Prostatitis-bacterial - self-care

Science.gov (United States)

... this page: //medlineplus.gov/ency/patientinstructions/000395.htm Prostatitis - bacterial - self-care To use the sharing features ... enable JavaScript. You have been diagnosed with bacterial prostatitis . This is an infection of the prostate gland. ...

BACTERIAL CHEMOTAXIS AND FLAVONOIDS: PROSPECTS FOR THE USE OF PROBIOTICS

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Monica Marcela Galicia Jimenez

2011-08-01

Full Text Available The application of different diets have focused on seeking greater production in the ruminant animal feed varies, thus affecting rumen microbial population, however, the production efficiency of ruminants has been reported inconsistently. Furthermore, studies have been conducted secondary metabolites secreted by plants and has been having a function of attractant or repellent in plant-microbe interactions. So our goal is to integrate knowledge of rumen bacteria-particle interactions of forage used for food and flavonoids as stimulants in the flagellar movement. Thus, understanding the signaling pathways used by rumen bacteria to colonize food particles and degradation. Research and implement programs using genomic tools to help us discover chemotactic genes in rumen bacteria that contribute to elucidate principles governing the communication of microbial populations, their interactions and main products of microbial metabolism, and thus could raise the handling of ruminal fermentation, creating the probiotic cultures for cattle.

[Spontaneous bacterial peritonitis].

Science.gov (United States)

Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

2017-01-01

Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

Rifaximin has minor effects on bacterial composition, inflammation and bacterial translocation in cirrhosis

DEFF Research Database (Denmark)

Kimer, Nina; Pedersen, Julie S.; Tavenier, Juliette

2018-01-01

.4), and MELD score 12 (±3.9). Patients received rifaximin 550 mg BD (n=36) or placebo BD (n=18). Blood and faecal (n=15) sampling were conducted at baseline and after four weeks. Bacterial DNA in blood was determined by real-time qPCR 16S rRNA gene quantification. Bacterial composition in faeces was analysed......BACKGROUND & AIMS: Decompensated cirrhosis is characterized by disturbed haemodynamics, immune dysfunction, and high risk of infections. Translocation of viable bacteria and bacterial products from the gut to the blood is considered a key driver in this process. Intestinal decontamination...... with rifaximin may reduce bacterial translocation (BT) and decrease inflammation. In a randomized, placebo-controlled trial investigated the effects of rifaximin on inflammation and BT in decompensated cirrhosis. METHODS: Fifty-four out-patients with cirrhosis and ascites were randomized, mean age 56 years (±8...

Prevention of bacterial adhesion

DEFF Research Database (Denmark)

Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

2010-01-01

. As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

Humoral and cellular immune responses in BALB/c and C57BL/6 mice immunized with cytoplasmic (CRA) and flagellar (FRA) recombinant repetitive antigens, in acute experimental Trypanosoma cruzi infection.

Science.gov (United States)

Pereira, Valéria R A; Lorena, Virginia M B; Nakazawa, Mineo; Luna, Carlos F; Silva, Edimilson D; Ferreira, Antonio G P; Krieger, Marco Aurélio; Goldenberg, Samuel; Soares, Milena B P; Coutinho, Eridan M; Correa-Oliveira, Rodrigo; Gomes, Yara M

2005-06-01

In previous studies, cytoplasmic repetitive antigen (CRA) and flagellar repetitive antigen (FRA) proteins induced specific humoral and cellular immune responses in susceptible and resistant mice in the absence of Trypanosoma cruzi infection with a significant induction of the Interferon-gamma (IFN-gamma) production in those animals. In this follow-up paper, the immunostimulatory and protective effects of these proteins were evaluated by immunizing with CRA or FRA antigens, BALB/c and C57BL/6 mice and challenging with a T. cruzi (Y strain). Both proteins induced humoral response with high levels of IgG isotypes as well as cellular immunity with high levels of IFN-gamma when compared to controls. However, the lymphocyte proliferative response was minimal. The survival rate at 30 days post-infection was significant in CRA (60%) or FRA (50%)--immunized BALB/c mice and CRA (83.3%)--immunized C57BL/6 mice. Taken as a whole these findings indicate that CRA and FRA are immunogenic and potentially important for protective immunity.

Bacteriële meningitis

NARCIS (Netherlands)

Brouwer, M. C.; van de Beek, D.

2012-01-01

Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria

Postviral Complications: Bacterial Pneumonia.

Science.gov (United States)

Prasso, Jason E; Deng, Jane C

2017-03-01

Secondary bacterial pneumonia after viral respiratory infection remains a significant source of morbidity and mortality. Susceptibility is mediated by a variety of viral and bacterial factors, and complex interactions with the host immune system. Prevention and treatment strategies are limited to influenza vaccination and antibiotics/antivirals respectively. Novel approaches to identifying the individuals with influenza who are at increased risk for secondary bacterial pneumonias are urgently needed. Given the threat of further pandemics and the heightened prevalence of these viruses, more research into the immunologic mechanisms of this disease is warranted with the hope of discovering new potential therapies. Published by Elsevier Inc.

Biodegradability of bacterial surfactants.

Science.gov (United States)

Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Carvalho, André M X; Tótola, Marcos R; Borges, Arnaldo C

2011-06-01

This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO(2) evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO(2) emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

Molecular approaches for bacterial azoreductases

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Montira Leelakriangsak

2013-12-01

Full Text Available Azo dyes are the dominant types of synthetic dyes, widely used in textiles, foods, leather, printing, tattooing, cosmetics, and pharmaceutical industries. Many microorganisms are able to decolorize azo dyes, and there is increasing interest in biological waste treatment methods. Bacterial azoreductases can cleave azo linkages (-N=N- in azo dyes, forming aromatic amines. This review mainly focuses on employing molecular approaches, including gene manipulation and recombinant strains, to study bacterial azoreductases. The construction of the recombinant protein by cloning and the overexpression of azoreductase is described. The mechanisms and function of bacterial azoreductases can be studied by other molecular techniques discussed in this review, such as RT-PCR, southern blot analysis, western blot analysis, zymography, and muta-genesis in order to understand bacterial azoreductase properties, function and application. In addition, understanding the regulation of azoreductase gene expression will lead to the systematic use of gene manipulation in bacterial strains for new strategies in future waste remediation technologies.

Transport by negative eddy viscosity in soliton turbulence

Science.gov (United States)

Tchen, C. M.

1986-01-01

The forced Schrodinger equation is used to describe the microhydrodynamical state of strong soliton turbulence. The Schrodinger equation is transformed into a master equation and is decomposed into a macrogroup, a microgroup, and a submicrogroup, representative of the three transport processes of spectral evolution, transport property, and relaxation. The kinetic equation for the macrodistribution is derived and reverted to the continuum by the method of moments in order to find the equation of spectral evolution. The spectral flow is found to be governed by three types of transport, which are discussed.

Bacterial membrane proteomics.

Science.gov (United States)

Poetsch, Ansgar; Wolters, Dirk

2008-10-01

About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

Molecular diagnosis of bacterial vaginosis: Does adjustment for total bacterial load or human cellular content improve diagnostic performance?

Science.gov (United States)

Plummer, E L; Garland, S M; Bradshaw, C S; Law, M G; Vodstrcil, L A; Hocking, J S; Fairley, C K; Tabrizi, S N

2017-02-01

We investigated the utility of quantitative PCR assays for diagnosis of bacterial vaginosis and found that while the best model utilized bacterial copy number adjusted for total bacterial load (sensitivity=98%, specificity=93%, AUC=0.95[95%CI=0.93,0.97]), adjusting for total bacterial or human cell load did not consistently increase the diagnostic performance of the assays. Copyright © 2017 Elsevier B.V. All rights reserved.

Arsenic uptake in bacterial calcite

Science.gov (United States)

Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

2018-02-01

Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03 Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

Arsenic uptake in bacterial calcite

Energy Technology Data Exchange (ETDEWEB)

Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew G.; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

2018-02-01

Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and Xray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

Large behavioral variability of motile E. coli revealed in 3D spatial exploration

Science.gov (United States)

Figueroa-Morales, N.; Darnige, T.; Martinez, V.; Douarche, C.; Soto, R.; Lindner, A.; Clement, E.

2017-11-01

Bacterial motility determines the spatio-temporal structure of microbial communities, controls infection spreading and the microbiota organization in guts or in soils. Quantitative modeling of chemotaxis and statistical descriptions of active bacterial suspensions currently rely on the classical vision of a run-and-tumble strategy exploited by bacteria to explore their environment. Here we report a large behavioral variability of wild-type E. coli, revealed in their three-dimensional trajectories. We found a broad distribution of run times for individual cells, in stark contrast with the accepted vision of a single characteristic time. We relate our results to the slow fluctuations of a signaling protein which triggers the switching of the flagellar motor reversal responsible for tumbles. We demonstrate that such a large distribution of run times introduces measurement biases in most practical situations. These results reconcile a notorious conundrum between observations of run times and motor switching statistics. Our study implies that the statistical modeling of transport properties and of the chemotactic response of bacterial populations need to be profoundly revised to correctly account for the large variability of motility features.

Bacterial communities of two ubiquitous Great Barrier Reef corals reveals both site- and species-specificity of common bacterial associates.

Directory of Open Access Journals (Sweden)

E Charlotte E Kvennefors

Full Text Available BACKGROUND: Coral-associated bacteria are increasingly considered to be important in coral health, and altered bacterial community structures have been linked to both coral disease and bleaching. Despite this, assessments of bacterial communities on corals rarely apply sufficient replication to adequately describe the natural variability. Replicated data such as these are crucial in determining potential roles of bacteria on coral. METHODOLOGY/PRINCIPAL FINDINGS: Denaturing Gradient Gel Electrophoresis (DGGE of the V3 region of the 16S ribosomal DNA was used in a highly replicated approach to analyse bacterial communities on both healthy and diseased corals. Although site-specific variations in the bacterial communities of healthy corals were present, host species-specific bacterial associates within a distinct cluster of gamma-proteobacteria could be identified, which are potentially linked to coral health. Corals affected by "White Syndrome" (WS underwent pronounced changes in their bacterial communities in comparison to healthy colonies. However, the community structure and bacterial ribotypes identified in diseased corals did not support the previously suggested theory of a bacterial pathogen as the causative agent of the syndrome. CONCLUSIONS/SIGNIFICANCE: This is the first study to employ large numbers of replicated samples to assess the bacterial communities of healthy and diseased corals, and the first culture-independent assessment of bacterial communities on WS affected Acroporid corals on the GBR. Results indicate that a minimum of 6 replicate samples are required in order to draw inferences on species, spatial or health-related changes in community composition, as a set of clearly distinct bacterial community profiles exist in healthy corals. Coral bacterial communities may be both site and species specific. Furthermore, a cluster of gamma-proteobacterial ribotypes may represent a group of specific common coral and marine

Bacterial meningitis in children

International Nuclear Information System (INIS)

Marji, S.

2007-01-01

To demonstrate the epidemiology, clinical manifestations and bacteriological profile of bacterial meningitis in children beyond the neonatal period in our hospital. This was a retrospective descriptive study conducted at Prince Rashid Hospital in Irbid, Jordan. The medical records of 50 children with the diagnosis of bacterial meningitis during 4 years period, were reviewed. The main cause of infection was streptococcus pneumoniae, followed by Haemophilus influenza and Niesseria meningitides. Mortality was higher in infants and meningococcal infection, while complications were more encountered in cases of streptococcus pneumoniae. Cerebrospinal fluid culture was positive in 11 cases and Latex agglutination test in 39. There is a significant reduction of the numbers of bacterial meningitis caused by Haemophilus influenza type B species. (author)

Bacterial growth kinetics

International Nuclear Information System (INIS)

Boonkitticharoen, V.; Ehrhardt, J.C.; Kirchner, P.T.

1989-01-01

Quantitative measurement of bacterial growth may be made using a radioassay technique. This method measures, by scintillation counting, the 14 CO 2 derived from the bacterial metabolism of a 14 C-labeled substrate. Mathematical growth models may serve as reliable tools for estimation of the generation rate constant (or slope of the growth curve) and provide a basis for evaluating assay performance. Two models, i.e., exponential and logistic, are proposed. Both models yielded an accurate fit to the data from radioactive measurement of bacterial growth. The exponential model yielded high precision values of the generation rate constant, with an average relative standard deviation of 1.2%. Under most conditions the assay demonstrated no changes in the slopes of growth curves when the number of bacteria per inoculation was changed. However, the radiometric assay by scintillation method had a growth-inhibiting effect on a few strains of bacteria. The source of this problem was thought to be hypersensitivity to trace amounts of toluene remaining on the detector

Bacterial infec tions in travellers

African Journals Online (AJOL)

namely bacterial causes of travellers' diarrhoea and skin infections, as well as .... Vaccination: protective efficacy against typhoid may be overcome by ingesting a high bacterial load. Vaccine ..... preparation such as cream sauce. Only after ...

Bacterial carbon cycling in a subarctic fjord

DEFF Research Database (Denmark)

Middelboe, Mathias; Glud, Ronnie Nøhr; Sejr, M.K.

2012-01-01

of viruses on bacterial mortality (4–36% of cell production) and carbon cycling. Heterotrophic bacterial consumption was closely coupled with autochthonous BDOC production, and the majority of the primary production was consumed by pelagic bacteria at all seasons. The relatively low measured BGE emphasized......In this seasonal study, we examined the environmental controls and quantitative importance of bacterial carbon consumption in the water column and the sediment in the subarctic Kobbefjord, Greenland. Depth-integrated bacterial production in the photic zone varied from 5.0 ± 2.7 mg C m−2 d−1...... in February to 42 ± 28 mg C m−2 d−1 in May and 34 ± 7 mg C m−2 d−1 in September, corresponding to a bacterial production to primary production ratio of 0.34 ± 0.14, 0.07 ± 0.04, and 0.08 ± 0.06, respectively. Based on measured bacterial growth efficiencies (BGEs) of 0.09–0.10, pelagic bacterial carbon...

Cysteine Biosynthesis Controls Serratia marcescens Phospholipase Activity.

Science.gov (United States)

Anderson, Mark T; Mitchell, Lindsay A; Mobley, Harry L T

2017-08-15

biosynthesis results in decreased phlA and flagellar gene transcription, which can be restored by supplying bacteria with exogenous cysteine. These results identify a previously unrecognized role for CysE and cysteine in the secretion of S. marcescens phospholipase and in bacterial motility. Copyright © 2017 American Society for Microbiology.

Bacterial cells with improved tolerance to polyamines

DEFF Research Database (Denmark)

2017-01-01

Provided are bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as polyamines, and methods of preparing and using such bacterial cells for production of polyamines and other compounds.......Provided are bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as polyamines, and methods of preparing and using such bacterial cells for production of polyamines and other compounds....

Viral-bacterial associations in acute apical abscesses.

Science.gov (United States)

Ferreira, Dennis C; Rôças, Isabela N; Paiva, Simone S M; Carmo, Flávia L; Cavalcante, Fernanda S; Rosado, Alexandre S; Santos, Kátia R N; Siqueira, José F

2011-08-01

Viral-bacterial and bacterial synergism have been suggested to contribute to the pathogenesis of several human diseases. This study sought to investigate the possible associations between 9 candidate endodontic bacterial pathogens and 9 human viruses in samples from acute apical abscesses. DNA extracts from purulent exudate aspirates of 33 cases of acute apical abscess were surveyed for the presence of 9 selected bacterial species using a 16S ribosomal RNA gene-based nested polymerase chain reaction (PCR) approach. Single or nested PCR assays were used for detection of the human papillomavirus (HPV) and herpesviruses types 1 to 8. Two-thirds of the abscess samples were positive for at least one of the target viruses. Specifically, the most frequently detected viruses were HHV-8 (54.5%); HPV (9%); and varicella zoster virus (VZV), Epstein-Barr virus (EBV), and HHV-6 (6%). Bacterial DNA was present in all cases and the most prevalent bacterial species were Treponema denticola (70%), Tannerella forsythia (67%), Porphyromonas endodontalis (67%), Dialister invisus (61%), and Dialister pneumosintes (57.5%). HHV-8 was positively associated with 7 of the target bacterial species and HPV with 4, but all these associations were weak. Several bacterial pairs showed a moderate positive association. Viral coinfection was found in 6 abscess cases, but no significant viral association could be determined. Findings demonstrated that bacterial and viral DNA occurred concomitantly in two-thirds of the samples from endodontic abscesses. Although this may suggest a role for viruses in the etiology of apical abscesses, the possibility also exists that the presence of viruses in abscess samples is merely a consequence of the bacterially induced disease process. Further studies are necessary to clarify the role of these viral-bacterial interactions, if any, in the pathogenesis of acute apical abscesses. Copyright © 2011 Mosby, Inc. All rights reserved.

Adult bacterial meningitis

DEFF Research Database (Denmark)

Meyer, C N; Samuelsson, I S; Galle, M

2004-01-01

Episodes of adult bacterial meningitis (ABM) at a Danish hospital in 1991-2000 were identified from the databases of the Department of Clinical Microbiology, and compared with data from the Danish National Patient Register and the Danish National Notification System. Reduced penicillin susceptibi......Episodes of adult bacterial meningitis (ABM) at a Danish hospital in 1991-2000 were identified from the databases of the Department of Clinical Microbiology, and compared with data from the Danish National Patient Register and the Danish National Notification System. Reduced penicillin...

Bacterial Communities: Interactions to Scale

Directory of Open Access Journals (Sweden)

Reed M. Stubbendieck

2016-08-01

Full Text Available In the environment, bacteria live in complex multispecies communities. These communities span in scale from small, multicellular aggregates to billions or trillions of cells within the gastrointestinal tract of animals. The dynamics of bacterial communities are determined by pairwise interactions that occur between different species in the community. Though interactions occur between a few cells at a time, the outcomes of these interchanges have ramifications that ripple through many orders of magnitude, and ultimately affect the macroscopic world including the health of host organisms. In this review we cover how bacterial competition influences the structures of bacterial communities. We also emphasize methods and insights garnered from culture-dependent pairwise interaction studies, metagenomic analyses, and modeling experiments. Finally, we argue that the integration of multiple approaches will be instrumental to future understanding of the underlying dynamics of bacterial communities.

Oral bacterial DNA findings in pericardial fluid

Directory of Open Access Journals (Sweden)

Anne-Mari Louhelainen

2014-11-01

Full Text Available Background: We recently reported that large amounts of oral bacterial DNA can be found in thrombus aspirates of myocardial infarction patients. Some case reports describe bacterial findings in pericardial fluid, mostly done with conventional culturing and a few with PCR; in purulent pericarditis, nevertheless, bacterial PCR has not been used as a diagnostic method before. Objective: To find out whether bacterial DNA can be measured in the pericardial fluid and if it correlates with pathologic–anatomic findings linked to cardiovascular diseases. Methods: Twenty-two pericardial aspirates were collected aseptically prior to forensic autopsy at Tampere University Hospital during 2009–2010. Of the autopsies, 10 (45.5% were free of coronary artery disease (CAD, 7 (31.8% had mild and 5 (22.7% had severe CAD. Bacterial DNA amounts were determined using real-time quantitative PCR with specific primers and probes for all bacterial strains associated with endodontic disease (Streptococcus mitis group, Streptococcus anginosus group, Staphylococcus aureus/Staphylococcus epidermidis, Prevotella intermedia, Parvimonas micra and periodontal disease (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatus, and Dialister pneumosintes. Results: Of 22 cases, 14 (63.6% were positive for endodontic and 8 (36.4% for periodontal-disease-associated bacteria. Only one case was positive for bacterial culturing. There was a statistically significant association between the relative amount of bacterial DNA in the pericardial fluid and the severity of CAD (p=0.035. Conclusions: Oral bacterial DNA was detectable in pericardial fluid and an association between the severity of CAD and the total amount of bacterial DNA in pericardial fluid was found, suggesting that this kind of measurement might be useful for clinical purposes.

Endocarditis in adults with bacterial meningitis.

Science.gov (United States)

Lucas, Marjolein J; Brouwer, Matthijs C; van der Ende, Arie; van de Beek, Diederik

2013-05-21

Endocarditis may precede or complicate bacterial meningitis, but the incidence and impact of endocarditis in bacterial meningitis are unknown. We assessed the incidence and clinical characteristics of patients with meningitis and endocarditis from a nationwide cohort study of adults with community-acquired bacterial meningitis in the Netherlands from 2006 to 2012. Endocarditis was identified in 24 of 1025 episodes (2%) of bacterial meningitis. Cultures yielded Streptococcus pneumoniae in 13 patients, Staphylococcus aureus in 8 patients, and Streptococcus agalactiae, Streptococcus pyogenes, and Streptococcus salivarius in 1 patient each. Clues leading to the diagnosis of endocarditis were cardiac murmurs, persistent or recurrent fever, a history of heart valve disease, and S aureus as the causative pathogen of bacterial meningitis. Treatment consisted of prolonged antibiotic therapy in all patients and surgical valve replacement in 10 patients (42%). Two patients were treated with oral anticoagulants, and both developed life-threatening intracerebral hemorrhage. Systemic (70%) and neurological (54%) complications occurred frequently, leading to a high proportion of patients with unfavorable outcome (63%). Seven of 24 patients (29%) with meningitis and endocarditis died. Endocarditis is an uncommon coexisting condition in bacterial meningitis but is associated with a high rate of unfavorable outcome.

[The composition of the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora].

Science.gov (United States)

Lei, D; Lin, Y; Jiang, X; Lan, L; Zhang, W; Wang, B X

2017-03-02

Objective: To explore the composition of the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora. Method: Twenty-four specimens were collected from pregnant Kunming mouse including 8 mice of early embryonic (12-13 days) gastrointestinal tissues, 8 cases of late embryonic (19-20 days)gastrointestinal tissues, 8 of late pregnancy placental tissues.The 24 samples were extracted by DNeasy Blood & Tissue kit for high-throughput DNA sequencing. Result: The level of Proteobacteria, Bacteroidetes, Actino-bacteria and Firmicutes were predominantin all specimens.The relative content of predominant bacterial phyla in each group: Proteobacteria (95.00%, 88.14%, 87.26%), Bacteroidetes(1.71%, 2.15%, 2.63%), Actino-Bacteria(1.16%, 4.10%, 3.38%), Firmicutes(0.75%, 2.62%, 2.01%). At the level of family, there were nine predominant bacterial families in which Enterobacteriaeae , Shewanel laceae and Moraxellaceae were dominant.The relative content of dominant bacterial family in eachgroup: Enterobacteriaeae (46.99%, 44.34%, 41.08%), Shewanellaceae (21.99%, 21.10%, 19.05%), Moraxellaceae (9.18%, 7.09%, 5.64%). From the species of flora, the flora from fetal gastrointestinal in early pregnancy and late pregnancy (65.44% and 62.73%) were the same as that from placenta tissue in the late pregnancy.From the abundance of bacteria, at the level of family, the same content of bacteria in three groups accounted for 78.16%, 72.53% and 65.78% respectively. Conclusion: It was proved that the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora were colonized. At the same time the bacteria are classified.

C-reactive protein and bacterial meningitis

DEFF Research Database (Denmark)

Gerdes, Lars Ulrik; Jørgensen, P E; Nexø, E

1998-01-01

The aim of the study was to review published articles on the diagnostic accuracy of C-reactive protein (CRP) tests with cerebrospinal fluid and serum in diagnosing bacterial meningitis. The literature from 1980 and onwards was searched using the electronic databases of MEDLINE, and we used summary...... measured in serum, and 4 in which it had been measured in both cerebrospinal fluid and serum. The odds ratio for bacterial meningitis versus aseptic meningitis for a positive CRP test with cerebrospinal fluid was estimated at 241 (95% confidence interval [CI]: 59-980), and the central tendencies.......06-0.08, respectively, the post-test probability of not having bacterial meningitis given a negative test is very high (> or = 97%), in the range of a pre-test probability (prevalence of bacterial meningitis) from 10 to 30%, whereas the post-test probability of bacterial meningitis given a positive test is considerably...

Bacterial meningitis in immunocompromised patients

NARCIS (Netherlands)

van Veen, K.E.B.

2018-01-01

Bacterial meningitis is an acute infection of the meninges, in The Netherlands most commonly caused by Streptococcus pneumoniae and Neisseria meningitides. Risk factors for acquiring bacterial meningitis include a decreased function of the immune system. The aim of this thesis was to study

Bacterial cellulose/boehmite composites

International Nuclear Information System (INIS)

Salvi, Denise T.B. de; Barud, Hernane S.; Messaddeq, Younes; Ribeiro, Sidney J.L.; Caiut, Jose Mauricio A.

2011-01-01

Composites based on bacterial cellulose membranes and boehmite were obtained. SEM results indicate that the bacterial cellulose (BC) membranes are totally covered by boehmite and obtained XRD patterns suggest structural changes due to this boehmite addition. Thermal stability is accessed through TG curves and is dependent on boehmite content. Transparency is high comparing to pure BC as can be seen through UV-vis absorption spectroscopy. (author)

Molecular detection of human bacterial pathogens

National Research Council Canada - National Science Library

Liu, Dongyou

2011-01-01

.... Molecular Detection of Human Bacterial Pathogens addresses this issue, with international scientists in respective bacterial pathogen research and diagnosis providing expert summaries on current...

[Bacterial vaginosis].

Science.gov (United States)

Romero Herrero, Daniel; Andreu Domingo, Antonia

2016-07-01

Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Radiological aspects of bacterial lung abscess

International Nuclear Information System (INIS)

Groskin, S.A.; Panicek, D.; Ewing, D.; Rivera, F.; Math, K.; Teixeira, J.; Heitzman, E.R.

1987-01-01

Clinical, radiological, and pathological data derived from an analysis of over 70 cases of bacterial lung abscess are presented. Etiologic agents and risk factors are presented. Key radiographic findings are discussed, and those that are most useful in differentiating bacterial lung abscess from cavitated carcinoma, infected cyst, and emphysema are emphasized. Radiographic aspects of the complications of bacterial lung abscess are illustrated, and radiological approaches to their therapy are discussed

Bacterial, Fungal, Parasitic, and Viral Myositis

OpenAIRE

Crum-Cianflone, Nancy F.

2008-01-01

Infectious myositis may be caused by a broad range of bacterial, fungal, parasitic, and viral agents. Infectious myositis is overall uncommon given the relative resistance of the musculature to infection. For example, inciting events, including trauma, surgery, or the presence of foreign bodies or devitalized tissue, are often present in cases of bacterial myositis. Bacterial causes are categorized by clinical presentation, anatomic location, and causative organisms into the categories of pyo...

Bacterial cells with improved tolerance to polyols

DEFF Research Database (Denmark)

2017-01-01

The present invention relates to bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as diols and other polyols, and to methods of preparing and using such bacterial cells for production of polyols and other compounds.......The present invention relates to bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as diols and other polyols, and to methods of preparing and using such bacterial cells for production of polyols and other compounds....

Bacterial Vaginosis

Science.gov (United States)

... Archive STDs Home Page Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ( ... of getting other STDs, such as chlamydia and gonorrhea . These bacteria can sometimes cause pelvic inflammatory disease ( ...

The intrinsic resistome of bacterial pathogens.

Science.gov (United States)

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B Sanchez, Maria; Martinez, Jose L

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

The intrinsic resistome of bacterial pathogens

Directory of Open Access Journals (Sweden)

Jorge Andrés Olivares Pacheco

2013-04-01

Full Text Available Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally a low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyse recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

Bacterial flora of sturgeon fingerling

International Nuclear Information System (INIS)

Arani, A.S.; Mosahab, R.

2008-01-01

The study on microbial populations is a suitable tool to understand and apply control methods to improve the sanitary level of production in fish breeding and rearing centers, ensure health of sturgeon fingerlings at the time of their release into the rivers and also in the conversation and restoration of these valuable stocks in the Caspian Sea, Iran. A laboratory research based on Austin methods (Austin, B., Austin, D.A. 1993) was conducted for bacterial study on 3 sturgeon species naming A. persicus, A. stellatus and A. nudiventris during different growth stages. Bacterial flora of Acinetobacter, Moraxella, Aeromonas, Vibrio, Edwardsiella, Staphylococcus, Proteus, Yersinia, Pseudomonas and Plesiomonas were determined. The factors which may induce changes in bacterial populations during different stages of fife are the followings: quality of water in rearing ponds, different conditions for growth stages, suitable time for colonization of bacterial flora in rearing pond, water temperature increase in fingerlings size and feeding condition. (author)

Characterisation of the gill mucosal bacterial communities of four butterflyfish species: a reservoir of bacterial diversity in coral reef ecosystems.

Science.gov (United States)

Reverter, Miriam; Sasal, Pierre; Tapissier-Bontemps, N; Lecchini, D; Suzuki, M

2017-06-01

While recent studies have suggested that fish mucus microbiota play an important role in homeostasis and prevention of infections, very few studies have investigated the bacterial communities of gill mucus. We characterised the gill mucus bacterial communities of four butterflyfish species and although the bacterial diversity of gill mucus varied significantly between species, Shannon diversities were high (H = 3.7-5.7) in all species. Microbiota composition differed between butterflyfishes, with Chaetodon lunulatus and C. ornatissimus having the most similar bacterial communities, which differed significantly from C. vagabundus and C. reticulatus. The core bacterial community of all species consisted of mainly Proteobacteria followed by Actinobacteria and Firmicutes. Chaetodonlunulatus and C. ornatissimus bacterial communities were mostly dominated by Gammaproteobacteria with Vibrio as the most abundant genus. Chaetodonvagabundus and C. reticulatus presented similar abundances of Gammaproteobacteria and Alphaproteobacteria, which were well represented by Acinetobacter and Paracoccus, respectively. In conclusion, our results indicate that different fish species present specific bacterial assemblages. Finally, as mucus layers are nutrient hotspots for heterotrophic bacteria living in oligotrophic environments, such as coral reef waters, the high bacterial diversity found in butterflyfish gill mucus might indicate external fish mucus surfaces act as a reservoir of coral reef bacterial diversity. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mechanical Homogenization Increases Bacterial Homogeneity in Sputum

Science.gov (United States)

Stokell, Joshua R.; Khan, Ammad

2014-01-01

Sputum obtained from patients with cystic fibrosis (CF) is highly viscous and often heterogeneous in bacterial distribution. Adding dithiothreitol (DTT) is the standard method for liquefaction prior to processing sputum for molecular detection assays. To determine if DTT treatment homogenizes the bacterial distribution within sputum, we measured the difference in mean total bacterial abundance and abundance of Burkholderia multivorans between aliquots of DTT-treated sputum samples with and without a mechanical homogenization (MH) step using a high-speed dispersing element. Additionally, we measured the effect of MH on bacterial abundance. We found a significant difference between the mean bacterial abundances in aliquots that were subjected to only DTT treatment and those of the aliquots which included an MH step (all bacteria, P = 0.04; B. multivorans, P = 0.05). There was no significant effect of MH on bacterial abundance in sputum. Although our results are from a single CF patient, they indicate that mechanical homogenization increases the homogeneity of bacteria in sputum. PMID:24759710

Epitope mapping of salmonella flagellar hook-associated protein, FlgK, with mass spectrometry-based immuno-capture proteomics using chicken (gallus gallus domesticus] sera

Science.gov (United States)

Salmonella, a Gram-negative rod, is the leading foodborne pathogen associated with human acute bacterial gastroenteritis worldwide. The Salmonella flagellum is responsible for bacterial movement, colonization and invasion in the host gastrointestinal tract. The flagellum has a complex structure, c...

Significant relationship between soil bacterial community structure and incidence of bacterial wilt disease under continuous cropping system.

Science.gov (United States)

She, Siyuan; Niu, Jiaojiao; Zhang, Chao; Xiao, Yunhua; Chen, Wu; Dai, Linjian; Liu, Xueduan; Yin, Huaqun

2017-03-01

Soil bacteria are very important in biogeochemical cycles and play significant role in soil-borne disease suppression. Although continuous cropping is responsible for soil-borne disease enrichment, its effect on tobacco plant health and how soil bacterial communities change are yet to be elucidated. In this study, soil bacterial communities across tobacco continuous cropping time-series fields were investigated through high-throughput sequencing of 16S ribosomal RNA genes. The results showed that long-term continuous cropping could significantly alter soil microbial communities. Bacterial diversity indices and evenness indices decreased over the monoculture span and obvious variations for community structures across the three time-scale tobacco fields were detected. Compared with the first year, the abundances of Arthrobacter and Lysobacter showed a significant decrease. Besides, the abundance of the pathogen Ralstonia spp. accumulated over the monoculture span and was significantly correlated with tobacco bacterial wilt disease rate. Moreover, Pearson's correlation demonstrated that the abundance of Arthrobacter and Lysobacter, which are considered to be beneficial bacteria had significant negative correlation with tobacco bacterial wilt disease. Therefore, after long-term continuous cropping, tobacco bacterial wilt disease could be ascribed to the alteration of the composition as well as the structure of the soil microbial community.

Temperate bacterial viruses as double-edged swords in bacterial warfare.

Science.gov (United States)

Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco

2013-01-01

It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails.

Temperate bacterial viruses as double-edged swords in bacterial warfare.

Directory of Open Access Journals (Sweden)

João Alves Gama

Full Text Available It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails.

Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

Science.gov (United States)

Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

2016-12-01

Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

Analysis of bacterial communities and bacterial pathogens in a biogas plant by the combination of ethidium monoazide, PCR and Ion Torrent sequencing.

Science.gov (United States)

Luo, Gang; Angelidaki, Irini

2014-09-01

The present study investigated the changes of bacterial community composition including bacterial pathogens along a biogas plant, i.e. from the influent, to the biogas reactor and to the post-digester. The effects of post-digestion temperature and time on the changes of bacterial community composition and bacterial pathogens were also studied. Microbial analysis was made by Ion Torrent sequencing of the PCR amplicons from ethidium monoazide treated samples, and ethidium monoazide was used to cleave DNA from dead cells and exclude it from PCR amplification. Both similarity and taxonomic analysis showed that the bacterial community composition in the influent was changed after anaerobic digestion. Firmicutes were dominant in all the samples, while Proteobacteria decreased in the biogas reactor compared with the influent. Variations of bacterial community composition in the biogas reactor with time were also observed. This could be attributed to varying composition of the influent. Batch experiments showed that the methane recovery from the digested residues (obtained from biogas reactor) was mainly related with post-digestion temperature. However, post-digestion time rather than temperature had a significant effect on the changes of bacterial community composition. The changes of bacterial community composition were also reflected in the changes of relative abundance of bacterial pathogens. The richness and relative abundance of bacterial pathogens were reduced after anaerobic digestion in the biogas reactor. It was found in batch experiments that bacterial pathogens showed the highest relative abundance and richness after 30 days' post-digestion. Streptococcus bovis was found in all the samples. Our results showed that special attention should be paid to the post-digestion since the increase in relative abundance of bacterial pathogens after post-digestion might reflect regrowth of bacterial pathogens and limit biosolids disposal vectors. Copyright © 2014 Elsevier

Non-homogeneous flow profiles in sheared bacterial suspensions

Science.gov (United States)

Samanta, Devranjan; Cheng, Xiang

Bacterial suspensions under shear exhibit interesting rheological behaviors including the remarkable ``superfluidic'' state with vanishing viscosity at low shear rates. Theoretical studies have shown that such ``superfluidic'' state is linked with non-homogeneous shear flows, which are induced by coupling between nematic order of active fluids and hydrodynamics of shear flows. However, although bulk rheology of bacterial suspensions has been experimentally studied, shear profiles within bacterial suspensions have not been explored so far. Here, we experimentally investigate the flow behaviors of E. coli suspensions under planar oscillatory shear. Using confocal microscopy and PIV, we measure velocity profiles across gap between two shear plates. We find that with increasing shear rates, high-concentration bacterial suspensions exhibit an array of non-homogeneous flow behaviors like yield-stress flows and shear banding. We show that these non-homogeneous flows are due to collective motion of bacterial suspensions. The phase diagram of sheared bacterial suspensions is systematically mapped as functions of shear rates an bacterial concentrations. Our experiments provide new insights into rheology of bacterial suspensions and shed light on shear induced dynamics of active fluids. Chemical Engineering and Material Science department.

Bacterial reproductive pathogens of cats and dogs.

Science.gov (United States)

Graham, Elizabeth M; Taylor, David J

2012-05-01

With the notable exception of Brucella canis, exogenous bacterial pathogens are uncommon causes of reproductive disease in cats and dogs. Most bacterial reproductive infections are endogenous, and predisposing factors for infection are important. This article reviews the etiology, pathogenesis, clinical presentation, diagnosis, treatment, and public health significance of bacterial reproductive pathogens in cats and dogs.

Bacterial Community Succession in Pine-Wood Decomposition.

Science.gov (United States)

Kielak, Anna M; Scheublin, Tanja R; Mendes, Lucas W; van Veen, Johannes A; Kuramae, Eiko E

2016-01-01

Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here, we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities.

Spontaneous Bacterial Peritonitis in Subclinical Hypothyroidism

Directory of Open Access Journals (Sweden)

Dalip Gupta

2013-11-01

Full Text Available Hypothyroidism is an uncommon cause of ascites. Here we describe a case of a 75 year-old female patient with spontaneous bacterial peritonitis and subclinical hypothyroidism that resolved with thyroid replacement and antibiotic therapy respectively. Ascitic fluid analysis revealed a gram-positive bacterium on gram staining. A review of the literature revealed just one other reported case of myxoedema ascites with concomitant spontaneous bacterial peritonitis and no case has till been reported of spontaneous bacterial peritonitis in subclinical hypothyroidism.

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Maruthupandy, Muthusamy; Anand, Muthusamy; Beevi, Akbar Sait Hameedha; Priya, Radhakrishnan Jeeva; Maduraiveeran, Govindhan

2015-01-01

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices. (paper)

Bacterial stress

Indian Academy of Sciences (India)

First page Back Continue Last page Graphics. Bacterial stress. Physicochemical and chemical parameters: temperature, pressure, pH, salt concentration, oxygen, irradiation. Nutritional depravation: nutrient starvation, water shortage. Toxic compounds: Antibiotics, heavy metals, toxins, mutagens. Interactions with other cells: ...

Corticosteroids for Bacterial Keratitis

Science.gov (United States)

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

2013-01-01

Objective To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Methods Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. Main Outcome Measures The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Results Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (−0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, −0.31 to −0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (−0.37 to −0.04; P = .02). Conclusions We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Application to Clinical Practice Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. PMID:21987582

Diagnosis and treatment of bacterial prostatitis.

Science.gov (United States)

Videčnik Zorman, Jerneja; Matičič, Mojca; Jeverica, Samo; Smrkolj, Tomaž

2015-01-01

Prostate inflammation is a common syndrome, especially in men under 50. It usually presents with voiding symptoms and pain in the genitourinary area, and sometimes as sexual dysfunction. Based on clinical and laboratory characteristics, prostatitis is classified as acute bacterial prostatitis, chronic bacterial prostatitis, chronic inflammatory and non-inflammatory prostatitis or chronic pelvic pain syndrome, and asymptomatic inflammatory prostatitis. Bacterial prostatitis is most often caused by infection with uropathogens, mainly Gram-negative bacilli, but Gram-positive and atypical microorganisms have also been identified as causative organisms of chronic prostatitis. According to reports by several authors, Chlamydia trachomatis and Trichomonas vaginalis are some of the most common pathogens, making chronic prostatitis a sexually transmitted disease. Diagnosis and treatment of acute and chronic bacterial prostatitis in particular can be challenging.

Bacterial endophytes enhance competition by invasive plants.

Science.gov (United States)

Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

2013-09-01

Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

Autophagy and bacterial clearance: a not so clear picture

OpenAIRE

Mostowy, Serge

2012-01-01

Autophagy, an intracellular degradation process highly conserved from yeast to humans, is viewed as an important defence mechanism to clear intracellular bacteria. However, recent work has shown that autophagy may have different roles during different bacterial infections that restrict bacterial replication (antibacterial autophagy), act in cell autonomous signalling (non-bacterial autophagy) or support bacterial replication (pro-bacterial autophagy). This review will focus on newfound intera...

Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

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Sahar Hasim

2018-02-01

Full Text Available The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity. Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.

Hygrocin C from marine-derived Streptomyces sp. SCSGAA 0027 inhibits biofilm formation in Bacillus amyloliquefaciens SCSGAB0082 isolated from South China Sea gorgonian.

Science.gov (United States)

Wang, Jie; Nong, Xu-Hua; Amin, Muhammad; Qi, Shu-Hua

2018-02-01

Several ansamycins have been reported to inhibit bacterial biofilm formation and accelerate the eradication of developed biofilms, but little is known about the effect of hygrocin C, an ansamycin, on bacterial biofilm formation. Here, hygrocin C was isolated from the marine-derived Streptomyces sp. SCSGAA 0027 and reported for the first time to be capable of inhibiting the biofilm formation of Staphylococcus aureus and Bacillus amyloliquefaciens SCSGAB0082 with the production of anti-microbial lipopeptides from South China Sea gorgonian Subergorgia suberosa at concentrations of less than minimum inhibitory concentrations. Moreover, hygrocin C also promoted the eradication of developed biofilms, affected the biofilm architecture, and lowered the extracellular polymeric matrix formation, cell motility, and surface hydrophobicity in B. amyloliquefaciens, which was in accordance with the inhibition of biofilm formation. Furthermore, transcriptome analysis revealed that hygrocin C altered the transcripts of several genes associated with bacterial chemotaxis and flagellar, two-component system and the synthesis of arginine and histidine, which are important for bacterial biofilm formation. In conclusion, hygrocin C could be used as a potential biofilm inhibitor against S. aureus and B. amyloliquefaciens. But further genetic investigations are needed to provide more details for elucidation of the molecular mechanisms responsible for the effects of hygrocin C on B. amyloliquefaciens biofilm formation.

Bacterial meningitis

NARCIS (Netherlands)

Heckenberg, Sebastiaan G. B.; Brouwer, Matthijs C.; van de Beek, Diederik

2014-01-01

Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained,

Impact of cranberry on Escherichia coli cellular surface characteristics

International Nuclear Information System (INIS)

Johnson, Brandy J.; Lin Baochuan; Dinderman, Michael A.; Rubin, Robert A.; Malanoski, Anthony P.; Ligler, Frances S.

2008-01-01

The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports.

Antimicrobial susceptibility in community-acquired bacterial ...

African Journals Online (AJOL)

Objectives: To determine the antimicrobial susceptibility patterns of Streptococcus pneumoniae and Haemophilus influenzae, two bacterial pathogens commonly associated with communityacquired pneumonia. Design: Cross-sectional study. Setting: Bacterial isolates were obtained from adults suspected to have ...

Insights from 20 years of bacterial genome sequencing

DEFF Research Database (Denmark)

Land, Miriam; Hauser, Loren; Jun, Se-Ran

2015-01-01

Since the first two complete bacterial genome sequences were published in 1995, the science of bacteria has dramatically changed. Using third-generation DNA sequencing, it is possible to completely sequence a bacterial genome in a few hours and identify some types of methylation sites along...... the genome as well. Sequencing of bacterial genome sequences is now a standard procedure, and the information from tens of thousands of bacterial genomes has had a major impact on our views of the bacterial world. In this review, we explore a series of questions to highlight some insights that comparative...... genomics has produced. To date, there are genome sequences available from 50 different bacterial phyla and 11 different archaeal phyla. However, the distribution is quite skewed towards a few phyla that contain model organisms. But the breadth is continuing to improve, with projects dedicated to filling...

Peritonitis - spontaneous bacterial

Science.gov (United States)

Spontaneous bacterial peritonitis (SBP); Ascites - peritonitis; Cirrhosis - peritonitis ... who are on peritoneal dialysis for kidney failure. Peritonitis may have other causes . These include infection from ...

Bacterial lipases

NARCIS (Netherlands)

Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation,

Stimulation of bacterial DNA synthesis by algal exudates in attached algal-bacterial consortia

International Nuclear Information System (INIS)

Murray, R.E.; Cooksey, K.E.; Priscu, J.C.

1986-01-01

Algal-bacterial consortia attached to polystyrene surfaces were prepared in the laboratory by using the marine diatom Amphora coffeaeformis and the marine bacterium Vibrio proteolytica (the approved name of this bacterium is Vibrio proteolyticus. The organisms were attached to the surfaces at cell densities of approximately 5 x 10 4 cells cm -2 (diatoms) and 5 x 10 6 cells cm -2 (bacteria). The algal-bacterial consortia consistently exhibited higher rates of [ 3 H]thymidine incorporation than did biofilms composed solely of bacteria. The rates of [ 3 H]thymidine incorporation by the algal-bacterial consortia were fourfold greater than the rates of incorporation by monobacterial biofilms 16 h after biofilm formation and were 16-fold greater 70 h after biofilm formation. Extracellular material released from the attached Amphora cells supported rates of bacterial activity (0.8 x 10 -21 mol to 17.9 x 10 -21 mol of [ 3 H]thymidine incorporated cell -1 h -1 ) and growth (doubling time, 29.5 to 1.4 days) comparable to values reported for a wide variety of marine and freshwater ecosystems. In the presence of sessile diatom populations, DNA synthesis by attached V. proteolytica cells was light dependent and increased with increasing algal abundance. The metabolic activity of diatoms thus appears to be the rate-limiting process in biofilm development on illuminated surfaces under conditions of low bulk-water dissolved organic carbon

Bacterial cells with improved tolerance to isobutyric acid

DEFF Research Database (Denmark)

2017-01-01

Bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as isobutyric acid and related compounds, and methods of preparing and using such bacterial cells for production of isobutyric acid and related compounds.......Bacterial cells genetically modified to improve their tolerance to certain commodity chemicals, such as isobutyric acid and related compounds, and methods of preparing and using such bacterial cells for production of isobutyric acid and related compounds....

Flagellin based biomimetic coatings: From cell-repellent surfaces to highly adhesive coatings.

Science.gov (United States)

Kovacs, Boglarka; Patko, Daniel; Szekacs, Inna; Orgovan, Norbert; Kurunczi, Sandor; Sulyok, Attila; Khanh, Nguyen Quoc; Toth, Balazs; Vonderviszt, Ferenc; Horvath, Robert

2016-09-15

Biomimetic coatings with cell-adhesion-regulating functionalities are intensively researched today. For example, cell-based biosensing for drug development, biomedical implants, and tissue engineering require that the surface adhesion of living cells is well controlled. Recently, we have shown that the bacterial flagellar protein, flagellin, adsorbs through its terminal segments to hydrophobic surfaces, forming an oriented monolayer and exposing its variable D3 domain to the solution. Here, we hypothesized that this nanostructured layer is highly cell-repellent since it mimics the surface of the flagellar filaments. Moreover, we proposed flagellin as a carrier molecule to display the cell-adhesive RGD (Arg-Gly-Asp) peptide sequence and induce cell adhesion on the coated surface. The D3 domain of flagellin was replaced with one or more RGD motifs linked by various oligopeptides modulating flexibility and accessibility of the inserted segment. The obtained flagellin variants were applied to create surface coatings inducing cell adhesion and spreading to different levels, while wild-type flagellin was shown to form a surface layer with strong anti-adhesive properties. As reference surfaces synthetic polymers were applied which have anti-adhesive (PLL-g-PEG poly(l-lysine)-graft-poly(ethylene glycol)) or adhesion inducing properties (RGD-functionalized PLL-g-PEG). Quantitative adhesion data was obtained by employing optical biochips and microscopy. Cell-adhesion-regulating coatings can be simply formed on hydrophobic surfaces by using the developed flagellin-based constructs. The developed novel RGD-displaying flagellin variants can be easily obtained by bacterial production and can serve as alternatives to create cell-adhesion-regulating biomimetic coatings. In the present work, we show for the first time that. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bacterial community succession in pine-wood decomposition

Directory of Open Access Journals (Sweden)

Anna eKielak

2016-03-01

Full Text Available Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities.

Endocarditis in adults with bacterial meningitis

NARCIS (Netherlands)

Lucas, Marjolein J.; Brouwer, Matthijs C.; van der Ende, Arie; van de Beek, Diederik

2013-01-01

Endocarditis may precede or complicate bacterial meningitis, but the incidence and impact of endocarditis in bacterial meningitis are unknown. We assessed the incidence and clinical characteristics of patients with meningitis and endocarditis from a nationwide cohort study of adults with

Bacterial Degradation of Aromatic Compounds

Directory of Open Access Journals (Sweden)

Qing X. Li

2009-01-01

Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

Bacterial community affects toxin production by Gymnodinium catenatum.

Directory of Open Access Journals (Sweden)

Maria E Albinsson

Full Text Available The paralytic shellfish toxin (PST-producing dinoflagellate Gymnodinium catenatum grows in association with a complex marine bacterial community that is both essential for growth and can alter culture growth dynamics. Using a bacterial community replacement approach, we examined the intracellular PST content, production rate, and profile of G. catenatum cultures grown with bacterial communities of differing complexity and composition. Clonal offspring were established from surface-sterilized resting cysts (produced by sexual crosses of strain GCDE06 and strain GCLV01 and grown with: 1 complex bacterial communities derived from each of the two parent cultures; 2 simplified bacterial communities composed of the G. catenatum-associated bacteria Marinobacter sp. strain DG879 or Alcanivorax sp. strain DG881; 3 a complex bacterial community associated with an untreated, unsterilized sexual cross of the parents. Toxin content (STX-equivalent per cell of clonal offspring (134-197 fmol STX cell(-1 was similar to the parent cultures (169-206 fmol STX cell(-1, however cultures grown with single bacterial types contained less toxin (134-146 fmol STX cell(-1 than offspring or parent cultures grown with more complex mixed bacterial communities (152-176 fmol STX cell(-1. Specific toxin production rate (fmol STX day(-1 was strongly correlated with culture growth rate. Net toxin production rate (fmol STX cell(-1 day(-1 did not differ among treatments, however, mean net toxin production rate of offspring was 8-fold lower than the parent cultures, suggesting that completion of the sexual lifecycle in laboratory cultures leads to reduced toxin production. The PST profiles of offspring cultures were most similar to parent GCDE06 with the exception of cultures grown with Marinobacter sp. DG879 which produced higher proportions of dcGTX2+3 and GC1+2, and lower proportions of C1+2 and C3+4. Our data demonstrate that the bacterial community can alter intracellular STX

Bacterial community affects toxin production by Gymnodinium catenatum.

Science.gov (United States)

Albinsson, Maria E; Negri, Andrew P; Blackburn, Susan I; Bolch, Christopher J S

2014-01-01

The paralytic shellfish toxin (PST)-producing dinoflagellate Gymnodinium catenatum grows in association with a complex marine bacterial community that is both essential for growth and can alter culture growth dynamics. Using a bacterial community replacement approach, we examined the intracellular PST content, production rate, and profile of G. catenatum cultures grown with bacterial communities of differing complexity and composition. Clonal offspring were established from surface-sterilized resting cysts (produced by sexual crosses of strain GCDE06 and strain GCLV01) and grown with: 1) complex bacterial communities derived from each of the two parent cultures; 2) simplified bacterial communities composed of the G. catenatum-associated bacteria Marinobacter sp. strain DG879 or Alcanivorax sp. strain DG881; 3) a complex bacterial community associated with an untreated, unsterilized sexual cross of the parents. Toxin content (STX-equivalent per cell) of clonal offspring (134-197 fmol STX cell(-1)) was similar to the parent cultures (169-206 fmol STX cell(-1)), however cultures grown with single bacterial types contained less toxin (134-146 fmol STX cell(-1)) than offspring or parent cultures grown with more complex mixed bacterial communities (152-176 fmol STX cell(-1)). Specific toxin production rate (fmol STX day(-1)) was strongly correlated with culture growth rate. Net toxin production rate (fmol STX cell(-1) day(-1)) did not differ among treatments, however, mean net toxin production rate of offspring was 8-fold lower than the parent cultures, suggesting that completion of the sexual lifecycle in laboratory cultures leads to reduced toxin production. The PST profiles of offspring cultures were most similar to parent GCDE06 with the exception of cultures grown with Marinobacter sp. DG879 which produced higher proportions of dcGTX2+3 and GC1+2, and lower proportions of C1+2 and C3+4. Our data demonstrate that the bacterial community can alter intracellular STX

Copper effects on bacterial activity of estuarine silty sediments

Science.gov (United States)

Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

2007-07-01

Bacteria of silty estuarine sediments were spiked with copper to 200 μg Cu g -1 dry weight sediment in order to assess the impact of copper on bacterial degradation of organic matter and on bacterial biomass production. Bacterial density was determined by direct counting under epifluorescence microscopy and bacterial production by the incorporation of 3H-Leucine. Leucine turnover rate was evaluated by 14C-leucine incorporation and ectoenzymatic activities were estimated as the hydrolysis rate of model substrates for β-glucosidase and leucine-aminopeptidase. The presence of added copper in the microcosms elicited, after 21 days of incubation, generalised anoxia and a decrease in organic matter content. The non-eroded surface of the copper-spiked sediment showed, when compared to the control, a decrease in bacterial abundance and significant lower levels of bacterial production and of leucine turnover rate. Bacterial production and leucine turnover rate decreased to 1.4% and 13% of the control values, respectively. Ectoenzymatic activities were also negatively affected but by smaller factors. After erosion by the water current in laboratory flume conditions, the eroded surface of the control sediment showed a generalised decline in all bacterial activities. The erosion of the copper-spiked sediment showed, however, two types of responses with respect to bacterial activities at the exposed surface: positive responses of bacterial production and leucine turnover rate contrasting with slight negative responses of ectoenzymatic activities. The effects of experimental erosion in the suspended cells were also different in the control and in the copper-spiked sediment. Bacterial cells in the control microcosm exhibited, when compared to the non-eroded sediment cells, decreases in all activities after the 6-h suspension. The response of the average suspended copper-spiked sediment cell differed from the control by a less sharp decrease in ectoenzymatic activities and

Algal-bacterial interactions in metal contaminated floodplain sediments

International Nuclear Information System (INIS)

Boivin, M.E.Y.; Greve, G.D.; Garcia-Meza, J.V.; Massieux, B.; Sprenger, W.; Kraak, M.H.S.; Breure, A.M.; Rutgers, M.; Admiraal, W.

2007-01-01

The aim of the present study was to investigate algal-bacterial interactions in a gradient of metal contaminated natural sediments. By means of multivariate techniques, we related the genetic structure (denaturing gradient gel electrophoresis, DGGE) and the physiological structure (community-level physiological profiling, CLPP) of the bacterial communities to the species composition of the algal communities and to the abiotic environmental variables, including metal contamination. The results revealed that genetic and physiological structure of the bacterial communities correlated with the species composition of the algal community, but hardly to the level of metal pollution. This must be interpreted as an indication for a strong and species-specific linkage of algal and bacterial species in floodplain sediments. Metals were, however, not proven to affect either the algal or the bacterial communities of the Dutch river floodplains. - Algal and bacterial communities in floodplain sediments are interlinked, but are not affected by metal pollution

Neonatal Bacterial Meningitis And Dexamethasone Adjunctive ...

African Journals Online (AJOL)

Methodology: Babies admitted from1992 to 1995 in the Special Care Baby Unit of the University of Maiduguri Teaching Hospital, Maduguri, Nigeria, with bacterial meningitis were studied prospectively. Neonatal bacterial meningitis was confirmed if the cerebrospinal fluid (CSF) microbiological, chemical, immunological and ...

Bacterial fatty acid metabolism in modern antibiotic discovery.

Science.gov (United States)

Yao, Jiangwei; Rock, Charles O

2017-11-01

Bacterial fatty acid synthesis is essential for many pathogens and different from the mammalian counterpart. These features make bacterial fatty acid synthesis a desirable target for antibiotic discovery. The structural divergence of the conserved enzymes and the presence of different isozymes catalyzing the same reactions in the pathway make bacterial fatty acid synthesis a narrow spectrum target rather than the traditional broad spectrum target. Furthermore, bacterial fatty acid synthesis inhibitors are single-targeting, rather than multi-targeting like traditional monotherapeutic, broad-spectrum antibiotics. The single-targeting nature of bacterial fatty acid synthesis inhibitors makes overcoming fast-developing, target-based resistance a necessary consideration for antibiotic development. Target-based resistance can be overcome through multi-targeting inhibitors, a cocktail of single-targeting inhibitors, or by making the single targeting inhibitor sufficiently high affinity through a pathogen selective approach such that target-based mutants are still susceptible to therapeutic concentrations of drug. Many of the pathogens requiring new antibiotic treatment options encode for essential bacterial fatty acid synthesis enzymes. This review will evaluate the most promising targets in bacterial fatty acid metabolism for antibiotic therapeutics development and review the potential and challenges in advancing each of these targets to the clinic and circumventing target-based resistance. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

Campylobacter jejuni cocultured with epithelial cells reduces surface capsular polysaccharide expression.

LENUS (Irish Health Repository)

Corcionivoschi, N

2012-02-01

The host cell environment can alter bacterial pathogenicity. We employed a combination of cellular and molecular techniques to study the expression of Campylobacter jejuni polysaccharides cocultured with HCT-8 epithelial cells. After two passages, the amount of membrane-bound high-molecular-weight polysaccharide was considerably reduced. Microarray profiling confirmed significant downregulation of capsular polysaccharide (CPS) locus genes. Experiments using conditioned media showed that sugar depletion occurred only when the bacterial and epithelial cells were cocultured. CPS depletion occurred when C. jejuni organisms were exposed to conditioned media from a different C. jejuni strain but not when exposed to conditioned media from other bacterial species. Proteinase K or heat treatment of conditioned media under coculture conditions abrogated the effect on the sugars, as did formaldehyde fixation and cycloheximide treatment of host cells or chloramphenicol treatment of the bacteria. However, sugar depletion was not affected in flagellar export (fliQ) and quorum-sensing (luxS) gene mutants. Passaged C. jejuni showed reduced invasiveness and increased serum sensitivity in vitro. C. jejuni alters its surface polysaccharides when cocultured with epithelial cells, suggesting the existence of a cross talk mechanism that modulates CPS expression during infection.

Initial insights into bacterial succession during human decomposition.

Science.gov (United States)

Hyde, Embriette R; Haarmann, Daniel P; Petrosino, Joseph F; Lynne, Aaron M; Bucheli, Sibyl R

2015-05-01

Decomposition is a dynamic ecological process dependent upon many factors such as environment, climate, and bacterial, insect, and vertebrate activity in addition to intrinsic properties inherent to individual cadavers. Although largely attributed to microbial metabolism, very little is known about the bacterial basis of human decomposition. To assess the change in bacterial community structure through time, bacterial samples were collected from several sites across two cadavers placed outdoors to decompose and analyzed through 454 pyrosequencing and analysis of variable regions 3-5 of the bacterial 16S ribosomal RNA (16S rRNA) gene. Each cadaver was characterized by a change in bacterial community structure for all sites sampled as time, and decomposition, progressed. Bacteria community structure is variable at placement and before purge for all body sites. At bloat and purge and until tissues began to dehydrate or were removed, bacteria associated with flies, such as Ignatzschineria and Wohlfahrtimonas, were common. After dehydration and skeletonization, bacteria associated with soil, such as Acinetobacter, were common at most body sites sampled. However, more cadavers sampled through multiple seasons are necessary to assess major trends in bacterial succession.

SEXUAL DYSFUNCTION ASSOCIATION WITH THE CHRONIC BACTERIAL PROSTATITIS

Directory of Open Access Journals (Sweden)

H. S. Ibishev

2013-01-01

Full Text Available The study involved 230 patients aged 20 to 45 years with a diagnosis of chronic bacterial prostatitis. The study found that in patients with chronic bacterial prostatitis clinical picture, in addition to pain, is a lower urinary tract symptoms, neuro-vegetative and sexual dysfunction. In patients with chronic bacterial prostatitis, recorded various sexual disorders, most of which are normalized after antibiotic therapy. Erectile dysfunction, which are recorded in patients with chronic bacterial prostatitis is psychogenic in nature dysfunction.

The burden of bacterial vaginosis: women's experience of the physical, emotional, sexual and social impact of living with recurrent bacterial vaginosis.

Directory of Open Access Journals (Sweden)

Jade E Bilardi

Full Text Available BACKGROUND: Bacterial vaginosis is a common vaginal infection, causing an abnormal vaginal discharge and/or odour in up to 50% of sufferers. Recurrence is common following recommended treatment. There are limited data on women's experience of bacterial vaginosis, and the impact on their self-esteem, sexual relationships and quality of life. The aim of this study was to explore the experiences and impact of recurrent bacterial vaginosis on women. METHODS: A social constructionist approach was chosen as the framework for the study. Thirty five women with male and/or female partners participated in semi-structured interviews face-to-face or by telephone about their experience of recurrent bacterial vaginosis. RESULTS: Recurrent bacterial vaginosis impacted on women to varying degrees, with some women reporting it had little impact on their lives but most reporting it had a moderate to severe impact. The degree to which it impacted on women physically, emotionally, sexually and socially often depended on the frequency of episodes and severity of symptoms. Women commonly reported that symptoms of bacterial vaginosis made them feel embarrassed, ashamed, 'dirty' and very concerned others may detect their malodour and abnormal discharge. The biggest impact of recurrent bacterial vaginosis was on women's self-esteem and sex lives, with women regularly avoiding sexual activity, in particular oral sex, as they were too embarrassed and self-conscious of their symptoms to engage in these activities. Women often felt confused about why they were experiencing recurrent bacterial vaginosis and frustrated at their lack of control over recurrence. CONCLUSION: Women's experience of recurrent bacterial vaginosis varied broadly and significantly in this study. Some women reported little impact on their lives but most reported a moderate to severe impact, mainly on their self-esteem and sex life. Further support and acknowledgement of these impacts are required when

Bacterial flora of conjunctiva after death

Directory of Open Access Journals (Sweden)

Sagili Chandrasekhara Reddy

2013-10-01

Full Text Available AIM:To evaluate the frequency of bacterial flora of conjunctiva after death (cadaver eyes which will give information about the bacterial contamination of donor eyes, and the in-vitro sensitivity of isolated bacteria to the commonly used antibiotics in ophthalmic practice.METHODS: Conjunctival swabs were taken from the cadavers (motor vehicle accident deaths and patients who died in the hospital, within 6h after death, and sent for culture and sensitivity test. Conjunctival swabs, taken from the healthy conjunctiva of patients admitted for cataract surgery, were sent for culture and sensitivity as controls (eyes in those of living status. The bacterial isolates were tested against the commonly used antibiotics (chloramphenicol, gentamicin, ciprofloxacin in ophthalmology practice.RESULTS: Bacteria were isolated in 41 out of 100 conjunctival swabs (41%, taken from 50 cadavers (study group. Coagulase negative staphylococcus was the most common bacteria isolated (15%, followed by pseudomonas aeruginosa (5%. Gentamicin was effective against majority of the bacterial isolates (82%. Bacteria were isolated from 7 out of 100 conjunctival swabs taken as control group (eyes in living state. Coagulase negative staphylococcus was the most common organism (5% isolated in control group; the others were staphylococcus aureus (1% and beta hemolyticus streptococci (1%.CONCLUSION: Bacteria were isolated from 41% of the cadaver eyes. High percentage sensitivity of the bacterial isolates to gentamicin (82% supports the practice of thorough irrigation of the eyes with gentamicin solution before starting the procedure of enucleation followed by immersion of the enucleated eyeballs in gentamycin solution, to prevent the bacterial contamination.

Does circumcision alter the periurethral uropathogenic bacterial flora

African Journals Online (AJOL)

Background: The aim of this study was to assess the pattern of periurethral bacterial flora in uncircumcised boys and to evaluate the effect of circumcision on alteration of periurethral uropathogenic bacterial flora. Materials and Methods: Pattern of periurethral bacterial flora before and after circumcision was studied ...

Diazotrophic Bacterial Community of Degraded Pastures

Directory of Open Access Journals (Sweden)

João Tiago Correia Oliveira

2017-01-01

Full Text Available Pasture degradation can cause changes in diazotrophic bacterial communities. Thus, this study aimed to evaluate the culturable and total diazotrophic bacterial community, associated with regions of the rhizosphere and roots of Brachiaria decumbens Stapf. pastures in different stages of degradation. Samples of roots and rhizospheric soil were collected from slightly, partially, and highly degraded pastures. McCrady’s table was used to obtain the Most Probable Number (MPN of bacteria per gram of sample, in order to determine population density and calculate the Shannon-Weaver diversity index. The diversity of total diazotrophic bacterial community was determined by the technique of Denaturing Gradient Gel Electrophoresis (DGGE of the nifH gene, while the diversity of the culturable diazotrophic bacteria was determined by the Polymerase Chain Reaction (BOX-PCR technique. The increase in the degradation stage of the B. decumbens Stapf. pasture did not reduce the population density of the cultivated diazotrophic bacterial community, suggesting that the degradation at any degree of severity was highly harmful to the bacteria. The structure of the total diazotrophic bacterial community associated with B. decumbens Stapf. was altered by the pasture degradation stage, suggesting a high adaptive capacity of the bacteria to altered environments.

The epidemiology of bacterial meningitis in Kosovo.

Science.gov (United States)

Namani, Sadie A; Koci, Remzie A; Qehaja-Buçaj, Emine; Ajazaj-Berisha, Lindita; Mehmeti, Murat

2014-07-14

The purpose of this study was to present the epidemiologic features of bacterial meningitis in the developing country of Kosovo. Data were collected from active surveillance of bacterial meningitis cases treated at the University Clinical Center of Kosovo in the years 2000 (first post-war year) and 2010. Meningitis cases in 2000 compared with 2010 showed a 35.5% decline in incidence (from 4.8 to 3.1 cases per 100,000 population) and a decrease in the case fatality rate from 10% to 5%. In children, there was a lower mortality rate (5% versus 2%) and a lower incidence of neurological complications (13% versus 16%) as compared to adults (32% versus 10% and 16% versus 35%, respectively). Neisseria meningitidis was the most common pathogen of bacterial meningitis in both study periods. Bacterial meningitis was most prevalent in the pediatric population, and showed an increase in the median age, from three years in 2000 to seven years in 2010. A steady number of bacterial meningitis cases in adults throughout last decade (around 20 cases per year) was recorded. During the last decade, gradual changes have been observed in the epidemiology of bacterial meningitis that are unrelated to the introduction of new vaccines, but are partly due to the improvement of living conditions.

NCBI nr-aa BLAST: CBRC-DYAK-02-0067 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-DYAK-02-0067 ref|ZP_01869402.1| flagellar biosynthetic protein [Vibrio shiloni...i AK1] gb|EDL51961.1| flagellar biosynthetic protein [Vibrio shilonii AK1] ZP_01869402.1 2.1 21% ...

The use of 14C-FIAU to predict bacterial thymidine kinase presence: Implications for radiolabeled FIAU bacterial imaging

International Nuclear Information System (INIS)

Peterson, Kristin L.; Reid, William C.; Freeman, Alexandra F.; Holland, Steven M.; Pettigrew, Roderic I.; Gharib, Ahmed M.; Hammoud, Dima A.

2013-01-01

Currently available infectious disease imaging techniques cannot differentiate between infection and sterile inflammation or between different types of infections. Recently, radiolabeled FIAU was found to be a substrate for the thymidine kinase (TK) enzyme of multiple pathogenic bacteria, leading to its translational use in the imaging of bacterial infections. Patients with immunodeficiencies, however, are susceptible to a different group of pathogenic bacteria when compared to immunocompetent subjects. In this study, we wanted to predict the usefulness of radiolabeled FIAU in the detection of bacterial infections commonly occurring in patients with immunodeficiencies, in vitro, prior to attempting in vivo imaging with 124 I-FIAU-PET. Methods: We obtained representative strains of bacterial pathogens isolated from actual patients with genetic immunodeficiencies. We evaluated the bacterial susceptibility of different strains to the effect of incubation with FIAU, which would implicate the presence of the thymidine kinase (TK) enzyme. We also incubated the bacteria with 14 C-FIAU and consequently measured its rate of incorporation in the bacterial DNA using a liquid scintillation counter. Results: Unlike the other bacterial strains, the growth of Pseudomonas aeruginosa was not halted by FIAU at any concentration. All the tested clinical isolates demonstrated different levels of 14 C-FIAU uptake, except for P. aeruginosa. Conclusion: Radiolabeled FIAU has been successful in delineating bacterial infections, both in preclinical and pilot translational studies. In patients with immunodeficiencies, Pseudomonas infections are commonly encountered and are usually difficult to differentiate from fungal infections. The use of radiolabeled FIAU for in vivo imaging of those patients, however, would not be useful, considering the apparent lack of TK enzyme in Pseudomonas. One has to keep in mind that not all pathogenic bacteria possess the TK enzyme and as such will not all

Antibiotic resistance of bacterial biofilms

DEFF Research Database (Denmark)

Hoiby, N.; Bjarnsholt, T.; Givskov, M.

2010-01-01

A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and DNA. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and disinfectant chemicals as well as resisting phagocytosis...... and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains....... Characteristically, gradients of nutrients and oxygen exist from the top to the bottom of biofilms and these gradients are associated with decreased bacterial metabolic activity and increased doubling times of the bacterial cells; it is these more or less dormant cells that are responsible for some of the tolerance...

Nest Material Shapes Eggs Bacterial Environment.

Directory of Open Access Journals (Sweden)

Cristina Ruiz-Castellano

Full Text Available Selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. Due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. However, experimental evidence suggesting such effects is scarce in the literature. During two consecutive years, we explored experimentally the effects of these nest materials on loads of different groups of bacteria (mesophilic bacteria, Enterobacteriaceae, Staphylococcus and Enterococcus of eggshells in nests of spotless starlings (Sturnus unicolor at the beginning and at the end of the incubation period. This was also explored in artificial nests without incubation activity. We also experimentally increased bacterial density of eggs in natural and artificial nests and explored the effects of nest lining treatments on eggshell bacterial load. Support for the hypothetical antimicrobial function of nest materials was mainly detected for the year and location with larger average values of eggshell bacterial density. The beneficial effects of feathers and plants were more easily detected in artificial nests with no incubation activity, suggesting an active role of incubation against bacterial colonization of eggshells. Pigmented and unpigmented feathers reduced eggshell bacterial load in starling nests and artificial nest boxes. Results from artificial nests allowed us to discuss and discard alternative scenarios explaining the detected association, particularly those related to the possible sexual role of feathers and aromatic plants in starling nests. All these results considered together confirm the antimicrobial functionality mainly of feathers but also of plants used as nest materials, and highlight the importance of temporally and

Nest Material Shapes Eggs Bacterial Environment.

Science.gov (United States)

Ruiz-Castellano, Cristina; Tomás, Gustavo; Ruiz-Rodríguez, Magdalena; Martín-Gálvez, David; Soler, Juan José

2016-01-01

Selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. Due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. However, experimental evidence suggesting such effects is scarce in the literature. During two consecutive years, we explored experimentally the effects of these nest materials on loads of different groups of bacteria (mesophilic bacteria, Enterobacteriaceae, Staphylococcus and Enterococcus) of eggshells in nests of spotless starlings (Sturnus unicolor) at the beginning and at the end of the incubation period. This was also explored in artificial nests without incubation activity. We also experimentally increased bacterial density of eggs in natural and artificial nests and explored the effects of nest lining treatments on eggshell bacterial load. Support for the hypothetical antimicrobial function of nest materials was mainly detected for the year and location with larger average values of eggshell bacterial density. The beneficial effects of feathers and plants were more easily detected in artificial nests with no incubation activity, suggesting an active role of incubation against bacterial colonization of eggshells. Pigmented and unpigmented feathers reduced eggshell bacterial load in starling nests and artificial nest boxes. Results from artificial nests allowed us to discuss and discard alternative scenarios explaining the detected association, particularly those related to the possible sexual role of feathers and aromatic plants in starling nests. All these results considered together confirm the antimicrobial functionality mainly of feathers but also of plants used as nest materials, and highlight the importance of temporally and geographically

Detergent-compatible bacterial amylases.

Science.gov (United States)

Niyonzima, Francois N; More, Sunil S

2014-10-01

Proteases, lipases, amylases, and cellulases are enzymes used in detergent formulation to improve the detergency. The amylases are specifically supplemented to the detergent to digest starchy stains. Most of the solid and liquid detergents that are currently manufactured contain alkaline enzymes. The advantages of using alkaline enzymes in the detergent formulation are that they aid in removing tough stains and the process is environmentally friendly since they reduce the use of toxic detergent ingredients. Amylases active at low temperature are preferred as the energy consumption gets reduced, and the whole process becomes cost-effective. Most microbial alkaline amylases are used as detergent ingredients. Various reviews report on the production, purification, characterization, and application of amylases in different industry sectors, but there is no specific review on bacterial or fungal alkaline amylases or detergent-compatible amylases. In this mini-review, an overview on the production and property studies of the detergent bacterial amylases is given, and the stability and compatibility of the alkaline bacterial amylases in the presence of the detergents and the detergent components are highlighted.

Bacterial pathogen manipulation of host membrane trafficking.

Science.gov (United States)

Asrat, Seblewongel; de Jesús, Dennise A; Hempstead, Andrew D; Ramabhadran, Vinay; Isberg, Ralph R

2014-01-01

Pathogens use a vast number of strategies to alter host membrane dynamics. Targeting the host membrane machinery is important for the survival and pathogenesis of several extracellular, vacuolar, and cytosolic bacteria. Membrane manipulation promotes bacterial replication while suppressing host responses, allowing the bacterium to thrive in a hostile environment. This review provides a comprehensive summary of various strategies used by both extracellular and intracellular bacteria to hijack host membrane trafficking machinery. We start with mechanisms used by bacteria to alter the plasma membrane, delve into the hijacking of various vesicle trafficking pathways, and conclude by summarizing bacterial adaptation to host immune responses. Understanding bacterial manipulation of host membrane trafficking provides insights into bacterial pathogenesis and uncovers the molecular mechanisms behind various processes within a eukaryotic cell.

Grepafloxacin in Patients with Acute Bacterial Exacerbations of Chronic Bronchitis - a Question of Speed in Bacterial Killing

Directory of Open Access Journals (Sweden)

Jerome J Schentag

1998-01-01

Full Text Available OBJECTIVE: To characterize the population pharmacokinetics and pharmacodynamics of oral grepafloxacin in patients with acute bacterial exacerbations of chronic bronchitis (ABECB, with particular attention to the speed of bacterial killing. This was possible because the study design incorporated daily cultures of the patients’ sputum.

Bacterial vaginosis - aftercare

Science.gov (United States)

Bacterial vaginosis (BV) is a type of vaginal infection. The vagina normally contains both healthy bacteria and unhealthy bacteria. BV occurs when more unhealthy bacteria grow than healthy bacteria. No one knows ...

The bacterial meningitis score to distinguish bacterial from aseptic meningitis in children from Sao Paulo, Brazil.

Science.gov (United States)

Mekitarian Filho, Eduardo; Horita, Sérgio Massaru; Gilio, Alfredo Elias; Alves, Anna Cláudia Dominguez; Nigrovic, Lise E

2013-09-01

In a retrospective cohort of 494 children with meningitis in Sao Paulo, Brazil, the Bacterial Meningitis Score identified all the children with bacterial meningitis (sensitivity 100%, 95% confidence interval: 92-100% and negative predictive value 100%, 95% confidence interval: 98-100%). Addition of cerebrospinal fluid lactate to the score did not improve clinical prediction rule performance.

[Bacterial biofilms and infection].

Science.gov (United States)

Lasa, I; Del Pozo, J L; Penadés, J R; Leiva, J

2005-01-01

In developed countries we tend to think of heart disease and the numerous forms of cancer as the main causes of mortality, but on a global scale infectious diseases come close, or may even be ahead: 14.9 million deaths in 2002 compared to cardiovascular diseases (16.9 million deaths) and cancer (7.1 million deaths) (WHO report 2004). The infectious agents responsible for human mortality have evolved as medical techniques and hygienic measures have changed. Modern-day acute infectious diseases caused by specialized bacterial pathogens such as diphtheria, tetanus, cholera, plague, which represented the main causes of death at the beginning of XX century, have been effectively controlled with antibiotics and vaccines. In their place, more than half of the infectious diseases that affect mildly immunocompromised patients involve bacterial species that are commensal with the human body; these can produce chronic infections, are resistant to antimicrobial agents and there is no effective vaccine against them. Examples of these infections are the otitis media, native valve endocarditis, chronic urinary infections, bacterial prostatitis, osteomyelitis and all the infections related to medical devices. Direct analysis of the surface of medical devices or of tissues that have been foci of chronic infections shows the presence of large numbers of bacteria surrounded by an exopolysaccharide matrix, which has been named the "biofilm". Inside the biofilm, bacteria grow protected from the action of the antibodies, phagocytic cells and antimicrobial treatments. In this article, we describe the role of bacterial biofilms in human persistent infections.

Abdominal radiation causes bacterial translocation

International Nuclear Information System (INIS)

Guzman-Stein, G.; Bonsack, M.; Liberty, J.; Delaney, J.P.

1989-01-01

The purpose of this study was to determine if a single dose of radiation to the rat abdomen leads to bacterial translocation into the mesenteric lymph nodes (MLN). A second issue addressed was whether translocation correlates with anatomic damage to the mucosa. The radiated group (1100 cGy) which received anesthesia also was compared with a control group and a third group which received anesthesia alone but no abdominal radiation. Abdominal radiation lead to 100% positive cultures of MLN between 12 hr and 4 days postradiation. Bacterial translocation was almost nonexistent in the control and anesthesia group. Signs of inflammation and ulceration of the intestinal mucosa were not seen until Day 3 postradiation. Mucosal damage was maximal by Day 4. Bacterial translocation onto the MLN after a single dose of abdominal radiation was not apparently dependent on anatomical, histologic damage of the mucosa

Presence of bacterial DNA and bacterial peptidoglycans in joints of patients with rheumatoid arthritis and other arthritides

NARCIS (Netherlands)

van der Heijden, I. M.; Wilbrink, B.; Tchetverikov, I.; Schrijver, I. A.; Schouls, L. M.; Hazenberg, M. P.; Breedveld, F. C.; Tak, P. P.

2000-01-01

The continuous presence of bacteria or their degraded antigens in the synovium may be involved in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to determine the presence of bacterial nucleic acids and bacterial cell wall constituents in the joints of patients with RA and

The Burden of Bacterial Vaginosis: Women’s Experience of the Physical, Emotional, Sexual and Social Impact of Living with Recurrent Bacterial Vaginosis

Science.gov (United States)

Bilardi, Jade E.; Walker, Sandra; Temple-Smith, Meredith; McNair, Ruth; Mooney-Somers, Julie; Bellhouse, Clare; Fairley, Christopher K.; Chen, Marcus Y.; Bradshaw, Catriona

2013-01-01

Background Bacterial vaginosis is a common vaginal infection, causing an abnormal vaginal discharge and/or odour in up to 50% of sufferers. Recurrence is common following recommended treatment. There are limited data on women’s experience of bacterial vaginosis, and the impact on their self-esteem, sexual relationships and quality of life. The aim of this study was to explore the experiences and impact of recurrent bacterial vaginosis on women. Methods A social constructionist approach was chosen as the framework for the study. Thirty five women with male and/or female partners participated in semi-structured interviews face-to-face or by telephone about their experience of recurrent bacterial vaginosis. Results Recurrent bacterial vaginosis impacted on women to varying degrees, with some women reporting it had little impact on their lives but most reporting it had a moderate to severe impact. The degree to which it impacted on women physically, emotionally, sexually and socially often depended on the frequency of episodes and severity of symptoms. Women commonly reported that symptoms of bacterial vaginosis made them feel embarrassed, ashamed, ‘dirty’ and very concerned others may detect their malodour and abnormal discharge. The biggest impact of recurrent bacterial vaginosis was on women’s self-esteem and sex lives, with women regularly avoiding sexual activity, in particular oral sex, as they were too embarrassed and self-conscious of their symptoms to engage in these activities. Women often felt confused about why they were experiencing recurrent bacterial vaginosis and frustrated at their lack of control over recurrence. Conclusion Women’s experience of recurrent bacterial vaginosis varied broadly and significantly in this study. Some women reported little impact on their lives but most reported a moderate to severe impact, mainly on their self-esteem and sex life. Further support and acknowledgement of these impacts are required when managing women

Bacterial pyomyositis in a patient with aplastic anaemia.

OpenAIRE

Mitsuyasu, R.; Gale, R. P.

1980-01-01

Bacterial pyomyositis is common in the tropids but is rare in temperate climates. A patient with aplastic anaemia who had never left the continental United States developed bacterial pyomyositis secondary to Staphylococcus aureus which responded to antibiotics and surgical drainage. Bacterial pyomyositis should be considered in the differential diagnosis of fever and myalgias in the immunocompromised patient.

Minerals in soil select distinct bacterial communities in their microhabitats.

Science.gov (United States)

Carson, Jennifer K; Campbell, Louise; Rooney, Deirdre; Clipson, Nicholas; Gleeson, Deirdre B

2009-03-01

We tested the hypothesis that different minerals in soil select distinct bacterial communities in their microhabitats. Mica (M), basalt (B) and rock phosphate (RP) were incubated separately in soil planted with Trifolium subterraneum, Lolium rigidum or left unplanted. After 70 days, the mineral and soil fractions were separated by sieving. Automated ribosomal intergenic spacer analysis was used to determine whether the bacterial community structure was affected by the mineral, fraction and plant treatments. Principal coordinate plots showed clustering of bacterial communities from different fraction and mineral treatments, but not from different plant treatments. Permutational multivariate anova (permanova) showed that the microhabitats of M, B and RP selected bacterial communities different from each other in unplanted and L. rigidum, and in T. subterraneum, bacterial communities from M and B differed (Ppermanova also showed that each mineral fraction selected bacterial communities different from the surrounding soil fraction (P<0.05). This study shows that the structure of bacterial communities in soil is influenced by the mineral substrates in their microhabitat and that minerals in soil play a greater role in bacterial ecology than simply providing an inert matrix for bacterial growth. This study suggests that mineral heterogeneity in soil contributes to the spatial variation in bacterial communities.

Bacterial strategies of resistance to antimicrobial peptides.

Science.gov (United States)

Joo, Hwang-Soo; Fu, Chih-Iung; Otto, Michael

2016-05-26

Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. © 2016 The Author(s).

Probing bacterial adhesion at the single-cell level

DEFF Research Database (Denmark)

Zeng, Guanghong; Müller, Torsten; Meyer, Rikke Louise

be considered. We have developed a simple and versatile method to make single-cell bacterial probes for measuring single cell adhesion by force spectroscopy using atomic force microscopy (AFM). A single-cell probe was readily made by picking up a bacterial cell from a glass surface by approaching a tipless AFM...... cantilever coated with the commercial cell adhesive CellTakTM. We applied the method to study adhesion of living cells to abiotic surfaces at the single-cell level. Immobilisation of single bacterial cells to the cantilever was stable for several hours, and viability was confirmed by Live/Dead staining...... on the adhesion force, we explored the bond formation and adhesive strength of four different bacterial strains towards three abiotic substrates with variable hydrophobicity and surface roughness. The adhesion force and final rupture length were dependent on bacterial strains, surfaces properties, and time...

Contrasting ability to take up leucine and thymidine among freshwater bacterial groups: implications for bacterial production measurements

Science.gov (United States)

Pérez, María Teresa; Hörtnagl, Paul; Sommaruga, Ruben

2010-01-01

We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiography. Our results showed that leucine was taken up by 70–80% of Bacteria-positive cells, whereas only 15–43% of Bacteria-positive cells were able to take up thymidine. When a saturating substrate concentration in combination with a short incubation was used, 80–90% of Betaproteobacteria and 67–79% of Actinobacteria were positive for leucine uptake, whereas thymidine was taken up by bacterial group. Bacterial abundance was a good predictor of the relative contribution of bacterial groups to leucine uptake, whereas when thymidine was used Actinobacteria represented the large majority (> 80%) of the cells taking up this substrate. Increasing the substrate concentration to 100 nM did not affect the percentage of R-BT cells taking up leucine (> 90% even at low concentrations), but moderately increased the fraction of thymidine-positive R-BT cells to a maximum of 35% of the hybridized cells. Our results show that even at very high concentrations, thymidine is not taken up by all, otherwise active, bacterial cells. PMID:19725866

9 CFR 113.64 - General requirements for live bacterial vaccines.

Science.gov (United States)

2010-01-01

... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

The Bacterial Sequential Markov Coalescent.

Science.gov (United States)

De Maio, Nicola; Wilson, Daniel J

2017-05-01

Bacteria can exchange and acquire new genetic material from other organisms directly and via the environment. This process, known as bacterial recombination, has a strong impact on the evolution of bacteria, for example, leading to the spread of antibiotic resistance across clades and species, and to the avoidance of clonal interference. Recombination hinders phylogenetic and transmission inference because it creates patterns of substitutions (homoplasies) inconsistent with the hypothesis of a single evolutionary tree. Bacterial recombination is typically modeled as statistically akin to gene conversion in eukaryotes, i.e. , using the coalescent with gene conversion (CGC). However, this model can be very computationally demanding as it needs to account for the correlations of evolutionary histories of even distant loci. So, with the increasing popularity of whole genome sequencing, the need has emerged for a faster approach to model and simulate bacterial genome evolution. We present a new model that approximates the coalescent with gene conversion: the bacterial sequential Markov coalescent (BSMC). Our approach is based on a similar idea to the sequential Markov coalescent (SMC)-an approximation of the coalescent with crossover recombination. However, bacterial recombination poses hurdles to a sequential Markov approximation, as it leads to strong correlations and linkage disequilibrium across very distant sites in the genome. Our BSMC overcomes these difficulties, and shows a considerable reduction in computational demand compared to the exact CGC, and very similar patterns in simulated data. We implemented our BSMC model within new simulation software FastSimBac. In addition to the decreased computational demand compared to previous bacterial genome evolution simulators, FastSimBac provides more general options for evolutionary scenarios, allowing population structure with migration, speciation, population size changes, and recombination hotspots. FastSimBac is

Bacterial binding to extracellular proteins - in vitro adhesion

DEFF Research Database (Denmark)

Schou, C.; Fiehn, N.-E.

1999-01-01

Viridans streptococci, bacterial adherence, extracellular matrix proteins, surface receptors, endocarditis......Viridans streptococci, bacterial adherence, extracellular matrix proteins, surface receptors, endocarditis...

Bacterial translocation: impact of probiotics

OpenAIRE

Jeppsson, Bengt; Mangell, Peter; Adawi, Diya; Molin, Göran

2004-01-01

There is a considerable amount of data in humans showing that patients who cannot take in nutrients enterally have more organ failure in the intensive care unit, a less favourable prognosis, and a higher frequency of septicaemia, in particular involving bacterial species from the intestinal tract. However, there is little evidence that this is connected with translocation of bacterial species in humans. Animal data more uniformly imply the existence of such a connection. The main focus of thi...

Antibiotics promote aggregation within aquatic bacterial communities

Directory of Open Access Journals (Sweden)

Gianluca eCorno

2014-07-01

Full Text Available The release of antibiotics (AB into the environment poses several threats for human health due to potential development of ABresistant natural bacteria. Even though the use of low-dose antibiotics has been promoted in health care and farming, significant amounts of AB are observed in aquatic environments. Knowledge on the impact of AB on natural bacterial communities is missing both in terms of spread and evolution of resistance mechanisms, and of modifications of community composition and productivity. New approaches are required to study the response of microbial communities rather than individual resistance genes. In this study a chemostat-based experiment with 4 coexisting bacterial strains has been performed to mimicking the response of a freshwater bacterial community to the presence of antibiotics in low and high doses. Bacterial abundance rapidly decreased by 75% in the presence of AB, independently of their concentration, and remained constant until the end of the experiment. The bacterial community was mainly dominated by Aeromonas hydrophila and Brevundimonas intermedia while the other two strains, Micrococcus luteus and Rhodococcus sp. never exceed 10%. Interestingly, the bacterial strains, which were isolated at the end of the experiment, were not AB-resistant, while reassembled communities composed of the 4 strains, isolated from treatments under AB stress, significantly raised their performance (growth rate, abundance in the presence of AB compared to the communities reassembled with strains isolated from the treatment without AB. By investigating the phenotypic adaptations of the communities subjected to the different treatments, we found that the presence of AB significantly increased co-aggregation by 5-6 fold.These results represent the first observation of co-aggregation as a successful strategy of AB resistance based on phenotype in aquatic bacterial communities, and can represent a fundamental step in the understanding of

Photoinactivation of major bacterial pathogens in aquaculture

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Heyong Jin Roh

2016-08-01

Full Text Available Abstract Background Significant increases in the bacterial resistance to various antibiotics have been found in fish farms. Non-antibiotic therapies for infectious diseases in aquaculture are needed. In recent years, light-emitting diode technology has been applied to the inactivation of pathogens, especially those affecting humans. The purpose of this study was to assess the effect of blue light (wavelengths 405 and 465 nm on seven major bacterial pathogens that affect fish and shellfish important in aquaculture. Results We successfully demonstrate inactivation activity of a 405/465-nm LED on selected bacterial pathogens. Although some bacteria were not fully inactivated by the 465-nm light, the 405-nm light had a bactericidal effect against all seven pathogens, indicating that blue light can be effective without the addition of a photosensitizer. Photobacterium damselae, Vibrio anguillarum, and Edwardsiella tarda were the most susceptible to the 405-nm light (36.1, 41.2, and 68.4 J cm−2, respectively, produced one log reduction in the bacterial populations, whereas Streptococcus parauberis was the least susceptible (153.8 J cm−2 per one log reduction. In general, optical density (OD values indicated that higher bacterial densities were associated with lower inactivating efficacy, with the exception of P. damselae and Vibrio harveyi. In conclusion, growth of the bacterial fish and shellfish pathogens evaluated in this study was inactivated by exposure to either the 405- or 465-nm light. In addition, inactivation was dependent on exposure time. Conclusions This study presents that blue LED has potentially alternative therapy for treating fish and shellfish bacterial pathogens. It has great advantages in aspect of eco-friendly treating methods differed from antimicrobial methods.

Does circumcision alter the periurethral uropathogenic bacterial flora

Directory of Open Access Journals (Sweden)

Mushtaq Ahmad Laway

2012-01-01

Full Text Available Background: The aim of this study was to assess the pattern of periurethral bacterial flora in uncircumcised boys and to evaluate the effect of circumcision on alteration of periurethral uropathogenic bacterial flora. Materials and Methods: Pattern of periurethral bacterial flora before and after circumcision was studied prospectively in 124 boys. The results were analysed to compare change in bacterial colonisation before and after circumcision. Results: The age range was 6 weeks to 96 months. Most (94.3% of the boys had religious indication and 5.7% had medical indication for circumcision. E. coli, Proteus and Klebsiella were most common periurethral bacterial flora in uncircumcised subjects. Coagulase-negative staphylococcus and Staphylococcus aureus was most common periurethral bacterial flora in circumcised subjects. In 66.1% of circumcised subjects, no bacteria were grown from periurethral region. Conclusion: We conclude that presence of prepuce is associated with great quantity of periurethral bacteria, greater likelihood of the presence of high concentration of uropathogens and high incidence of urinary tract infection (UTI. This study provides circumstantial evidence supporting the idea that early circumcision may be beneficial for prevention of UTI.

Metamorphosis of a butterfly-associated bacterial community.

Science.gov (United States)

Hammer, Tobin J; McMillan, W Owen; Fierer, Noah

2014-01-01

Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar) and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies.

Metamorphosis of a butterfly-associated bacterial community.

Directory of Open Access Journals (Sweden)

Tobin J Hammer

Full Text Available Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies.

Identifying Bacterial Immune Evasion Proteins Using Phage Display.

Science.gov (United States)

Fevre, Cindy; Scheepmaker, Lisette; Haas, Pieter-Jan

2017-01-01

Methods aimed at identification of immune evasion proteins are mainly rely on in silico prediction of sequence, structural homology to known evasion proteins or use a proteomics driven approach. Although proven successful these methods are limited by a low efficiency and or lack of functional identification. Here we describe a high-throughput genomic strategy to functionally identify bacterial immune evasion proteins using phage display technology. Genomic bacterial DNA is randomly fragmented and ligated into a phage display vector that is used to create a phage display library expressing bacterial secreted and membrane bound proteins. This library is used to select displayed bacterial secretome proteins that interact with host immune components.

Acute Bacterial Prostatitis: Diagnosis and Management.

Science.gov (United States)

Coker, Timothy J; Dierfeldt, Daniel M

2016-01-15

Acute bacterial prostatitis is an acute infection of the prostate gland that causes pelvic pain and urinary tract symptoms, such as dysuria, urinary frequency, and urinary retention, and may lead to systemic symptoms, such as fevers, chills, nausea, emesis, and malaise. Although the true incidence is unknown, acute bacterial prostatitis is estimated to comprise approximately 10% of all cases of prostatitis. Most acute bacterial prostatitis infections are community acquired, but some occur after transurethral manipulation procedures, such as urethral catheterization and cystoscopy, or after transrectal prostate biopsy. The physical examination should include abdominal, genital, and digital rectal examination to assess for a tender, enlarged, or boggy prostate. Diagnosis is predominantly made based on history and physical examination, but may be aided by urinalysis. Urine cultures should be obtained in all patients who are suspected of having acute bacterial prostatitis to determine the responsible bacteria and its antibiotic sensitivity pattern. Additional laboratory studies can be obtained based on risk factors and severity of illness. Radiography is typically unnecessary. Most patients can be treated as outpatients with oral antibiotics and supportive measures. Hospitalization and broad-spectrum intravenous antibiotics should be considered in patients who are systemically ill, unable to voluntarily urinate, unable to tolerate oral intake, or have risk factors for antibiotic resistance. Typical antibiotic regimens include ceftriaxone and doxycycline, ciprofloxacin, and piperacillin/tazobactam. The risk of nosocomial bacterial prostatitis can be reduced by using antibiotics, such as ciprofloxacin, before transrectal prostate biopsy.

NCBI nr-aa BLAST: CBRC-DRER-26-0282 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-DRER-26-0282 ref|ZP_01869403.1| putative flagellar biosynthetic protein FliR [Vibrio shilo...nii AK1] gb|EDL51962.1| putative flagellar biosynthetic protein FliR [Vibrio shilonii AK1] ZP_01869403.1 0.99 31% ...

Dispersal networks for enhancing bacterial degradation in heterogeneous environments

International Nuclear Information System (INIS)

Banitz, Thomas; Wick, Lukas Y.; Fetzer, Ingo; Frank, Karin; Harms, Hauke; Johst, Karin

2011-01-01

Successful biodegradation of organic soil pollutants depends on their bioavailability to catabolically active microorganisms. In particular, environmental heterogeneities often limit bacterial access to pollutants. Experimental and modelling studies revealed that fungal networks can facilitate bacterial dispersal and may thereby improve pollutant bioavailability. Here, we investigate the influence of such bacterial dispersal networks on biodegradation performance under spatially heterogeneous abiotic conditions using a process-based simulation model. To match typical situations in polluted soils, two types of abiotic conditions are studied: heterogeneous bacterial dispersal conditions and heterogeneous initial resource distributions. The model predicts that networks facilitating bacterial dispersal can enhance biodegradation performance for a wide range of these conditions. Additionally, the time horizon over which this performance is assessed and the network's spatial configuration are key factors determining the degree of biodegradation improvement. Our results support the idea of stimulating the establishment of fungal mycelia for enhanced bioremediation of polluted soils. - Highlights: → Bacterial dispersal networks can considerably improve biodegradation performance. → They facilitate bacterial access to dispersal-limited areas and remote resources. → Abiotic conditions, time horizon and network structure govern the improvements. → Stimulating the establishment of fungal mycelia promises enhanced soil remediation. - Simulation modelling demonstrates that fungus-mediated bacterial dispersal can considerably improve the bioavailability of organic pollutants under spatially heterogeneous abiotic conditions typical for water-unsaturated soils.

Dispersal networks for enhancing bacterial degradation in heterogeneous environments

Energy Technology Data Exchange (ETDEWEB)

Banitz, Thomas, E-mail: thomas.banitz@ufz.de [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Wick, Lukas Y.; Fetzer, Ingo [Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Frank, Karin [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Harms, Hauke [Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany); Johst, Karin [Department of Ecological Modelling, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig (Germany)

2011-10-15

Successful biodegradation of organic soil pollutants depends on their bioavailability to catabolically active microorganisms. In particular, environmental heterogeneities often limit bacterial access to pollutants. Experimental and modelling studies revealed that fungal networks can facilitate bacterial dispersal and may thereby improve pollutant bioavailability. Here, we investigate the influence of such bacterial dispersal networks on biodegradation performance under spatially heterogeneous abiotic conditions using a process-based simulation model. To match typical situations in polluted soils, two types of abiotic conditions are studied: heterogeneous bacterial dispersal conditions and heterogeneous initial resource distributions. The model predicts that networks facilitating bacterial dispersal can enhance biodegradation performance for a wide range of these conditions. Additionally, the time horizon over which this performance is assessed and the network's spatial configuration are key factors determining the degree of biodegradation improvement. Our results support the idea of stimulating the establishment of fungal mycelia for enhanced bioremediation of polluted soils. - Highlights: > Bacterial dispersal networks can considerably improve biodegradation performance. > They facilitate bacterial access to dispersal-limited areas and remote resources. > Abiotic conditions, time horizon and network structure govern the improvements. > Stimulating the establishment of fungal mycelia promises enhanced soil remediation. - Simulation modelling demonstrates that fungus-mediated bacterial dispersal can considerably improve the bioavailability of organic pollutants under spatially heterogeneous abiotic conditions typical for water-unsaturated soils.

Adjunctive Corticosteroids in Adults with Bacterial Meningitis

NARCIS (Netherlands)

van de Beek, Diederik; de Gans, Jan

2005-01-01

Bacterial meningitis is a complex disorder in which neurologic injury is caused, in part, by the causative organism and, in part, by the host's own inflammatory response. In studies of experimental bacterial meningitis, adjuvant treatment with corticosteroids, specifically dexamethasone, has

Bacterial Communities in Women with Bacterial Vaginosis: High Resolution Phylogenetic Analyses Reveal Relationships of Microbiota to Clinical Criteria

Science.gov (United States)

Srinivasan, Sujatha; Hoffman, Noah G.; Morgan, Martin T.; Matsen, Frederick A.; Fiedler, Tina L.; Hall, Robert W.; Ross, Frederick J.; McCoy, Connor O.; Bumgarner, Roger; Marrazzo, Jeanne M.; Fredricks, David N.

2012-01-01

Background Bacterial vaginosis (BV) is a common condition that is associated with numerous adverse health outcomes and is characterized by poorly understood changes in the vaginal microbiota. We sought to describe the composition and diversity of the vaginal bacterial biota in women with BV using deep sequencing of the 16S rRNA gene coupled with species-level taxonomic identification. We investigated the associations between the presence of individual bacterial species and clinical diagnostic characteristics of BV. Methodology/Principal Findings Broad-range 16S rRNA gene PCR and pyrosequencing were performed on vaginal swabs from 220 women with and without BV. BV was assessed by Amsel’s clinical criteria and confirmed by Gram stain. Taxonomic classification was performed using phylogenetic placement tools that assigned 99% of query sequence reads to the species level. Women with BV had heterogeneous vaginal bacterial communities that were usually not dominated by a single taxon. In the absence of BV, vaginal bacterial communities were dominated by either Lactobacillus crispatus or Lactobacillus iners. Leptotrichia amnionii and Eggerthella sp. were the only two BV-associated bacteria (BVABs) significantly associated with each of the four Amsel’s criteria. Co-occurrence analysis revealed the presence of several sub-groups of BVABs suggesting metabolic co-dependencies. Greater abundance of several BVABs was observed in Black women without BV. Conclusions/Significance The human vaginal bacterial biota is heterogeneous and marked by greater species richness and diversity in women with BV; no species is universally present. Different bacterial species have different associations with the four clinical criteria, which may account for discrepancies often observed between Amsel and Nugent (Gram stain) diagnostic criteria. Several BVABs exhibited race-dependent prevalence when analyzed in separate groups by BV status which may contribute to increased incidence of BV in

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments

Directory of Open Access Journals (Sweden)

Lidianne L. Rocha

2016-01-01

Full Text Available We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1 to habitats covered by Avicennia schaueriana (S2 and Rhizophora mangle (S3. Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole.

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments

Science.gov (United States)

Rocha, Lidianne L.; Colares, Geórgia B.; Nogueira, Vanessa L. R.; Paes, Fernanda A.; Melo, Vânia M. M.

2016-01-01

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole. PMID:26989418

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

Science.gov (United States)

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Bacterial intermediate filaments

DEFF Research Database (Denmark)

Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

2009-01-01

Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...

Analysis of bacterial communities and bacterial pathogens in a biogas plant by the combination of ethidium monoazide, PCR and Ion Torrent sequencing

DEFF Research Database (Denmark)

Luo, Gang; Angelidaki, Irini

2014-01-01

with time were also observed. This could be attributed to varying composition of the influent. Batch experiments showed that the methane recovery from the digested residues (obtained from biogas reactor) was mainly related with post-digestion temperature. However, post-digestion time rather than temperature......The present study investigated the changes of bacterial community composition including bacterial pathogens along a biogas plant, i.e. from the influent, to the biogas reactor and to the post-digester. The effects of post-digestion temperature and time on the changes of bacterial community...... showed that the bacterial community composition in the influent was changed after anaerobic digestion. Firmicutes were dominant in all the samples, while Proteobacteria decreased in the biogas reactor compared with the influent. Variations of bacterial community composition in the biogas reactor...

Molecular Analysis of Bacterial Microbiota on Brazilian Currency Note Surfaces

Directory of Open Access Journals (Sweden)

Tairacan Augusto Pereira da Fonseca

2015-10-01

Full Text Available Currency notes have been implicated as a vehicle for transmitting community-acquired bacterial infections. However, the overall diversity of the bacterial population residing on banknotes is still unknown in Brazil. In this study, we aimed to investigate the overall bacterial population from 150 different Brazilian Rial (R$ notes in circulation using a culture-independent Illumina massively parallel sequencing approach of the 16S rRNA genes. Samples were randomly collected from three different street markets or “feiras” in the metropolitan region of São Paulo. Taxonomical composition revealed the abundance of Proteobacteria phyla, followed by Firmicutes and Streptophyta, with a total of 1193 bacterial families and 3310 bacterial genera. Most of these bacterial genera are of human, animal, and environmental origins. Also, our analysis revealed the presence of some potential pathogenic bacterial genera including Salmonella, Staphylococcus, and Klebsiella. The results demonstrate that there is a tremendous diversity of bacterial contamination on currency notes, including organisms known to be opportunistic pathogens. One of the factors that may contribute to the richness of bacterial diversity in currency notes is personal hygiene. Thus, our results underscore the need to increase public awareness of the importance of personal hygiene of money handlers who also handle food.

Molecular Analysis of Bacterial Microbiota on Brazilian Currency Note Surfaces.

Science.gov (United States)

Pereira da Fonseca, Tairacan Augusto; Pessôa, Rodrigo; Sanabani, Sabri Saeed

2015-10-22

Currency notes have been implicated as a vehicle for transmitting community-acquired bacterial infections. However, the overall diversity of the bacterial population residing on banknotes is still unknown in Brazil. In this study, we aimed to investigate the overall bacterial population from 150 different Brazilian Rial (R$) notes in circulation using a culture-independent Illumina massively parallel sequencing approach of the 16S rRNA genes. Samples were randomly collected from three different street markets or "feiras" in the metropolitan region of São Paulo. Taxonomical composition revealed the abundance of Proteobacteria phyla, followed by Firmicutes and Streptophyta, with a total of 1193 bacterial families and 3310 bacterial genera. Most of these bacterial genera are of human, animal, and environmental origins. Also, our analysis revealed the presence of some potential pathogenic bacterial genera including Salmonella, Staphylococcus, and Klebsiella. The results demonstrate that there is a tremendous diversity of bacterial contamination on currency notes, including organisms known to be opportunistic pathogens. One of the factors that may contribute to the richness of bacterial diversity in currency notes is personal hygiene. Thus, our results underscore the need to increase public awareness of the importance of personal hygiene of money handlers who also handle food.

Bacterial biofilms: prokaryotic adventures in multicellularity

DEFF Research Database (Denmark)

Webb, J.S.; Givskov, Michael Christian; Kjelleberg, S.

2003-01-01

The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight...... into differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity....

Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

Science.gov (United States)

Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

2018-06-15

The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

Bacterial desorption from food container and food processing surfaces.

Science.gov (United States)

McEldowney, S; Fletcher, M

1988-03-01

The desorption ofStaphylococcus aureus, Acinetobacter calcoaceticus, and a coryneform from the surfaces of materials used for manufacturing food containers (glass, tin plate, and polypropylene) or postprocess canning factory conveyor belts (stainless steel and nylon) was investigated. The effect of time, pH, temperature, and adsorbed organic layers on desorption was studied.S. aureus did not detach from the substrata at any pH investigated (between pH 5 and 9).A. calcoaceticus and the coryneform in some cases detached, depending upon pH and substratum composition. The degree of bacterial detachment from the substrata was not related to bacterial respiration at experimental pH values. Bacterial desorption was not affected by temperature (4-30°C) nor by an adsorbed layer of peptone and yeast extract on the substrata. The results indicate that bacterial desorption, hence bacterial removal during cleaning or their transfer via liquids flowing over colonized surfaces, is likely to vary with the surface composition and the bacterial species colonizing the surfaces.

Trade-off between bile resistance and nutritional competence drives Escherichia coli diversification in the mouse gut.

Directory of Open Access Journals (Sweden)

Marianne De Paepe

2011-06-01

Full Text Available Bacterial diversification is often observed, but underlying mechanisms are difficult to disentangle and remain generally unknown. Moreover, controlled diversification experiments in ecologically relevant environments are lacking. We studied bacterial diversification in the mammalian gut, one of the most complex bacterial environments, where usually hundreds of species and thousands of bacterial strains stably coexist. Herein we show rapid genetic diversification of an Escherichia coli strain upon colonisation of previously germ-free mice. In addition to the previously described mutations in the EnvZ/OmpR operon, we describe the rapid and systematic selection of mutations in the flagellar flhDC operon and in malT, the transcriptional activator of the maltose regulon. Moreover, within each mouse, the three mutant types coexisted at different levels after one month of colonisation. By combining in vivo studies and determination of the fitness advantages of the selected mutations in controlled in vitro experiments, we provide evidence that the selective forces that drive E. coli diversification in the mouse gut are the presence of bile salts and competition for nutrients. Altogether our results indicate that a trade-off between stress resistance and nutritional competence generates sympatric diversification of the gut microbiota. These results illustrate how experimental evolution in natural environments enables identification of both the selective pressures that organisms face in their natural environment and the diversification mechanisms.

Burkholderia glumae: next major pathogen of rice?

Science.gov (United States)

Ham, Jong Hyun; Melanson, Rebecca A; Rush, Milton C

2011-05-01

Burkholderia glumae causes bacterial panicle blight of rice, which is an increasingly important disease problem in global rice production. Toxoflavin and lipase are known to be major virulence factors of this pathogen, and their production is dependent on the TofI/TofR quorum-sensing system, which is mediated by N-octanoyl homoserine lactone. Flagellar biogenesis and a type III secretion system are also required for full virulence of B. glumae. Bacterial panicle blight is thought to be caused by seed-borne B. glumae; however, its disease cycle is not fully understood. In spite of its economic importance, neither effective control measures for bacterial panicle blight nor rice varieties showing complete resistance to the disease are currently available. A better understanding of the molecular mechanisms underlying B. glumae virulence and of the rice defence mechanisms against the pathogen would lead to the development of better methods of disease control for bacterial panicle blight. Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Burkholderia. Gram-negative, capsulated, motile, lophotrichous flagella, pectolytic. Aborted seed, empty grains as a result of failure of grain filling, brown spots on panicles, seedling rot. Seed sterilization, planting partially resistant lines (no completely resistant line is available). KNOWN VIRULENCE FACTORS: Toxoflavin, lipase, type III effectors. © 2010 LSU AGCENTER. MOLECULAR PLANT PATHOLOGY © 2010 BSPP AND BLACKWELL PUBLISHING LTD.

Bacterial Exposures and Associations with Atopy and Asthma in Children.

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Maria Valkonen

Full Text Available The increase in prevalence of asthma and atopic diseases in Western countries has been linked to aspects of microbial exposure patterns of people. It remains unclear which microbial aspects contribute to the protective farm effect.The objective of this study was to identify bacterial groups associated with prevalence of asthma and atopy, and to quantify indoor exposure to some of these bacterial groups.A DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE, was applied to mattress dust samples of farm children and control children in the context of the GABRIEL Advanced study. Associations between signals in DGGE and atopy, asthma and other allergic health outcomes were analyzed. Quantitative DNA based assays (qPCR for four bacterial groups were applied on the dust samples to seek quantitative confirmation of associations indicated in DNA fingerprinting.Several statistically significant associations between individual bacterial signals and also bacterial diversity in DGGE and health outcomes in children were observed. The majority of these associations showed inverse relationships with atopy, less so with asthma. Also, in a subsequent confirmation study using a quantitative method (qPCR, higher mattress levels of specifically targeted bacterial groups - Mycobacterium spp., Bifidobacteriaceae spp. and two different clusters of Clostridium spp. - were associated with a lower prevalence of atopy.DNA fingerprinting proved useful in identifying bacterial signals that were associated with atopy in particular. These findings were quantitatively confirmed for selected bacterial groups with a second method. High correlations between the different bacterial exposures impede a clear attribution of protective effects to one specific bacterial group. More diverse bacterial flora in mattress dust may link to microbial exposure patterns that protect against development of atopic diseases.

Bacterial contaminations of informally marketed raw milk in Ghana ...

African Journals Online (AJOL)

Background: Milk has an outstanding nutritional quality but is also an excellent medium for bacterial growth and an important source of bacterial infection when consumed without pasteurization. Objective: To estimate the bacterial health risk of milk consumption in Accra and Kumasi, the twomajor cities in Ghana. Method: A ...

Community-acquired bacterial meningitis in alcoholic patients.

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Martijn Weisfelt

2010-02-01

Full Text Available Alcoholism is associated with susceptibility to infectious disease, particularly bacterial pneumonia. In the present study we described characteristics in alcoholic patients with bacterial meningitis and delineate the differences with findings in non-alcoholic adults with bacterial meningitis.This was a prospective nationwide observational cohort study including patients aged >16 years who had bacterial meningitis confirmed by culture of cerebrospinal fluid (696 episodes of bacterial meningitis occurring in 671 patients. Alcoholism was present in 27 of 686 recorded episodes of bacterial meningitis (4% and alcoholics were more often male than non-alcoholics (82% vs 48%, P = 0.001. A higher proportion of alcoholics had underlying pneumonia (41% vs 11% P<0.001. Alcoholics were more likely to have meningitis due to infection with Streptococcus pneumoniae (70% vs 50%, P = 0.01 and Listeria monocytogenes (19% vs 4%, P = 0.005, whereas Neisseria meningitidis was more common in non-alcoholic patients (39% vs 4%, P = 0.01. A large proportion of alcoholics developed complications during clinical course (82% vs 62%, as compared with non-alcoholics; P = 0.04, often cardiorespiratory failure (52% vs 28%, as compared with non-alcoholics; P = 0.01. Alcoholic patients were at risk for unfavourable outcome (67% vs 33%, as compared with non-alcoholics; P<0.001.Alcoholic patients are at high risk for complications resulting in high morbidity and mortality. They are especially at risk for cardiorespiratory failure due to underlying pneumonia, and therefore, aggressive supportive care may be crucial in the treatment of these patients.

Determinants of bacterial communities in Canadian agroforestry systems.

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Banerjee, Samiran; Baah-Acheamfour, Mark; Carlyle, Cameron N; Bissett, Andrew; Richardson, Alan E; Siddique, Tariq; Bork, Edward W; Chang, Scott X

2016-06-01

Land-use change is one of the most important factors influencing soil microbial communities, which play a pivotal role in most biogeochemical and ecological processes. Using agroforestry systems as a model, this study examined the effects of land uses and edaphic properties on bacterial communities in three agroforestry types covering a 270 km soil-climate gradient in Alberta, Canada. Our results demonstrate that land-use patterns exert stronger effects on soil bacterial communities than soil zones in these agroforestry systems. Plots with trees in agroforestry systems promoted greater bacterial abundance and to some extent species richness, which was associated with more nutrient-rich soil resources. While Acidobacteria, Actinobacteria and Alphaproteobacteria were the dominant bacterial phyla and subphyla across land uses, Arthrobacter, Acidobacteria_Gp16, Burkholderia, Rhodanobacter and Rhizobium were the keystone taxa in these agroforestry systems. Soil pH and carbon contents emerged as the major determinants of bacterial community characteristics. We found non-random co-occurrence and modular patterns of soil bacterial communities, and these patterns were controlled by edaphic factors and not their taxonomy. Overall, this study highlights the drivers and co-occurrence patterns of soil microbial communities in agroforestry systems. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Centrioles are freed from cilia by severing prior to mitosis.

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Parker, Jeremy D K; Hilton, Laura K; Diener, Dennis R; Rasi, M Qasim; Mahjoub, Moe R; Rosenbaum, Joel L; Quarmby, Lynne M

2010-07-01

Cilia are necessary for normal tissue development and homeostasis and are generally present during interphase, but not in mitosis. The precise mechanism of premitotic ciliary loss has been controversial, with data supporting either sequential disassembly through the transition zone or, alternatively, a severing event at the base of the cilia. Here we show by live cell imaging and immunofluorescence microscopy that resorbing flagella of Chlamydomonas leave remnants associated with the mother cell wall. We postulated that the remnants are the product of severing of doublet microtubules between the basal bodies and the flagellar transition zone, thereby freeing the centrioles to participate in spindle organization. We show via TEM that flagellar remnants are indeed flagellar transition zones encased in vesicles derived from the flagellar membrane. This transition zone vesicle can be lodged within the cell wall or it can be expelled into the environment. This process is observable in Chlamydomonas, first because the released flagellar remnants can remain associated with the cell by virtue of attachments to the cell wall, and second because the Chlamydomonas transition zone is particularly rich with electron-dense structure. However, release of basal bodies for spindle-associated function is likely to be conserved among the eukaryotes. 2010 Wiley-Liss, Inc.

Bacterial successions in the Broiler Gastrointestinal tract

DEFF Research Database (Denmark)

Ranjitkar, Samir; Lawley, Blair; Tannock, Gerald

2016-01-01

diversity, data were pooled for downstream analysis. With increasing age, a clear succession of bacterial communities and an increased bacterial diversity was observed. Lactobacillaceae (mainly Lactobacillus) represented most of the Firmicutes at all ages and in all segments of the gut except the ceca...

neonatal bacterial meningitis in Cape Town children

African Journals Online (AJOL)

neonatal bacterial meningitis in Cape Town children. Bacterial meningitis is a major cause of childhood morbidity and mortality in South Africa. However, comprehensive regional or national epidemiological data, essential for rational public health interventions, are lacking. The purpose of this 1-year prospective study, from.

Specific amplification of bacterial DNA by optimized so-called universal bacterial primers in samples rich of plant DNA.

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Dorn-In, Samart; Bassitta, Rupert; Schwaiger, Karin; Bauer, Johann; Hölzel, Christina S

2015-06-01

Universal primers targeting the bacterial 16S-rRNA-gene allow quantification of the total bacterial load in variable sample types by qPCR. However, many universal primer pairs also amplify DNA of plants or even of archaea and other eukaryotic cells. By using these primers, the total bacterial load might be misevaluated, whenever samples contain high amounts of non-target DNA. Thus, this study aimed to provide primer pairs which are suitable for quantification and identification of bacterial DNA in samples such as feed, spices and sample material from digesters. For 42 primers, mismatches to the sequence of chloroplasts and mitochondria of plants were evaluated. Six primer pairs were further analyzed with regard to the question whether they anneal to DNA of archaea, animal tissue and fungi. Subsequently they were tested with sample matrix such as plants, feed, feces, soil and environmental samples. To this purpose, the target DNA in the samples was quantified by qPCR. The PCR products of plant and feed samples were further processed for the Single Strand Conformation Polymorphism method followed by sequence analysis. The sequencing results revealed that primer pair 335F/769R amplified only bacterial DNA in samples such as plants and animal feed, in which the DNA of plants prevailed. Copyright © 2015 Elsevier B.V. All rights reserved.

Temporal relationships exist between cecum, ileum and litter bacterial microbiomes in a commercial turkey flock, and subtherapeutic penicillin treatment impacts ileum bacterial community establishment

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Jessica L Danzeisen

2015-11-01

Full Text Available Gut health is paramount for commercial poultry production, and improved methods to assess gut health are critically needed to better understand how the avian gastrointestinal tract matures over time. One important aspect of gut health is the totality of bacterial populations inhabiting different sites of the avian gastrointestinal tract, and associations of these populations with the poultry farm environment, since these bacteria are thought to drive metabolism and prime the developing host immune system. In this study, a single flock of commercial turkeys was followed over the course of twelve weeks to examine bacterial microbiome inhabiting the ceca, ileum, and corresponding poultry litter. Furthermore, the effects of low-dose, growth-promoting penicillin treatment (50 g/ton in feed on the ileum bacterial microbiome were also examined during the early brood period. The cecum and ileum bacterial communities of turkeys were distinct, yet shifted in parallel to one another over time during bird maturation. Corresponding poultry litter was also distinct yet more closely represented the ileal bacterial populations than cecal bacterial populations, and also changed parallel to ileum bacterial populations over time. Penicillin applied at low dose in feed significantly enhanced early weight gain in commercial poults, and this correlated with predictable shifts in the ileum bacterial populations in control versus treatment groups. Overall, this study identified the dynamics of the turkey gastrointestinal microbiome during development, correlations between bacterial populations in the gastrointestinal tract and the litter environment, and the impact of low-dose penicillin on modulation of bacterial communities in the ileum. Such modulations provide a target for alternatives to low-dose antibiotics.

Structure of bacterial lipopolysaccharides.

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Caroff, Martine; Karibian, Doris

2003-11-14

Bacterial lipopolysaccharides are the major components of the outer surface of Gram-negative bacteria They are often of interest in medicine for their immunomodulatory properties. In small amounts they can be beneficial, but in larger amounts they may cause endotoxic shock. Although they share a common architecture, their structural details exert a strong influence on their activity. These molecules comprise: a lipid moiety, called lipid A, which is considered to be the endotoxic component, a glycosidic part consisting of a core of approximately 10 monosaccharides and, in "smooth-type" lipopolysaccharides, a third region, named O-chain, consisting of repetitive subunits of one to eight monosaccharides responsible for much of the immunospecificity of the bacterial cell.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

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Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María Del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio; Muñoz-Rojas, Jesús

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

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Dalia Molina-Romero

Full Text Available Plant growth-promoting rhizobacteria (PGPR increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440 and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02 strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

Normal bacterial flora from vaginas of Criollo Limonero cows.

Science.gov (United States)

Zambrano-Nava, Sunny; Boscán-Ocando, Julio; Nava, Jexenia

2011-02-01

In order to describe the normal bacterial flora in vaginas of Criollo Limonero cows, 51 healthy multiparous cows, at least 90-day postpartum, were selected. Duplicated swabs (N = 102) were taken from the vaginal fornix of cows to perform aerobic and anaerobic cultures as well as conventional biochemical tests. Out of 102 swabs, bacterial growth was obtained in 55 (53.9%) while the remaining 47 (46.1%) did not exhibited any bacterial growth. Of the 55 bacterial growths, 23 (41.8%) were aerobic whereas 32 (58.1%) were anaerobic. Likewise, 29 (52.72%) of bacterial growths were pure and 26 (47.27%) were mixed. Under both aerobic and anaerobic conditions, Gram positive bacteria were predominant (81.82% and 73.08%, respectively) over Gram negative bacteria (18.18% and 26.92%, respectively). Isolated bacteria were Arcanobacterium pyogenes (22.92%), Staphylococcus aureus (15.63%), Staphylococcus coagulase negative (17.71%), Erysipelothrix rhusiopathiae (6.25%), Bacteroides spp. (13.54%), and Peptostreptococcus spp. (7.29%). In conclusion, normal vaginal bacterial flora of Criollo Limonero cows was predominantly Gram positive and included A. pyogenes, S. aureus, coagulase negative Staphylococcus, E. rhusiopathiae, Bacteroides spp., and Peptostreptococcus spp. In Criollo Limonero cattle, adaptive aspects such as development of humoral and physical mechanisms for defense, and bacterial adaptation to host deserve research attention.

Applications of bacterial cellulose and its composites in biomedicine.

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Rajwade, J M; Paknikar, K M; Kumbhar, J V

2015-03-01

Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.

Bacterial carbon utilization in vertical subsurface flow constructed wetlands.

Science.gov (United States)

Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T

2008-03-01

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

Cytosolic access of intracellular bacterial pathogens: the Shigella paradigm

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Nora eMellouk

2016-04-01

Full Text Available Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Adaptive Bacterial Foraging Optimization

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Hanning Chen

2011-01-01

Full Text Available Bacterial Foraging Optimization (BFO is a recently developed nature-inspired optimization algorithm, which is based on the foraging behavior of E. coli bacteria. Up to now, BFO has been applied successfully to some engineering problems due to its simplicity and ease of implementation. However, BFO possesses a poor convergence behavior over complex optimization problems as compared to other nature-inspired optimization techniques. This paper first analyzes how the run-length unit parameter of BFO controls the exploration of the whole search space and the exploitation of the promising areas. Then it presents a variation on the original BFO, called the adaptive bacterial foraging optimization (ABFO, employing the adaptive foraging strategies to improve the performance of the original BFO. This improvement is achieved by enabling the bacterial foraging algorithm to adjust the run-length unit parameter dynamically during algorithm execution in order to balance the exploration/exploitation tradeoff. The experiments compare the performance of two versions of ABFO with the original BFO, the standard particle swarm optimization (PSO and a real-coded genetic algorithm (GA on four widely-used benchmark functions. The proposed ABFO shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.

Vaginal epithelial cells regulate membrane adhesiveness to co-ordinate bacterial adhesion

NARCIS (Netherlands)

Younes, Jessica A.; Klappe, Karin; Kok, Jan Willem; Busscher, Henk J.; Reid, Gregor; van der Mei, Henny C.

Vaginal epithelium is colonized by different bacterial strains and species. The bacterial composition of vaginal biofilms controls the balance between health and disease. Little is known about the relative contribution of the epithelial and bacterial cell surfaces to bacterial adhesion and whether

Isolation of cell-free bacterial inclusion bodies.

Science.gov (United States)

Rodríguez-Carmona, Escarlata; Cano-Garrido, Olivia; Seras-Franzoso, Joaquin; Villaverde, Antonio; García-Fruitós, Elena

2010-09-17

Bacterial inclusion bodies are submicron protein clusters usually found in recombinant bacteria that have been traditionally considered as undesirable products from protein production processes. However, being fully biocompatible, they have been recently characterized as nanoparticulate inert materials useful as scaffolds for tissue engineering, with potentially wider applicability in biomedicine and material sciences. Current protocols for inclusion body isolation from Escherichia coli usually offer between 95 to 99% of protein recovery, what in practical terms, might imply extensive bacterial cell contamination, not compatible with the use of inclusion bodies in biological interfaces. Using an appropriate combination of chemical and mechanical cell disruption methods we have established a convenient procedure for the recovery of bacterial inclusion bodies with undetectable levels of viable cell contamination, below 10⁻¹ cfu/ml, keeping the particulate organization of these aggregates regarding size and protein folding features. The application of the developed protocol allows obtaining bacterial free inclusion bodies suitable for use in mammalian cell cultures and other biological interfaces.

Identification and Characterization of Novel Biocontrol Bacterial

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Young Cheol Kim

2014-09-01

Full Text Available Because bacterial isolates from only a few genera have been developed commercially as biopesticides, discovery and characterization of novel bacterial strains will be a key to market expansion. Our previous screen using plant bioassays identified 24 novel biocontrol isolates representing 12 different genera. In this study, we characterized the 3 isolates showing the best biocontrol activities. The isolates were Pantoea dispersa WCU35, Proteus myxofaciens WCU244, and Exiguobacterium acetylicum WCU292 based on 16S rRNA sequence analysis. The isolates showed differential production of extracellular enzymes, antimicrobial activity against various fungal or bacterial plant pathogens, and induced systemic resistance activity against tomato gray mold disease caused by Botrytis cinerea. E. acetylicum WCU292 lacked strong in vitro antimicrobial activity against plant pathogens, but induced systemic resistance against tomato gray mold disease. These results confirm that the trait of biological control is found in a wide variety of bacterial genera

Endolymphatic sac involvement in bacterial meningitis

DEFF Research Database (Denmark)

Møller, Martin Nue; Brandt, Christian; Østergaard, Christian

2015-01-01

The commonest sequelae of bacterial meningitis are related to the inner ear. Little is known about the inner ear immune defense. Evidence suggests that the endolymphatic sac provides some protection against infection. A potential involvement of the endolymphatic sac in bacterial meningitis...... is largely unaccounted for, and thus the object of the present study. A well-established adult rat model of Streptococcus pneumoniae meningitis was employed. Thirty adult rats were inoculated intrathecally with Streptococcus pneumoniae and received no additional treatment. Six rats were sham...... days. Bacteria invaded the inner ear through the cochlear aquaduct. On days 5-6, the bacteria invaded the endolymphatic sac through the endolymphatic duct subsequent to invasion of the vestibular endolymphatic compartment. No evidence of direct bacterial invasion of the sac through the meninges...

Bacterial computing with engineered populations.

Science.gov (United States)

Amos, Martyn; Axmann, Ilka Maria; Blüthgen, Nils; de la Cruz, Fernando; Jaramillo, Alfonso; Rodriguez-Paton, Alfonso; Simmel, Friedrich

2015-07-28

We describe strategies for the construction of bacterial computing platforms by describing a number of results from the recently completed bacterial computing with engineered populations project. In general, the implementation of such systems requires a framework containing various components such as intracellular circuits, single cell input/output and cell-cell interfacing, as well as extensive analysis. In this overview paper, we describe our approach to each of these, and suggest possible areas for future research. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Bacterial community changes in an industrial algae production system.

Science.gov (United States)

Fulbright, Scott P; Robbins-Pianka, Adam; Berg-Lyons, Donna; Knight, Rob; Reardon, Kenneth F; Chisholm, Stephen T

2018-04-01

While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms. Even with closed systems, bacteria are known to enter and cohabitate, but little is known about these communities. Therefore, the richness, structure, and composition of bacterial communities were characterized in closed photobioreactor cultivations of Nannochloropsis salina in F/2 medium at different scales, across nine months spanning late summer-early spring, and during a sequence of serially inoculated cultivations. Using 16S rRNA sequence data from 275 samples, bacterial communities in small, medium, and large cultures were shown to be significantly different. Larger systems contained richer bacterial communities compared to smaller systems. Relationships between bacterial communities and algae growth were complex. On one hand, blooms of a specific bacterial type were observed in three abnormal, poorly performing replicate cultivations, while on the other, notable changes in the bacterial community structures were observed in a series of serial large-scale batch cultivations that had similar growth rates. Bacteria common to the majority of samples were identified, including a single OTU within the class Saprospirae that was found in all samples. This study contributes important information for crop protection in algae systems, and demonstrates the complex ecosystems that need to be understood for consistent, successful industrial algae cultivation. This is the first study to profile bacterial communities during the scale-up process of industrial algae systems.

Hydrodebridement of wounds: effectiveness in reducing wound bacterial contamination and potential for air bacterial contamination.

Science.gov (United States)

Bowling, Frank L; Stickings, Daryl S; Edwards-Jones, Valerie; Armstrong, David G; Boulton, Andrew Jm

2009-05-08

The purpose of this study was to assess the level of air contamination with bacteria after surgical hydrodebridement and to determine the effectiveness of hydro surgery on bacterial reduction of a simulated infected wound. Four porcine samples were scored then infected with a broth culture containing a variety of organisms and incubated at 37 degrees C for 24 hours. The infected samples were then debrided with the hydro surgery tool (Versajet, Smith and Nephew, Largo, Florida, USA). Samples were taken for microbiology, histology and scanning electron microscopy pre-infection, post infection and post debridement. Air bacterial contamination was evaluated before, during and after debridement by using active and passive methods; for active sampling the SAS-Super 90 air sampler was used, for passive sampling settle plates were located at set distances around the clinic room. There was no statistically significant reduction in bacterial contamination of the porcine samples post hydrodebridement. Analysis of the passive sampling showed a significant (p air whilst using hydro surgery equipment compared with a basal count of 582 CFUs/m3. During removal of the wound dressing, a significant increase was observed relative to basal counts (p air samples was still significantly raised 1 hour post-therapy. The results suggest a significant increase in bacterial air contamination both by active sampling and passive sampling. We believe that action might be taken to mitigate fallout in the settings in which this technique is used.

Predicted Bacterial Interactions Affect in Vivo Microbial Colonization Dynamics in Nematostella

Science.gov (United States)

Domin, Hanna; Zurita-Gutiérrez, Yazmín H.; Scotti, Marco; Buttlar, Jann; Hentschel Humeida, Ute; Fraune, Sebastian

2018-01-01

The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition, and diet. In contrast, the importance of bacteria–bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria–bacteria interactions through co-occurrence networks. The analysis indicates that bacteria–bacteria interactions are dynamic during host colonization and change according to the host’s developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within 3 days of recolonization, all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Only 1 week after recolonization, almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within 1 week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community. PMID:29740401

Predicted Bacterial Interactions Affect in Vivo Microbial Colonization Dynamics in Nematostella

Directory of Open Access Journals (Sweden)

Hanna Domin

2018-04-01

Full Text Available The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition, and diet. In contrast, the importance of bacteria–bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria–bacteria interactions through co-occurrence networks. The analysis indicates that bacteria–bacteria interactions are dynamic during host colonization and change according to the host’s developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within 3 days of recolonization, all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Only 1 week after recolonization, almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within 1 week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community.

[Combination therapy of chronic bacterial prostatitis].

Science.gov (United States)

Khryanin, A A; Reshetnikov, O V

2016-08-01

The article discusses the possible etiological factors in the development of chronic bacterial prostatitis. The authors presented a comparative long-term analysis of morbidity from non-viral sexually transmitted infections (STIs) in Russia. Against the background of general decline in STIs incidence, a significant percentage of them is made up by urogenital trichomoniasis. The findings substantiated the advantages of combination therapy (ornidazole and ofloxacin) for bacterial urinary tract infections.

S1PR3 Signaling Drives Bacterial Killing and Is Required for Survival in Bacterial Sepsis.

Science.gov (United States)

Hou, JinChao; Chen, QiXing; Wu, XiaoLiang; Zhao, DongYan; Reuveni, Hadas; Licht, Tamar; Xu, MengLong; Hu, Hu; Hoeft, Andreas; Ben-Sasson, Shmuel A; Shu, Qiang; Fang, XiangMing

2017-12-15

Efficient elimination of pathogenic bacteria is a critical determinant in the outcome of sepsis. Sphingosine-1-phosphate receptor 3 (S1PR3) mediates multiple aspects of the inflammatory response during sepsis, but whether S1PR3 signaling is necessary for eliminating the invading pathogens remains unknown. To investigate the role of S1PR3 in antibacterial immunity during sepsis. Loss- and gain-of-function experiments were performed using cell and murine models. S1PR3 levels were determined in patients with sepsis and healthy volunteers. S1PR3 protein levels were up-regulated in macrophages upon bacterial stimulation. S1pr3 -/- mice showed increased mortality and increased bacterial burden in multiple models of sepsis. The transfer of wild-type bone marrow-derived macrophages rescued S1pr3 -/- mice from lethal sepsis. S1PR3-overexpressing macrophages further ameliorated the mortality rate of sepsis. Loss of S1PR3 led to markedly decreased bacterial killing in macrophages. Enhancing endogenous S1PR3 activity using a peptide agonist potentiated the macrophage bactericidal function and improved survival rates in multiple models of sepsis. Mechanically, the reactive oxygen species levels were decreased and phagosome maturation was delayed in S1pr3 -/- macrophages due to impaired recruitment of vacuolar protein-sorting 34 to the phagosomes. In addition, S1RP3 expression levels were elevated in monocytes from patients with sepsis. Higher levels of monocytic S1PR3 were associated with efficient intracellular bactericidal activity, better immune status, and preferable outcomes. S1PR3 signaling drives bacterial killing and is essential for survival in bacterial sepsis. Interventions targeting S1PR3 signaling could have translational implications for manipulating the innate immune response to combat pathogens.

Bacterial leaching of uranium ores - a review

International Nuclear Information System (INIS)

Lowson, R.T.

1975-11-01

The bacterial leaching of uranium ores involves the bacterially catalysed oxidation of associated pyrite to sulphuric acid and Fe 3+ by autotrophic bacteria and the leaching of the uranium by the resulting acidic, oxidising solution. Industrial application has been limited to Thiobacillus thiooxidans and Thiobacillus ferrooxidans at pH 2 to 3, and examples of these are described. The bacterial catalysis can be improved with nutrients or prevented with poisons. The kinetics of leaching are controlled by the bed depth, particle size, percolation rate, mineralogy and temperature. Current work is aimed at quantitatively defining the parameters controlling the kinetics and extending the method to alkaline conditions with other autotrophic bacteria. (author)

Bacterial growth and DOC consumption in a tropical coastal lagoon

Directory of Open Access Journals (Sweden)

V. F. Farjalla

Full Text Available The aims of this research were to determine the main limiting nutrient to bacterial growth in Imboassica lagoon, southeastern Brazil, to estimate the percentage of dissolved organic carbon (DOC available for bacterial growth, and to determine the bacterial growth efficiency (BGE of natural assemblages. Bacterial growth and DOC consumption were determined in batch culture experiments, in which water samples were supplemented with nitrogen and phosphorus together or separately, or incubated without nutrient additions. When added together, N and P stimulated higher bacterial growth rates and production, as well as higher DOC consumption. The BGEs and DOC consumption rates were strongly dependent on the method used to determine bacterial production. The BGE ranged from 11 to 72%. However, only a minor fraction of bulk DOC was consumed by the planktonic bacteria (from 0.7 to 3.4%. The results suggest that low availability of phosphorus and nitrogen coupled with excess organic carbon was the main factor responsible for the relatively low bacterial utilization of DOC in Imboassica lagoon.

Bacterial sex in dental plaque.

Science.gov (United States)

Olsen, Ingar; Tribble, Gena D; Fiehn, Nils-Erik; Wang, Bing-Yan

2013-01-01

Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

Bacterial sex in dental plaque

Directory of Open Access Journals (Sweden)

Ingar Olsen

2013-06-01

Full Text Available Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

SOS System Induction Inhibits the Assembly of Chemoreceptor Signaling Clusters in Salmonella enterica.

Science.gov (United States)

Irazoki, Oihane; Mayola, Albert; Campoy, Susana; Barbé, Jordi

2016-01-01

Swarming, a flagellar-driven multicellular form of motility, is associated with bacterial virulence and increased antibiotic resistance. In this work we demonstrate that activation of the SOS response reversibly inhibits swarming motility by preventing the assembly of chemoreceptor-signaling polar arrays. We also show that an increase in the concentration of the RecA protein, generated by SOS system activation, rather than another function of this genetic network impairs chemoreceptor polar cluster formation. Our data provide evidence that the molecular balance between RecA and CheW proteins is crucial to allow polar cluster formation in Salmonella enterica cells. Thus, activation of the SOS response by the presence of a DNA-injuring compound increases the RecA concentration, thereby disturbing the equilibrium between RecA and CheW and resulting in the cessation of swarming. Nevertheless, when the DNA-damage decreases and the SOS response is no longer activated, basal RecA levels and thus polar cluster assembly are reestablished. These results clearly show that bacterial populations moving over surfaces make use of specific mechanisms to avoid contact with DNA-damaging compounds.

ATP Production in Chlamydomonas reinhardtii Flagella by Glycolytic Enzymes

DEFF Research Database (Denmark)

Mitchell, Beth F; Pedersen, Lotte B; Feely, Michael

2005-01-01

reside in the detergent-soluble (membrane + matrix) compartments. We further show that axonemal enolase is a subunit of the CPC1 central pair complex and that reduced flagellar enolase levels in the cpc1 mutant correlate with the reduced flagellar ATP concentrations and reduced in vivo beat frequencies...

Pediatric bacterial meningitis in French Guiana.

Science.gov (United States)

Elenga, N; Sicard, S; Cuadro-Alvarez, E; Long, L; Njuieyon, F; Martin, E; Kom-Tchameni, R; Balcaen, J; Moreau, B; Boukhari, R

2015-01-01

Controlling vaccine-preventable infectious diseases is a public health priority in French Guiana but there is currently no epidemiological data on pediatric bacterial meningitis in this overseas department. Our aim was to describe data related to pediatric bacterial meningitis in French Guiana and compare it with that of metropolitan France. We conducted a multicenter retrospective study from 2000 to 2010 to describe the clinical picture, biological data, epidemiology, and outcome of pediatric bacterial meningitis case patients in French Guiana. The median age of bacterial meningitis patients was 6months [0-15] and the sex ratio 1.06. We observed a total of 60 bacterial meningitis case patients. Most presented with pneumococcal meningitis (24 patients; 40%); 11 with Haemophilus influenzae type b meningitis (23%), five with group B streptococcal meningitis (8.5%), and five others (8.5%) with staphylococcal meningitis (three patients presented with coagulase-negative staphylococci and two with Staphylococcus aureus). Only one patient presented with group B meningococcal meningitis, an 18-month-old infant. We recorded 14 deaths (overall case fatality: 23%); eight were due to Streptococcus pneumoniae (case fatality: 33%). The overall sequelae rate was 28%. It was 32% for patients presenting with pneumococcal meningitis. We observed that 38% of children who had never been vaccinated were infected by a vaccine-preventable bacterium. We observed many differences in the distribution of the bacteria and in the patients' prognosis when comparing the French Guiana data with that of metropolitan France. Improving vaccination coverage would decrease the incidence of H. influenzae meningitis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Biosensors for Whole-Cell Bacterial Detection

Science.gov (United States)

Rushworth, Jo V.; Hirst, Natalie A.; Millner, Paul A.

2014-01-01

SUMMARY Bacterial pathogens are important targets for detection and identification in medicine, food safety, public health, and security. Bacterial infection is a common cause of morbidity and mortality worldwide. In spite of the availability of antibiotics, these infections are often misdiagnosed or there is an unacceptable delay in diagnosis. Current methods of bacterial detection rely upon laboratory-based techniques such as cell culture, microscopic analysis, and biochemical assays. These procedures are time-consuming and costly and require specialist equipment and trained users. Portable stand-alone biosensors can facilitate rapid detection and diagnosis at the point of care. Biosensors will be particularly useful where a clear diagnosis informs treatment, in critical illness (e.g., meningitis) or to prevent further disease spread (e.g., in case of food-borne pathogens or sexually transmitted diseases). Detection of bacteria is also becoming increasingly important in antibioterrorism measures (e.g., anthrax detection). In this review, we discuss recent progress in the use of biosensors for the detection of whole bacterial cells for sensitive and earlier identification of bacteria without the need for sample processing. There is a particular focus on electrochemical biosensors, especially impedance-based systems, as these present key advantages in terms of ease of miniaturization, lack of reagents, sensitivity, and low cost. PMID:24982325

Bacterial leaching of pyritic gold ores

International Nuclear Information System (INIS)

Gagliardi, F.M.; Cashion, J.D.; Brown, J.; Jay, W.H.

1998-01-01

Full text: Pyritic ores (pyrite and arsenopyrite) containing gold concentrations in excess of 50g Au/t can be processed to recover the gold by the removal of the sulphur from the ore. This may be achieved by roasting (producing sulphur dioxide emissions), pressure oxidation (expensive and suitable for large high grade deposits), pressure leaching (still currently being developed) or bacterial oxidation. The bacterial oxidation process is a well known process in nature but has only recently come under investigation as a economically viable and relatively clean method of gold recovery from deep low grade sulphidic ores. Samples were obtained from the Wiluna Gold Mine in Western Australia consisting of the original ore, six successive bacterial reactors and the final products. Moessbauer experiments have been performed at room temperature, liquid nitrogen and liquid helium temperatures, and in applied magnetic fields. The main components of the iron phases which were present during the bacterial treatment were pyrite and arsenopyrite which were readily oxidised by the bacteria. Ferric sulfates and ferric arsenates were identified as by-products of the process with a small amount of the oxyhydroxide goethite. These results are in contrast to the similar study of the Fairview Mine in South Africa where principally Fe(II) species were observed

Bacterial leaching of pyritic gold ores

Energy Technology Data Exchange (ETDEWEB)

Gagliardi, F.M.; Cashion, J.D.; Brown, L.J. [Monash Univ., Clayton, VIC (Australia). Dept. of Physics; Jay, W.H. [Monash Univ., Clayton, VIC (Australia). Chemical Engineering Department

1996-12-31

The bacterial oxidation process is well known in nature but has only recently come under investigation as a viable and relatively clean method of gold recovery from ores. However there is currently little information about the process at an atomic scale. It is known that the bacterial attack progresses preferentially along grain boundaries which is precisely where the gold has been deposited from aqueous infiltration. Samples have been obtained from the Wiluna mine in Western Australia consisting of the original ore, 2 pre-treatments, and from six successive bacterial reactors. {sup 57}Fe Moessbauer spectra taken at room temperature show only two quadrupole split doublets which can be ascribed to pyrite, FeS{sub 2}, and arsenopyrite, FeAsS. However, the presence of any superparamagnetic oxide or oxyhydroxide species would be expected to give a spectrum very similar to that of pyrite and would be undetectable in small quantities. At a temperature of 5K, a broad magnetically split sextet is observable with a mean hyperfine field of approximately 50T. This field is characteristic of magnetically ordered ferric iron surrounded by an octahedron of oxygens. The intensity and characteristics of this subspectrum alters through the series and interpretations will be given on the oxidation products of the bacterial leaching

Bacterial leaching of pyritic gold ores

International Nuclear Information System (INIS)

Gagliardi, F.M.; Cashion, J.D.; Brown, L.J.; Jay, W.H.

1996-01-01

The bacterial oxidation process is well known in nature but has only recently come under investigation as a viable and relatively clean method of gold recovery from ores. However there is currently little information about the process at an atomic scale. It is known that the bacterial attack progresses preferentially along grain boundaries which is precisely where the gold has been deposited from aqueous infiltration. Samples have been obtained from the Wiluna mine in Western Australia consisting of the original ore, 2 pre-treatments, and from six successive bacterial reactors. 57 Fe Moessbauer spectra taken at room temperature show only two quadrupole split doublets which can be ascribed to pyrite, FeS 2 , and arsenopyrite, FeAsS. However, the presence of any superparamagnetic oxide or oxyhydroxide species would be expected to give a spectrum very similar to that of pyrite and would be undetectable in small quantities. At a temperature of 5K, a broad magnetically split sextet is observable with a mean hyperfine field of approximately 50T. This field is characteristic of magnetically ordered ferric iron surrounded by an octahedron of oxygens. The intensity and characteristics of this subspectrum alters through the series and interpretations will be given on the oxidation products of the bacterial leaching

Characterization of TEMPO-oxidized bacterial cellulose

International Nuclear Information System (INIS)

Nascimento, Eligenes S.; Pereira, Andre L.S.; Lima, Helder L.; Barroso, Maria K. de A.; Barros, Matheus de O.; Morais, Joao P.S.; Borges, Maria de F.; Rosa, Morsyleide de F.

2015-01-01

The aim of this study was to characterize the TEMPO-oxidized bacterial cellulose, as a preliminary research for further application in nanocomposites. Bacterial cellulose (BC) was selectively oxidized at C-6 carbon by TEMPO radical. Oxidized bacterial cellulose (BCOX) was characterized by TGA, FTIR, XRD, and zeta potential. BCOX suspension was stable at pH 7.0, presented a crystallinity index of 83%, in spite of 92% of BC, because of decrease in the free hydroxyl number. FTIR spectra showed characteristic BC bands and, in addition, band of carboxylic group, proving the oxidation. BCOX DTG showed, in addition to characteristic BC thermal events, a maximum degradation peak at 233 °C, related to sodium anhydro-glucuronate groups formed during the cellulose oxidation. Thus, BC can be TEMPO-oxidized without great loss in its structure and properties. (author)

Composition and variation of sediment bacterial and nirS-harboring bacterial communities at representative sites of the Bohai Gulf coastal zone, China.

Science.gov (United States)

Guan, Xiangyu; Zhu, Lingling; Li, Youxun; Xie, Yuxuan; Zhao, Mingzhang; Luo, Ximing

2014-04-01

With rapid urbanization, anthropogenic activities are increasingly influencing the natural environment of the Bohai Bay. In this study, the composition and variation of bacterial and nirS-harboring bacterial communities in the coastal zone sediments of the Bohai Gulf were analyzed using PCR-based clone libraries. A total of 95 genera were detected in the bacterial communities, with Proteobacteria (72.1 %), Acidobacteria (10.5 %), Firmicutes (1.7 %), Bacteroidetes (1.4 %), Chloroflexi (0.7 %) and Planctomycetes (0.7 %) being the dominated phyla. The NirS sequences were divided into nine Clusters (A-I). Canonical correlation analysis showed that the bacterial or denitrifying communities were correlated with different environmental factors, such as total organic carbon, total nitrogen, ammonium, sulfate, etc. Furthermore, bacterial communities' composition and diversity are influenced by oil exploration, sewage discharge and other anthropogenic activities in the coastal area of the Bohai Sea. Thus, this study provided useful information on further research on regional or global environmental control and restore.

Activity of Proteus mirabilis FliL is viscosity dependent and requires extragenic DNA.

Science.gov (United States)

Lee, Yi-Ying; Patellis, Julius; Belas, Robert

2013-02-01

Proteus mirabilis is a urinary tract pathogen and well known for its ability to move over agar surfaces by flagellum-dependent swarming motility. When P. mirabilis encounters a highly viscous environment, e.g., an agar surface, it differentiates from short rods with few flagella to elongated, highly flagellated cells that lack septa and contain multiple nucleoids. The bacteria detect a surface by monitoring the rotation of their flagellar motors. This process involves an enigmatic flagellar protein called FliL, the first gene in an operon (fliLMNOPQR) that encodes proteins of the flagellar rotor switch complex and flagellar export apparatus. We used a fliL knockout mutant to gain further insight into the function of FliL. Loss of FliL results in cells that cannot swarm (Swr(-)) but do swim (Swm(+)) and produces cells that look like wild-type swarmer cells, termed "pseudoswarmer cells," that are elongated, contain multiple nucleoids, and lack septa. Unlike swarmer cells, pseudoswarmer cells are not hyperflagellated due to reduced expression of flaA (the gene encoding flagellin), despite an increased transcription of both flhD and fliA, two positive regulators of flagellar gene expression. We found that defects in fliL prevent viscosity-dependent sensing of a surface and viscosity-dependent induction of flaA transcription. Studies with fliL cells unexpectedly revealed that the fliL promoter, fliL coding region, and a portion of fliM DNA are needed to complement the Swr(-) phenotype. The data support a dual role for FliL as a critical link in sensing a surface and in the maintenance of flagellar rod integrity.

Emerging antibiotic resistant enteric bacterial flora among food ...

African Journals Online (AJOL)

Emerging antibiotic resistant enteric bacterial flora among food animals in Abeokuta, Nigeria. ... Nigerian Journal of Animal Production ... Bacterial resistance to antibiotic in food animals is an emerging public health concern as a result of ...

Diagnosis of bacterial infection

African Journals Online (AJOL)

direct or indirect evidence of a compatible bacterial pathogen. Inflammation may be .... cardinal features (fever, confusion, headache and neck stiffness). .... specificity, inappropriate indications or poor sampling technique may diminish this ...

Diazotrophic Bacterial Community of Degraded Pastures

OpenAIRE

João Tiago Correia Oliveira; Everthon Fernandes Figueredo; Williane Patrícia da Silva Diniz; Lucianne Ferreira Paes de Oliveira; Pedro Avelino Maia de Andrade; Fernando Dini Andreote; Júlia Kuklinsky-Sobral; Danúbia Ramos de Lima; Fernando José Freire

2017-01-01

Pasture degradation can cause changes in diazotrophic bacterial communities. Thus, this study aimed to evaluate the culturable and total diazotrophic bacterial community, associated with regions of the rhizosphere and roots of Brachiaria decumbens Stapf. pastures in different stages of degradation. Samples of roots and rhizospheric soil were collected from slightly, partially, and highly degraded pastures. McCrady’s table was used to obtain the Most Probable Number (MPN) of bacteria per gram ...

A study of bacterial contamination of rattlesnake venom

Directory of Open Access Journals (Sweden)

E. Garcia-Lima

1987-03-01

Full Text Available The authors studied the bacterial contamination of rattlesnake venom isolated from snakes in captivity and wild snakes caught recently. The captive snakes showed a relatively high incidence of bacterial contamination of their venom.

Metallization of bacterial cellulose for electrical and electronic device manufacture

Science.gov (United States)

Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

2010-09-28

A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

Functional recovery of biofilm bacterial communities after copper exposure

International Nuclear Information System (INIS)

Boivin, Marie-Elene Y.; Massieux, Boris; Breure, Anton M.; Greve, Gerdit D.; Rutgers, Michiel; Admiraal, Wim

2006-01-01

Potential of bacterial communities in biofilms to recover after copper exposure was investigated. Biofilms grown outdoor in shallow water on glass dishes were exposed in the laboratory to 0.6, 2.1, 6.8 μmol/l copper amended surface water and a reference and subsequently to un-amended surface water. Transitions of bacterial communities were characterised with denaturing gradient gel electrophoresis (DGGE) and community-level physiological profiles (CLPP). Exposure to 6.8 μmol/l copper provoked distinct changes in DGGE profiles of bacterial consortia, which did not reverse upon copper depuration. Exposure to 2.1 and 6.8 μmol/l copper was found to induce marked changes in CLPP of bacterial communities that proved to be reversible during copper depuration. Furthermore, copper exposure induced the development of copper-tolerance, which was partially lost during depuration. It is concluded that bacterial communities exposed to copper contaminated water for a period of 26 days are capable to restore their metabolic attributes after introduction of unpolluted water in aquaria for 28 days. - Genetically different bacterial communities can have similar functions and tolerance to copper

Biomimicry of quorum sensing using bacterial lifecycle model.

Science.gov (United States)

Niu, Ben; Wang, Hong; Duan, Qiqi; Li, Li

2013-01-01

Recent microbiologic studies have shown that quorum sensing mechanisms, which serve as one of the fundamental requirements for bacterial survival, exist widely in bacterial intra- and inter-species cell-cell communication. Many simulation models, inspired by the social behavior of natural organisms, are presented to provide new approaches for solving realistic optimization problems. Most of these simulation models follow population-based modelling approaches, where all the individuals are updated according to the same rules. Therefore, it is difficult to maintain the diversity of the population. In this paper, we present a computational model termed LCM-QS, which simulates the bacterial quorum-sensing (QS) mechanism using an individual-based modelling approach under the framework of Agent-Environment-Rule (AER) scheme, i.e. bacterial lifecycle model (LCM). LCM-QS model can be classified into three main sub-models: chemotaxis with QS sub-model, reproduction and elimination sub-model and migration sub-model. The proposed model is used to not only imitate the bacterial evolution process at the single-cell level, but also concentrate on the study of bacterial macroscopic behaviour. Comparative experiments under four different scenarios have been conducted in an artificial 3-D environment with nutrients and noxious distribution. Detailed study on bacterial chemotatic processes with quorum sensing and without quorum sensing are compared. By using quorum sensing mechanisms, artificial bacteria working together can find the nutrient concentration (or global optimum) quickly in the artificial environment. Biomimicry of quorum sensing mechanisms using the lifecycle model allows the artificial bacteria endowed with the communication abilities, which are essential to obtain more valuable information to guide their search cooperatively towards the preferred nutrient concentrations. It can also provide an inspiration for designing new swarm intelligence optimization algorithms

Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion.

Science.gov (United States)

Hovingh, Elise S; van den Broek, Bryan; Jongerius, Ilse

2016-01-01

The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed.

Determination of Bacterial Growth in Culture Media

International Nuclear Information System (INIS)

Elly Ellyna Rashid; Shariza Hanim Zainal Abidin; Mok, P.S.

2015-01-01

Bacteria is one of the important microorganism in our daily life. Bacteria provides human beings with products in the field of medical, industry, food, agriculture and others. Determination of bacteria growth is important so that we can enjoy the most benefit from it. Spread-plate method is one of the methods to obtain the bacterial counts. Agar plates, such as Nutrient Agar or Plate Count Agar are usually used for this purpose. Bacterial culture will be diluted first before being spread on the agar plate and incubated at specific temperature. The number of bacteria in colony-forming unit (CFU) will be counted the next day. The count will be used to determine the bacterial growth. (author)

[Etiology of bacterial vaginosis (non-specific vaginitis)].

Science.gov (United States)

Lefèvre, J C; Jean, M; Averous, S; Viraben, R; Blanc, C; Bauriaud, R; Lareng, M B

1985-01-01

56 women who were diagnosed bioclinically as having a bacterial vaginal infection were studied, as were 35 women as a control group. The study was a semi-quantitative analysis of the vaginal bacterial flora, both aerobic and anaerobic. It shows that Gardnerella vaginalis and anaerobic bacteria such as Peptococcus, Peptostreptococcus, Bacteroïdes, Veillonella and Mobiluncus were associated in a statistically significant way with bacterial vaginitis. On the other hand Lactobacilli were less frequently found (p less than 0.001) than in the control group of women. The way in which the microbial flora is changed has been observed during attacks of vaginitis and is discussed, as is the importance of making the diagnosis and of treating this syndrome.

Cholinesterase modulations in patients with acute bacterial meningitis

DEFF Research Database (Denmark)

Berg, Ronan M G; Ofek, Keren; Qvist, Tavs

2011-01-01

The circulating cholinesterases acetyl- and butyrylcholinesterase may be suppressed and subsequently released from the brain in acute bacterial meningitis.......The circulating cholinesterases acetyl- and butyrylcholinesterase may be suppressed and subsequently released from the brain in acute bacterial meningitis....

Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

Science.gov (United States)

Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

2016-10-01

Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms underlying the emergence of these greatly different morphologies. Ginzburg-Landau kinetic method and Fourier spectral method are integrated to simulate the morphological evolution of bacterial biofilms. It is shown that the morphological instability of biofilms is triggered by the stresses induced by anisotropic and heterogeneous bacterial expansion, and involves the competition between membrane energy and bending energy. Local interfacial delamination further enriches the morphologies of biofilms. Phase diagrams are established to reveal how the anisotropy and spatial heterogeneity of growth modulate the surface patterns. The mechanics of three-dimensional microbial morphogenesis may also underpin self-organization in other development systems and provide a potential strategy for engineering microscopic structures from bacterial aggregates.

Benthic bacterial diversity in submerged sinkhole ecosystems.

Science.gov (United States)

Nold, Stephen C; Pangborn, Joseph B; Zajack, Heidi A; Kendall, Scott T; Rediske, Richard R; Biddanda, Bopaiah A

2010-01-01

Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities.

Interspecies chemical communication in bacterial development.

Science.gov (United States)

Straight, Paul D; Kolter, Roberto

2009-01-01

Our view of bacteria, from the earliest observations through the heyday of antibiotic discovery, has shifted dramatically. We recognize communities of bacteria as integral and functionally important components of diverse habitats, ranging from soil collectives to the human microbiome. To function as productive communities, bacteria coordinate metabolic functions, often requiring shifts in growth and development. The hallmark of cellular development, which we characterize as physiological change in response to environmental stimuli, is a defining feature of many bacterial interspecies interactions. Bacterial communities rely on chemical exchanges to provide the cues for developmental change. Traditional methods in microbiology focus on isolation and characterization of bacteria in monoculture, separating the organisms from the surroundings in which interspecies chemical communication has relevance. Developing multispecies experimental systems that incorporate knowledge of bacterial physiology and metabolism with insights from biodiversity and metagenomics shows great promise for understanding interspecies chemical communication in the microbial world.

The Prevalence of Bacterial Vaginosis among Pregnant Women ...

African Journals Online (AJOL)

60.4%) were asymptomatic. There were 92 out of 250 pregnant women (36.8%) that had three or more of the Amsel's criteria for the diagnosis of bacterial vaginosis. The associated risk factors for developing bacterial vaginosis in the study ...

Bacterial colonization and gut development in preterm neonates

DEFF Research Database (Denmark)

Cilieborg, Malene S.; Boye, Mette; Sangild, Per Torp

2012-01-01

Necrotizing enterocolitis (NEC) develops in 5–10% of preterm infants in association with enteral feeding and bacterial colonization. It remains unclear how diet and bacteria interact to protect or provoke the immature gastrointestinal tract. Understanding the factors that control bacterial...

Bacterial contamination of platelet concentrates: pathogen detection and inactivation methods

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Dana Védy

2009-04-01

Full Text Available Whereas the reduction of transfusion related viral transmission has been a priority during the last decade, bacterial infection transmitted by transfusion still remains associated to a high morbidity and mortality, and constitutes the most frequent infectious risk of transfusion. This problem especially concerns platelet concentrates because of their favorable bacterial growth conditions. This review gives an overview of platelet transfusion-related bacterial contamination as well as on the different strategies to reduce this problem by using either bacterial detection or inactivation methods.

Altered Bacterial Profiles in Saliva from Adults with Caries Lesions

DEFF Research Database (Denmark)

Belstrøm, D; Fiehn, N-E; Nielsen, C H

2014-01-01

-Whitney's test with Benjamini-Hochberg correction for multiple comparisons. Principal component analysis was used to visualize bacterial community profiles. A reduced bacterial diversity was observed in samples from subjects with dental caries. Five bacterial taxa (Veillonella parvula, Veillonella atypica......, Megasphaera micronuciformis, Fusobacterium periodontium and Achromobacter xylosoxidans) and one bacterial cluster (Leptotrichia sp. clones C3MKM102 and GT018_ot417/462) were less frequently found in the caries group (adjusted p value ... salivarius) and three bacterial clusters (Streptococcus parasanguinis I and II and sp. clone BE024_ot057/411/721, Streptococcus parasanguinis I and II and sinensis_ot411/721/767, Streptococcus salivarius and sp. clone FO042_ot067/755) were present at significantly higher levels (adjusted p value

Bacterial Acclimation Inside an Aqueous Battery.

Science.gov (United States)

Dong, Dexian; Chen, Baoling; Chen, P

2015-01-01

Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm(-2) and 1.4-2.1 V. Bacterial addition within 1.0×10(10) cells mL(-1) did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms.

DNA Supercoiling Regulates the Motility of Campylobacter jejuni and Is Altered by Growth in the Presence of Chicken Mucus

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Claire Shortt

2016-09-01

Full Text Available Campylobacter jejuni is the leading cause of bacterial gastroenteritis in humans, but relatively little is known about the global regulation of virulence factors during infection of chickens or humans. This study identified DNA supercoiling as playing a key role in regulating motility and flagellar protein production and found that this supercoiling-controlled regulon is induced by growth in chicken mucus. A direct correlation was observed between motility and resting DNA supercoiling levels in different strains of C. jejuni, and relaxation of DNA supercoiling resulted in decreased motility. Transcriptional analysis and Western immunoblotting revealed that a reduction in motility and DNA supercoiling affected the two-component regulatory system FlgRS and was associated with reduced FlgR expression, increased FlgS expression, and aberrant expression of flagellin subunits. Electron microscopy revealed that the flagellar structure remained intact. Growth in the presence of porcine mucin resulted in increased negative supercoiling, increased motility, increased FlgR expression, and reduced FlgS expression. Finally, this supercoiling-dependent regulon was shown to be induced by growth in chicken mucus, and the level of activation was dependent on the source of the mucus from within the chicken intestinal tract. In conclusion, this study reports for the first time the key role played by DNA supercoiling in regulating motility in C. jejuni and indicates that the induction of this supercoiling-induced regulon in response to mucus from different sources could play a critical role in regulating motility in vivo.

Vaginal epithelial cells regulate membrane adhesiveness to co-ordinate bacterial adhesion.

Science.gov (United States)

Younes, Jessica A; Klappe, Karin; Kok, Jan Willem; Busscher, Henk J; Reid, Gregor; van der Mei, Henny C

2016-04-01

Vaginal epithelium is colonized by different bacterial strains and species. The bacterial composition of vaginal biofilms controls the balance between health and disease. Little is known about the relative contribution of the epithelial and bacterial cell surfaces to bacterial adhesion and whether and how adhesion is regulated over cell membrane regions. Here, we show that bacterial adhesion forces with cell membrane regions not located above the nucleus are stronger than with regions above the nucleus both for vaginal pathogens and different commensal and probiotic lactobacillus strains involved in health. Importantly, adhesion force ratios over membrane regions away from and above the nucleus coincided with the ratios between numbers of adhering bacteria over both regions. Bacterial adhesion forces were dramatically decreased by depleting the epithelial cell membrane of cholesterol or sub-membrane cortical actin. Thus, epithelial cells can regulate membrane regions to which bacterial adhesion is discouraged, possibly to protect the nucleus. © 2015 John Wiley & Sons Ltd.

Molecular methods for bacterial genotyping and analyzed gene regions

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İbrahim Halil Yıldırım1, Seval Cing Yıldırım2, Nadir Koçak3

2011-06-01

Full Text Available Bacterial strain typing is an important process for diagnosis, treatment and epidemiological investigations. Current bacterial strain typing methods may be classified into two main categories: phenotyping and genotyping. Phenotypic characters are the reflection of genetic contents. Genotyping, which refers discrimination of bacterial strains based on their genetic content, has recently become widely used for bacterial strain typing. The methods already used in genotypingof bacteria are quite different from each other. In this review we tried to summarize the basic principles of DNA-based methods used in genotyping of bacteria and describe some important DNA regions that are used in genotyping of bacteria. J Microbiol Infect Dis 2011;1(1:42-46.

Bacterial Cell Surface Damage Due to Centrifugal Compaction

NARCIS (Netherlands)

Peterson, Brandon W.; Sharma, Prashant K.; van der Mei, Henny C.; Busscher, Henk J.

Centrifugal damage has been known to alter bacterial cell surface properties and interior structures, including DNA. Very few studies exist on bacterial damage caused by centrifugation because of the difficulty in relating centrifugation speed and container geometry to the damage caused. Here, we

Bacterial Carriers for Glioblastoma Therapy

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Nalini Mehta

2017-03-01

Full Text Available Treatment of aggressive glioblastoma brain tumors is challenging, largely due to diffusion barriers preventing efficient drug dosing to tumors. To overcome these barriers, bacterial carriers that are actively motile and programmed to migrate and localize to tumor zones were designed. These carriers can induce apoptosis via hypoxia-controlled expression of a tumor suppressor protein p53 and a pro-apoptotic drug, Azurin. In a xenograft model of human glioblastoma in rats, bacterial carrier therapy conferred a significant survival benefit with 19% overall long-term survival of >100 days in treated animals relative to a median survival of 26 days in control untreated animals. Histological and proteomic analyses were performed to elucidate the safety and efficacy of these carriers, showing an absence of systemic toxicity and a restored neural environment in treated responders. In the treated non-responders, proteomic analysis revealed competing mechanisms of pro-apoptotic and drug-resistant activity. This bacterial carrier opens a versatile avenue to overcome diffusion barriers in glioblastoma by virtue of its active motility in extracellular space and can lead to tailored therapies via tumor-specific expression of tumoricidal proteins.

Bacterial identification and subtyping using DNA microarray and DNA sequencing.

Science.gov (United States)

Al-Khaldi, Sufian F; Mossoba, Magdi M; Allard, Marc M; Lienau, E Kurt; Brown, Eric D

2012-01-01

The era of fast and accurate discovery of biological sequence motifs in prokaryotic and eukaryotic cells is here. The co-evolution of direct genome sequencing and DNA microarray strategies not only will identify, isotype, and serotype pathogenic bacteria, but also it will aid in the discovery of new gene functions by detecting gene expressions in different diseases and environmental conditions. Microarray bacterial identification has made great advances in working with pure and mixed bacterial samples. The technological advances have moved beyond bacterial gene expression to include bacterial identification and isotyping. Application of new tools such as mid-infrared chemical imaging improves detection of hybridization in DNA microarrays. The research in this field is promising and future work will reveal the potential of infrared technology in bacterial identification. On the other hand, DNA sequencing by using 454 pyrosequencing is so cost effective that the promise of $1,000 per bacterial genome sequence is becoming a reality. Pyrosequencing technology is a simple to use technique that can produce accurate and quantitative analysis of DNA sequences with a great speed. The deposition of massive amounts of bacterial genomic information in databanks is creating fingerprint phylogenetic analysis that will ultimately replace several technologies such as Pulsed Field Gel Electrophoresis. In this chapter, we will review (1) the use of DNA microarray using fluorescence and infrared imaging detection for identification of pathogenic bacteria, and (2) use of pyrosequencing in DNA cluster analysis to fingerprint bacterial phylogenetic trees.

Gene calling and bacterial genome annotation with BG7.

Science.gov (United States)

Tobes, Raquel; Pareja-Tobes, Pablo; Manrique, Marina; Pareja-Tobes, Eduardo; Kovach, Evdokim; Alekhin, Alexey; Pareja, Eduardo

2015-01-01

New massive sequencing technologies are providing many bacterial genome sequences from diverse taxa but a refined annotation of these genomes is crucial for obtaining scientific findings and new knowledge. Thus, bacterial genome annotation has emerged as a key point to investigate in bacteria. Any efficient tool designed specifically to annotate bacterial genomes sequenced with massively parallel technologies has to consider the specific features of bacterial genomes (absence of introns and scarcity of nonprotein-coding sequence) and of next-generation sequencing (NGS) technologies (presence of errors and not perfectly assembled genomes). These features make it convenient to focus on coding regions and, hence, on protein sequences that are the elements directly related with biological functions. In this chapter we describe how to annotate bacterial genomes with BG7, an open-source tool based on a protein-centered gene calling/annotation paradigm. BG7 is specifically designed for the annotation of bacterial genomes sequenced with NGS. This tool is sequence error tolerant maintaining their capabilities for the annotation of highly fragmented genomes or for annotating mixed sequences coming from several genomes (as those obtained through metagenomics samples). BG7 has been designed with scalability as a requirement, with a computing infrastructure completely based on cloud computing (Amazon Web Services).

Bacterial nucleotide-based second messengers.

Science.gov (United States)

Pesavento, Christina; Hengge, Regine

2009-04-01

In all domains of life nucleotide-based second messengers transduce signals originating from changes in the environment or in intracellular conditions into appropriate cellular responses. In prokaryotes cyclic di-GMP has emerged as an important and ubiquitous second messenger regulating bacterial life-style transitions relevant for biofilm formation, virulence, and many other bacterial functions. This review describes similarities and differences in the architecture of the cAMP, (p)ppGpp, and c-di-GMP signaling systems and their underlying signaling principles. Moreover, recent advances in c-di-GMP-mediated signaling will be presented and the integration of c-di-GMP signaling with other nucleotide-based signaling systems will be discussed.

Role of Autophagy and Apoptosis in the Postinfluenza Bacterial Pneumonia

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Zhen Qin

2016-01-01

Full Text Available The risk of influenza A virus (IAV is more likely caused by secondary bacterial infections. During the past decades, a great amount of studies have been conducted on increased morbidity from secondary bacterial infections following influenza and provide an increasing number of explanations for the mechanisms underlying the infections. In this paper, we first review the recent research progress that IAV infection increased susceptibility to bacterial infection. We then propose an assumption that autophagy and apoptosis manipulation are beneficial to antagonize post-IAV bacterial infection and discuss the clinical significance.

Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants.

Science.gov (United States)

Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

2016-02-16

Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

Bacterial degradation of monocyclic aromatic amines

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Pankaj Kumar Arora

2015-08-01

Full Text Available Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic compounds has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines.

Mineral phosphate solubilizing bacterial community in agro-ecosystem

African Journals Online (AJOL)

Mineral phosphate solubilizing bacterial community in agro-ecosystem. N Saha, S Biswas. Abstract. The present communication deals with the assessment of phosphate solubilizing bacterial community structure across artificially created fertility gradient with regards to N, P and K status of soil in the experimental site.

Partial drying accelerates bacterial growth recovery to rewetting

DEFF Research Database (Denmark)

Meisner, Annelein; Leizeaga, Ainara; Rousk, Johannes

2017-01-01

, bacterial growth rates increase immediately in a linear fashion. In the Type 2 pattern, bacterial growth rates increase exponentially after a lag period. However, soils are often only partially dried. Partial drying (higher remaining moisture content before rewetting) may be considered a less harsh...

Extensive Identification of Bacterial Riboflavin Transporters and Their Distribution across Bacterial Species

Science.gov (United States)

Merino, Enrique; Bonomi, Hernán Ruy; Goldbaum, Fernando Alberto; García-Angulo, Víctor Antonio

2015-01-01

Riboflavin, the precursor for the cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide, is an essential metabolite in all organisms. While the functions for de novo riboflavin biosynthesis and riboflavin import may coexist in bacteria, the extent of this co-occurrence is undetermined. The RibM, RibN, RfuABCD and the energy-coupling factor-RibU bacterial riboflavin transporters have been experimentally characterized. In addition, ImpX, RfnT and RibXY are proposed as riboflavin transporters based on positional clustering with riboflavin biosynthetic pathway (RBP) genes or conservation of the FMN riboswitch regulatory element. Here, we searched for the FMN riboswitch in bacterial genomes to identify genes encoding riboflavin transporters and assessed their distribution among bacteria. Two new putative riboflavin transporters were identified: RibZ in Clostridium and RibV in Mesoplasma florum. Trans-complementation of an Escherichia coli riboflavin auxotroph strain confirmed the riboflavin transport activity of RibZ from Clostridium difficile, RibXY from Chloroflexus aurantiacus, ImpX from Fusobacterium nucleatum and RfnT from Ochrobactrum anthropi. The analysis of the genomic distribution of all known bacterial riboflavin transporters revealed that most occur in species possessing the RBP and that some bacteria may even encode functional riboflavin transporters from two different families. Our results indicate that some species possess ancestral riboflavin transporters, while others possess transporters that appear to have evolved recently. Moreover, our data suggest that unidentified riboflavin transporters also exist. The present study doubles the number of experimentally characterized riboflavin transporters and suggests a specific, non-accessory role for these proteins in riboflavin-prototrophic bacteria. PMID:25938806

Dynamic Computational Model of Symptomatic Bacteremia to Inform Bacterial Separation Treatment Requirements.

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Sinead E Miller

Full Text Available The rise of multi-drug resistance has decreased the effectiveness of antibiotics, which has led to increased mortality rates associated with symptomatic bacteremia, or bacterial sepsis. To combat decreasing antibiotic effectiveness, extracorporeal bacterial separation approaches have been proposed to capture and separate bacteria from blood. However, bacteremia is dynamic and involves host-pathogen interactions across various anatomical sites. We developed a mathematical model that quantitatively describes the kinetics of pathogenesis and progression of symptomatic bacteremia under various conditions, including bacterial separation therapy, to better understand disease mechanisms and quantitatively assess the biological impact of bacterial separation therapy. Model validity was tested against experimental data from published studies. This is the first multi-compartment model of symptomatic bacteremia in mammals that includes extracorporeal bacterial separation and antibiotic treatment, separately and in combination. The addition of an extracorporeal bacterial separation circuit reduced the predicted time of total bacteria clearance from the blood of an immunocompromised rodent by 49%, compared to antibiotic treatment alone. Implementation of bacterial separation therapy resulted in predicted multi-drug resistant bacterial clearance from the blood of a human in 97% less time than antibiotic treatment alone. The model also proposes a quantitative correlation between time-dependent bacterial load among tissues and bacteremia severity, analogous to the well-known 'area under the curve' for characterization of drug efficacy. The engineering-based mathematical model developed may be useful for informing the design of extracorporeal bacterial separation devices. This work enables the quantitative identification of the characteristics required of an extracorporeal bacteria separation device to provide biological benefit. These devices will potentially

Particle surface area and bacterial activity in recirculating aquaculture systems

DEFF Research Database (Denmark)

Pedersen, Per Bovbjerg; von Ahnen, Mathis; Fernandes, Paulo

2017-01-01

Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, culture...... but may provide significant surface area. Hence, the study substantiates that particles in RAS provide surface area supporting bacterial activity, and that particles play a key role in controlling the bacterial carrying capacity at least in less intensive RAS. Applying fast, culture-independent techniques......-independent fluorometric detection method (Bactiquant®) for measuring bacterial activity, the current study explored the relationship between total particle surface area (TSA, derived from the size distribution of particles >5 μm) and bacterial activity in freshwater RAS operated at increasing intensity of recirculation...

Soil bacterial community shifts associated with sugarcane straw removal

Science.gov (United States)

Pimentel, Laisa; Gumiere, Thiago; Andreote, Fernando; Cerri, Carlos

2017-04-01

In Brazil, the adoption of the mechanical unburned sugarcane harvest potentially increase the quantity of residue left in the field after harvesting. Economically, this material has a high potential for second generation ethanol (2G) production. However, crop residues have an essential role in diverse properties and processes in the soil. The greater part of the uncertainties about straw removal for 2G ethanol production is based on its effects in soil microbial community. In this sense, it is important to identify the main impacts of sugarcane straw removal on soil microbial community. Therefore, we conducted a field study, during one year, in Valparaíso (São Paulo state - Brazil) to evaluate the effects of straw decomposition on soil bacterial community. Specifically, we wanted: i) to compare the rates of straw removal and ii) to evaluate the effects of straw decomposition on soil bacterial groups over one year. The experiment was in a randomized block design with treatments arranged in strip plot. The treatments are different rates of sugarcane straw removal, namely: no removal, 50, 75 and 100% of straw removal. Soil sampling was carried out at 0, 4, 8 and 12 months after the sugarcane harvest (August 2015). Total DNA was extracted from soil using the PowersoilTM DNA Isolation kit. And the abundance of bacterial in each soil sample was estimated via quantification of 16S rRNA gene. The composition of the bacterial communities was estimated via terminal restriction fragment length polymorphism (T-RFLP) analysis, and the T-RF sizes were performed on a 3500 Genetic Analyzer. Finally, the results were examined with GeneMapper 4.1 software. There was bacterial community shifts through the time and among the rates of sugarcane straw removal. Bacterial community was firstly determined by the time scale, which explained 29.16% of total variation. Rates of straw removal explained 11.55% of shifts on bacterial community. Distribution through the time is an important

Skin bacterial flora as a potential risk factor predisposing to late bacterial infection after cross-linked hyaluronic acid gel augmentation.

Science.gov (United States)

Netsvyetayeva, Irina; Marusza, Wojciech; Olszanski, Romuald; Szyller, Kamila; Krolak-Ulinska, Aneta; Swoboda-Kopec, Ewa; Sierdzinski, Janusz; Szymonski, Zachary; Mlynarczyk, Grazyna

2018-01-01

Cross-linked hyaluronic acid (HA) gel is widely used in esthetic medicine. Late bacterial infection (LBI) is a rare, but severe complication after HA augmentation. The aim of this study was to determine whether patients who underwent the HA injection procedure and developed LBI had qualitatively different bacterial flora on the skin compared to patients who underwent the procedure without any complications. The study group comprised 10 previously healthy women with recently diagnosed, untreated LBI after HA augmentation. The control group comprised 17 healthy women who had a similar amount of HA injected with no complications. To assess the difference between the two groups, their skin flora was cultured from nasal swabs, both before and after antibiotic treatment in the study group. A significant increase in the incidence of Staphylococcus epidermidis was detected in the control group ( P =0.000) compared to the study group. The study group showed a significantly higher incidence of Staphylococcus aureus ( P =0.005), Klebsiella pneumoniae ( P =0.006), Klebsiella oxytoca ( P =0.048), and Staphylococcus haemolyticus ( P =0.048) compared to the control group. The bacterial flora on the skin differed in patients with LBI from the control group. The control group's bacterial skin flora was dominated by S. epidermidis . Patients with LBI had a bacterial skin flora dominated by potentially pathogenic bacteria.

Factors influencing bacterial adhesion to contact lenses.

Science.gov (United States)

Dutta, Debarun; Cole, Nerida; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria.

Demodex-associated bacterial proteins induce neutrophil activation.

LENUS (Irish Health Repository)

2012-02-01

Background: Patients with rosacea demonstrate a higher density of Demodex mites in their skin than controls. A bacterium isolated from a Demodex mite from a patient with papulopustular rosacea (PPR) was previously shown to provoke an immune response in patients with PPR or ocular rosacea thus suggesting a possible role for bacterial proteins in the etiology of this condition. Objectives: To examine the response of neutrophils to proteins derived from a bacterium isolated from a Demodex mite. Methods: Bacterial cells were lysed and proteins were partially purified by AKTA-FPLC. Isolated neutrophils were exposed to bacterial proteins and monitored for alterations in migration, degranulation and cytokine production. Results: Neutrophils exposed to proteins from Bacillus cells demonstrated increased levels of migration and elevated release of MMP-9, an enzyme known to degrade collagen and cathelicidin, an antimicrobial peptide. In addition neutrophils exposed to the bacterial proteins demonstrated elevated rates of Il-8 and TNF-alpha production. Conclusions: Proteins produced by a bacterium isolated from a Demodex mite have the ability to increase the migration, degranulation and cytokine production abilities of neutrophils. These results suggest that bacteria may play a role in the inflammatory erythema associated with rosacea.

Bacterial flora of spices and its control by gamma irradiation

International Nuclear Information System (INIS)

El-Zawahry, Y.A.; Youssef, Y.A.; Awny, N.M.; Hussein, H.A.

1985-01-01

The bacterial contamination was tested in 26 samples of spices. Chili, allspice and paprika were the most contaminated spices by bacteria. Five bacterial genera were isolated, namely bacillus, staphylococcus, streptococcus, micrococcus, and coccobacillus, all being gram-positive. Most isolates have been related to the genus bacillus. The bacterial isolates were identified as B. alvei, B. circulans, B. megaterium, B. pasteurii, B. pumilus, B. thuringiensis, B. sphaericus, B. incertaesedis, Micrococcus luteus, staphylococcus aureus, streptococcus sp. and coccobacillus sp. Irradiation of spices led to a significant decrease in the bacterial count of all samples. The dose required to inhibit completely the natural bacterial flora was 25 KGY. The most radioresistant isolates were staphylococcus aureus and micrococcus luteus which were subjected to sublethal doses of 15 and 20 KGY respectively. The dose response curves of the 2 most radioresistant isolates showed simple exponential relationship. The D 10-value of S. aureus and M. luteus were 0.9 and 1.1 KGY, respectively. The effect of storage period on the bacterial load of, as well as, the antibacterial activity of the tested spices were investigated. (author)

Bacterial flora of spices and its control by gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

El-Zawahry, Y A; Youssef, Y A; Awny, N M; Hussein, H A

1985-01-01

The bacterial contamination was tested in 26 samples of spices. Chili, allspice and paprika were the most contaminated spices by bacteria. Five bacterial genera were isolated, namely bacillus, staphylococcus, streptococcus, micrococcus, and coccobacillus, all being gram-positive. Most isolates have been related to the genus bacillus. The bacterial isolates were identified as B. alvei, B. circulans, B. megaterium, B. pasteurii, B. pumilus, B. thuringiensis, B. sphaericus, B. incertaesedis, Micrococcus luteus, staphylococcus aureus, streptococcus sp. and coccobacillus sp. Irradiation of spices led to a significant decrease in the bacterial count of all samples. The dose required to inhibit completely the natural bacterial flora was 25 KGY. The most radioresistant isolates were staphylococcus aureus and micrococcus luteus which were subjected to sublethal doses of 15 and 20 KGY respectively. The dose response curves of the 2 most radioresistant isolates showed simple exponential relationship. The D 10-value of S. aureus and M. luteus were 0.9 and 1.1 KGY, respectively. The effect of storage period on the bacterial load of, as well as, the antibacterial activity of the tested spices were investigated.

Cooperative Bacterial Foraging Optimization

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Hanning Chen

2009-01-01

Full Text Available Bacterial Foraging Optimization (BFO is a novel optimization algorithm based on the social foraging behavior of E. coli bacteria. This paper presents a variation on the original BFO algorithm, namely, the Cooperative Bacterial Foraging Optimization (CBFO, which significantly improve the original BFO in solving complex optimization problems. This significant improvement is achieved by applying two cooperative approaches to the original BFO, namely, the serial heterogeneous cooperation on the implicit space decomposition level and the serial heterogeneous cooperation on the hybrid space decomposition level. The experiments compare the performance of two CBFO variants with the original BFO, the standard PSO and a real-coded GA on four widely used benchmark functions. The new method shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.

Systems Biology Analysis of Temporal In vivo Brucella melitensis and Bovine Transcriptomes Predicts host:Pathogen Protein–Protein Interactions

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Carlos A. Rossetti

2017-07-01

Full Text Available To date, fewer than 200 gene-products have been identified as Brucella virulence factors, and most were characterized individually without considering how they are temporally and coordinately expressed or secreted during the infection process. Here, we describe and analyze the in vivo temporal transcriptional profile of Brucella melitensis during the initial 4 h interaction with cattle. Pathway analysis revealed an activation of the “Two component system” providing evidence that the in vivo Brucella sense and actively regulate their metabolism through the transition to an intracellular lifestyle. Contrarily, other Brucella pathways involved in virulence such as “ABC transporters” and “T4SS system” were repressed suggesting a silencing strategy to avoid stimulation of the host innate immune response very early in the infection process. Also, three flagellum-encoded loci (BMEII0150-0168, BMEII1080-1089, and BMEII1105-1114, the “flagellar assembly” pathway and the cell components “bacterial-type flagellum hook” and “bacterial-type flagellum” were repressed in the tissue-associated B. melitensis, while RopE1 sigma factor, a flagellar repressor, was activated throughout the experiment. These results support the idea that Brucella employ a stealthy strategy at the onset of the infection of susceptible hosts. Further, through systems-level in silico host:pathogen protein–protein interactions simulation and correlation of pathogen gene expression with the host gene perturbations, we identified unanticipated interactions such as VirB11::MAPK8IP1; BtaE::NFKBIA, and 22 kDa OMP precursor::BAD and MAP2K3. These findings are suggestive of new virulence factors and mechanisms responsible for Brucella evasion of the host's protective immune response and the capability to maintain a dormant state. The predicted protein–protein interactions and the points of disruption provide novel insights that will stimulate advanced hypothesis

Mathematical Modelling of Bacterial Populations in Bio-remediation Processes

Science.gov (United States)

Vasiliadou, Ioanna A.; Vayenas, Dimitris V.; Chrysikopoulos, Constantinos V.

2011-09-01

An understanding of bacterial behaviour concerns many field applications, such as the enhancement of water, wastewater and subsurface bio-remediation, the prevention of environmental pollution and the protection of human health. Numerous microorganisms have been identified to be able to degrade chemical pollutants, thus, a variety of bacteria are known that can be used in bio-remediation processes. In this study the development of mathematical models capable of describing bacterial behaviour considered in bio-augmentation plans, such as bacterial growth, consumption of nutrients, removal of pollutants, bacterial transport and attachment in porous media, is presented. The mathematical models may be used as a guide in designing and assessing the conditions under which areas contaminated with pollutants can be better remediated.

Bacterial community structure in the Cerasus sachalinensis Kom ...

African Journals Online (AJOL)

Jane

2011-07-21

Jul 21, 2011 ... The bacterial community structures of the Cerasus sachalinensis Kom. rhizosphere in wild and cultivated soil were studied and the community changes in different growth stages were analyzed by the PCR-denaturing gradient gel electrophoresis (PCR-DGGE) method. The results showed that the bacterial ...

Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective

Directory of Open Access Journals (Sweden)

Benjamin Rémy

2018-03-01

Full Text Available Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs, as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs to block the action of AIs and quorum quenching (QQ enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria.

Towards revealing the structure of bacterial inclusion bodies.

Science.gov (United States)

Wang, Lei

2009-01-01

Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6-12 nm, they are comprised of residue-specific cross-beta structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies.

Temperature adaptation of bacterial communities in experimentally warmed forest soils.

Science.gov (United States)

Rousk, Johannes; Frey, Serita D; Bååth, Erland

2012-10-01

A detailed understanding of the influence of temperature on soil microbial activity is critical to predict future atmospheric CO 2 concentrations and feedbacks to anthropogenic warming. We investigated soils exposed to 3-4 years of continuous 5 °C-warming in a field experiment in a temperate forest. We found that an index for the temperature adaptation of the microbial community, T min for bacterial growth, increased by 0.19 °C per 1 °C rise in temperature, showing a community shift towards one adapted to higher temperature with a higher temperature sensitivity (Q 10(5-15 °C) increased by 0.08 units per 1 °C). Using continuously measured temperature data from the field experiment we modelled in situ bacterial growth. Assuming that warming did not affect resource availability, bacterial growth was modelled to become 60% higher in warmed compared to the control plots, with the effect of temperature adaptation of the community only having a small effect on overall bacterial growth (bacterial growth, most likely due to substrate depletion because of the initially higher growth in warmed plots. When this was factored in, the result was similar rates of modelled in situ bacterial growth in warmed and control plots after 3 years, despite the temperature difference. We conclude that although temperature adaptation for bacterial growth to higher temperatures was detectable, its influence on annual bacterial growth was minor, and overshadowed by the direct temperature effect on growth rates. © 2012 Blackwell Publishing Ltd.

Investigation of multimodal forward scatter phenotyping from bacterial colonies

Science.gov (United States)

Kim, Huisung

A rapid, label-free, and elastic light scattering (ELS) based bacterial colony phenotyping technology, bacterial rapid detection using optical scattering technology (BARDOT) provides a successful classification of several bacterial genus and species. For a thorough understanding of the phenomena and overcoming the limitations of the previous design, five additional modalities from a bacterial colony: 3D morphology, spatial optical density (OD) distribution, spectral forward scattering pattern, spectral OD, and surface backward reflection pattern are proposed to enhance the classification/identification ratio, and the feasibilities of each modality are verified. For the verification, three different instruments: integrated colony morphology analyzer (ICMA), multi-spectral BARDOT (MS-BARDOT) , and multi-modal BARDOT (MM-BARDOT) are proposed and developed. The ICMA can measure 3D morphology and spatial OD distribution of the colony simultaneously. A commercialized confocal displacement meter is used to measure the profiles of the bacterial colonies, together with a custom built optical density measurement unit to interrogate the biophysics behind the collective behavior of a bacterial colony. The system delivers essential information related to the quantitative growth dynamics (height, diameter, aspect ratio, optical density) of the bacterial colony, as well as, a relationship in between the morphological characteristics of the bacterial colony and its forward scattering pattern. Two different genera: Escherichia coli O157:H7 EDL933, and Staphylococcus aureus ATCC 25923 are selected for the analysis of the spatially resolved growth dynamics, while, Bacillus spp. such as B. subtilis ATCC 6633, B. cereus ATCC 14579, B. thuringiensis DUP6044, B. polymyxa B719W, and B. megaterium DSP 81319, are interrogated since some of the Bacillus spp. provides strikingly different characteristics of ELS patterns, and the origin of the speckle patterns are successfully correlated with

Bacterial contamination of platelet components not detected by BacT/ALERT®.

Science.gov (United States)

Abela, M A; Fenning, S; Maguire, K A; Morris, K G

2018-02-01

To investigate the possible causes for false negative results in BacT/ALERT ® 3D Signature System despite bacterial contamination of platelet units. The Northern Ireland Blood Transfusion Service (NIBTS) routinely extends platelet component shelf life to 7 days. Components are sampled and screened for bacterial contamination using an automated microbial detection system, the BacT/ALERT ® 3D Signature System. We report on three platelet components with confirmed bacterial contamination, which represent false negative BacT/ALERT ® results and near-miss serious adverse events. NIBTS protocols for risk reduction of bacterial contamination of platelet components are described. The methodology for bacterial detection using BacT/ALERT ® is outlined. Laboratory tests, relevant patient details and relevant follow-up information are analysed. In all three cases, Staphylococcus aureus was isolated from the platelet residue and confirmed on terminal sub-culture using BacT/ALERT ® . In two cases, S. aureus with similar genetic makeup was isolated from the donors. Risk reduction measures for bacterial contamination of platelet components are not always effective. Automated bacterial culture detection does not eliminate the risk of bacterial contamination. Visual inspection of platelet components prior to release, issue and administration remains an important last line of defence. © 2017 British Blood Transfusion Society.

C-reactive protein velocity to distinguish febrile bacterial infections from non-bacterial febrile illnesses in the emergency department

OpenAIRE

Paran, Yael; Yablecovitch, Doron; Choshen, Guy; Zeitlin, Ina; Rogowski, Ori; Ben-Ami, Ronen; Katzir, Michal; Saranga, Hila; Rosenzweig, Tovit; Justo, Dan; Orbach, Yaffa; Halpern, Pinhas; Berliner, Shlomo

2009-01-01

Introduction C-reactive protein (CRP) is a real-time and low-cost biomarker to distinguish febrile bacterial infections from non-bacterial febrile illnesses. We hypothesised that measuring the velocity of the biomarker instead of its absolute serum concentration could enhance its ability to differentiate between these two conditions. Methods We prospectively recruited adult patients (age ? 18 years) who presented to the emergency department with fever. We recorded their data regarding the ons...

Childhood asthma after bacterial colonization of the airway in neonates

DEFF Research Database (Denmark)

Bisgaard, Hans; Hermansen, Mette Northman; Buchvald, Frederik

2007-01-01

Pathological features of the airway in young children with severe recurrent wheeze suggest an association between bacterial colonization and the initiating events of early asthma. We conducted a study to investigate a possible association between bacterial colonization of the hypopharynx in asymp......Pathological features of the airway in young children with severe recurrent wheeze suggest an association between bacterial colonization and the initiating events of early asthma. We conducted a study to investigate a possible association between bacterial colonization of the hypopharynx...... in asymptomatic neonates and later development of recurrent wheeze, asthma, and allergy during the first 5 years of life....

Carbon nanomaterials alter plant physiology and soil bacterial community composition in a rice-soil-bacterial ecosystem.

Science.gov (United States)

Hao, Yi; Ma, Chuanxin; Zhang, Zetian; Song, Youhong; Cao, Weidong; Guo, Jing; Zhou, Guopeng; Rui, Yukui; Liu, Liming; Xing, Baoshan

2018-01-01

The aim of this study was to compare the toxicity effects of carbon nanomaterials (CNMs), namely fullerene (C 60 ), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), on a mini-ecosystem of rice grown in a loamy potted soil. We measured plant physiological and biochemical parameters and examined bacterial community composition in the CNMs-treated plant-soil system. After 30 days of exposure, all the three CNMs negatively affected the shoot height and root length of rice, significantly decreased root cortical cells diameter and resulted in shrinkage and deformation of cells, regardless of exposure doses (50 or 500 mg/kg). Additionally, at the high exposure dose of CNM, the concentrations of four phytohormones, including auxin, indoleacetic acid, brassinosteroid and gibberellin acid 4 in rice roots significantly increased as compared to the control. At the high exposure dose of MWCNTs and C 60 , activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) in roots increased significantly. High-throughput sequencing showed that three typical CNMs had little effect on shifting the predominant soil bacterial species, but the presence of CNMs significantly altered the composition of the bacterial community. Our results indicate that different CNMs indeed resulted in environmental toxicity to rice and soil bacterial community in the rhizosphere and suggest that CNMs themselves and their incorporated products should be reasonably used to control their release/discharge into the environment to prevent their toxic effects on living organisms and the potential risks to food safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Heme Synthesis and Acquisition in Bacterial Pathogens.

Science.gov (United States)

Choby, Jacob E; Skaar, Eric P

2016-08-28

Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Counterimmunoelectrophoresis in the diagnosis of bacterial meningitis

DEFF Research Database (Denmark)

Colding, H; Lind, I

1977-01-01

The aim of the present study was to investigate whether counterimmunoelectrophoresis (CIE) would facilitate the rapid, etiological diagnosis of bacterial meningitis when used in parallel with other routine methods in a medical bacteriological laboratory. Of 3,674 consecutive specimens of cerebros......The aim of the present study was to investigate whether counterimmunoelectrophoresis (CIE) would facilitate the rapid, etiological diagnosis of bacterial meningitis when used in parallel with other routine methods in a medical bacteriological laboratory. Of 3,674 consecutive specimens....../139) of the culture-negative specimens. CSF specimens from 21 patients with bacterial meningitis caused by other species were all negative in CIE, except four, three of which contained Escherichia coli antigen reacting with antiserum to N. meningitidis group B and one E. coli antigen reacting with antiserum to H...

Bacterial colonization of psoriasis plaques. Is it relevant?

Directory of Open Access Journals (Sweden)

Eva Marcus

2011-08-01

Full Text Available Bacterial colonization was investigated retrospectively in patients with plaque psoriasis (n=98 inpatient treatments, n=73 patients. At least one pathogen was found in 46% of all cases. Staphylococcus aureus was the most frequent bacterium. Bacterial colonization of psoriasis plaques could be relevant in individual cases.

Engineering nanoparticles to silence bacterial communication

Directory of Open Access Journals (Sweden)

Kristen Publicover Miller

2015-03-01

Full Text Available The alarming spread of bacterial resistance to traditional antibiotics has warranted the study of alternative antimicrobial agents. Quorum sensing is a chemical cell-to-cell communication mechanism utilized by bacteria to coordinate group behaviors and establish infections. Quorum sensing is integral to bacterial survival, and therefore provides a unique target for antimicrobial therapy. In this study, silicon dioxide nanoparticles (Si-NP were engineered to target the signaling molecules (i.e. acylhomoserine lactones (HSL used for quorum sensing in order to halt bacterial communication. Specifically, when Si-NP were surface functionalized with beta-cyclodextrin (beta-CD, then added to cultures of bacteria (Vibrio fischeri, whose luminous output depends upon HSL-mediated quorum sensing, the cell-to-cell communication was dramatically reduced. Reductions in luminescence were further verified by quantitative polymerase chain reaction (qPCR analyses of luminescence genes. Binding of AHLs to Si-NPs was examined using nuclear magnetic resonance (NMR spectroscopy. The results indicated that by delivering high concentrations of engineered NPs with associated quenching compounds, the chemical signals were removed from the immediate bacterial environment. In actively-metabolizing cultures, this treatment blocked the ability of bacteria to communicate and regulate quorum sensing, effectively silencing and isolating the cells. Si-NPs provide a scaffold and critical stepping-stone for more pointed developments in antimicrobial therapy, especially with regard to quorum sensing – a target that will reduce resistance pressures imposed by traditional antibiotics.

Bacterial fingerprints across Europe

NARCIS (Netherlands)

Glasner, Corinna

2014-01-01

Bacterial pathogens, such as Staphylococcus aureus and carbapenemase-producing Enterobacteriaceae (CPE), impose major threats to human health worldwide. Both have a ‘Jekyll & Hyde’ character, since they can be present as human commensals, but can also become harmful invasive pathogens especially

Modeling of scale-dependent bacterial growth by chemical kinetics approach.

Science.gov (United States)

Martínez, Haydee; Sánchez, Joaquín; Cruz, José-Manuel; Ayala, Guadalupe; Rivera, Marco; Buhse, Thomas

2014-01-01

We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V) of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

Modeling of Scale-Dependent Bacterial Growth by Chemical Kinetics Approach

Directory of Open Access Journals (Sweden)

Haydee Martínez

2014-01-01

Full Text Available We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli  JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

The effect of loss of O-antigen ligase on phagocytic susceptibility of motile and non-motile Pseudomonas aeruginosa.

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Demirdjian, Sally; Schutz, Kristin; Wargo, Matthew J; Lam, Joseph S; Berwin, Brent

2017-12-01

The bacterial pathogen Pseudomonas aeruginosa undergoes adaptation and selection over the course of chronic respiratory tract infections which results in repeatedly-observed phenotypic changes that are proposed to enable its persistence. Two of the clinically significant P. aeruginosa phenotypic changes are loss of flagellar motility and modifications to LPS structure, including loss of O-antigen expression. The effect of loss of O-antigen, frequently described as conversion from smooth to rough LPS, and the combined effect of loss of motility and O-antigen on phagocytic susceptibility by immune cells remain unknown. To address this, we generated genetic deletion mutants of waaL, which encodes the O-antigen ligase responsible for linking O-antigen to lipid A-core oligosaccharide, in both motile and non-motile P. aeruginosa strains. With the use of these bacterial strains we provide the first demonstration that, despite a progressive selection for P. aeruginosa with rough LPS during chronic pulmonary infections, loss of the LPS O-antigen does not confer phagocytic resistance in vitro. However, use of the waaLmotABmotCD mutant revealed that loss of motility confers resistance to phagocytosis regardless of the smooth or rough LPS phenotype. These findings reveal how the O-antigen of P. aeruginosa can influence bacterial clearance during infection and expand our current knowledge about the impact of bacterial phenotypic changes during chronic infection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ice formation and growth shape bacterial community structure in Baltic Sea drift ice.

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Eronen-Rasimus, Eeva; Lyra, Christina; Rintala, Janne-Markus; Jürgens, Klaus; Ikonen, Vilma; Kaartokallio, Hermanni

2015-02-01

Drift ice, open water and under-ice water bacterial communities covering several developmental stages from open water to thick ice were studied in the northern Baltic Sea. The bacterial communities were assessed with 16S rRNA gene terminal-restriction fragment length polymorphism and cloning, together with bacterial abundance and production measurements. In the early stages, open water and pancake ice were dominated by Alphaproteobacteria and Actinobacteria, which are common bacterial groups in Baltic Sea wintertime surface waters. The pancake ice bacterial communities were similar to the open-water communities, suggesting that the parent water determines the sea-ice bacterial community in the early stages of sea-ice formation. In consolidated young and thick ice, the bacterial communities were significantly different from water bacterial communities as well as from each other, indicating community development in Baltic Sea drift ice along with ice-type changes. The thick ice was dominated by typical sea-ice genera from classes Flavobacteria and Gammaproteobacteria, similar to those in polar sea-ice bacterial communities. Since the thick ice bacterial community was remarkably different from that of the parent seawater, results indicate that thick ice bacterial communities were recruited from the rarer members of the seawater bacterial community. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Bacterial Cellulose Production from Industrial Waste and by-Product Streams.

Science.gov (United States)

Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

2015-07-01

The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102-138 g · water/g · dry bacterial cellulose, viscosities of 4.7-9.3 dL/g, degree of polymerization of 1889.1-2672.8, stress at break of 72.3-139.5 MPa and Young's modulus of 0.97-1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

High level bacterial contamination of secondary school students' mobile phones.

Science.gov (United States)

Kõljalg, Siiri; Mändar, Rando; Sõber, Tiina; Rööp, Tiiu; Mändar, Reet

2017-06-01

While contamination of mobile phones in the hospital has been found to be common in several studies, little information about bacterial abundance on phones used in the community is available. Our aim was to quantitatively determine the bacterial contamination of secondary school students' mobile phones. Altogether 27 mobile phones were studied. The contact plate method and microbial identification using MALDI-TOF mass spectrometer were used for culture studies. Quantitative PCR reaction for detection of universal 16S rRNA, Enterococcus faecalis 16S rRNA and Escherichia coli allantoin permease were performed, and the presence of tetracycline ( tet A, tet B, tet M), erythromycin ( erm B) and sulphonamide ( sul 1) resistance genes was assessed. We found a high median bacterial count on secondary school students' mobile phones (10.5 CFU/cm 2 ) and a median of 17,032 bacterial 16S rRNA gene copies per phone. Potentially pathogenic microbes ( Staphylococcus aureus , Acinetobacter spp. , Pseudomonas spp., Bacillus cereus and Neisseria flavescens ) were found among dominant microbes more often on phones with higher percentage of E. faecalis in total bacterial 16S rRNA. No differences in contamination level or dominating bacterial species between phone owner's gender and between phone types (touch screen/keypad) were found. No antibiotic resistance genes were detected on mobile phone surfaces. Quantitative study methods revealed high level bacterial contamination of secondary school students' mobile phones.

Bacterial diversity at different stages of the composting process

Directory of Open Access Journals (Sweden)

Paulin Lars

2010-03-01

Full Text Available Abstract Background Composting is an aerobic microbiological process that is facilitated by bacteria and fungi. Composting is also a method to produce fertilizer or soil conditioner. Tightened EU legislation now requires treatment of the continuously growing quantities of organic municipal waste before final disposal. However, some full-scale composting plants experience difficulties with the efficiency of biowaste degradation and with the emission of noxious odours. In this study we examine the bacterial species richness and community structure of an optimally working pilot-scale compost plant, as well as a full-scale composting plant experiencing typical problems. Bacterial species composition was determined by isolating total DNA followed by amplifying and sequencing the gene encoding the 16S ribosomal RNA. Results Over 1500 almost full-length 16S rRNA gene sequences were analysed and of these, over 500 were present only as singletons. Most of the sequences observed in either one or both of the composting processes studied here were similar to the bacterial species reported earlier in composts, including bacteria from the phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria and Deinococcus-Thermus. In addition, a number of previously undetected bacterial phylotypes were observed. Statistical calculations estimated a total bacterial diversity of over 2000 different phylotypes in the studied composts. Conclusions Interestingly, locally enriched or evolved bacterial variants of familiar compost species were observed in both composts. A detailed comparison of the bacterial diversity revealed a large difference in composts at the species and strain level from the different composting plants. However, at the genus level, the difference was much smaller and illustrated a delay of the composting process in the full-scale, sub-optimally performing plants.

Alternatives to overcoming bacterial resistances: State-of-the-art.

Science.gov (United States)

Rios, Alessandra C; Moutinho, Carla G; Pinto, Flávio C; Del Fiol, Fernando S; Jozala, Angela; Chaud, Marco V; Vila, Marta M D C; Teixeira, José A; Balcão, Victor M

2016-10-01

Worldwide, bacterial resistance to chemical antibiotics has reached such a high level that endangers public health. Presently, the adoption of alternative strategies that promote the elimination of resistant microbial strains from the environment is of utmost importance. This review discusses and analyses several (potential) alternative strategies to current chemical antibiotics. Bacteriophage (or phage) therapy, although not new, makes use of strictly lytic phage particles as an alternative, or a complement, in the antimicrobial treatment of bacterial infections. It is being rediscovered as a safe method, because these biological entities devoid of any metabolic machinery do not possess any affinity whatsoever to eukaryotic cells. Lysin therapy is also recognized as an innovative antimicrobial therapeutic option, since the topical administration of preparations containing purified recombinant lysins with amounts in the order of nanograms, in infections caused by Gram-positive bacteria, demonstrated a high therapeutic potential by causing immediate lysis of the target bacterial cells. Additionally, this therapy exhibits the potential to act synergistically when combined with certain chemical antibiotics already available on the market. Another potential alternative antimicrobial therapy is based on the use of antimicrobial peptides (AMPs), amphiphilic polypeptides that cause disruption of the bacterial membrane and can be used in the treatment of bacterial, fungal and viral infections, in the prevention of biofilm formation, and as antitumoral agents. Interestingly, bacteriocins are a common strategy of bacterial defense against other bacterial agents, eliminating the potential opponents of the former and increasing the number of available nutrients in the environment for their own growth. They can be applied in the food industry as biopreservatives and as probiotics, and also in fighting multi-resistant bacterial strains. The use of antibacterial antibodies

Carbon nanotubes as anti-bacterial agents.

Science.gov (United States)

Mocan, Teodora; Matea, Cristian T; Pop, Teodora; Mosteanu, Ofelia; Buzoianu, Anca Dana; Suciu, Soimita; Puia, Cosmin; Zdrehus, Claudiu; Iancu, Cornel; Mocan, Lucian

2017-10-01

Multidrug-resistant bacterial infections that have evolved via natural selection have increased alarmingly at a global level. Thus, there is a strong need for the development of novel antibiotics for the treatment of these infections. Functionalized carbon nanotubes through their unique properties hold great promise in the fight against multidrug-resistant bacterial infections. This new family of nanovectors for therapeutic delivery proved to be innovative and efficient for the transport and cellular translocation of therapeutic molecules. The current review examines the latest progress in the antibacterial activity of carbon nanotubes and their composites.

A two-dimensional electrophoretic profile of the proteins secreted by Herbaspirillum seropedicae strain Z78.

Science.gov (United States)

Chaves, Daniela Fojo Seixas; de Souza, Emanuel Maltempi; Monteiro, Rose Adele; de Oliveira Pedrosa, Fábio

2009-11-02

Herbaspirillum seropedicae is an endophytic bacterium that associates with rice, sugarcane and other economically important crops. Secreted proteins play a key role in the plant-bacterial interaction. Using 2D electrophoresis and peptide mass fingerprint mass spectrometry, 63 protein spots representing 41 different secreted proteins were identified during growth of H. seropedicae under nitrogen-sufficient conditions. In silico analysis showed that 25.4% of the proteins had signal peptides and 15.9% were predicted to be non-classically secreted. Among the most abundant were flagellar components and ABC-type transport system proteins. Nine secreted proteins had also been identified in the cellular proteome, suggesting that they also play a role in the extracellular environment. No type III secreted proteins were detected by comparison of the wild type strain with an hrcN mutant strain.

21 CFR 868.5260 - Breathing circuit bacterial filter.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Breathing circuit bacterial filter. 868.5260 Section 868.5260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... filter. (a) Identification. A breathing circuit bacterial filter is a device that is intended to remove...

Binding and entry of DNA in bacterial transformation

Energy Technology Data Exchange (ETDEWEB)

Lacks, S.A.

1976-01-01

Bacterial transformation in relation to DNA transport and competence in Streptococcus pneumoniae (also called Diplococcus pneumoniae) is discussed. This species will serve as a model with which to compare transformation in other bacterial species, particularly Bacillus subtilis and Haemophilus influenzae, with emphasis on the many similarities as well as differences.

Heme Synthesis and Acquisition in Bacterial Pathogens

OpenAIRE

Choby, Jacob E.; Skaar, Eric P.

2016-01-01

Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host source...

Bacterial Vaginosis Presence in Sexually Active Women in Tuzla Canton Area

Directory of Open Access Journals (Sweden)

Fatima Numanović

2008-11-01

Full Text Available The goal of our research was to determine the presence of bacterial vaginosis in sexually active women in Tuzla Canton area. Diagnosis determination for bacterial vaginosis was conducted on the basis of three out of four internationally accepted criteria according to Amsel and isolation and identification of Gard- nerella vaginalis (G. vaginalis by standard microbiological procedures. Bacterial vaginosis was diagnosed in 20,5 % (41/200 women who asked for gynaecologist’s help due to their personal discomfort, since significantly higher percentage of diagnosed bacterial vaginosis of 48,80% (41/84 was determined in women with personal discomfort typical for this disease. All relevant factors, according to available literature, for genesis of bacterial vaginosis were processed in this research. In respect to the obtained outputs, bacterial vaginosis is significantly more frequent occurrence in women who are not married, since the number of sexual partners, the time of the first sexual intercourse, the use of intrauterine contraceptive device and smoking do not cause the genesis of bacterial vaginosis. According to Nugent, an increased vaginal discharge with unpleasant odour after sexual discourse, its pH>4,5, a positive amino odour test, an occurrence of clue cells in a direct microscopic concoction of vaginal discharge and assessment of the state of vaginal flora for bacterial vaginosis are significantly more frequent occurrences in women with individual discomforts. It was proved that G. vaginalisis a dominant micro organism in 95% of women with clinical signs of vaginosis although it was isolated from vaginal discharge in 40 to 50% of healthy women. In our research, G. vaginalis was isolated in 63,41% of examined women with all signs of bacterial vaginosis, in 36,59% of examined women with one or more clinical signs of bacterial vaginosis and in 2,58% of examined women of control group without clinical signs.

Bacterial Communities Associated with the Lichen Symbiosis▿ †

Science.gov (United States)

Bates, Scott T.; Cropsey, Garrett W. G.; Caporaso, J. Gregory; Knight, Rob; Fierer, Noah

2011-01-01

Lichens are commonly described as a mutualistic symbiosis between fungi and “algae” (Chlorophyta or Cyanobacteria); however, they also have internal bacterial communities. Recent research suggests that lichen-associated microbes are an integral component of lichen thalli and that the classical view of this symbiotic relationship should be expanded to include bacteria. However, we still have a limited understanding of the phylogenetic structure of these communities and their variability across lichen species. To address these knowledge gaps, we used bar-coded pyrosequencing to survey the bacterial communities associated with lichens. Bacterial sequences obtained from four lichen species at multiple locations on rock outcrops suggested that each lichen species harbored a distinct community and that all communities were dominated by Alphaproteobacteria. Across all samples, we recovered numerous bacterial phylotypes that were closely related to sequences isolated from lichens in prior investigations, including those from a lichen-associated Rhizobiales lineage (LAR1; putative N2 fixers). LAR1-related phylotypes were relatively abundant and were found in all four lichen species, and many sequences closely related to other known N2 fixers (e.g., Azospirillum, Bradyrhizobium, and Frankia) were recovered. Our findings confirm the presence of highly structured bacterial communities within lichens and provide additional evidence that these bacteria may serve distinct functional roles within lichen symbioses. PMID:21169444

Diversity and abundance of the bacterial community of the red Macroalga Porphyra umbilicalis: did bacterial farmers produce macroalgae?

Directory of Open Access Journals (Sweden)

Lilibeth N Miranda

Full Text Available Macroalgae harbor microbial communities whose bacterial biodiversity remains largely uncharacterized. The goals of this study were 1 to examine the composition of the bacterial community associated with Porphyra umbilicalis Kützing from Schoodic Point, ME, 2 determine whether there are seasonal trends in species diversity but a core group of bacteria that are always present, and 3 to determine how the microbial community associated with a laboratory strain (P.um.1 established in the presence of antibiotics has changed. P. umbilicalis blades (n = 5, fall 2010; n = 5, winter 2011; n = 2, clonal P.um.1 were analyzed by pyrosequencing over two variable regions of the 16 S rDNA (V5-V6 and V8; 147,880 total reads. The bacterial taxa present were classified at an 80% confidence threshold into eight phyla (Bacteroidetes, Proteobacteria, Planctomycetes, Chloroflexi, Actinobacteria, Deinococcus-Thermus, Firmicutes, and the candidate division TM7. The Bacteroidetes comprised the majority of bacterial sequences on both field and lab blades, but the Proteobacteria (Alphaproteobacteria, Gammaproteobacteria were also abundant. Sphingobacteria (Bacteroidetes and Flavobacteria (Bacteroidetes had inverse abundances on natural versus P.um.1 blades. Bacterial communities were richer and more diverse on blades sampled in fall compared to winter. Significant differences were observed between microbial communities among all three groups of blades examined. Only two OTUs were found on all 12 blades, and only one of these, belonging to the Saprospiraceae (Bacteroidetes, was abundant. Lewinella (as 66 OTUs was found on all field blades and was the most abundant genus. Bacteria from the Bacteroidetes, Proteobacteria and Planctomycetes that are known to digest the galactan sulfates of red algal cell walls were well-represented. Some of these taxa likely provide essential morphogenetic and beneficial nutritive factors to P. umbilicalis and may have had

Do Honeybees Shape the Bacterial Community Composition in Floral Nectar?

Science.gov (United States)

Aizenberg-Gershtein, Yana; Izhaki, Ido; Halpern, Malka

2013-01-01

Floral nectar is considered the most important reward animal-pollinated plants offer to attract pollinators. Here we explore whether honeybees, which act as pollinators, affect the composition of bacterial communities in the nectar. Nectar and honeybees were sampled from two plant species: Amygdalus communis and Citrus paradisi. To prevent the contact of nectar with pollinators, C. paradisi flowers were covered with net bags before blooming (covered flowers). Comparative analysis of bacterial communities in the nectar and on the honeybees was performed by the 454-pyrosequencing technique. No significant differences were found among bacterial communities in honeybees captured on the two different plant species. This resemblance may be due to the presence of dominant bacterial OTUs, closely related to the Arsenophonus genus. The bacterial communities of the nectar from the covered and uncovered C. paradisi flowers differed significantly; the bacterial communities on the honeybees differed significantly from those in the covered flowers’ nectar, but not from those in the uncovered flowers’ nectar. We conclude that the honeybees may introduce bacteria into the nectar and/or may be contaminated by bacteria introduced into the nectar by other sources such as other pollinators and nectar thieves. PMID:23844027

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

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Belén Álvarez

2017-07-01

Full Text Available Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture.

Science.gov (United States)

Álvarez, Belén; Biosca, Elena G

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum , R. pseudosolanacearum , and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis , not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta . Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

Characterization of Novel Factors Involved in Swimming and Swarming Motility in Salmonella enterica Serovar Typhimurium.

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Julia Andrea Deditius

Full Text Available Salmonella enterica utilizes flagellar motility to swim through liquid environments and on surfaces. The biosynthesis of the flagellum is regulated on various levels, including transcriptional and posttranscriptional mechanisms. Here, we investigated the motility phenotype of 24 selected single gene deletions that were previously described to display swimming and swarming motility effects. Mutations in flgE, fliH, ydiV, rfaG, yjcC, STM1267 and STM3363 showed an altered motility phenotype. Deletions of flgE and fliH displayed a non-motile phenotype in both swimming and swarming motility assays as expected. The deletions of STM1267, STM3363, ydiV, rfaG and yjcC were further analyzed in detail for flagellar and fimbrial gene expression and filament formation. A ΔydiV mutant showed increased swimming motility, but a decrease in swarming motility, which coincided with derepression of curli fimbriae. A deletion of yjcC, encoding for an EAL domain-containing protein, increased swimming motility independent on flagellar gene expression. A ΔSTM1267 mutant displayed a hypermotile phenotype on swarm agar plates and was found to have increased numbers of flagella. In contrast, a knockout of STM3363 did also display an increase in swarming motility, but did not alter flagella numbers. Finally, a deletion of the LPS biosynthesis-related protein RfaG reduced swimming and swarming motility, associated with a decrease in transcription from flagellar class II and class III promoters and a lack of flagellar filaments.

Biogenesis and fate of the cell-cell adhesion molecule, agglutinin, during gametogenesis and fertilization of Chlamydomonas reinhardtii

International Nuclear Information System (INIS)

Hunnicutt, G.R.

1989-01-01

Fertilization in Chlamydomonas begins with the species-specific recognition and adhesion between gametes of opposite mating types via agglutinin molecules on the flagellar surface. This adhesion generates a cAMP-mediated sexual signal that initiates the subsequent events of call wall release, mating structure activation, and cell fusion. Although flagella of paired gametes remain attached to each other until the zygote forms, the process is dynamic. Engaged agglutinins rapidly become inactivated and turnover, requiring the constant supply of new agglutinins to replace the lost molecules. A population of cell body associated agglutinins has been postulated to the pool of agglutinins recruited during this turnover. Cell body agglutinins, therefore were identified, purified, localized within the cells and compared to flagellar agglutinins. The relationship between these two agglutinin populations was also examined. Cell body agglutinins were biochemically indistinguishable from the flagellar form with respect to their M r , sedimentation coefficient, and hydrophobicity elution properties. Functionally, however, these molecules were inactive in situ. The calculated surface density of agglutinins in the cell body and flagellar domains was similar and thus could not explain their functional difference, but two domains contiguous and yet distinctive suggested they may be separated by a functional barrier. To test this, a method was developed, using a monoclonal antibody and cycloheximide, that removed the flagellar agglutinins so movement between the domains could be monitored. Mobilization of agglutinins onto the flagella did not occur unless sexual signaling was induced with cAMP and papaverine

Isolation of the bacterial causes of tonsillitis in dogs

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B. Al-Mufti

2014-06-01

Full Text Available The study was performed to identify the bacterial causes of tonsillitis in dogs. Twelve clinical cases of dogs (5 males and 7 females of different ages and breeds were observed. Tonsils swabs were taken from all the dogs, then cultured on different agars and bacterial smears prepared from all cultures and Gram stains were done. The study confirmed that the most bacterial causes of tonsillitis in dogs were Escherichia coli, Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus albus, Streptococcus pyogenes, Klebsiella spp. and Pasteurella spp.

Bacterial infection increases risk of carcinogenesis by targeting mitochondria

DEFF Research Database (Denmark)

Strickertsson, Jesper A.B.; Desler, Claus; Rasmussen, Lene Juel

2017-01-01

pathways, and compares the impact of the bacterial alteration of mitochondrial function to that of cancer. Bacterial virulence factors have been demonstrated to induce mutations of mitochondrial DNA (mtDNA) and to modulate DNA repair pathways of the mitochondria. Furthermore, virulence factors can induce...... or impair the intrinsic apoptotic pathway. The effect of bacterial targeting of mitochondria is analogous to behavior of mitochondria in a wide array of tumours, and this strongly suggests that mitochondrial targeting of bacteria is a risk factor for carcinogenesis....

Soil bacterial diversity in degraded and restored lands of Northeast Brazil.

Science.gov (United States)

Araújo, Ademir Sérgio Ferreira; Borges, Clovis Daniel; Tsai, Siu Mui; Cesarz, Simone; Eisenhauer, Nico

2014-11-01

Land degradation deteriorates biological productivity and affects environmental, social, and economic sustainability, particularly so in the semi-arid region of Northeast Brazil. Although some studies exist reporting gross measures of soil microbial parameters and processes, limited information is available on how land degradation and restoration strategies influence the diversity and composition of soil microbial communities. In this study we compare the structure and diversity of bacterial communities in degraded and restored lands in Northeast Brazil and determine the soil biological and chemical properties influencing bacterial communities. We found that land degradation decreased the diversity of soil bacteria as indicated by both reduced operational taxonomic unit (OTU) richness and Shannon index. Soils under native vegetation and restoration had significantly higher bacterial richness and diversity than degraded soils. Redundancy analysis revealed that low soil bacterial diversity correlated with a high respiratory quotient, indicating stressed microbial communities. By contrast, soil bacterial communities in restored land positively correlated with high soil P levels. Importantly, however, we found significant differences in the soil bacterial community composition under native vegetation and in restored land, which may indicate differences in their functioning despite equal levels of bacterial diversity.

Removal of Triphenylmethane Dyes by Bacterial Consortium

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Jihane Cheriaa

2012-01-01

Full Text Available A new consortium of four bacterial isolates (Agrobacterium radiobacter; Bacillus spp.; Sphingomonas paucimobilis, and Aeromonas hydrophila-(CM-4 was used to degrade and to decolorize triphenylmethane dyes. All bacteria were isolated from activated sludge extracted from a wastewater treatment station of a dyeing industry plant. Individual bacterial isolates exhibited a remarkable color-removal capability against crystal violet (50 mg/L and malachite green (50 mg/L dyes within 24 h. Interestingly, the microbial consortium CM-4 shows a high decolorizing percentage for crystal violet and malachite green, respectively, 91% and 99% within 2 h. The rate of chemical oxygen demand (COD removal increases after 24 h, reaching 61.5% and 84.2% for crystal violet and malachite green, respectively. UV-Visible absorption spectra, FTIR analysis and the inspection of bacterial cells growth indicated that color removal by the CM-4 was due to biodegradation. Evaluation of mutagenicity by using Salmonella typhimurium test strains, TA98 and TA100 studies revealed that the degradation of crystal violet and malachite green by CM-4 did not lead to mutagenic products. Altogether, these results demonstrated the usefulness of the bacterial consortium in the treatment of the textile dyes.

Assessing Bacterial Interactions Using Carbohydrate-Based Microarrays

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Andrea Flannery

2015-12-01

Full Text Available Carbohydrates play a crucial role in host-microorganism interactions and many host glycoconjugates are receptors or co-receptors for microbial binding. Host glycosylation varies with species and location in the body, and this contributes to species specificity and tropism of commensal and pathogenic bacteria. Additionally, bacterial glycosylation is often the first bacterial molecular species encountered and responded to by the host system. Accordingly, characterising and identifying the exact structures involved in these critical interactions is an important priority in deciphering microbial pathogenesis. Carbohydrate-based microarray platforms have been an underused tool for screening bacterial interactions with specific carbohydrate structures, but they are growing in popularity in recent years. In this review, we discuss carbohydrate-based microarrays that have been profiled with whole bacteria, recombinantly expressed adhesins or serum antibodies. Three main types of carbohydrate-based microarray platform are considered; (i conventional carbohydrate or glycan microarrays; (ii whole mucin microarrays; and (iii microarrays constructed from bacterial polysaccharides or their components. Determining the nature of the interactions between bacteria and host can help clarify the molecular mechanisms of carbohydrate-mediated interactions in microbial pathogenesis, infectious disease and host immune response and may lead to new strategies to boost therapeutic treatments.

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

OpenAIRE

?lvarez, Bel?n; Biosca, Elena G.

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the a...

Community-acquired bacterial meningitis

NARCIS (Netherlands)

van de Beek, Diederik; Brouwer, Matthijs; Hasbun, Rodrigo; Koedel, Uwe; Whitney, Cynthia G.; Wijdicks, Eelco

2016-01-01

Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma

Bacterial Cellulose Production from Industrial Waste and by-Product Streams

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Erminda Tsouko

2015-07-01

Full Text Available The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L and commercial sucrose (4.9 g/L were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

Bacterial contribution to iodine volatilization in the environment

Energy Technology Data Exchange (ETDEWEB)

Amachi, S; Kasahara, M; Fujii, T [Chiba Univ., Dept. of Bioresources Chemistry, Matsudo, Chiba (Japan); Muramatsu, Y [National Inst. of Radiological Sciences, Chiba (Japan)

2003-09-01

The roles of microorganisms in iodine volatilization from the environment were studied. More than 100 bacterial strains were isolated from various environments such as soils, seawater and marine sediments, and were examined their capacities for volatilizing iodine. Approximately 40% of these bacteria showed significant capacities for volatilizing iodine. Gas chromatographic determinations revealed that the chemical species of gaseous iodine is methyl iodide (CH{sub 3}I). Phylogenetic analysis based on 16S ribosomal DNA showed that these 'iodine-volatilizing bacteria' are widely distributed through the bacterial domain. The iodide-methylating reaction was mediated by an enzyme protein with S-adenosyl-L-methionine (SAM) as the methyl donor. We then estimated bacterial contribution to iodine volatilization from soils. Iodine in soils was volatilized mainly as CH{sub 3}I. CH{sub 3}I emission was enhanced in the presence of glucose or yeast extract, but was inhibited by autoclaving of soils. Little CH{sub 3}I was produced under anaerobic conditions. Furthermore, the addition of streptomycin and tetracycline, antibiotics which inhibit bacterial growth, strongly inhibited CH{sub 3}I emission, while a fungal inhibitor cycloheximide caused little effect. These results suggest that iodine in soils is volatilized as CH{sub 3}I mainly by the action of aerobic soil bacteria. Similar experiment was carried out by using sea water samples. The emission of iodine from sea waters occurred biologically, and bacterial (and also other microbial) contribution was confirmed. Our results suggest that iodine is methylated and volatilized into the atmosphere as a result of bacterial activities. Since bacteria are so abundant and widespread in the environments, they may significantly contribute to global iodine volatilization. This indicates that if {sup 129}I would be released from nuclear facilities, weapons testing or ground storage of nuclear wastes, the pathway of volatilization by

[Congenital skull base defect causing recurrent bacterial meningitis].

Science.gov (United States)

Berliner, Elihay; Bar Meir, Maskit; Megged, Orli

2012-08-01

Bacterial meningitis is a life threatening disease. Most patients will experience only one episode throughout life. Children who experience bacterial meningitis more than once, require further immunologic or anatomic evaluation. We report a 9 year old child with five episodes of bacterial meningitis due to a congenital defect of the skull base. A two and a half year old boy first presented to our medical center with pneumococcal meningitis. He was treated with antibiotics and fully recovered. Two months later he presented again with a similar clinical picture. Streptococcus pneumoniae grew in cerebrospinal fluid (CSF) culture. CT scan and later MRI of the brain revealed a defect in the anterior middle fossa floor, with protrusion of brain tissue into the sphenoidal sinus. Corrective surgery was recommended but the parents refused. Three months later, a third episode of pneumococcal meningitis occurred. The child again recovered with antibiotics and this time corrective surgery was performed. Five years later, the boy presented once again with clinical signs and symptoms consistent with bacterial meningitis. CSF culture was positive, but the final identification of the bacteria was conducted by broad spectrum 16S ribosomal RNA PCR (16S rRNA PCR) which revealed a sequence of Neisseria lactamica. CT and MRI showed recurrence of the skull base defect with encephalocele in the sphenoid sinus. The parents again refused neurosurgical intervention. A year later the patient presented with bacterial meningitis. CSF culture obtained after initiation of antibiotics was negative, but actinobacillus was identified in the CSF by 16S rRNA PCR. The patient is scheduled for neurosurgical intervention. In patients with recurrent bacterial meningitis caused by organisms colonizing the oropharynx or nasopharynx, an anatomical defect should be carefully sought and surgically repaired.

Bacterial Meningitis in Adults After Splenectomy and Hyposplenic States

NARCIS (Netherlands)

Adriani, Kirsten S.; Brouwer, Matthijs C.; van der Ende, Arie; van de Beek, Diederik

2013-01-01

Objective: To examine the occurrence, disease course, prognosis, and vaccination status of patients with community-acquired bacterial meningitis with a history of splenectomy or functional hyposplenia. Patients and Methods: Patients with bacterial meningitis proven by cerebrospinal fluid culture

Bacterial communities in the fruit bodies of ground basidiomycetes

Science.gov (United States)

Zagryadskaya, Yu. A.; Lysak, L. V.; Chernov, I. Yu.

2015-06-01

Fruit bodies of basidiomycetes at different stages of decomposition serve as specific habitats in forest biocenoses for bacteria and differ significantly with respect to the total bacterial population and abundance of particular bacterial genera. A significant increase in the total bacterial population estimated by the direct microscopic method with acridine orange staining and in the population of saprotrophic bacteria (inoculation of glucose peptone yeast agar) in fruit bodies of basidiomycetes Armillaria mellea and Coprinus comatus was recorded at the final stage of their decomposition in comparison with the initial stage. Gramnegative bacteria predominated in the tissues of fruit bodies at all the stages of decomposition and were represented at the final stage by the Aeromonas, Vibrio, and Pseudomonas genera (for fruit bodies of A. mellea) the Pseudomonas genus (for fruit bodies of C. comatus). The potential influence of bacterial communities in the fruit bodies of soil basidiomycetes on the formation of bacterial communities in the upper soil horizons in forest biocenoses is discussed. The loci connected with the development and decomposition of fruit bodies of basidiomycetes on the soil surface are promising for targeted search of Gram-negative bacteria, the important objects of biotechnology.

Bacterial growth in solar heating prepared and traditional tanks

International Nuclear Information System (INIS)

Bagh, L.K.

2000-01-01

In Denmark it has been put forward that the introduction of solar heating prepared tanks into the building regulation can cause increased nuisance with respect to bacterial growth in hot water for domestic use. The reason is that solar heating prepared tanks have a larger volume and another form of operation than traditional tanks. In this investigation the difference between bacterial growth in solar heating prepared and traditional tanks was measured by heterotrophic plate counts as a general parameter for microbiological growth. There was no significant difference between the bacterial number in the solar heating prepared tanks and in the traditional tanks, either for bacteria determined at 37 deg. C, 44 deg. C, 55 deg. C or at 65 deg. C. The hot water for domestic use from the solar heating prepared tanks and the traditional tanks had in most cases a bacterial number below 1.000 CFU/ml, and all tests had a bacterial number below 10.000 CFU/ml. The number of bacteria must be considered low seen in relation to the other measurements of bacteria in hot water for domestic use, particularly in larger block of flats. (au)

TBK1 protects vacuolar integrity during intracellular bacterial infection.

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Andrea L Radtke

2007-03-01

Full Text Available TANK-binding kinase-1 (TBK1 is an integral component of Type I interferon induction by microbial infection. The importance of TBK1 and Type I interferon in antiviral immunity is well established, but the function of TBK1 in bacterial infection is unclear. Upon infection of murine embryonic fibroblasts with Salmonella enterica serovar Typhimurium (Salmonella, more extensive bacterial proliferation was observed in tbk1(-/- than tbk1(+/+ cells. TBK1 kinase activity was required for restriction of bacterial infection, but interferon regulatory factor-3 or Type I interferon did not contribute to this TBK1-dependent function. In tbk1(-/-cells, Salmonella, enteropathogenic Escherichia coli, and Streptococcus pyogenes escaped from vacuoles into the cytosol where increased replication occurred, which suggests that TBK1 regulates the integrity of pathogen-containing vacuoles. Knockdown of tbk1 in macrophages and epithelial cells also resulted in increased bacterial localization in the cytosol, indicating that the role of TBK1 in maintaining vacuolar integrity is relevant in different cell types. Taken together, these data demonstrate a requirement for TBK1 in control of bacterial infection distinct from its established role in antiviral immunity.

TBK1 Protects Vacuolar Integrity during Intracellular Bacterial Infection

Science.gov (United States)

Radtke, Andrea L; Delbridge, Laura M; Balachandran, Siddharth; Barber, Glen N; O'Riordan, Mary X. D

2007-01-01

TANK-binding kinase-1 (TBK1) is an integral component of Type I interferon induction by microbial infection. The importance of TBK1 and Type I interferon in antiviral immunity is well established, but the function of TBK1 in bacterial infection is unclear. Upon infection of murine embryonic fibroblasts with Salmonella enterica serovar Typhimurium (Salmonella), more extensive bacterial proliferation was observed in tbk1−/− than tbk1+/+ cells. TBK1 kinase activity was required for restriction of bacterial infection, but interferon regulatory factor-3 or Type I interferon did not contribute to this TBK1-dependent function. In tbk1−/−cells, Salmonella, enteropathogenic Escherichia coli, and Streptococcus pyogenes escaped from vacuoles into the cytosol where increased replication occurred, which suggests that TBK1 regulates the integrity of pathogen-containing vacuoles. Knockdown of tbk1 in macrophages and epithelial cells also resulted in increased bacterial localization in the cytosol, indicating that the role of TBK1 in maintaining vacuolar integrity is relevant in different cell types. Taken together, these data demonstrate a requirement for TBK1 in control of bacterial infection distinct from its established role in antiviral immunity. PMID:17335348

Bacterial strain changes during chronic otitis media surgery.

Science.gov (United States)

Kim, G J; Yoo, S; Han, S; Bu, J; Hong, Y; Kim, D-K

2017-09-01

Cultures obtained from pre-operative middle-ear swabs from patients with chronic otitis media have traditionally been used to guide antibiotic selection. This study investigated changes in the bacterial strains of the middle ear during chronic otitis media surgery. Pre-operative bacterial cultures of otorrhoea, and peri-operative cultures of the granulation tissue in either the middle ear or mastoid cavity, were obtained. Post-operative cultures were selectively obtained when otorrhoea developed after surgery. Bacterial growth was observed in 45.5 per cent of pre-operative cultures, 13.5 per cent of peri-operative cultures and 4.5 per cent of post-operative cultures. Methicillin-resistant Staphylococcus aureus was identified as the most common bacteria in all pre-operative (32.4 per cent), peri-operative (52.4 per cent) and post-operative (71.4 per cent) tests, and the percentage of Methicillin-resistant S aureus increased from the pre- to the post-operative period. The bacterial culture results for post-operative otorrhoea showed low agreement with those for pre-operative or peri-operative culture, and strain re-identification was required.

A precise, efficient radiometric assay for bacterial growth

International Nuclear Information System (INIS)

Boonkitticharoen, V.; Ehrhardt, C.; Kirchner, P.T.

1984-01-01

The two-compartment radiometric assay for bacterial growth promised major advantages over systems in clinical use, but poor reproducibility and counting efficiency limited its application. In this method, 14-CO/sub 2/ produced by bacterial metabolism of C-14-glucose is trapped and counted on filter paper impregnated with NaOH and fluors. The authors sought to improve assay efficiency and precision through a systematic study of relevant physical and chemical factors. Improvements in efficiency (88% vs. 10%) and in precision (relative S.D. 5% vs. 40%) were produced by a) reversing growth medium and scintillator chambers to permit vigorous agitation, b) increasing NaOH quantity and using a supersaturated PPO solution and c) adding detergent to improve uniformity of NaOH-PPO mixture. Inoculum size, substrate concentration and O/sub 2/ transfer rate affected assay sensitivity but not bacterial growth rate. The authors' assay reliably detects bacterial growth for inocula of 10,000 organisms in 1 hour and for 25 organisms within 4 1/2 hours, thus surpassing other existing clinical and research methods

Evaluation of localized bacterial infection using radioisotope-labeled nucleosides imaging modality

Energy Technology Data Exchange (ETDEWEB)

Jang, Su Jin; Kang, Joo Hyun; Lee, Yong Jin; Lee, Tae Sup; Kim, Kwang Il; Lee, Kyo Chul; An, Gwang II; Cheon, Gi Jeong; Lim, Sang Moo [KIRAMS, Seoul (Korea, Republic of); Lim, Sang Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-10-15

Conventional diagnostic methods for infections are difficult to distinguish localized bacterial infections from sites of sterile inflammation. For this reason, the importance of developing methods to image bacterial infections is widely recognized. In this study to acquire bacterial infection imaging with radiolabeled nucleosides, in vitro bacterial thymidine kinase (tk) activities of Salmonella typhimurium with [{sup 18}F]FLT and [{sup 125}I]IVDU were measured and localized infections model in BALB/c mice was imaged with [{sup 18}F]FLT or [{sup 125}I]FIAU

Characterization of Halophilic Bacterial Communities in Turda Salt Mine (Romania)

Science.gov (United States)

Carpa, Rahela; Keul, Anca; Muntean, Vasile; Dobrotă, Cristina

2014-09-01

Halophilic organisms are having adaptations to extreme salinity, the majority of them being Archaean, which have the ability to grow at extremely high salt concentrations, (from 3 % to 35 %). Level of salinity causes natural fluctuations in the halophilic populations that inhabit this particular habitat, raising problems in maintaining homeostasis of the osmotic pressure. Samples such as salt and water taken from Turda Salt Mine were analyzed in order to identify the eco-physiological bacterial groups. Considering the number of bacteria of each eco-physiological group, the bacterial indicators of salt quality (BISQ) were calculated and studied for each sample. The phosphatase, catalase and dehydrogenases enzymatic activities were quantitatively determined and the enzymatic indicators of salt quality (EISQ) were calculated. Bacterial isolates were analyzed using 16S rRNA gene sequence analysis. Universal bacterial primers, targeting the consensus region of the bacterial 16S rRNA gene were used. Analysis of a large fragment, of 1499 bp was performed to improve discrimination at the species level.

Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces

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Bradon R. McDonald

2017-06-01

Full Text Available Lateral gene transfer (LGT profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces. Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution.

Bacterial Communities in the Groundwater of Xikuangshan Antimony Mine, China

Science.gov (United States)

Wu, M.; Wang, H.; Wang, N.; Wang, M.

2017-12-01

Xikuangshan (XKS) is the biggest antimony (Sb) mine around the word, which causes serious environmental contamination due to the mining actives. To fully understand the bacterial compositions in the groundwater around the mining area in XKS and their correlation with environmental factors, groundwater samples were collected and subject to 16S rDNA high throughput sequencing. Results indicated that Proteobacteria (especially Gamma-Proteobacteria) dominated bacterial communities in high-Sb groundwater samples, whereas Bacteroidetes predominated in low-Sb groundwater. Furthermore, antimony concentration was found to be the most significant factor shaping bacterial communities (P=0.002) with an explanation of 9.16% of the variation. Other factors such as pH, contents of Mg, Ca and orthophosphate were also observed to significantly correlate with bacterial communities. This was the first report to show the important impact of Sb concentration on bacterial community structure in the groundwater in the mining area. Our results will enhance the understanding of subsurface biogeochemical processes mediated by microbes.

Airway fungal colonization compromises the immune system allowing bacterial pneumonia to prevail.

Science.gov (United States)

Roux, Damien; Gaudry, Stéphane; Khoy-Ear, Linda; Aloulou, Meryem; Phillips-Houlbracq, Mathilde; Bex, Julie; Skurnik, David; Denamur, Erick; Monteiro, Renato C; Dreyfuss, Didier; Ricard, Jean-Damien

2013-09-01

To study the correlation between fungal colonization and bacterial pneumonia and to test the effect of antifungal treatments on the development of bacterial pneumonia in colonized rats. Experimental animal investigation. University research laboratory. Pathogen-free male Wistar rats weighing 250-275 g. Rats were colonized by intratracheal instillation of Candida albicans. Fungal clearance from the lungs and immune response were measured. Both colonized and noncolonized animals were secondarily instilled with different bacterial species (Pseudomonas aeruginosa, Escherichia coli, or Staphylococcus aureus). Bacterial phagocytosis by alveolar macrophages was evaluated in the presence of interferon-gamma, the main cytokine produced during fungal colonization. The effect of antifungal treatments on fungal colonization and its immune response were assessed. The prevalence of P. aeruginosa pneumonia was compared in antifungal treated and control colonized rats. C. albicans was slowly cleared and induced a Th1-Th17 immune response with very high interferon-gamma concentrations. Airway fungal colonization favored the development of bacterial pneumonia. Interferon-gamma was able to inhibit the phagocytosis of unopsonized bacteria by alveolar macrophages. Antifungal treatment decreased airway fungal colonization, lung interferon-gamma levels and, consequently, the prevalence of subsequent bacterial pneumonia. C. albicans airway colonization elicited a Th1-Th17 immune response that favored the development of bacterial pneumonia via the inhibition of bacterial phagocytosis by alveolar macrophages. Antifungal treatment decreased the risk of bacterial pneumonia in colonized rats.

Incidence and Predictors of Bacterial infection in Febrile Children with Sickle Cell Disease.

Science.gov (United States)

Morrissey, Benita J; Bycroft, Thomas P; Almossawi, Ofran; Wilkey, Olufunke B; Daniels, Justin G

2015-01-01

Children with sickle cell disease are at increased risk of developing bacteremia and other serious bacterial infections. Fever is a common symptom in sickle cell disease and can also occur with sickle cell crises and viral infections. We aimed to evaluate the incidence and predictors of bacteremia and bacterial infection in children with sickle cell disease presenting with fever to a district hospital and sickle cell center in London. A retrospective analysis was performed on all attendances of children (aged under 16 years) with sickle cell disease presenting with a fever of 38.5 °C or higher over a 1-year period. Confirmed bacterial infection was defined as bacteremia, bacterial meningitis, urinary tract infection (UTI), pneumonia, osteomyelitis or other bacterial infection with positive identification of organism. Children were defined as having a suspected bacterial infection if a bacterial infection was suspected clinically, but no organism was identified. Over a 1-year period there were 88 episodes analyzed in 59 children. Bacteremia occurred in 3.4% of episodes and confirmed bacterial infection in 7.0%. Suspected bacterial infection occurred in 33.0%. One death occurred from Salmonella typhirium septicemia. C-reactive protein (CRP) level and white blood cell (WBC) count were both significantly associated with bacterial infection (p = 0.004 and 0.02, respectively.) In conclusion, bacterial infections continue to be a significant problem in children with sickle cell disease. C-reactive protein was significantly associated with bacterial infections, and could be included in clinical risk criteria for febrile children with sickle cell disease.

Drug Insight: adjunctive therapies in adults with bacterial meningitis

NARCIS (Netherlands)

van de Beek, Diederik; Weisfelt, Martijn; de Gans, Jan; Tunkel, Allan R.; Wijdicks, Eelco F. M.

2006-01-01

Despite the availability of effective antibiotics, mortality and morbidity rates associated with bacterial meningitis are high. Studies in animals have shown that bacterial lysis, induced by treatment with antibiotics, leads to inflammation in the subarachnoid space, which might contribute to an

In Situ Hydrocarbon Degradation by Indigenous Nearshore Bacterial Populations

International Nuclear Information System (INIS)

Cherrier, J.

2005-01-01

Potential episodic hydrocarbon inputs associated with oil mining and transportation together with chronic introduction of hydrocarbons via urban runoff into the relatively pristine coastal Florida waters poses a significant threat to Florida's fragile marine environment. It is therefore important to understand the extent to which indigenous bacterial populations are able to degrade hydrocarbon compounds and also determine factors that could potentially control and promote the rate at which these compounds are broken down in situ. Previous controlled laboratory experiments carried out by our research group demonstrated that separately both photo-oxidation and cometabolism stimulate bacterial hydrocarbon degradation by natural bacterial assemblages collected from a chronically petroleum contaminated site in Bayboro Bay, Florida. Additionally, we also demonstrated that stable carbon and radiocarbon abundances of respired CO 2 could be used to trace in situ hydrocarbon degradation by indigenous bacterial populations at this same site. This current proposal had two main objectives: (a) to evaluate the cumulative impact of cometabolism and photo-oxidation on hydrocarbon degradation by natural bacterial assemblages collected the same site in Bayboro Bay, Florida and (b) to determine if in situ hydrocarbon degradation by indigenous bacterial populations this site could be traced using natural radiocarbon and stable carbon abundances of assimilated bacterial carbon. Funds were used for 2 years of full support for one ESI Ph.D. student, April Croxton. To address our first objective a series of closed system bacterial incubations were carried out using photo-oxidized petroleum and pinfish (i.e. cometabolite). Bacterial production of CO 2 was used as the indicator of hydrocarbon degradation and (delta) 13 C analysis of the resultant CO 2 was used to evaluate the source of the respired CO 2 (i.e. petroleum hydrocarbons or the pinfish cometabolite). Results from these time

Changes of Bacterial Diversity Depend on the Spoilage of Fresh Vegetables

Directory of Open Access Journals (Sweden)

Dong Hwan Lee

2011-04-01

Full Text Available Almost 10~30% of vegetables were discarded by the spoilage from farms to tables. After harvest, vegetables are often spoiled by a wide variety of microorganisms including many bacterial and fungal species. This investigation was conducted to extent the knowledge of relationship the spoilage of vegetables and the diversity of microbes. The total aerobic bacterial numbers in fresh lettuce, perilla leaf, and chicory were 2.6~2.7×106, 4.6×105, 1.2×106 CFU/g of fresh weight, respectively. The most common bacterial species were Pseudomonas spp., Alysiella spp., and Burkholderia spp., and other 18 more genera were involved in. After one week of incubation of those vegetables at 28℃, the microbial diversity had been changed. The total aerobic bacterial numbers increased to 1.1~4.6×108, 4.9×107, and 7.6×108 CFU/g of fresh weight for lettuce, perilla leaf, and chicory that is about 102 times increased bacterial numbers than that before spoilage. However, the diversity of microbes isolated had been simplified and fewer bacterial species had been isolated. The most bacterial population (~48% was taken up by Pseudomonas spp., and followed by Arthrobacter spp. and Bacillus spp. The spoilage activity of individual bacterial isolates had been tested using axenic lettuce plants. Among tested isolates, Pseudomonas fluorescence and Pantoea agglomerans caused severe spoilage on lettuce.

Evaluating the effects of variable water chemistry on bacterial transport during infiltration.

Science.gov (United States)

Zhang, Haibo; Nordin, Nahjan Amer; Olson, Mira S

2013-07-01

Bacterial infiltration through the subsurface has been studied experimentally under different conditions of interest and is dependent on a variety of physical, chemical and biological factors. However, most bacterial transport studies fail to adequately represent the complex processes occurring in natural systems. Bacteria are frequently detected in stormwater runoff, and may present risk of microbial contamination during stormwater recharge into groundwater. Mixing of stormwater runoff with groundwater during infiltration results in changes in local solution chemistry, which may lead to changes in both bacterial and collector surface properties and subsequent bacterial attachment rates. This study focuses on quantifying changes in bacterial transport behavior under variable solution chemistry, and on comparing the influences of chemical variability and physical variability on bacterial attachment rates. Bacterial attachment rate at the soil-water interface was predicted analytically using a combined rate equation, which varies temporally and spatially with respect to changes in solution chemistry. Two-phase Monte Carlo analysis was conducted and an overall input-output correlation coefficient was calculated to quantitatively describe the importance of physiochemical variation on the estimates of attachment rate. Among physical variables, soil particle size has the highest correlation coefficient, followed by porosity of the soil media, bacterial size and flow velocity. Among chemical variables, ionic strength has the highest correlation coefficient. A semi-reactive microbial transport model was developed within HP1 (HYDRUS1D-PHREEQC) and applied to column transport experiments with constant and variable solution chemistries. Bacterial attachment rates varied from 9.10×10(-3)min(-1) to 3.71×10(-3)min(-1) due to mixing of synthetic stormwater (SSW) with artificial groundwater (AGW), while bacterial attachment remained constant at 9.10×10(-3)min(-1) in a constant

Interfering with bacterial gossip

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

2011-01-01

that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation...

ORF Alignment: NC_006905 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available NC_006905 gi|62181272 >1gdtA 1 182 1 183 1e-47 ... ref|YP_217689.1| H inversion: regu...lation of flagellar gene expression by ... site-specific inversion of DNA [Salmonella enterica ... ... ... subsp. enterica serovar Choleraesuis str. SC-B67] ... gb|AAX66608.1| H inversion: regulation of ...flagellar gene ... expression by site-specific inversion of DNA [Salmonell

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

Science.gov (United States)

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

Bacterial cellulose–kaolin nanocomposites for application as biomedical wound healing materials

International Nuclear Information System (INIS)

Wanna, Dwi; Alam, Parvez; Alam, Catharina; Toivola, Diana M

2013-01-01

This short communication provides preliminary experimental details on the structure–property relationships of novel biomedical kaolin–bacterial cellulose nanocomposites. Bacterial cellulose is an effective binding agent for kaolin particles forming reticulated structures at kaolin–cellulose interfaces and entanglements when the cellulose fraction is sufficiently high. The mechanical performance of these materials hence improves with an increased fraction of bacterial cellulose, though this also causes the rate of blood clotting to decrease. These composites have combined potential as both short-term (kaolin) and long-term (bacterial cellulose) wound healing materials. (paper)

Bacterial community diversity of the deep-sea octocoral Paramuricea placomus

Directory of Open Access Journals (Sweden)

Christina A. Kellogg

2016-09-01

Full Text Available Compared to tropical corals, much less is known about deep-sea coral biology and ecology. Although the microbial communities of some deep-sea corals have been described, this is the first study to characterize the bacterial community associated with the deep-sea octocoral, Paramuricea placomus. Samples from five colonies of P. placomus were collected from Baltimore Canyon (379–382 m depth in the Atlantic Ocean off the east coast of the United States of America. DNA was extracted from the coral samples and 16S rRNA gene amplicons were pyrosequenced using V4-V5 primers. Three samples sequenced deeply (>4,000 sequences each and were further analyzed. The dominant microbial phylum was Proteobacteria, but other major phyla included Firmicutes and Planctomycetes. A conserved community of bacterial taxa held in common across the three P. placomus colonies was identified, comprising 68–90% of the total bacterial community depending on the coral individual. The bacterial community of P. placomus does not appear to include the genus Endozoicomonas, which has been found previously to be the dominant bacterial associate in several temperate and tropical gorgonians. Inferred functionality suggests the possibility of nitrogen cycling by the core bacterial community.

Mapping and predictive variations of soil bacterial richness across France.

Science.gov (United States)

Terrat, Sébastien; Horrigue, Walid; Dequiedt, Samuel; Saby, Nicolas P A; Lelièvre, Mélanie; Nowak, Virginie; Tripied, Julie; Régnier, Tiffanie; Jolivet, Claudy; Arrouays, Dominique; Wincker, Patrick; Cruaud, Corinne; Karimi, Battle; Bispo, Antonio; Maron, Pierre Alain; Chemidlin Prévost-Bouré, Nicolas; Ranjard, Lionel

2017-01-01

Although numerous studies have demonstrated the key role of bacterial diversity in soil functions and ecosystem services, little is known about the variations and determinants of such diversity on a nationwide scale. The overall objectives of this study were i) to describe the bacterial taxonomic richness variations across France, ii) to identify the ecological processes (i.e. selection by the environment and dispersal limitation) influencing this distribution, and iii) to develop a statistical predictive model of soil bacterial richness. We used the French Soil Quality Monitoring Network (RMQS), which covers all of France with 2,173 sites. The soil bacterial richness (i.e. OTU number) was determined by pyrosequencing 16S rRNA genes and related to the soil characteristics, climatic conditions, geomorphology, land use and space. Mapping of bacterial richness revealed a heterogeneous spatial distribution, structured into patches of about 111km, where the main drivers were the soil physico-chemical properties (18% of explained variance), the spatial descriptors (5.25%, 1.89% and 1.02% for the fine, medium and coarse scales, respectively), and the land use (1.4%). Based on these drivers, a predictive model was developed, which allows a good prediction of the bacterial richness (R2adj of 0.56) and provides a reference value for a given pedoclimatic condition.

Plant innate immunity against human bacterial pathogens

Directory of Open Access Journals (Sweden)

Maeli eMelotto

2014-08-01

Full Text Available Certain human bacterial pathogens such as the enterohemorrhagic Escherichia coli and Salmonella enterica are not proven to be plant pathogens yet. Nonetheless, under certain conditions they can survive on, penetrate into, and colonize internal plant tissues causing serious food borne disease outbreaks. In this review, we highlight current understanding on the molecular mechanisms of plant responses against human bacterial pathogens and discuss salient common and contrasting themes of plant interactions with phytopathogens or human pathogens.

Bacterial filamentation accelerates colonization of adhesive spots embedded in biopassive surfaces

International Nuclear Information System (INIS)

Möller, Jens; Emge, Philippe; Vizcarra, Ima Avalos; Kollmannsberger, Philip; Vogel, Viola

2013-01-01

Sessile bacteria adhere to engineered surfaces and host tissues and pose a substantial clinical and economical risk when growing into biofilms. Most engineered and biological interfaces are of chemically heterogeneous nature and provide adhesive islands for bacterial attachment and growth. To mimic either defects in a surface coating of biomedical implants or heterogeneities within mucosal layers (Peyer's patches), we embedded micrometre-sized adhesive islands in a poly(ethylene glycol) biopassive background. We show experimentally and computationally that filamentation of Escherichia coli can significantly accelerate the bacterial surface colonization under physiological flow conditions. Filamentation can thus provide an advantage to a bacterial population to bridge non-adhesive distances exceeding 5 μm. Bacterial filamentation, caused by blocking of bacterial division, is common among bacterial species and can be triggered by environmental conditions or antibiotic treatment. While great awareness exists that the build-up of antibiotic resistance serves as intrinsic survival strategy, we show here that antibiotic treatment can actually promote surface colonization by triggering filamentation, which in turn prevents daughter cells from being washed away. Our combined microfabrication and computational approaches provide quantitative insights into mechanisms that enable biofouling of biopassive surfaces with embedded adhesive spots, even for spot distances that are multiples of the bacterial length. (paper)

Bacterial filamentation accelerates colonization of adhesive spots embedded in biopassive surfaces

Science.gov (United States)

Möller, Jens; Emge, Philippe; Avalos Vizcarra, Ima; Kollmannsberger, Philip; Vogel, Viola

2013-12-01

Sessile bacteria adhere to engineered surfaces and host tissues and pose a substantial clinical and economical risk when growing into biofilms. Most engineered and biological interfaces are of chemically heterogeneous nature and provide adhesive islands for bacterial attachment and growth. To mimic either defects in a surface coating of biomedical implants or heterogeneities within mucosal layers (Peyer's patches), we embedded micrometre-sized adhesive islands in a poly(ethylene glycol) biopassive background. We show experimentally and computationally that filamentation of Escherichia coli can significantly accelerate the bacterial surface colonization under physiological flow conditions. Filamentation can thus provide an advantage to a bacterial population to bridge non-adhesive distances exceeding 5 μm. Bacterial filamentation, caused by blocking of bacterial division, is common among bacterial species and can be triggered by environmental conditions or antibiotic treatment. While great awareness exists that the build-up of antibiotic resistance serves as intrinsic survival strategy, we show here that antibiotic treatment can actually promote surface colonization by triggering filamentation, which in turn prevents daughter cells from being washed away. Our combined microfabrication and computational approaches provide quantitative insights into mechanisms that enable biofouling of biopassive surfaces with embedded adhesive spots, even for spot distances that are multiples of the bacterial length.

MIPS bacterial genomes functional annotation benchmark dataset.

Science.gov (United States)

Tetko, Igor V; Brauner, Barbara; Dunger-Kaltenbach, Irmtraud; Frishman, Goar; Montrone, Corinna; Fobo, Gisela; Ruepp, Andreas; Antonov, Alexey V; Surmeli, Dimitrij; Mewes, Hans-Wernen

2005-05-15

Any development of new methods for automatic functional annotation of proteins according to their sequences requires high-quality data (as benchmark) as well as tedious preparatory work to generate sequence parameters required as input data for the machine learning methods. Different program settings and incompatible protocols make a comparison of the analyzed methods difficult. The MIPS Bacterial Functional Annotation Benchmark dataset (MIPS-BFAB) is a new, high-quality resource comprising four bacterial genomes manually annotated according to the MIPS functional catalogue (FunCat). These resources include precalculated sequence parameters, such as sequence similarity scores, InterPro domain composition and other parameters that could be used to develop and benchmark methods for functional annotation of bacterial protein sequences. These data are provided in XML format and can be used by scientists who are not necessarily experts in genome annotation. BFAB is available at http://mips.gsf.de/proj/bfab

Spatial variation of bacterial community composition near the Luzon ...

African Journals Online (AJOL)

Spatial variation of bacterial community composition near the Luzon strait assessed by polymerase chain reaction-denaturing gradient gel electrophoresis ... chain reaction (PCR)-amplified bacterial 16S ribosomal deoxyribonucleic acid (DNA) gene fragments and interpreted the results; its relationship with physical and ...

Strategies for managing rival bacterial communities: Lessons from burying beetles.

Science.gov (United States)

Duarte, Ana; Welch, Martin; Swannack, Chris; Wagner, Josef; Kilner, Rebecca M

2018-03-01

The role of bacteria in animal development, ecology and evolution is increasingly well understood, yet little is known of how animal behaviour affects bacterial communities. Animals that benefit from defending a key resource from microbial competitors are likely to evolve behaviours to control or manipulate the animal's associated external microbiota. We describe four possible mechanisms by which animals could gain a competitive edge by disrupting a rival bacterial community: "weeding," "seeding," "replanting" and "preserving." By combining detailed behavioural observations with molecular and bioinformatic analyses, we then test which of these mechanisms best explains how burying beetles, Nicrophorus vespilloides, manipulate the bacterial communities on their carcass breeding resource. Burying beetles are a suitable species to study how animals manage external microbiota because reproduction revolves around a small vertebrate carcass. Parents shave a carcass and apply antimicrobial exudates on its surface, shaping it into an edible nest for their offspring. We compared bacterial communities in mice carcasses that were either fresh, prepared by beetles or unprepared but buried underground for the same length of time. We also analysed bacterial communities in the burying beetle's gut, during and after breeding, to understand whether beetles could be "seeding" the carcass with particular microbes. We show that burying beetles do not "preserve" the carcass by reducing bacterial load, as is commonly supposed. Instead, our results suggest they "seed" the carcass with bacterial groups which are part of the Nicrophorus core microbiome. They may also "replant" other bacteria from the carcass gut onto the surface of their carrion nest. Both these processes may lead to the observed increase in bacterial load on the carcass surface in the presence of beetles. Beetles may also "weed" the bacterial community by eliminating some groups of bacteria on the carcass, perhaps through

Application of Sub-Micrometer Vibrations to Mitigate Bacterial Adhesion

Directory of Open Access Journals (Sweden)

Will R. Paces

2014-03-01

Full Text Available As a prominent concern regarding implantable devices, eliminating the threat of opportunistic bacterial infection represents a significant benefit to both patient health and device function. Current treatment options focus on chemical approaches to negate bacterial adhesion, however, these methods are in some ways limited. The scope of this study was to assess the efficacy of a novel means of modulating bacterial adhesion through the application of vibrations using magnetoelastic materials. Magnetoelastic materials possess unique magnetostrictive property that can convert a magnetic field stimulus into a mechanical deformation. In vitro experiments demonstrated that vibrational loads generated by the magnetoelastic materials significantly reduced the number of adherent bacteria on samples exposed to Escherichia coli, Staphylococcus epidermidis and Staphylococcus aureus suspensions. These experiments demonstrate that vibrational loads from magnetoelastic materials can be used as a post-deployment activated means to deter bacterial adhesion and device infection.

Sensitive Detection of Deliquescent Bacterial Capsules through Nanomechanical Analysis.

Science.gov (United States)

Nguyen, Song Ha; Webb, Hayden K

2015-10-20

Encapsulated bacteria usually exhibit strong resistance to a wide range of sterilization methods, and are often virulent. Early detection of encapsulation can be crucial in microbial pathology. This work demonstrates a fast and sensitive method for the detection of encapsulated bacterial cells. Nanoindentation force measurements were used to confirm the presence of deliquescent bacterial capsules surrounding bacterial cells. Force/distance approach curves contained characteristic linear-nonlinear-linear domains, indicating cocompression of the capsular layer and cell, indentation of the capsule, and compression of the cell alone. This is a sensitive method for the detection and verification of the encapsulation status of bacterial cells. Given that this method was successful in detecting the nanomechanical properties of two different layers of cell material, i.e. distinguishing between the capsule and the remainder of the cell, further development may potentially lead to the ability to analyze even thinner cellular layers, e.g. lipid bilayers.

Bacterial biofilm and associated infections

Directory of Open Access Journals (Sweden)

Muhsin Jamal

2018-01-01

Full Text Available Microscopic entities, microorganisms that drastically affect human health need to be thoroughly investigated. A biofilm is an architectural colony of microorganisms, within a matrix of extracellular polymeric substance that they produce. Biofilm contains microbial cells adherent to one-another and to a static surface (living or non-living. Bacterial biofilms are usually pathogenic in nature and can cause nosocomial infections. The National Institutes of Health (NIH revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation. The process of biofilm formation consists of many steps, starting with attachment to a living or non-living surface that will lead to formation of micro-colony, giving rise to three-dimensional structures and ending up, after maturation, with detachment. During formation of biofilm several species of bacteria communicate with one another, employing quorum sensing. In general, bacterial biofilms show resistance against human immune system, as well as against antibiotics. Health related concerns speak loud due to the biofilm potential to cause diseases, utilizing both device-related and non-device-related infections. In summary, the understanding of bacterial biofilm is important to manage and/or to eradicate biofilm-related diseases. The current review is, therefore, an effort to encompass the current concepts in biofilm formation and its implications in human health and disease.

Chronic bacterial prostatitis in men with spinal cord injury.

Science.gov (United States)

Krebs, Jörg; Bartel, Peter; Pannek, Jürgen

2014-12-01

Recurrent urinary tract infections (UTI) are a major problem affecting spinal cord injury (SCI) patients and may stem from chronic bacterial prostatitis. We have therefore investigated the presence of chronic bacterial prostatitis and its role in the development of recurrent symptomatic UTI in SCI men. This study is a prospective cross-sectional investigation of bacterial prostatitis in SCI men in a single SCI rehabilitation center. In 50 men with chronic SCI presenting for a routine urologic examination, urine samples before and after prostate massage were taken for microbiologic investigation and white blood cell counting. Furthermore, patient characteristics, bladder diary details, and the annual rate of symptomatic UTI were collected retrospectively. No participant reported current symptoms of UTI or prostatitis. In most men (39/50, 78 %), the microbiologic analysis of the post-massage urine sample revealed growth of pathogenic bacteria. The majority of these men (32/39, 82 %) also presented with mostly (27/39, 69 %) the same pathogenic bacteria in the pre-massage sample. There was no significant (p = 0.48) difference in the number of symptomatic UTI in men with a positive post-massage culture compared with those with a negative culture. No significant (p = 0.67) difference in the frequency distribution of positive versus negative post-massage cultures was detected between men with recurrent and sporadic UTI. Most SCI men are affected by asymptomatic bacterial prostatitis; however, bacterial prostatitis does not play a major role in the development of recurrent UTI. The indication for antibiotic treatment of chronic bacterial prostatitis in asymptomatic SCI men with recurrent UTI is questionable.

The bacterial community of entomophilic nematodes and host beetles.

Science.gov (United States)

Koneru, Sneha L; Salinas, Heilly; Flores, Gilberto E; Hong, Ray L

2016-05-01

Insects form the most species-rich lineage of Eukaryotes and each is a potential host for organisms from multiple phyla, including fungi, protozoa, mites, bacteria and nematodes. In particular, beetles are known to be associated with distinct bacterial communities and entomophilic nematodes. While entomopathogenic nematodes require symbiotic bacteria to kill and reproduce inside their insect hosts, the microbial ecology that facilitates other types of nematode-insect associations is largely unknown. To illuminate detailed patterns of the tritrophic beetle-nematode-bacteria relationship, we surveyed the nematode infestation profiles of scarab beetles in the greater Los Angeles area over a five-year period and found distinct nematode infestation patterns for certain beetle hosts. Over a single season, we characterized the bacterial communities of beetles and their associated nematodes using high-throughput sequencing of the 16S rRNA gene. We found significant differences in bacterial community composition among the five prevalent beetle host species, independent of geographical origin. Anaerobes Synergistaceae and sulphate-reducing Desulfovibrionaceae were most abundant in Amblonoxia beetles, while Enterobacteriaceae and Lachnospiraceae were common in Cyclocephala beetles. Unlike entomopathogenic nematodes that carry bacterial symbionts, insect-associated nematodes do not alter the beetles' native bacterial communities, nor do their microbiomes differ according to nematode or beetle host species. The conservation of Diplogastrid nematodes associations with Melolonthinae beetles and sulphate-reducing bacteria suggests a possible link between beetle-bacterial communities and their associated nematodes. Our results establish a starting point towards understanding the dynamic interactions between soil macroinvertebrates and their microbiota in a highly accessible urban environment. © 2016 John Wiley & Sons Ltd.

Modeling bacterial contamination of fuel ethanol fermentation.

Science.gov (United States)

Bischoff, Kenneth M; Liu, Siqing; Leathers, Timothy D; Worthington, Ronald E; Rich, Joseph O

2009-05-01

The emergence of antibiotic-resistant bacteria may limit the effectiveness of antibiotics to treat bacterial contamination in fuel ethanol plants, and therefore, new antibacterial intervention methods and tools to test their application are needed. Using shake-flask cultures of Saccharomyces cerevisiae grown on saccharified corn mash and strains of lactic acid bacteria isolated from a dry-grind ethanol facility, a simple model to simulate bacterial contamination and infection was developed. Challenging the model with 10(8) CFU/mL Lactobacillus fermentum decreased ethanol yield by 27% and increased residual glucose from 6.2 to 45.5 g/L. The magnitude of the effect was proportional to the initial bacterial load, with 10(5) CFU/mL L. fermentum still producing an 8% decrease in ethanol and a 3.2-fold increase in residual glucose. Infection was also dependent on the bacterial species used to challenge the fermentation, as neither L. delbrueckii ATCC 4797 nor L. amylovorus 0315-7B produced a significant decrease in ethanol when inoculated at a density of 10(8) CFU/mL. In the shake-flask model, treatment with 2 microg/mL virginiamycin mitigated the infection when challenged with a susceptible strain of L. fermentum (MIC for virginiamycin model may find application in developing new antibacterial agents and management practices for use in controlling contamination in the fuel ethanol industry. Copyright 2008 Wiley Periodicals, Inc.

Biosynthesis of highly porous bacterial cellulose nanofibers

Science.gov (United States)

Hosseini, Hadi; Kokabi, Mehrdad; Mousavi, Seyyed Mohammad

2018-01-01

Bacterial cellulose nanofibers (BCNFs) as a sustainable and biodegradable polymer has drawn tremendous research attention in tissue engineering, bacterial sensors and drug delivery due to its extraordinary properties such as high purity, high crystallinity, high water absorption capacity and excellent mechanical strength in the wet state. This awesome properties, is attributed to BCNFs structure, therefore its characterization is important. In this work, the bacterial strain, Gluconacetobacter xylinus (PTCC 1734, obtained from Iranian Research Organization for Science and Technology (IROST)), was used to produce BCNFs hydrogel using bacterial fermentation under static condition at 29 °C for 10 days in the incubator. Then, the biosynthesized BCNFs wet gel, were dried at ambient temperature and pressure and characterized using Brunauer-Emmett-Teller (BET) and Field emission scanning electron microscopy (FE-SEM) analysis. FESEM image displayed highly interconnected and porous structure composed of web-like continuous, nanofibers with an average diameter of 48.5±2.1 nm. BET result analysis depicted BCNFs dried at ambient conditions had IV isotherm type, according to the IUPAC classification, indicating that BCNFs dried at ambient condition is essentially mesoporous. On the other hand, BET results depicted, mesoporous structure is around 85%. In addition, Specific surface area (SBET) obtained 81.45 m2/g. These results are in accordance with the FESEM observation.

Benthic Bacterial Diversity in Submerged Sinkhole Ecosystems▿ †

Science.gov (United States)

Nold, Stephen C.; Pangborn, Joseph B.; Zajack, Heidi A.; Kendall, Scott T.; Rediske, Richard R.; Biddanda, Bopaiah A.

2010-01-01

Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities. PMID:19880643

[Validation of a clinical prediction rule to distinguish bacterial from aseptic meningitis].

Science.gov (United States)

Agüero, Gonzalo; Davenport, María C; Del Valle, María de la P; Gallegos, Paulina; Kannemann, Ana L; Bokser, Vivian; Ferrero, Fernando

2010-02-01

Despite most meningitis are not bacterial, antibiotics are usually administered on admission because bacterial meningitis is difficult to be rule-out. Distinguishing bacterial from aseptic meningitis on admission could avoid inappropriate antibiotic use and hospitalization. We aimed to validate a clinical prediction rule to distinguish bacterial from aseptic meningitis in children, on arriving to the emergency room. This prospective study included patients aged or = 1000 cells/mm(3), CSF protein > or = 80 mg/dl, peripheral blood absolute neutrophil count > or = 10.000/mm(3), seizure = 1 point each. Sensitivity (S), specificity (E), positive and negative predictive values (PPV and NPV), positive and negative likelihood ratios (PLR and NLR) of the BMS to predict bacterial meningitis were calculated. Seventy patients with meningitis were included (14 bacterial meningitis). When BMS was calculated, 25 patients showed a BMS= 0 points, 11 BMS= 1 point, and 34 BMS > or = 2 points. A BMS = 0 showed S: 100%, E: 44%, VPP: 31%, VPN: 100%, RVP: 1,81 RVN: 0. A BMS > or = 2 predicted bacterial meningitis with S: 100%, E: 64%, VPP: 41%, VPN: 100%, PLR: 2.8, NLR:0. Using BMS was simple, and allowed identifying children with very low risk of bacterial meningitis. It could be a useful tool to assist clinical decision making.

Radiology of bacterial pneumonia

International Nuclear Information System (INIS)

Vilar, Jose; Domingo, Maria Luisa; Soto, Cristina; Cogollos, Jonathan

2004-01-01

Bacterial pneumonia is commonly encountered in clinical practice. Radiology plays a prominent role in the evaluation of pneumonia. Chest radiography is the most commonly used imaging tool in pneumonias due to its availability and excellent cost benefit ratio. CT should be used in unresolved cases or when complications of pneumonia are suspected. The main applications of radiology in pneumonia are oriented to detection, characterisation and follow-up, especially regarding complications. The classical classification of pneumonias into lobar and bronchial pneumonia has been abandoned for a more clinical classification. Thus, bacterial pneumonias are typified into three main groups: Community acquired pneumonia (CAD), Aspiration pneumonia and Nosocomial pneumonia (NP).The usual pattern of CAD is that of the previously called lobar pneumonia; an air-space consolidation limited to one lobe or segment. Nevertheless, the radiographic patterns of CAD may be variable and are often related to the causative agent. Aspiration pneumonia generally involves the lower lobes with bilateral multicentric opacities. Nosocomial Pneumonia (NP) occurs in hospitalised patients. The importance of NP is related to its high mortality and, thus, the need to obtain a prompt diagnosis. The role of imaging in NP is limited but decisive. The most valuable information is when the chest radiographs are negative and rule out pneumonia. The radiographic patterns of NP are very variable, most commonly showing diffuse multifocal involvement and pleural effusion. Imaging plays also an important role in the detection and evaluation of complications of bacterial pneumonias. In many of these cases, especially in hospitalised patients, chest CT must be obtained in order to better depict these associate findings

Radiology of bacterial pneumonia

Energy Technology Data Exchange (ETDEWEB)

Vilar, Jose E-mail: vilar_jlu@gva.es; Domingo, Maria Luisa; Soto, Cristina; Cogollos, Jonathan

2004-08-01

Bacterial pneumonia is commonly encountered in clinical practice. Radiology plays a prominent role in the evaluation of pneumonia. Chest radiography is the most commonly used imaging tool in pneumonias due to its availability and excellent cost benefit ratio. CT should be used in unresolved cases or when complications of pneumonia are suspected. The main applications of radiology in pneumonia are oriented to detection, characterisation and follow-up, especially regarding complications. The classical classification of pneumonias into lobar and bronchial pneumonia has been abandoned for a more clinical classification. Thus, bacterial pneumonias are typified into three main groups: Community acquired pneumonia (CAD), Aspiration pneumonia and Nosocomial pneumonia (NP).The usual pattern of CAD is that of the previously called lobar pneumonia; an air-space consolidation limited to one lobe or segment. Nevertheless, the radiographic patterns of CAD may be variable and are often related to the causative agent. Aspiration pneumonia generally involves the lower lobes with bilateral multicentric opacities. Nosocomial Pneumonia (NP) occurs in hospitalised patients. The importance of NP is related to its high mortality and, thus, the need to obtain a prompt diagnosis. The role of imaging in NP is limited but decisive. The most valuable information is when the chest radiographs are negative and rule out pneumonia. The radiographic patterns of NP are very variable, most commonly showing diffuse multifocal involvement and pleural effusion. Imaging plays also an important role in the detection and evaluation of complications of bacterial pneumonias. In many of these cases, especially in hospitalised patients, chest CT must be obtained in order to better depict these associate findings.

Cerebral oxygenation and energy metabolism in bacterial meningitis

DEFF Research Database (Denmark)

Larsen, Lykke

Introduction: In a recent retrospective study of patients with severe bacterial meningitis we demonstrated that cerebral oxidative metabolism was affected in approximately 50% of the cases. An increase of lactate/pyruvate (LP) ratio above the upper normal limit, defined according to according...... bacterial meningitis; secondly to examine whether it is correct to separate the diagnosis of cerebral ischemia from mitochondrial dysfunction based exclusively on the biochemical pattern obtained during intracerebral microdialysis. Method: A prospective clinical study including patients with severe...... community acquired bacterial meningitis admitted to the Department of Infectious Diseases, Odense University Hospital, during the period January 2014 to June 2016. We relate data from measurements of brain tissue oxygen tension (PbtO2) to simultaneously recorded data reflecting cerebral cytoplasmic redox...

In vitro activity of difloxacin against canine bacterial isolates

NARCIS (Netherlands)

Hoven, van den J.R.; Wagenaar, J.A.; Walker, R.D.

2000-01-01

The in vitro activity of difloxacin against canine bacterial isolates from clinical cases was studied in the United States and The Netherlands. Minimal inhibitory concentrations (MIC), the postantibiotic effect, the effect of pH on antimicrobial activity, and the bacterial killing rate tests were

Risk factors for community-acquired bacterial meningitis in adults

NARCIS (Netherlands)

Adriani, K.S.

2015-01-01

Bacterial meningitis is an inflammation of the meninges and occurs when bacteria invade the subarachnoid space. The meninges are the protective membranes that surround the brain and the spinal cord. Bacterial meningitis is a life-threatening disease because the proximity of the infection to the

LATERAL GENE TRANSFER AND THE HISTORY OF BACTERIAL GENOMES

Energy Technology Data Exchange (ETDEWEB)

Howard Ochman

2006-02-22

The aims of this research were to elucidate the role and extent of lateral transfer in the differentiation of bacterial strains and species, and to assess the impact of gene transfer on the evolution of bacterial genomes. The ultimate goal of the project is to examine the dynamics of a core set of protein-coding genes (i.e., those that are distributed universally among Bacteria) by developing conserved primers that would allow their amplification and sequencing in any bacterial taxa. In addition, we adopted a bioinformatic approach to elucidate the extent of lateral gene transfer in sequenced genome.

Cellular reprogramming by gram-positive bacterial components: a review.

LENUS (Irish Health Repository)

Buckley, Julliette M

2012-02-03

LPS tolerance has been the focus of extensive scientific and clinical research over the last several decades in an attempt to elucidate the sequence of changes that occur at a molecular level in tolerized cells. Tolerance to components of gram-positive bacterial cell walls such as bacterial lipoprotein and lipoteichoic acid is a much lesser studied, although equally important, phenomenon. This review will focus on cellular reprogramming by gram-positive bacterial components and examines the alterations in cell surface receptor expression, changes in intracellular signaling, gene expression and cytokine production, and the phenomenon of cross-tolerance.

Connecting the dots between bacterial biofilms and ice cream

Science.gov (United States)

Stanley-Wall, Nicola R.; MacPhee, Cait E.

2015-12-01

Emerging research is revealing a diverse array of interfacially-active proteins that are involved in varied biological process from foaming horse sweat to bacterial raincoat formation. We describe an interdisciplinary approach to study the molecular and biophysical mechanisms controlling the activity of an unusual bacterial protein called BslA. This protein is needed for biofilm formation and forms a protective layer or raincoat over the bacterial community, but also has a multitude of potential applications in multiphase formulations. Here we document our journey from fundamental research to an examination of the applications for this surface-active protein in ice cream.

Bacterial flora of soil after application of oily waste

Energy Technology Data Exchange (ETDEWEB)

Jensen, V

1975-01-01

The influence of mineral oils and oily waste on the bacterial flora of soil was studied both in the field and in model experiments by plate counts followed by examination of the composition of the bacterial flora developing on the plates and by enrichment cultures followed by isolation of pure cultures. A strong increase in bacterial numbers after oil application was observed both in field and model experiments, and this increase occurred within all groups of bacteria, except spore formers and streptomycetes. The most important species of oil decomposing bacteria belonged to the genera Arthrobacter and Pseudomonas.

Locomotion of bacteria in liquid flow and the boundary layer effect on bacterial attachment

International Nuclear Information System (INIS)

Zhang, Chao; Liao, Qiang; Chen, Rong; Zhu, Xun

2015-01-01

The formation of biofilm greatly affects the performance of biological reactors, which highly depends on bacterial swimming and attachment that usually takes place in liquid flow. Therefore, bacterial swimming and attachment on flat and circular surfaces with the consideration of flow was studied experimentally. Besides, a mathematical model comprehensively combining bacterial swimming and motion with flow is proposed for the simulation of bacterial locomotion and attachment in flow. Both experimental and theoretical results revealed that attached bacteria density increases with decreasing boundary layer thickness on both flat and circular surfaces, the consequence of which is inherently related to the competition between bacterial swimming and the non-slip motion with flow evaluated by the Péclet number. In the boundary layer, where the Péclet number is relatively higher, bacterial locomotion mainly depends on bacterial swimming. Thinner boundary layer promotes bacterial swimming towards the surface, leading to higher attachment density. To enhance the performance of biofilm reactors, it is effective to reduce the boundary layer thickness on desired surfaces. - Highlights: • Study of bacterial locomotion in flow as an early stage in biofilm formation. • Mathematical model combining bacterial swimming and the motion with flow. • Boundary layer plays a key role in bacterial attachment under flow condition. • The competition between bacterial swimming and the motion with flow is evaluated

Locomotion of bacteria in liquid flow and the boundary layer effect on bacterial attachment

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chao, E-mail: zhangchao@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030 (China); Institute of Engineering Thermophysics, Chongqing University, Chongqing 400030 (China); Liao, Qiang, E-mail: lqzx@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030 (China); Institute of Engineering Thermophysics, Chongqing University, Chongqing 400030 (China); Chen, Rong, E-mail: rchen@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030 (China); Institute of Engineering Thermophysics, Chongqing University, Chongqing 400030 (China); Zhu, Xun, E-mail: zhuxun@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030 (China); Institute of Engineering Thermophysics, Chongqing University, Chongqing 400030 (China)

2015-06-12

The formation of biofilm greatly affects the performance of biological reactors, which highly depends on bacterial swimming and attachment that usually takes place in liquid flow. Therefore, bacterial swimming and attachment on flat and circular surfaces with the consideration of flow was studied experimentally. Besides, a mathematical model comprehensively combining bacterial swimming and motion with flow is proposed for the simulation of bacterial locomotion and attachment in flow. Both experimental and theoretical results revealed that attached bacteria density increases with decreasing boundary layer thickness on both flat and circular surfaces, the consequence of which is inherently related to the competition between bacterial swimming and the non-slip motion with flow evaluated by the Péclet number. In the boundary layer, where the Péclet number is relatively higher, bacterial locomotion mainly depends on bacterial swimming. Thinner boundary layer promotes bacterial swimming towards the surface, leading to higher attachment density. To enhance the performance of biofilm reactors, it is effective to reduce the boundary layer thickness on desired surfaces. - Highlights: • Study of bacterial locomotion in flow as an early stage in biofilm formation. • Mathematical model combining bacterial swimming and the motion with flow. • Boundary layer plays a key role in bacterial attachment under flow condition. • The competition between bacterial swimming and the motion with flow is evaluated.

Distributions of Bacterial Generalists among the Guts of Birds ...

Science.gov (United States)

Complex distributions of bacterial taxa within diverse animal microbiomes have inspired ecological and biogeographical approaches to revealing the functions of taxa that may be most important for host health. Of particular interest are bacteria that find many diverse habitats suitable for growth and remain competitive amongst finely-tuned host specialists. While previous work has focused on identifying these specialists, here our aims were to 1) identify generalist taxa, 2) identify taxonomic clades with enriched generalist diversity, and 3) describe the distribution of the largest generalist groups among hosts. We analyzed existing bacterial rRNA tag-sequencing data (v6) available on VAMPs (vamps.mbl.edu) from the microbiomes of 12 host species (106 samples total) spanning birds, mammals, and fish for generalist taxa using the CLAM test. OTUs with approximately equal abundance and a minimum of 10 reads in two hosts were classified as generalists. Generalist OTUs (n=2,982) were found in all hosts tested. Bacterial families Alcaligenaceae and Burkholderiaceae were significantly enriched with generalists OTUs compared to other families. Bacterial families such as Bacteroidaceae and Lachnospiraceae significantly lacked generalists OTUs compared to other families. Enterobacteriaceae, Peptostreptococcaceae, and Erysipelotrichaceae more so than other bacterial families were widely distributed and abundant in birds, mammals, and fish suggesting that these taxa mainta

Bacterial diversity among four healthcare-associated institutes in Taiwan.

Science.gov (United States)

Chen, Chang-Hua; Lin, Yaw-Ling; Chen, Kuan-Hsueh; Chen, Wen-Pei; Chen, Zhao-Feng; Kuo, Han-Yueh; Hung, Hsueh-Fen; Tang, Chuan Yi; Liou, Ming-Li

2017-08-15

Indoor microbial communities have important implications for human health, especially in health-care institutes (HCIs). The factors that determine the diversity and composition of microbiomes in a built environment remain unclear. Herein, we used 16S rRNA amplicon sequencing to investigate the relationships between building attributes and surface bacterial communities among four HCIs located in three buildings. We examined the surface bacterial communities and environmental parameters in the buildings supplied with different ventilation types and compared the results using a Dirichlet multinomial mixture (DMM)-based approach. A total of 203 samples from the four HCIs were analyzed. Four bacterial communities were grouped using the DMM-based approach, which were highly similar to those in the 4 HCIs. The α-diversity and β-diversity in the naturally ventilated building were different from the conditioner-ventilated building. The bacterial source composition varied across each building. Nine genera were found as the core microbiota shared by all the areas, of which Acinetobacter, Enterobacter, Pseudomonas, and Staphylococcus are regarded as healthcare-associated pathogens (HAPs). The observed relationship between environmental parameters such as core microbiota and surface bacterial diversity suggests that we might manage indoor environments by creating new sanitation protocols, adjusting the ventilation design, and further understanding the transmission routes of HAPs.

Bacterial Succession on Rat Carcasses and Applications for PMI Estimation.

Science.gov (United States)

Zhang, Lin; Guo, Juan-juan; Telet-Siyit; Peng, Yu-long; Xie, Dan; Guo, Ya-dong; Yan, Jie; Zha, Lagabaiyila; Cai, Ji-feng

2016-02-01

Abstract: To investigate the bacterial succession on rat carcasses and to evaluate the use of bacterial succession for postmortem interval (PMI) estimation. Adult female SD rat remains were placed in carton boxes. The bacterial colonization of circumocular skin, mouth and vagina was collected to be identified using culture-dependent biochemical methods. The changes in community composition were regularly documented. The bacterial succession in three habitats showed that Staphylococcus and Neisseria were predominated in early PMI, especially Staphylococcus aureus and Neisseria lactamica in 6 hours after death. Lactobacillus casei developed on the 3-4 days regularly, and kept stable at a certain level in late PMI. The involvement of normal and putrefactive bacteria in three body habitats of rat remains can be used for PMI estimation.

Bacterial invasion of the uterus and oviducts in bovine pyometra

DEFF Research Database (Denmark)

Karstrup, C. C.; Pedersen, H. G.; Jensen, Tim Kåre

2017-01-01

of bacterial pathogenicity and development of lesions, have not been investigated. Bacterial invasion of the uterus and oviducts was studied in 21 cows diagnosed with pyometra at the time of slaughter by applying fluorescence in situ hybridization using probes targeting 16S ribosomal RNA of Fusobacterium...... necrophorum, Porphyromonas levii, Trueperella pyogenes and the overall bacterial domain Bacteria. Fusobacterium necrophorum and P. levii were found to invade the endometrium, especially if the endometrium was ulcerated, and penetrated deep into the lamina propria. These species co-localized within the tissue...... thus indicating a synergism. Trueperella pyogenes did not invade the uterine tissue. In addition to endometrial lesions, most cows with pyometra also had salpingitis but without significant bacterial invasion of the oviductal wall....

Sugar Lego: gene composition of bacterial carbohydrate metabolism genomic loci.

Science.gov (United States)

Kaznadzey, Anna; Shelyakin, Pavel; Gelfand, Mikhail S

2017-11-25

Bacterial carbohydrate metabolism is extremely diverse, since carbohydrates serve as a major energy source and are involved in a variety of cellular processes. Bacterial genes belonging to same metabolic pathway are often co-localized in the chromosome, but it is not a strict rule. Gene co-localization in linked to co-evolution and co-regulation. This study focuses on a large-scale analysis of bacterial genomic loci related to the carbohydrate metabolism. We demonstrate that only 53% of 148,000 studied genes from over six hundred bacterial genomes are co-localized in bacterial genomes with other carbohydrate metabolism genes, which points to a significant role of singleton genes. Co-localized genes form cassettes, ranging in size from two to fifteen genes. Two major factors influencing the cassette-forming tendency are gene function and bacterial phylogeny. We have obtained a comprehensive picture of co-localization preferences of genes for nineteen major carbohydrate metabolism functional classes, over two hundred gene orthologous clusters, and thirty bacterial classes, and characterized the cassette variety in size and content among different species, highlighting a significant role of short cassettes. The preference towards co-localization of carbohydrate metabolism genes varies between 40 and 76% for bacterial taxa. Analysis of frequently co-localized genes yielded forty-five significant pairwise links between genes belonging to different functional classes. The number of such links per class range from zero to eight, demonstrating varying preferences of respective genes towards a specific chromosomal neighborhood. Genes from eleven functional classes tend to co-localize with genes from the same class, indicating an important role of clustering of genes with similar functions. At that, in most cases such co-localization does not originate from local duplication events. Overall, we describe a complex web formed by evolutionary relationships of bacterial

Manipulation of host membranes by bacterial effectors.

Science.gov (United States)

Ham, Hyeilin; Sreelatha, Anju; Orth, Kim

2011-07-18

Bacterial pathogens interact with host membranes to trigger a wide range of cellular processes during the course of infection. These processes include alterations to the dynamics between the plasma membrane and the actin cytoskeleton, and subversion of the membrane-associated pathways involved in vesicle trafficking. Such changes facilitate the entry and replication of the pathogen, and prevent its phagocytosis and degradation. In this Review, we describe the manipulation of host membranes by numerous bacterial effectors that target phosphoinositide metabolism, GTPase signalling and autophagy.

Bacterial Contribution in Chronicity of Wounds.

Science.gov (United States)

Rahim, Kashif; Saleha, Shamim; Zhu, Xudong; Huo, Liang; Basit, Abdul; Franco, Octavio Luiz

2017-04-01

A wound is damage of a tissue usually caused by laceration of a membrane, generally the skin. Wound healing is accomplished in three stages in healthy individuals, including inflammatory, proliferative, and remodeling stages. Healing of wounds normally starts from the inflammatory phase and ends up in the remodeling phase, but chronic wounds remain in an inflammatory stage and do not show progression due to some specific reasons. Chronic wounds are classified in different categories, such as diabetic foot ulcer (DFU), venous leg ulcers (VLU) and pressure ulcer (PU), surgical site infection (SSI), abscess, or trauma ulcers. Globally, the incidence rate of DFU is 1-4 % and prevalence rate is 5.3-10.5 %. However, colonization of pathogenic bacteria at the wound site is associated with wound chronicity. Most chronic wounds contain more than one bacterial species and produce a synergetic effect that results in previously non-virulent bacterial species becoming virulent and causing damage to the host. While investigating bacterial diversity in chronic wounds, Staphylococcus, Pseudomonas, Peptoniphilus, Enterobacter, Stenotrophomonas, Finegoldia, and Serratia were found most frequently in chronic wounds. Recently, it has been observed that bacteria in chronic wounds develop biofilms that contribute to a delay in healing. In a mature biofilm, bacteria grow slowly due to deficiency of nutrients that results in the resistance of bacteria to antibiotics. The present review reflects the reasons why acute wounds become chronic. Interesting findings include the bacterial load, which forms biofilms and shows high-level resistance toward antibiotics, which is a threat to human health in general and particularly to some patients who have acute wounds.

Bacterial community profiles in low microbial abundance sponges

KAUST Repository

Giles, Emily

2012-09-04

It has long been recognized that sponges differ in the abundance of associated microorganisms, and they are therefore termed either \\'low microbial abundance\\' (LMA) or \\'high microbial abundance\\' (HMA) sponges. Many previous studies concentrated on the dense microbial communities in HMA sponges, whereas little is known about microorganisms in LMA sponges. Here, two LMA sponges from the Red Sea, two from the Caribbean and one from the South Pacific were investigated. With up to only five bacterial phyla per sponge, all LMA sponges showed lower phylum-level diversity than typical HMA sponges. Interestingly, each LMA sponge was dominated by a large clade within either Cyanobacteria or different classes of Proteobacteria. The overall similarity of bacterial communities among LMA sponges determined by operational taxonomic unit and UniFrac analysis was low. Also the number of sponge-specific clusters, which indicate bacteria specifically associated with sponges and which are numerous in HMA sponges, was low. A biogeographical or host-dependent distribution pattern was not observed. In conclusion, bacterial community profiles of LMA sponges are clearly different from profiles of HMA sponges and, remarkably, each LMA sponge seems to harbour its own unique bacterial community. © 2012 Federation of European Microbiological Societies.

Effect of Weak Magnetic Field on Bacterial Growth

Science.gov (United States)

Masood, Samina

Effects of weak magnetic fields are observed on the growth of various bacterial strains. Different sources of a constant magnetic field are used to demonstrate that ion transport in the nutrient broth and bacterial cellular dynamics is perturbed in the presence of weak magnetic field which affects the mobility and absorption of nutrients in cells and hence their doubling rate. The change is obvious after a few hours of exposure and keeps on increasing with time for all the observed species. The growth rate depends on the field strength and the nature of the magnetic field. The field effect varies with the shape and the structure of the bacterial cell wall as well as the concentration of nutrient broth. We closely study the growth of three species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis with the same initial concentrations at the same temperature in the same laboratory environment. Our results indicate that the weak static field of a few gauss after a few hours gives a measurable change in the growth rates of all bacterial species. This shows that the same magnetic field has different effects on different species in the same environment.

Effect of different storage temperatures on bacterial spoilage of ...

African Journals Online (AJOL)

This study determined the bacterial organisms associated with Oreochromis niloticus spoilage at two storage temperatures (6 and 20°C) and also assessed the ability of the individual bacterial isolates to cause spoilage at the two storage temperatures. Bacteriological analysis revealed the association of five bacteria ...

Utilization of chitinolytic bacterial isolates to control anthracnose of ...

African Journals Online (AJOL)

Colletotrichum spp. are causal agents of anthracnose in many plant species. Biological control of Colletotrichum spp. utilizing bacterial isolates and fungi has been reported. However, chitinolytic bacterial isolate utilization to control anthracnose of cocoa leaf has not seemingly been studied yet. In this study, we used ...

Bioremoval of heavy metals by bacterial biomass.

Science.gov (United States)

Aryal, Mahendra; Liakopoulou-Kyriakides, Maria

2015-01-01

Heavy metals are among the most common pollutants found in the environment. Health problems due to the heavy metal pollution become a major concern throughout the world, and therefore, various treatment technologies such as reverse osmosis, ion exchange, solvent extraction, chemical precipitation, and adsorption are adopted to reduce or eliminate their concentration in the environment. Biosorption is a cost-effective and environmental friendly technique, and it can be used for detoxification of heavy metals in industrial effluents as an alternative treatment technology. Biosorption characteristics of various bacterial species are reviewed here with respect to the results reported so far. The role of physical, chemical, and biological modification of bacterial cells for heavy metal removal is presented. The paper evaluates the different kinetic, equilibrium, and thermodynamic models used in bacterial sorption of heavy metals. Biomass characterization and sorption mechanisms as well as elution of metal ions and regeneration of biomass are also discussed.

Bacterial tracheitis in Down's syndrome.

OpenAIRE

Cant, A J; Gibson, P J; West, R J

1987-01-01

Four children with Down's syndrome and bacterial tracheitis are described. In three the infection was due to Haemophilus influenza. In patients with Down's syndrome presenting with stridor tracheitis should be considered and appropriate treatment started.

Exploring bacterial outer membrane barrier to combat bad bugs.

Science.gov (United States)

Ghai, Ishan; Ghai, Shashank

2017-01-01

One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.

Hydrocarbon pollutants shape bacterial community assembly of harbor sediments

KAUST Repository

Barbato, Marta

2016-02-02

Petroleum pollution results in co-contamination by different classes of molecules, entailing the occurrence of marine sediments difficult to remediate, as in the case of the Ancona harbor (Mediterranean Sea, Italy). Autochthonous bioaugmentation (ABA), by exploiting the indigenous microbes of the environment to be treated, could represent a successful bioremediation strategy. In this perspective we aimed to i) identify the main drivers of the bacterial communities\\' richness in the sediments, ii) establish enrichment cultures with different hydrocarbon pollutants evaluating their effects on the bacterial communities\\' composition, and iii) obtain a collection of hydrocarbon degrading bacteria potentially exploitable in ABA. The correlation between the selection of different specialized bacterial populations and the type of pollutants was demonstrated by culture-independent analyses, and by establishing a collection of bacteria with different hydrocarbon degradation traits. Our observations indicate that pollution dictates the diversity of sediment bacterial communities and shapes the ABA potential in harbor sediments.

Bacterial and parasitic diseases of parrots.

Science.gov (United States)

Doneley, Robert J T

2009-09-01

As wild-caught birds become increasingly rare in aviculture, there is a corresponding decline in the incidence of bacterial and parasitic problems and an increase in the recognition of the importance of maintaining health through better nutrition and husbandry. Nevertheless, the relatively close confines of captivity mean an increased pathogen load in the environment in which companion and aviary parrots live. This increased pathogen load leads to greater exposure of these birds to bacteria and parasites, and consequently a greater risk of infection and disease. This article discusses bacterial and parasitic infections in companion and aviary parrots. It includes the origins, pathogens, diagnosis, treatment, and some of the associated risk factors.

Metatranscriptomics reveals overall active bacterial composition in caries lesions

Directory of Open Access Journals (Sweden)

Aurea Simón-Soro

2014-10-01

Full Text Available Background: Identifying the microbial species in caries lesions is instrumental to determine the etiology of dental caries. However, a significant proportion of bacteria in carious lesions have not been cultured, and the use of molecular methods has been limited to DNA-based approaches, which detect both active and inactive or dead microorganisms. Objective: To identify the RNA-based, metabolically active bacterial composition of caries lesions at different stages of disease progression in order to provide a list of potential etiological agents of tooth decay. Design: Non-cavitated enamel caries lesions (n=15 and dentin caries lesions samples (n=12 were collected from 13 individuals. RNA was extracted and cDNA was constructed, which was used to amplify the 16S rRNA gene. The resulting 780 bp polymerase chain reaction products were pyrosequenced using Titanium-plus chemistry, and the sequences obtained were used to determine the bacterial composition. Results: A mean of 4,900 sequences of the 16S rRNA gene with an average read length of 661 bp was obtained per sample, giving a comprehensive view of the active bacterial communities in caries lesions. Estimates of bacterial diversity indicate that the microbiota of cavities is highly complex, each sample containing between 70 and 400 metabolically active species. The composition of these bacterial consortia varied among individuals and between caries lesions of the same individuals. In addition, enamel and dentin lesions had a different bacterial makeup. Lactobacilli were found almost exclusively in dentin cavities. Streptococci accounted for 40% of the total active community in enamel caries, and 20% in dentin caries. However, Streptococcus mutans represented only 0.02–0.73% of the total bacterial community. Conclusions: The data indicate that the etiology of dental caries is tissue dependent and that the disease has a clear polymicrobial origin. The low proportion of mutans streptococci

Bacterial communities in batch and continuous-flow wetlands treating the herbicide S-metolachlor

Energy Technology Data Exchange (ETDEWEB)

Elsayed, O.F. [Laboratory of Hydrology and Geochemistry of Strasbourg (LHyGeS), UMR 7517 University of Strasbourg/ENGEES/CNRS (France); Génétique Moléculaire, Génomique, Microbiologie (GMGM), UMR 7156 University of Strasbourg/CNRS (France); Maillard, E. [Laboratory of Hydrology and Geochemistry of Strasbourg (LHyGeS), UMR 7517 University of Strasbourg/ENGEES/CNRS (France); Vuilleumier, S. [Génétique Moléculaire, Génomique, Microbiologie (GMGM), UMR 7156 University of Strasbourg/CNRS (France); Imfeld, G., E-mail: imfeld@unistra.fr [Laboratory of Hydrology and Geochemistry of Strasbourg (LHyGeS), UMR 7517 University of Strasbourg/ENGEES/CNRS (France)

2014-11-15

Knowledge of wetland bacterial communities in the context of pesticide contamination and hydrological regime is scarce. We investigated the bacterial composition in constructed wetlands receiving Mercantor Gold{sup ®} contaminated water (960 g L{sup −1} of the herbicide S-metolachlor, > 80% of the S-enantiomer) operated under continuous-flow or batch modes to evaluate the impact of the hydraulic regime. In the continuous-flow wetland, S-metolachlor mass removal was > 40%, whereas in the batch wetland, almost complete removal of S-metolachlor (93–97%) was observed. Detection of ethanesulfonic and oxanilic acid degradation products further indicated S-metolachlor biodegradation in the two wetlands. The dominant bacterial populations were characterised by terminal restriction fragment length polymorphism (T-RFLP) and 454 pyrosequencing. The bacterial profiles evolved during the first 35 days of the experiment, starting from a composition similar to that of inlet water, with the use of nitrate and to a lesser extent sulphate and manganese as terminal electron acceptors for microbial metabolism. Proteobacteria were the most abundant phylum, with Beta-, Alpha- and Gammaproteobacteria representing 26%, 19% and 17% respectively of total bacterial abundance. Bacterial composition in wetland water changed gradually over time in continuous-flow wetland and more abruptly in the batch wetland. Differences in overall bacterial water structure in the two systems were modest but significant (p = 0.008), and S-metolachlor, nitrate, and total inorganic carbon concentrations correlated with changes in the bacterial profiles. Together, the results highlight that bacterial composition profiles and their dynamics may be used as bioindicators of herbicide exposure and hydraulic disturbances in wetland systems. - Highlights: • We evaluated the bacterial composition in wetlands treating S-metolachlor • Hydraulic regime impacted biogeochemical processes and S-metolachlor removal �

Bacterial communities in batch and continuous-flow wetlands treating the herbicide S-metolachlor

International Nuclear Information System (INIS)

Elsayed, O.F.; Maillard, E.; Vuilleumier, S.; Imfeld, G.

2014-01-01

Knowledge of wetland bacterial communities in the context of pesticide contamination and hydrological regime is scarce. We investigated the bacterial composition in constructed wetlands receiving Mercantor Gold ® contaminated water (960 g L −1 of the herbicide S-metolachlor, > 80% of the S-enantiomer) operated under continuous-flow or batch modes to evaluate the impact of the hydraulic regime. In the continuous-flow wetland, S-metolachlor mass removal was > 40%, whereas in the batch wetland, almost complete removal of S-metolachlor (93–97%) was observed. Detection of ethanesulfonic and oxanilic acid degradation products further indicated S-metolachlor biodegradation in the two wetlands. The dominant bacterial populations were characterised by terminal restriction fragment length polymorphism (T-RFLP) and 454 pyrosequencing. The bacterial profiles evolved during the first 35 days of the experiment, starting from a composition similar to that of inlet water, with the use of nitrate and to a lesser extent sulphate and manganese as terminal electron acceptors for microbial metabolism. Proteobacteria were the most abundant phylum, with Beta-, Alpha- and Gammaproteobacteria representing 26%, 19% and 17% respectively of total bacterial abundance. Bacterial composition in wetland water changed gradually over time in continuous-flow wetland and more abruptly in the batch wetland. Differences in overall bacterial water structure in the two systems were modest but significant (p = 0.008), and S-metolachlor, nitrate, and total inorganic carbon concentrations correlated with changes in the bacterial profiles. Together, the results highlight that bacterial composition profiles and their dynamics may be used as bioindicators of herbicide exposure and hydraulic disturbances in wetland systems. - Highlights: • We evaluated the bacterial composition in wetlands treating S-metolachlor • Hydraulic regime impacted biogeochemical processes and S-metolachlor removal �

Study of bacterial meningitis in children below 5 years with comparative evaluation of gram staining, culture and bacterial antigen detection.

Science.gov (United States)

Yadhav Ml, Kala

2014-04-01

Bacterial meningitis is one of the most serious infections seen in infants and children, which is associated with acute complications and chronic morbidity. Infections of Central Nervous System (CNS) still dominate the scene of childhood neurological disorders in most of the developing tropical countries. To isolate, identify and determine the antibiotic susceptibility patterns of pathogens associated with bacterial meningitis. We also aimed to comparatively evaluate of Gram staining, culture and bacterial antigen detection in cerebrospinal fluid samples. Present comparative study included 100 CSF samples of children below the age of 5 years, who were clinically suspected meningitis cases. The samples were subjected to Gram staining, culture and Latex agglutination test (LAT). The organisms isolated in the study were characterized and antibiotic susceptibility test was done according to standard guidelines. It was done by using Gaussian test. Of the 100 cases, 24 were diagnosed as Acute bacterial meningitis (ABM) cases by. Gram staining, culture and latex agglutination test. 21 (87.5%) cases were culture positive, with 2 cases being positive for polymicrobial isolates. Gram staining was positive in 17 (70.53%) cases and LAT was positive in 18 (33.33%) cases. Streptococcus pneumoniae was the predominant organism which was isolated and it was sensitive to antibiotics. In the present study, male to female ratio was 1.27:1, which showed a male preponderance. With the combination of Gram staining, culture, and LAT, 100% sensitivity and specificity can be achieved (p Gram staining and LAT can detect 85% of cases of ABM. Bacterial meningitis is a medical emergency and making an early diagnosis and providing treatment early are life saving and they reduce chronic morbidity.

Mapping and predictive variations of soil bacterial richness across France.

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Sébastien Terrat

Full Text Available Although numerous studies have demonstrated the key role of bacterial diversity in soil functions and ecosystem services, little is known about the variations and determinants of such diversity on a nationwide scale. The overall objectives of this study were i to describe the bacterial taxonomic richness variations across France, ii to identify the ecological processes (i.e. selection by the environment and dispersal limitation influencing this distribution, and iii to develop a statistical predictive model of soil bacterial richness. We used the French Soil Quality Monitoring Network (RMQS, which covers all of France with 2,173 sites. The soil bacterial richness (i.e. OTU number was determined by pyrosequencing 16S rRNA genes and related to the soil characteristics, climatic conditions, geomorphology, land use and space. Mapping of bacterial richness revealed a heterogeneous spatial distribution, structured into patches of about 111km, where the main drivers were the soil physico-chemical properties (18% of explained variance, the spatial descriptors (5.25%, 1.89% and 1.02% for the fine, medium and coarse scales, respectively, and the land use (1.4%. Based on these drivers, a predictive model was developed, which allows a good prediction of the bacterial richness (R2adj of 0.56 and provides a reference value for a given pedoclimatic condition.

Bacterial meningitis in diabetes patients: a population-based prospective study