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Sample records for bacterial growth curve

  1. The Bacterial Growth Curve.

    ERIC Educational Resources Information Center

    Paulton, Richard J. L.

    1991-01-01

    A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)

  2. Bacterial streamers in curved microchannels

    NASA Astrophysics Data System (ADS)

    Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

    2009-11-01

    Biofilms, generally identified as microbial communities embedded in a self-produced matrix of extracellular polymeric substances, are involved in a wide variety of health-related problems ranging from implant-associated infections to disease transmissions and dental plaque. The usual picture of these bacterial films is that they grow and develop on surfaces. However, suspended biofilm structures, or streamers, have been found in natural environments (e.g., rivers, acid mines, hydrothermal hot springs) and are always suggested to stem from a turbulent flow. We report the formation of bacterial streamers in curved microfluidic channels. By using confocal laser microscopy we are able to directly image and characterize the spatial and temporal evolution of these filamentous structures. Such streamers, which always connect the inner corners of opposite sides of the channel, are always located in the middle plane. Numerical simulations of the flow provide evidences for an underlying hydrodynamic mechanism behind the formation of the streamers.

  3. Phenotypic Signatures Arising from Unbalanced Bacterial Growth

    PubMed Central

    Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

    2014-01-01

    Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains. PMID:25101949

  4. Solubilization and bio-conjugation of quantum dots and bacterial toxicity assays by growth curve and plate count.

    PubMed

    Park, Soonhyang; Chibli, Hicham; Nadeau, Jay

    2012-01-01

    Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells. QDs are also being widely investigated as cytotoxic agents for targeted killing of bacteria. The emergence of multiply-resistant bacterial strains is rapidly becoming a public health crisis, particularly in the case of Gram negative pathogens. Because of the well-known antimicrobial effect of certain nanomaterials, especially Ag, there are hundreds of studies examining the toxicity of nanoparticles to bacteria. Bacterial studies have been performed with other types of semiconductor nanoparticles as well, especially TiO(2), but also ZnO and others including CuO. Some comparisons of bacterial strains have been performed in these studies, usually comparing a Gram negative strain with a Gram positive. With all of these particles, mechanisms of toxicity are attributed to oxidation: either the photogeneration of reactive oxygen species (ROS) by the particles or the direct release of metal ions that can cause oxidative toxicity. Even with these materials, results of different studies vary greatly. In some studies the Gram positive test strain is reportedly more sensitive than the Gram negative; in others it is the opposite. These studies have been well reviewed. In all nanoparticle studies, particle composition, size, surface chemistry, sample aging/breakdown, and wavelength, power, and duration of light exposure can all dramatically affect the results. In addition, synthesis byproducts and solvents must be considered. High-throughput screening techniques are needed to be able to develop effective new nanomedicine agents. CdTe QDs have anti-microbial effects alone or in combination with antibiotics. In a

  5. Growth curves for Laron syndrome.

    PubMed Central

    Laron, Z; Lilos, P; Klinger, B

    1993-01-01

    Growth curves for children with Laron syndrome were constructed on the basis of repeated measurements made throughout infancy, childhood, and puberty in 24 (10 boys, 14 girls) of the 41 patients with this syndrome investigated in our clinic. Growth retardation was already noted at birth, the birth length ranging from 42 to 46 cm in the 12/20 available measurements. The postnatal growth curves deviated sharply from the normal from infancy on. Both sexes showed no clear pubertal spurt. Girls completed their growth between the age of 16-19 years to a final mean (SD) height of 119 (8.5) cm whereas the boys continued growing beyond the age of 20 years, achieving a final height of 124 (8.5) cm. At all ages the upper to lower body segment ratio was more than 2 SD above the normal mean. These growth curves constitute a model not only for primary, hereditary insulin-like growth factor-I (IGF-I) deficiency (Laron syndrome) but also for untreated secondary IGF-I deficiencies such as growth hormone gene deletion and idiopathic congenital isolated growth hormone deficiency. They should also be useful in the follow up of children with Laron syndrome treated with biosynthetic recombinant IGF-I. PMID:8333769

  6. Force-extension curves of bacterial flagella.

    PubMed

    Vogel, R; Stark, H

    2010-11-01

    Bacterial flagella assume different helical shapes during the tumbling phase of a bacterium but also in response to varying environmental conditions. Force-extension measurements by Darnton and Berg explicitly demonstrate a transformation from the coiled to the normal helical state (N.C. Darnton, H.C. Berg, Biophys. J. 92, 2230 (2007)). We here develop an elastic model for the flagellum based on Kirchhoff's theory of an elastic rod that describes such a polymorphic transformation and use resistive force theory to couple the flagellum to the aqueous environment. We present Brownian-dynamics simulations that quantitatively reproduce the force-extension curves and study how the ratio Γ of torsional to bending rigidity and the extensional rate influence the response of the flagellum. An upper bound for Γ is given. Using clamped flagella, we show in an adiabatic approximation that the mean extension, where a local coiled-to-normal transition occurs first, depends on the logarithm of the extensional rate. PMID:21046183

  7. Nonlinear Growth Curves in Developmental Research

    ERIC Educational Resources Information Center

    Grimm, Kevin J.; Ram, Nilam; Hamagami, Fumiaki

    2011-01-01

    Developmentalists are often interested in understanding change processes, and growth models are the most common analytic tool for examining such processes. Nonlinear growth curves are especially valuable to developmentalists because the defining characteristics of the growth process such as initial levels, rates of change during growth spurts, and…

  8. Electromagnetism of Bacterial Growth

    NASA Astrophysics Data System (ADS)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  9. Residual Structures in Latent Growth Curve Modeling

    ERIC Educational Resources Information Center

    Grimm, Kevin J.; Widaman, Keith F.

    2010-01-01

    Several alternatives are available for specifying the residual structure in latent growth curve modeling. Two specifications involve uncorrelated residuals and represent the most commonly used residual structures. The first, building on repeated measures analysis of variance and common specifications in multilevel models, forces residual variances…

  10. Growth curve analyses in selected duck lines.

    PubMed

    Maruyama, K; Vinyard, B; Akbar, M K; Shafer, D J; Turk, C M

    2001-12-01

    1. Growth patterns of male ducks from 4 lines (lines A, B, C and D) selected for market weight were analysed and compared to growth patterns of ducks in the respective line 7 generations earlier. Growth curves were analysed using procedures derived from the Weibull sigmoidal function and the linear-linear relative growth rate model and simple allometry. 2. The ducks were fed ad libitum under 24-h lighting throughout the experiment. At weekly intervals from the time of hatch through 70 d of age, 16 ducks from each line were killed to determine body, carcase, breast-muscle, leg and thigh-muscle, and abdominal fat weights. 3. Line A was the heaviest line, followed by line B, line C and line D. However, body weight, carcase weight and breast-muscle weight at 49 d of age were not significantly different between lines A and B. After 7 generations of selection, the breast-muscle yield was increased to >19% and the abdominal fat percent was reduced to <1.4% in all lines. 4. The Weibull growth curve analysis of body weight showed an increase in the asymptotes during selection, while the age of the inflection point remained constant in all lines (21.3 to 26.0 d). For breast-muscle growth, ducks reached the inflection point 12.8 to 14.3 d later than for body weight. Between line A and line B, asymptotes for body weight, asymptotes for breast-muscle weight and allometric growth coefficients of breast muscle and leg and thigh muscles from 14 to 49 d were not significantly different. 5. The relative growth rate model discriminated body and breast-muscle growth patterns of line A and line B. The initial decline in the relative body growth rate was less and the time to reach the transition was longer in line A than line B. On the other hand, the initial decline in the relative breast-muscle growth rate was greater in line A than line B. PMID:11811908

  11. Curved tails in polymerization-based bacterial motility

    NASA Astrophysics Data System (ADS)

    Rutenberg, Andrew D.; Grant, Martin

    2001-08-01

    The curved actin ``comet-tail'' of the bacterium Listeria monocytogenes is a visually striking signature of actin polymerization-based motility. Similar actin tails are associated with Shigella flexneri, spotted-fever Rickettsiae, the Vaccinia virus, and vesicles and microspheres in related in vitro systems. We show that the torque required to produce the curvature in the tail can arise from randomly placed actin filaments pushing the bacterium or particle. We find that the curvature magnitude determines the number of actively pushing filaments, independent of viscosity and of the molecular details of force generation. The variation of the curvature with time can be used to infer the dynamics of actin filaments at the bacterial surface.

  12. Bacterial volatiles promote growth in Arabidopsis

    PubMed Central

    Ryu, Choong-Min; Farag, Mohamed A.; Hu, Chia-Hui; Reddy, Munagala S.; Wei, Han-Xun; Paré, Paul W.; Kloepper, Joseph W.

    2003-01-01

    Several chemical changes in soil are associated with plant growth-promoting rhizobacteria (PGPR). Some bacterial strains directly regulate plant physiology by mimicking synthesis of plant hormones, whereas others increase mineral and nitrogen availability in the soil as a way to augment growth. Identification of bacterial chemical messengers that trigger growth promotion has been limited in part by the understanding of how plants respond to external stimuli. With an increasing appreciation of how volatile organic compounds signal plants and serve in plant defense, investigations into the role of volatile components in plant–bacterial systems now can follow. Here, we present chemical and plant-growth data showing that some PGPR release a blend of volatile components that promote growth of Arabidopsis thaliana. In particular, the volatile components 2,3-butanediol and acetoin were released exclusively from two bacterial strains that trigger the greatest level of growth promotion. Furthermore, pharmacological applications of 2,3-butanediol enhanced plant growth whereas bacterial mutants blocked in 2,3-butanediol and acetoin synthesis were devoid in this growth-promotion capacity. The demonstration that PGPR strains release different volatile blends and that plant growth is stimulated by differences in these volatile blends establishes an additional function for volatile organic compounds as signaling molecules mediating plant–microbe interactions. PMID:12684534

  13. Technological growth curves. A competition of forecasting models

    SciTech Connect

    Young, P.

    1993-12-01

    In order to determine procedures for appropriate model selection of technological growth curves, numerous time series that were representative of growth behavior were collected and categorized according to data characteristics. Nine different growth curve models were each fitted onto the various data sets in an attempt to determine which growth curve models achieved the best forecasts for differing types of growth data. The analysis of the results gives rise to a new approach for selecting appropriate growth curve models for a given set of data, prior to fitting the models, based on the characteristics of the data sets. 58 refs., 9 tabs.

  14. Enteral nutrient solutions. Limiting bacterial growth.

    PubMed

    Paauw, J D; Fagerman, K E; McCamish, M A; Dean, R E

    1984-06-01

    Bacterial contamination of enteral nutrient solutions ( ENS ) in FFcess of food product standards is known to occur in the hospital setting. The large amounts of bacteria often given with ENS have been shown to create a reservoir for nosocomial infections, and nonpathogenic bacteria have been implicated. Patient tolerance is dependent on immune status and the bacterial load delivered to the gut. The purpose of this study was to evaluate the bacterial growth-sustaining properties of various ENS and to devise methods to limit bacterial growth. Five commercial products were prepared under sterile conditions. After inoculation with approximately 5 X 10(3) organisms/cm3 of Enterobacter cloacae, each solution was hung at room temperature for 24 hours with samples drawn at fixed intervals and plated for bacterial counts. Bacterial growth rates in Ensure, Travasorb , and Vital were markedly higher than those in Precision and Vivonex. Vivonex was noted to contain potassium sorbate (KS) used as a fungistatic agent. Recent studies have identified KS as a broad-spectrum bacteriostatic food preservative that is federally approved for this use. KS (0.03%) was added to Travasorb inoculated with 5 X 10(3) organisms/cm(3) of E. cloacae. The bacterial growth rate was reduced by 75 per cent, and the final count of 2-3 X 10(4) organisms/ml was within the federally regulated limit for milk. This study suggests that initial inoculum, growth rate, and hang time can be altered to provide a significant reduction in final bacterial counts in ENS . PMID:6428286

  15. Bounded Population Growth: A Curve Fitting Lesson.

    ERIC Educational Resources Information Center

    Mathews, John H.

    1992-01-01

    Presents two mathematical methods for fitting the logistic curve to population data supplied by the U.S. Census Bureau utilizing computer algebra software to carry out the computations and plot graphs. (JKK)

  16. Hypothesis Generation in Latent Growth Curve Modeling Using Principal Components

    ERIC Educational Resources Information Center

    Davison, Mark L.

    2008-01-01

    While confirmatory latent growth curve analyses provide procedures for testing hypotheses about latent growth curves underlying data, one must first derive hypotheses to be tested. It is argued that such hypotheses should be generated from a combination of theory and exploratory data analyses. An exploratory components analysis is described and…

  17. Regime Switching in the Latent Growth Curve Mixture Model

    ERIC Educational Resources Information Center

    Dolan, Conor V.; Schmittmann, Verena D.; Lubke, Gitta H.; Neale, Michael C.

    2005-01-01

    A linear latent growth curve mixture model is presented which includes switching between growth curves. Switching is accommodated by means of a Markov transition model. The model is formulated with switching as a highly constrained multivariate mixture model and is fitted using the freely available Mx program. The model is illustrated by analyzing…

  18. Evaluating Latent Growth Curve Models Using Individual Fit Statistics

    ERIC Educational Resources Information Center

    Coffman, Donna L.; Millsap, Roger E.

    2006-01-01

    The usefulness of assessing individual fit in latent growth curve models was examined. The study used simulated data based on an unconditional and a conditional latent growth curve model with a linear component and a small quadratic component and a linear model was fit to the data. Then the overall fit of linear and quadratic models to these data…

  19. Bacterial cell curvature through mechanical control of cell growth

    PubMed Central

    Cabeen, Matthew T; Charbon, Godefroid; Vollmer, Waldemar; Born, Petra; Ausmees, Nora; Weibel, Douglas B; Jacobs-Wagner, Christine

    2009-01-01

    The cytoskeleton is a key regulator of cell morphogenesis. Crescentin, a bacterial intermediate filament-like protein, is required for the curved shape of Caulobacter crescentus and localizes to the inner cell curvature. Here, we show that crescentin forms a single filamentous structure that collapses into a helix when detached from the cell membrane, suggesting that it is normally maintained in a stretched configuration. Crescentin causes an elongation rate gradient around the circumference of the sidewall, creating a longitudinal cell length differential and hence curvature. Such curvature can be produced by physical force alone when cells are grown in circular microchambers. Production of crescentin in Escherichia coli is sufficient to generate cell curvature. Our data argue for a model in which physical strain borne by the crescentin structure anisotropically alters the kinetics of cell wall insertion to produce curved growth. Our study suggests that bacteria may use the cytoskeleton for mechanical control of growth to alter morphology. PMID:19279668

  20. Modeling growth curves to track growing obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our purpose was to examine the relationship between total physical activity (PA) and PA at various intensity levels with insulin resistance at increasing waist circumference and skinfold thickness levels. Being able to describe growth appropriately and succinctly is important in many nutrition and p...

  1. [The measurement of growth curve and generation time of lactobacillus

    PubMed

    Gu, S P; Liu, Z; Song, P Z

    1998-12-01

    OBJECTIVE:The purpose of this test was to understand the growth pattern of lactobacillus for the research of its cariogenicity. METHODS: The growth quantity of lactobacillus which was culture in a constant condition was measured periodically by spectrophotometry and flora counting,and its growth curve and generation time were measured. RESULTS: It was found that the logarithmic phase of lactobacillus was 6-16 hours after it was cultured.And its generatin time was 54 minutes. CONCLUSIN: The growth curve of lactobacillus was in accordance with streptococcus mutan. PMID:15071634

  2. BGFit: management and automated fitting of biological growth curves

    PubMed Central

    2013-01-01

    Background Existing tools to model cell growth curves do not offer a flexible integrative approach to manage large datasets and automatically estimate parameters. Due to the increase of experimental time-series from microbiology and oncology, the need for a software that allows researchers to easily organize experimental data and simultaneously extract relevant parameters in an efficient way is crucial. Results BGFit provides a web-based unified platform, where a rich set of dynamic models can be fitted to experimental time-series data, further allowing to efficiently manage the results in a structured and hierarchical way. The data managing system allows to organize projects, experiments and measurements data and also to define teams with different editing and viewing permission. Several dynamic and algebraic models are already implemented, such as polynomial regression, Gompertz, Baranyi, Logistic and Live Cell Fraction models and the user can add easily new models thus expanding current ones. Conclusions BGFit allows users to easily manage their data and models in an integrated way, even if they are not familiar with databases or existing computational tools for parameter estimation. BGFit is designed with a flexible architecture that focus on extensibility and leverages free software with existing tools and methods, allowing to compare and evaluate different data modeling techniques. The application is described in the context of bacterial and tumor cells growth data fitting, but it is also applicable to any type of two-dimensional data, e.g. physical chemistry and macroeconomic time series, being fully scalable to high number of projects, data and model complexity. PMID:24067087

  3. Modeling error distributions of growth curve models through Bayesian methods.

    PubMed

    Zhang, Zhiyong

    2016-06-01

    Growth curve models are widely used in social and behavioral sciences. However, typical growth curve models often assume that the errors are normally distributed although non-normal data may be even more common than normal data. In order to avoid possible statistical inference problems in blindly assuming normality, a general Bayesian framework is proposed to flexibly model normal and non-normal data through the explicit specification of the error distributions. A simulation study shows when the distribution of the error is correctly specified, one can avoid the loss in the efficiency of standard error estimates. A real example on the analysis of mathematical ability growth data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 is used to show the application of the proposed methods. Instructions and code on how to conduct growth curve analysis with both normal and non-normal error distributions using the the MCMC procedure of SAS are provided. PMID:26019004

  4. Visualization of Growth Curve Data from Phenotype MicroarrayExperiments

    SciTech Connect

    Jacobsen, Janet S.; Joyner, Dominique C.; Borglin, Sharon E.; Hazen, Terry C.; Arkin, Adam P.; Bethel, E. Wes

    2007-04-19

    Phenotype microarrays provide a technology to simultaneouslysurvey the response of an organism to nearly 2,000 substrates, includingcarbon, nitrogen and potassium sources; varying pH; varying saltconcentrations; and antibiotics. In order to more quickly and easily viewand compare the large number of growth curves produced by phenotypemicroarray experiments, we have developed software to produce and displaycolor images, each of which corresponds to a set of 96 growth curves.Using color images to represent growth curves data has proven to be avaluable way to assess experiment quality, compare replicates, facilitatecomparison of the responses of different organisms, and identifysignificant phenotypes. The color images are linked to traditional plotsof growth versus time, as well as to information about the experiment,organism, and substrate. In order to share and view information and dataproject-wide, all information, plots, and data are accessible using onlya Web browser.

  5. Interactions of cosmic rays in the atmosphere: growth curves revisited

    SciTech Connect

    Obermeier, A.; Boyle, P.; Müller, D.; Hörandel, J.

    2013-12-01

    Measurements of cosmic-ray abundances on balloons are affected by interactions in the residual atmosphere above the balloon. Corrections for such interactions are particularly important for observations of rare secondary particles such as boron, antiprotons, and positrons. These corrections either can be calculated if the relevant cross sections in the atmosphere are known or may be empirically determined by extrapolation of the 'growth curves', i.e., the individual particle intensities as functions of atmospheric depth. The growth-curve technique is particularly attractive for long-duration balloon flights where the periodic daily altitude variations permit rather precise determinations of the corresponding particle intensity variations. We determine growth curves for nuclei from boron (Z = 5) to iron (Z = 26) using data from the 2006 Arctic balloon flight of the TRACER detector for cosmic-ray nuclei, and we compare the growth curves with predictions from published cross section values. In general, good agreement is observed. We then study the boron/carbon abundance ratio and derive a simple and energy-independent correction term for this ratio. We emphasize that the growth-curve technique can be developed further to provide highly accurate tests of published interaction cross section values.

  6. R-Curve Instability Calculations Of Crack Growth

    NASA Technical Reports Server (NTRS)

    Orange, Thomas W.

    1989-01-01

    Report discusses use of instability method of calculation and R-curve mathematical models to analyze growth of cracks in fracture-mechanics specimens. In case of single material and structure, such analysis sometimes simple enough to be done on pocket calculator. Where microcomputer or larger computer available, comprehensive program includes libraries of driving-force equations for various configurations and R-curve mathematical models for different materials. Author concludes instability method simple and effective and model equations studied all viable in sense at lease one of them should fit almost any applicable set of crack-growth data. Method and models constitute powerful mathematical tools for analysis of fractures.

  7. Synergy of fresh and accumulated organic matter to bacterial growth.

    PubMed

    Farjalla, Vinicius F; Marinho, Claudio C; Faria, Bias M; Amado, André M; Esteves, Francisco de A; Bozelli, Reinaldo L; Giroldo, Danilo

    2009-05-01

    The main goal of this research was to evaluate whether the mixture of fresh labile dissolved organic matter (DOM) and accumulated refractory DOM influences bacterial production, respiration, and growth efficiency (BGE) in aquatic ecosystems. Bacterial batch cultures were set up using DOM leached from aquatic macrophytes as the fresh DOM pool and DOM accumulated from a tropical humic lagoon. Two sets of experiments were performed and bacterial growth was followed in cultures composed of each carbon substrate (first experiment) and by carbon substrates combined (second experiment), with and without the addition of nitrogen and phosphorus. In both experiments, bacterial production, respiration, and BGE were always higher in cultures with N and P additions, indicating a consistent inorganic nutrient limitation. Bacterial production, respiration, and BGE were higher in cultures set up with leachate DOM than in cultures set up with humic DOM, indicating that the quality of the organic matter pool influenced the bacterial growth. Bacterial production and respiration were higher in the mixture of substrates (second experiment) than expected by bacterial production and respiration in single substrate cultures (first experiment). We suggest that the differences in the concentration of some compounds between DOM sources, the co-metabolism on carbon compound decomposition, and the higher diversity of molecules possibly support a greater bacterial diversity which might explain the higher bacterial growth observed. Finally, our results indicate that the mixture of fresh labile and accumulated refractory DOM that naturally occurs in aquatic ecosystems could accelerate the bacterial growth and bacterial DOM removal. PMID:18985269

  8. Coupled effects of chemotaxis and growth on traveling bacterial waves

    NASA Astrophysics Data System (ADS)

    Yan, Zhifeng; Bouwer, Edward J.; Hilpert, Markus

    2014-08-01

    Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves.

  9. Coupled effects of chemotaxis and growth on traveling bacterial waves

    NASA Astrophysics Data System (ADS)

    Yan, Z.; Hilpert, M.; Bouwer, E. J.

    2014-12-01

    Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves.

  10. Twelve Frequently Asked Questions about Growth Curve Modeling

    ERIC Educational Resources Information Center

    Curran, Patrick J.; Obeidat, Khawla; Losardo, Diane

    2010-01-01

    Longitudinal data analysis has long played a significant role in empirical research within the developmental sciences. The past decade has given rise to a host of new and exciting analytic methods for studying between-person differences in within-person change. These methods are broadly organized under the term "growth curve models." The…

  11. Predicting Change in Postpartum Depression: An Individual Growth Curve Approach.

    ERIC Educational Resources Information Center

    Buchanan, Trey

    Recently, methodologists interested in examining problems associated with measuring change have suggested that developmental researchers should focus upon assessing change at both intra-individual and inter-individual levels. This study used an application of individual growth curve analysis to the problem of maternal postpartum depression.…

  12. The Multigroup Multilevel Categorical Latent Growth Curve Models

    ERIC Educational Resources Information Center

    Hung, Lai-Fa

    2010-01-01

    Longitudinal data describe developmental patterns and enable predictions of individual changes beyond sampled time points. Major methodological issues in longitudinal data include modeling random effects, subject effects, growth curve parameters, and autoregressive residuals. This study embedded the longitudinal model within a multigroup…

  13. Mediation Analysis in a Latent Growth Curve Modeling Framework

    ERIC Educational Resources Information Center

    von Soest, Tilmann; Hagtvet, Knut A.

    2011-01-01

    This article presents several longitudinal mediation models in the framework of latent growth curve modeling and provides a detailed account of how such models can be constructed. Logical and statistical challenges that might arise when such analyses are conducted are also discussed. Specifically, we discuss how the initial status (intercept) and…

  14. Developmental Trajectories of Adolescent Popularity: A Growth Curve Modelling Analysis

    ERIC Educational Resources Information Center

    Cillessen, Antonius H. N.; Borch, Casey

    2006-01-01

    Growth curve modelling was used to examine developmental trajectories of sociometric and perceived popularity across eight years in adolescence, and the effects of gender, overt aggression, and relational aggression on these trajectories. Participants were 303 initially popular students (167 girls, 136 boys) for whom sociometric data were…

  15. Sensitivity of Fit Indices to Misspecification in Growth Curve Models

    ERIC Educational Resources Information Center

    Wu, Wei; West, Stephen G.

    2010-01-01

    This study investigated the sensitivity of fit indices to model misspecification in within-individual covariance structure, between-individual covariance structure, and marginal mean structure in growth curve models. Five commonly used fit indices were examined, including the likelihood ratio test statistic, root mean square error of…

  16. Latent Growth Curves within Developmental Structural Equation Models.

    ERIC Educational Resources Information Center

    McArdle, J. J.; Epstein, David

    1987-01-01

    Uses structural equation modeling to combine traditional ideas from repeated-measures ANOVA with some traditional ideas from longitudinal factor analysis. The model describes a latent growth curve model that permits the estimation of parameters representing individual and group dynamics. (Author/RH)

  17. Diagnostics of Robust Growth Curve Modeling Using Student's "t" Distribution

    ERIC Educational Resources Information Center

    Tong, Xin; Zhang, Zhiyong

    2012-01-01

    Growth curve models with different types of distributions of random effects and of intraindividual measurement errors for robust analysis are compared. After demonstrating the influence of distribution specification on parameter estimation, 3 methods for diagnosing the distributions for both random effects and intraindividual measurement errors…

  18. Analysis of growth curves of fowl. III. Geese.

    PubMed

    Knízetová, H; Hyánek, J; Veselský, A

    1994-07-01

    1. Growth curves of two lines (S,D) and their reciprocal hybrids (in total,. n = 344) were evaluated by the Richards function. Geese were weighed at 7 d intervals to the ninth week, and then at 92, 154, 192 and 217 d of age. Food and water were supplied ad libitum. 2. The accuracy of curve fit measured by the coefficient of determination (R2) for different genetic groups ranged from 0.9840 to 0.9918. The highest percentage deviations between observed and estimated live weights were recorded at hatching (on average 15.1%), while at the others points of curve they were significantly lower (from 0.6 to 6.8%). 3. The geese are characterised by an early maturing rate. The peak of the absolute growth rate (the inflection point of the curve) occurred at 18.7 to 23.5 d of age (t+). The degree of maturity at a slaughter age of 63 d (u63 = y63/A) ranged from 0.69 to 0.76. Fitting the inflection point at the beginning of the linear growth phase significantly affects the maturing rate (k) and the ratio between the inflection (y+) and the asymptotic (A) weights. The values of these correlated parameters were very low (y+/A = 0.233 to 0.294, k = 0.0281 to 0.0373 ln theta/d). 4. The live weights of geese from 28 d of age and the parameters of the Richards function were significantly higher (P < 0.05, P < 0.01) in th sire line (S) than in the dam line (D). A low negative heterosis was observed at all points of the growth curves (-0.01 to -9.7%). The results indicated the effect of sex-linked growth genes. 5. The phenotypic correlations between parameters of the Richards function within genetic groups are discussed. PMID:7953778

  19. Curves of growth for van der Waals broadened spectral lines

    NASA Technical Reports Server (NTRS)

    Park, C.

    1980-01-01

    Curves of growth are evaluated for a spectral line broadened by the van der Waals interactions during collisions. The growth of the equivalent widths of such lines is shown to be dependent on the product of the perturber density and the 6/10 power of the van der Waals potential coefficient. When the parameter is small, the widths grow as the 1/2 power of the optical depth as they do for the Voigt profile: but when the parameter is large, they grow as 2/3 power and, hence, faster than the Voigt profile. An approximate analytical expression for the computed growth characteristics is given.

  20. Bayesian Inference and Application of Robust Growth Curve Models Using Student's "t" Distribution

    ERIC Educational Resources Information Center

    Zhang, Zhiyong; Lai, Keke; Lu, Zhenqiu; Tong, Xin

    2013-01-01

    Despite the widespread popularity of growth curve analysis, few studies have investigated robust growth curve models. In this article, the "t" distribution is applied to model heavy-tailed data and contaminated normal data with outliers for growth curve analysis. The derived robust growth curve models are estimated through Bayesian…

  1. Analysis of growth curves of fowl. II. Ducks.

    PubMed

    Knízetová, H; Hyánek, J; Kníze, B; Procházková, H

    1991-12-01

    1. Growth curves of nine selected lines and one random-bred control population (in total, n = 1070) were evaluated by the Richards function. The ducks were weighed at 7-d intervals and, after the tenth week, every second week (up to 18 weeks). Food and water were supplied ad libitum. 2. The predicted curves closely fitted the weight data points (R2 = 0.9991-0.9997). 3. The ducks are characterized by early maturity rate. The peak of the absolute growth rate (the inflection point of the curve) occurred at 24.1-27.6 d of age (t+). A higher ratio of the inflection to the asymptotic weights (y+/A = 0.380-0.424) was found in comparison to those from the Gompertz-type function of growth (y+/A = 0.368). 4. In the selected lines the degree of maturity at a slaughter age of 7 weeks (u7 = y7/A) ranged from 0.784 to 0.835 for males and from 0.819 to 0.889 for females. 5. Ducks within the non-selected control line had a significantly lower maturing rate than the selected lines. 6. Sexual dimorphism was recorded for all growth parameters analysed. Females have faster maturation rate than males (higher values of y+/A, u7, k and a shorter auto-acceleration phase of growth). 7. High interline differences were found for body weight (A, y+, y7) and for absolute growth rate (v, v+) and smaller ones for parameters of the maturation rate (y+/A, u7, k and t+). 8. The intragroup phenotype correlation between growth parameters and the use of weight data only up to 7 weeks of age for the estimation of parameters of the Richards function are discussed. PMID:1786569

  2. A brief history of bacterial growth physiology

    PubMed Central

    Schaechter, Moselio

    2015-01-01

    Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid-19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism. Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the “Copenhagen School.” During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell. Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs. PMID:25954250

  3. Logistic growth curve of chickens: heritability of parameters.

    PubMed

    Grossman, M; Bohren, B B

    1985-01-01

    Parameters of the logistic function of growth, fit to individual body weight curves of two randombred control populations of each sex of chickens from hatching to 45 weeks of age, were evaluated. Growth-rate constant and age at the infection point in the curve were estimated by the method of sample quantiles from individual weekly body weights of 225 males and 281 females of the Rhode Island Red (RIR) line, and 164 males and 239 females of the White Leghorn (WL) line. Heritability estimates, based on correlation among full-sibs, of growth rate constant were 0.18 +/- 0.32 in males and 0.29 +/- 0.29 in females of the RIR line, and 0.41 +/- 0.40 in males and 0.46 +/- 0.32 in females of the WL line. Estimates of heritability of age at the inflection point were 0.36 +/- 0.44 in males and 0.42 +/- 0.32 in females of the RIR line, and 0.46 +/- 0.41 in males and 0.50 +/- 0.28 in females of the WL line. Observed variation for each trait probably does not provide evidence for heritable differences. No genetic correlations were evident among growth-rate constant, age at the point of inflection, and initial or maximum weight. According to these results, it does not appear that selection for growth-rate constant or age at the point of inflection will change the shape of the growth curve of these populations genetically. Moreover, correlated genetic change in initial or maximum weight would not be expected. PMID:4086789

  4. Analysis of growth curves of fowl. I. Chickens.

    PubMed

    Knízetová, H; Hyánek, J; Kníze, B; Roubícek, J

    1991-12-01

    1. The Richards function was used to describe the growth curves (n = 989) of 9 broiler lines. Chickens were fed ad libitum and body weight was recorded every second week from hatching to 26 weeks of age. 2. The accuracy of curve fit measured by the coefficient of determination (R2) was better for males than for females (0.9986-0.9995 vs 0.9972-0.9988, respectively). 3. The estimation of the asymptotic final weight (A) for different lines enabled the degree of maturity (ut = yt/A) to be determined at any fixed point of the curve. At the age of 7 weeks this had a value of 0.318-0.369 for cockerels and 0.325-0.377 for pullets and represented the slaughter maturity of individual lines. The ratio of inflection/asymptotic weight (y+/A = 0.370-0.388) indicated that in some cases chicken growth can be described approximately by the Gompertz function (y+/A = 0.368). 4. It was found that the age at the inflection point of curves (t+ 48.2-55.7 d for cockerels and t+ = 47.8-52.8 d for pullets) roughly corresponds to the slaughter age of the chickens. 5. The interline differences in the parameters of maturation rate for weight (y+/A, k, t+, u7) are low in comparison with the differences in body weight (A, y+, y7) and absolute growth rate (v, v+). 6. The intragroup phenotypic correlation among growth parameters and the importance of the mathematical models are discussed. PMID:1786568

  5. Comparative Study of Bacterial Growth in Magnet Fields

    NASA Astrophysics Data System (ADS)

    Smith, Derek; Masood, Samina

    It has been shown that magnetic fields affect bacterial growth. A comparative study of growth rates for gram-positive and gram-negative bacteria with different types of magnetic fields is done. Special focus is placed upon growth within liquid media, and the effect of magnetic fields relative to the chosen growth medium is considered.

  6. Practical application of generic growth theory and the significance of the growth curve parameters.

    PubMed

    Pruitt, K M; DeMuth, R E; Turner, M E

    1979-03-01

    The generic growth curve is developed by plausibility arguments based on simple growth models. Parameters of the generic curve include the maximum size, maximum specific growth rate, and a dimensionless velocity constant which can be related to metabolic efficiency in the case of nutrient-limited growth. Parameter estimates are obtained from estimates of the size and time at the point of inflection, the size and time at any other arbitrarily selected point, and the maximum size. Parameter estimates thus obtained and used as initial estimates in nonlinear least squares analysis often give rapid convergence to a minimum error mean square. [For the growth of Escherichia coli K-12 in liquid medium, the generic curve could be simplified to a form containing only three parameters: the maximum specific growth rate, the maximum size, and the time required to reach maximum size. When the bacteria were inhibited by the addition of increasing amounts of the lactoperoxidase antimicrobial factor, there was no significant change in viable counts or maximum specific growth rate, but the time required to reach maximum growth increased linearly with increasing amounts of added antimicrobial factor.] Analysis of growth in terms of the generic growth curve can be a powerful technique for finding relationships which may not be apparent from qualitative consideration of the data. PMID:378773

  7. Multiscale study of bacterial growth: Experiments and model to understand the impact of gas exchange on global growth

    NASA Astrophysics Data System (ADS)

    Lalanne-Aulet, David; Piacentini, Adalberto; Guillot, Pierre; Marchal, Philippe; Moreau, Gilles; Colin, Annie

    2015-11-01

    Using a millifluidics and macroscale setup, we study quantitatively the impact of gas exchange on bacterial growth. In millifluidic environments, the permeability of the incubator materials allows an unlimited oxygen supply by diffusion. Moreover, the efficiency of diffusion at small scales makes the supply instantaneous in comparison with the cell division time. In hermetic closed vials, the amount of available oxygen is low. The growth curve has the same trend but is quantitatively different from the millifluidic situation. The analysis of all the data allows us to write a quantitative modeling enabling us to capture the entire growth process.

  8. A Bayesian analysis of the effect of selection for growth rate on growth curves in rabbits

    PubMed Central

    Blasco, Agustín; Piles, Miriam; Varona, Luis

    2003-01-01

    Gompertz growth curves were fitted to the data of 137 rabbits from control (C) and selected (S) lines. The animals came from a synthetic rabbit line selected for an increased growth rate. The embryos from generations 3 and 4 were frozen and thawed to be contemporary of rabbits born in generation 10. Group C was the offspring of generations 3 and 4, and group S was the contemporary offspring of generation 10. The animals were weighed individually twice a week during the first four weeks of life, and once a week thereafter, until 20 weeks of age. Subsequently, the males were weighed weekly until 40 weeks of age. The random samples of the posterior distributions of the growth curve parameters were drawn by using Markov Chain Monte Carlo (MCMC) methods. As a consequence of selection, the selected animals were heavier than the C animals throughout the entire growth curve. Adult body weight, estimated as a parameter of the Gompertz curve, was 7% higher in the selected line. The other parameters of the Gompertz curve were scarcely affected by selection. When selected and control growth curves are represented in a metabolic scale, all differences disappear. PMID:12605849

  9. Complementarity among plant growth promoting traits in rhizospheric bacterial communities promotes plant growth

    PubMed Central

    Singh, Mangal; Awasthi, Ashutosh; Soni, Sumit K.; Singh, Rakshapal; Verma, Rajesh K.; Kalra, Alok

    2015-01-01

    An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants. PMID:26503744

  10. Catecholamines and in vitro growth of pathogenic bacteria: enhancement of growth varies greatly among bacterial species

    NASA Technical Reports Server (NTRS)

    Belay, Tesfaye; Aviles, Hernan; Vance, Monique; Fountain, Kimberly; Sonnenfeld, Gerald

    2003-01-01

    The purpose of this study was to examine the effects of catecholamines on in vitro growth of a range of bacterial species, including anaerobes. Bacteria tested included: Porphyromonas gingivalis, Bacteriodes fragilis, Shigella boydii, Shigella sonnie, Enterobacter Sp, and Salmonella choleraesuis. The results of the current study indicated that supplementation of bacterial cultures in minimal medium with norepinephrine or epinephrine did not result in increased growth of bacteria. Positive controls involving treatment of Escherichia coli with catecholamines did result in increased growth of that bacterial species. The results of the present study extend previous observations that showed differential capability of catecholamines to enhance bacterial growth in vitro.

  11. Parent involvement and science achievement: A latent growth curve analysis

    NASA Astrophysics Data System (ADS)

    Johnson, Ursula Yvette

    This study examined science achievement growth across elementary and middle school and parent school involvement using the Early Childhood Longitudinal Study - Kindergarten Class of 1998--1999 (ECLS-K). The ECLS-K is a nationally representative kindergarten cohort of students from public and private schools who attended full-day or half-day kindergarten class in 1998--1999. The present study's sample (N = 8,070) was based on students that had a sampling weight available from the public-use data file. Students were assessed in science achievement at third, fifth, and eighth grades and parents of the students were surveyed at the same time points. Analyses using latent growth curve modeling with time invariant and varying covariates in an SEM framework revealed a positive relationship between science achievement and parent involvement at eighth grade. Furthermore, there were gender and racial/ethnic differences in parents' school involvement as a predictor of science achievement. Findings indicated that students with lower initial science achievement scores had a faster rate of growth across time. The achievement gap between low and high achievers in earth, space and life sciences lessened from elementary to middle school. Parents' involvement with school usually tapers off after elementary school, but due to parent school involvement being a significant predictor of eighth grade science achievement, later school involvement may need to be supported and better implemented in secondary schooling.

  12. Paenibacillus dendritiformis Bacterial Colony Growth Depends on Surfactant but Not on Bacterial Motion▿ †

    PubMed Central

    Be'er, Avraham; Smith, Rachel S.; Zhang, H. P.; Florin, E.-L.; Payne, Shelley M.; Swinney, Harry L.

    2009-01-01

    Most research on growing bacterial colonies on agar plates has concerned the effect of genetic or morphotype variation. Some studies have indicated that there is a correlation between microscopic bacterial motion and macroscopic colonial expansion, especially for swarming strains, but no measurements have been obtained for a single strain to relate the microscopic scale to the macroscopic scale. We examined here a single strain (Paenibacillus dendritiformis type T; tip splitting) to determine both the macroscopic growth of colonies and the microscopic bacterial motion within the colonies. Our multiscale measurements for a variety of growth conditions revealed that motion on the microscopic scale and colonial growth are largely independent. Instead, the growth of the colony is strongly affected by the availability of a surfactant that reduces surface tension. PMID:19617369

  13. Can we estimate bacterial growth rates from ribosomal RNA content?

    SciTech Connect

    Kemp, P.F.

    1995-12-31

    Several studies have demonstrated a strong relationship between the quantity of RNA in bacterial cells and their growth rate under laboratory conditions. It may be possible to use this relationship to provide information on the activity of natural bacterial communities, and in particular on growth rate. However, if this approach is to provide reliably interpretable information, the relationship between RNA content and growth rate must be well-understood. In particular, a requisite of such applications is that the relationship must be universal among bacteria, or alternately that the relationship can be determined and measured for specific bacterial taxa. The RNA-growth rate relationship has not been used to evaluate bacterial growth in field studies, although RNA content has been measured in single cells and in bulk extracts of field samples taken from coastal environments. These measurements have been treated as probable indicators of bacterial activity, but have not yet been interpreted as estimators of growth rate. The primary obstacle to such interpretations is a lack of information on biological and environmental factors that affect the RNA-growth rate relationship. In this paper, the available data on the RNA-growth rate relationship in bacteria will be reviewed, including hypotheses regarding the regulation of RNA synthesis and degradation as a function of growth rate and environmental factors; i.e. the basic mechanisms for maintaining RNA content in proportion to growth rate. An assessment of the published laboratory and field data, the current status of this research area, and some of the remaining questions will be presented.

  14. Effects of time, temperature, and preservative on bacterial growth in enteral nutrient solutions.

    PubMed

    Fagerman, K E; Paauw, J D; McCamish, M A; Dean, R E

    1984-06-01

    Bacterial contamination and the effects of time, temperature, and preservative on bacterial growth in enteral nutrient solutions were studied. Bacteria were counted after 24-hour incubation of five samples of frozen Travasorb STD (Travenol Laboratories) from the pharmacy and five samples freshly reconstituted in the dietary department. Growth in samples of Travasorb STD prepared in the pharmacy was studied after (1) fresh mixing, 24-hour refrigeration, and 12 hours at room temperature, (2) freezing, thawing, and 12 hours at room temperature, and (3) freezing, thawing, 24-hour refrigeration, and 12 hours at room temperature. Duplicate samples of five products [Ensure (Ross Laboratories), Precision LR (Doyle Pharmaceuticals), Travasorb STD, Vital (Ross Laboratories), and Vivonex STD ( Norwich -Eaton)] were inoculated with Enterobacter cloacae, and growth curves for 24 hours were plotted. This challenge study was repeated using Travasorb STD as a control and Travasorb STD with potassium sorbate added. Bacterial contamination following reconstitution was not significantly different between pharmacy and dietary department samples. Growth after 12 hours at room temperature was not significantly different for the three sets of storage conditions. Logarithmic growth occurred only at room temperature. All products supported growth of E. cloacae, but growth was significantly lower in Vivonex STD (which contains potassium sorbate) and Precision LR. Growth was reduced by 70% versus control at 12 hours in Travasorb STD containing 0.036% potassium sorbate and by 90% with 0.2% potassium sorbate. Microbial growth in enteral nutrient solutions was dependent on the initial inoculum and the storage time at room temperature. Addition of potassium sorbate to these solutions may greatly reduce bacterial growth. PMID:6430069

  15. Economic growth and energy regulation in the environmental Kuznets curve.

    PubMed

    Lorente, Daniel Balsalobre; Álvarez-Herranz, Agustín

    2016-08-01

    This study establishes the existence of a pattern of behavior, between economic growth and environmental degradation, consistent with the environmental Kuznets curve (EKC) hypothesis for 17 Organization for Economic Cooperation and Development (OECD) countries between 1990 and 2012. Based on this EKC pattern, it shows that energy regulation measures help reduce per capita greenhouse gas (GHG) emissions. To validate this hypothesis, we also add the explanatory variables: renewable energy promotion, energy innovation processes, and the suppression effect of income level on the contribution of renewable energy sources to total energy consumption. It aims to be a tool for decision-making regarding energy policy. This paper provides a two-stage econometric analysis of instrumental variables with the aim of correcting the existence of endogeneity in the variable GDP per capita, verifying that the instrumental variables used in this research are appropriate for our aim. To this end, it first makes a methodological contribution before incorporating additional variables associated with environmental air pollution into the EKC hypothesis and showing how they positively affect the explanation of the correction in the GHG emission levels. This study concludes that air pollution will not disappear on its own as economic growth increases. Therefore, it is necessary to promote energy regulation measures to reduce environmental pollution. PMID:27164892

  16. Biological Consequences and Advantages of Asymmetric Bacterial Growth

    PubMed Central

    Kysela, David T.; Brown, Pamela J.B.; Huang, Kerwyn Casey; Brun, Yves V.

    2014-01-01

    Asymmetries in cell growth and division occur in eukaryotes and prokaryotes alike. Even seemingly simple and morphologically symmetric cell division processes belie inherent underlying asymmetries in the composition of the resulting daughter cells. We consider the types of asymmetry that arise in various bacterial cell growth and division processes, which include both conditionally activated mechanisms and constitutive, hardwired aspects of bacterial life histories. Although asymmetry disposes some cells to the deleterious effects of aging, it may also benefit populations by efficiently purging accumulated damage and rejuvenating newborn cells. Asymmetries may also generate phenotypic variation required for successful exploitation of variable environments, even when extrinsic changes outpace the capacity of cells to sense and respond to challenges. We propose specific experimental approaches to further develop our understanding of the prevalence and the ultimate importance of asymmetric bacterial growth. PMID:23808335

  17. Integrated kinetic and probabilistic modeling of the growth potential of bacterial populations.

    PubMed

    George, S M; Métris, A; Baranyi, J

    2015-05-01

    When bacteria are exposed to osmotic stress, some cells recover and grow, while others die or are unculturable. This leads to a viable count growth curve where the cell number decreases before the onset of the exponential growth phase. From such curves, it is impossible to estimate what proportion of the initial cells generates the growth because it leads to an ill-conditioned numerical problem. Here, we applied a combination of experimental and statistical methods, based on optical density measurements, to infer both the probability of growth and the maximum specific growth rate of the culture. We quantified the growth potential of a bacterial population as a quantity composed from the probability of growth and the "suitability" of the growing subpopulation to the new environment. We found that, for all three laboratory media studied, the probability of growth decreased while the "work to be done" by the growing subpopulation (defined as the negative logarithm of their suitability parameter) increased with NaCl concentration. The results suggest that the effect of medium on the probability of growth could be described by a simple shift parameter, a differential NaCl concentration that can be accounted for by the change in the medium composition. Finally, we highlighted the need for further understanding of the effect of the osmoprotectant glycine betaine on metabolism. PMID:25747002

  18. Quantification of antibiotic drug potency by a two-compartment radioassay of bacterial growth

    SciTech Connect

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

    1990-06-01

    The two-compartment radioassay for microbial kinetics based on continuous measurement of the {sup 14}CO{sub 2} released by bacterial metabolism of 14C-labeled substrate offers a valuable approach to testing the potency of antimicrobial drugs. By using a previously validated radioassay with gram-positive and gram-negative bacteria, a group of protein synthesis inhibitors was evaluated for their effect on microbial growth kinetics. All tested drugs induced changes in both the slopes and intercepts of the growth curves. An exponential growth model was applied to quantify the drug effect on the processes of bacterial {sup 14}CO{sub 2} liberation and cell generation. The response was measured in terms of a generation rate constant. A linear dependence of the generation rate constant on the dose of spectinomycin was observed with Escherichia coli. Sigmoidal-shaped curves were found in the assays of chloramphenicol and tetracycline. The implications of dose-response curves are discussed on the basis of the receptor site concept for drug action. The assay sensitivities for chloramphenicol and tetracycline were similar to those obtained by the cell counting method, but the sensitivity of the radioassay was at least 10 times greater for spectinomycin.

  19. The Biasing Effects of Unmodeled ARMA Time Series Processes on Latent Growth Curve Model Estimates

    ERIC Educational Resources Information Center

    Sivo, Stephen; Fan, Xitao; Witta, Lea

    2005-01-01

    The purpose of this study was to evaluate the robustness of estimated growth curve models when there is stationary autocorrelation among manifest variable errors. The results suggest that when, in practice, growth curve models are fitted to longitudinal data, alternative rival hypotheses to consider would include growth models that also specify…

  20. Tracking bacterial growth in liquid media and a new bacterial life model.

    PubMed

    Liu, S

    1999-12-01

    By increasing viscosity of liquid media above 8.4 centipoise (cp) i.e. 0.084 g * cm(-1) * s(-1), individual growth and family formation of Escherichia coli was continuously observed in real-time for up to 6 h. The observations showed primarily unidirectional growth and reproduction of E. coli and suggested more than one reproduction in the observed portion of E. coli life span. A new bacterial life model is proposed: each bacterium has a stable cell polarity that ultimately transforms into two bacteria of different generations; the life cycle of a bacterium can contain more than one reproduction cycle; and the age of a bacterium should be defined by its experienced chronological time. This new bacterial life model differs from the dominant concepts of bacterial life but complies with all basic life principles based on direct observation of macroorganisms. PMID:18726488

  1. Impact of medications on bacterial growth in syringes.

    PubMed

    Kerenyi, M; Borza, Z; Csontos, C; Ittzes, B; Batai, I

    2011-11-01

    Syringes used to administer intravenous medications in an intensive care unit were cultured, and the isolates were compared with those from positive blood cultures from the same patients. The overall contamination rate was 16%, and syringes used for drugs such as insulin, which support bacterial growth, had higher contamination rates. All syringes should be changed routinely after 6h. PMID:21864939

  2. Kinetics of bacterial growth on chlorinated aliphatic compounds

    SciTech Connect

    Wijngaard, A.J. van den; Wind, R.E.; Janssen, D.B. )

    1993-07-01

    Halogenated aliphatic compounds are frequent constituents of industrial waste gases. Because of the environmental and biological toxic effects of these compounds, there is a growing interest in technologies for their removal. Biological waste gas purification is an option if specialized bacterial strains that use halogenated aliphatics as sole carbon and energy sources can be used. Elimination efficiency of the compounds depends not only on the process technology but on the degradation properties of the bacterial strains. Important aspects of bacterial growth are the Monod half-saturation constant and the maximum growth rate. In this study the kinetic properties of the organisms (Ancylobacter aquaticus AD20 and AD25, Xanthobacter autotrophicus GJ10, Pseudomonas sp. strain AD1) weree measured during growth in continuous cultures and wer compared with the kinetic properties of the first catabolic enzyme involved in the degradation of the growth substrate. The results indicate that the growth of the strains examined followed Monod kinetics. Stains AD20 and GJ10 showed growth rates on DCE somewhat higher than predicted from the amount of haloalkane dehalogenase present in the cells, while strain AD25 was much lower. 33 refs., 3 figs., 4 tabs.

  3. Evolution of bacterial and fungal growth media

    PubMed Central

    Basu, Srijoni; Bose, Chandra; Ojha, Nupur; Das, Nabajit; Das, Jagaree; Pal, Mrinmoy; Khurana, Sukant

    2015-01-01

    Microbial media has undergone several changes since its inception but some key challenges remain. In recent years, there has been exploration of several alternative nutrient sources, both to cater to the specificity in requirement of growth of “fussy microorganisms” and also to reduce costs for large-scale fermentation that is required for biotechnology. Our mini-review explores these developments and also points at lacunas in the present areas of exploration, such as a lack of concerted effort in pH and osmolarity regulation. We hope that our commentary provides direction for future research in microbial media. PMID:26124557

  4. Relationship between model bacterial peptidoglycan network structures and AFM force-distance curves

    NASA Astrophysics Data System (ADS)

    Brown, Aidan; Wickham, Robert; Touhami, Ahmed; Dutcher, John

    2010-03-01

    Recent atomic force microscopy (AFM) measurements have involved pulling on Gram-negative bacterial sacculi with the AFM tip as a means of distinguishing between different proposed structures of the peptidoglycan network. The goal of the present study is to provide the theoretical connection between a given network structure and its response to the pulling force. We model the glycan strands as hinged rods, and the peptide cross-links as wormlike chains. Using Monte Carlo simulation to equilibrate the three-dimensional network, subject to a fixed AFM tip-to-substrate distance, we can compute the force exerted by the network on the AFM tip. The effects of adhesion of the sacculi to the substrate and enzymatic action on the network are included. We have modeled both the layered and the scaffold model for the peptidoglycan network structure. We have compared our theoretical force-distance curves for each network structure with experimental curves to determine which structure provides the best agreement with experiment.

  5. Cooperative Bacterial Growth Dynamics Predict the Evolution of Antibiotic Resistance

    NASA Astrophysics Data System (ADS)

    Artemova, Tatiana; Gerardin, Ylaine; Hsin-Jung Li, Sophia; Gore, Jeff

    2011-03-01

    Since the discovery of penicillin, antibiotics have been our primary weapon against bacterial infections. Unfortunately, bacteria can gain resistance to penicillin by acquiring the gene that encodes beta-lactamase, which inactivates the antibiotic. However, mutations in this gene are necessary to degrade the modern antibiotic cefotaxime. Understanding the conditions that favor the spread of these mutations is a challenge. Here we show that bacterial growth in beta-lactam antibiotics is cooperative and that the nature of this growth determines the conditions in which resistance evolves. Quantitative analysis of the growth dynamics predicts a peak in selection at very low antibiotic concentrations; competition between strains confirms this prediction. We also find significant selection at higher antibiotic concentrations, close to the minimum inhibitory concentrations of the strains. Our results argue that an understanding of the evolutionary forces that lead to antibiotic resistance requires a quantitative understanding of the evolution of cooperation in bacteria.

  6. Crack growth measured on flat and curved surfaces at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Orange, T. W.; Sullivan, T. L.

    1967-01-01

    Multiple element continuity gage measures plane stress crack growth plus surface crack growth under plane strain conditions. The gage measures flat and curved surfaces and operates at cryogenic temperatures.

  7. Effect of DSS on Bacterial Growth in Gastrointestinal Tract.

    PubMed

    Hlinková, J; Svobodová, H; Brachtlová, T; Gardlík, R

    2016-01-01

    Inflammatory bowel disease is an idiopathic autoimmune disorder that is mainly divided into ulcerative colitis and Crohn's disease. Probiotics are known for their beneficial effect and used as a treatment option in different gastrointestinal problems. The aim of our study was to find suitable bacterial vectors for gene therapy of inflammatory bowel disease. Salmonella enterica serovar Typhimurium SL7207 and Escherichia coli Nissle 1917 were investigated as potential vectors. Our results show that the growth of Escherichia coli Nissle 1917 was inhibited in the majority of samples collected from dextran sodium sulphate-treated animals compared with control growth in phosphate-buffered saline. The growth of Salmonella enterica serovar Typhimurium SL7207 in all investigated samples was enhanced or unaffected in comparison with phosphate-buffered saline; however, it did not reach the growth rates of Escherichia coli Nissle 1917. Dextran sodium sulphate treatment had a stimulating effect on the growth of both strains in homogenates of distant small intestine and proximal colon samples. The gastrointestinal tract contents and tissue homogenates did not inhibit growth of Salmonella enterica serovar Typhimurium SL7207 in comparison with the negative control, and provided more suitable environment for growth compared to Escherichia coli Nissle 1917. We therefore conclude that Salmonella enterica serovar Typhimurium SL7207 is a more suitable candidate for a potential bacterial vector, even though it has no known probiotic properties. PMID:27085009

  8. Using Design-Based Latent Growth Curve Modeling with Cluster-Level Predictor to Address Dependency

    ERIC Educational Resources Information Center

    Wu, Jiun-Yu; Kwok, Oi-Man; Willson, Victor L.

    2014-01-01

    The authors compared the effects of using the true Multilevel Latent Growth Curve Model (MLGCM) with single-level regular and design-based Latent Growth Curve Models (LGCM) with or without the higher-level predictor on various criterion variables for multilevel longitudinal data. They found that random effect estimates were biased when the…

  9. Modeling Pacing Behavior and Test Speededness Using Latent Growth Curve Models

    ERIC Educational Resources Information Center

    Kahraman, Nilufer; Cuddy, Monica M.; Clauser, Brian E.

    2013-01-01

    This research explores the usefulness of latent growth curve modeling in the study of pacing behavior and test speededness. Examinee response times from a high-stakes, computerized examination, collected before and after the examination was subjected to a timing change, were analyzed using a series of latent growth curve models to detect…

  10. Growth Curve Models for Zero-Inflated Count Data: An Application to Smoking Behavior

    ERIC Educational Resources Information Center

    Liu, Hui; Powers, Daniel A.

    2007-01-01

    This article applies growth curve models to longitudinal count data characterized by an excess of zero counts. We discuss a zero-inflated Poisson regression model for longitudinal data in which the impact of covariates on the initial counts and the rate of change in counts over time is the focus of inference. Basic growth curve models using a…

  11. Evaluating the Power of Latent Growth Curve Models to Detect Individual Differences in Change

    ERIC Educational Resources Information Center

    Hertzog, Christopher; von Oertzen, Timo; Ghisletta, Paolo; Lindenberger, Ulman

    2008-01-01

    We evaluated the statistical power of single-indicator latent growth curve models to detect individual differences in change (variances of latent slopes) as a function of sample size, number of longitudinal measurement occasions, and growth curve reliability. We recommend the 2 degree-of-freedom generalized test assessing loss of fit when both…

  12. The Role of Coding Time in Estimating and Interpreting Growth Curve Models.

    ERIC Educational Resources Information Center

    Biesanz, Jeremy C.; Deeb-Sossa, Natalia; Papadakis, Alison A.; Bollen, Kenneth A.; Curran, Patrick J.

    2004-01-01

    The coding of time in growth curve models has important implications for the interpretation of the resulting model that are sometimes not transparent. The authors develop a general framework that includes predictors of growth curve components to illustrate how parameter estimates and their standard errors are exactly determined as a function of…

  13. ULTRASOUND INCREASES THE RATE OF BACTERIAL CELL GROWTH

    PubMed Central

    Pitt, William G.; Ross, S. Aaron

    2006-01-01

    Ultrasound was employed to increase the growth rate of bacterial cells attached to surfaces. Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli cells adhered to and grew on a polyethylene surface in the presence of ultrasound. It was found that low frequency ultrasound (70 kHz) of low acoustic intensity (<2 W/cm2) increased the growth rate of the cells compared to growth without ultrasound. However, at high intensity levels, cells were partially removed from the surface. Ultrasound also enhanced planktonic growth of S. epidermidis and other planktonic bacteria. It is hypothesized that ultrasound increases the rate of transport of oxygen and nutrients to the cells and increases the rate of transport of waste products away from the cells, thus enhancing their growth. PMID:12790676

  14. Individual based simulations of bacterial growth on agar plates

    NASA Astrophysics Data System (ADS)

    Ginovart, M.; López, D.; Valls, J.; Silbert, M.

    2002-03-01

    The individual based simulator, INDividual DIScrete SIMulations (INDISIM) has been used to study the behaviour of the growth of bacterial colonies on a finite dish. The simulations reproduce the qualitative trends of pattern formation that appear during the growth of Bacillus subtilis on an agar plate under different initial conditions of nutrient peptone concentration, the amount of agar on the plate, and the temperature. The simulations are carried out by imposing closed boundary conditions on a square lattice divided into square spatial cells. The simulator studies the temporal evolution of the bacterial population possible by setting rules of behaviour for each bacterium, such as its uptake, metabolism and reproduction, as well as rules for the medium in which the bacterial cells grow, such as concentration of nutrient particles and their diffusion. The determining factors that characterize the structure of the bacterial colony patterns in the presents simulations, are the initial concentrations of nutrient particles, that mimic the amount of peptone in the experiments, and the set of values for the microscopic diffusion parameter related, in the experiments, to the amount of the agar medium.

  15. Effect of surgical hand scrub time on subsequent bacterial growth.

    PubMed

    Wheelock, S M; Lookinland, S

    1997-06-01

    In this experimental study, the researchers evaluated the effect of surgical hand scrub time on subsequent bacterial growth and assessed the effectiveness of the glove juice technique in a clinical setting. In a randomized crossover design, 25 perioperative staff members scrubbed for two or three minutes in the first trial and vice versa in the second trial, after which the wore sterile surgical gloves for one hour under clinical conditions. The researchers then sampled the subjects' nondominant hands for bacterial growth, cultured aliquots from the sampling solution, and counted microorganisms. Scrubbing for three minutes produced lower mean log bacterial counts than scrubbing for two minutes. Although the mean bacterial count differed significantly (P = .02) between the two-minute and three-minute surgical hand scrub times, it fell below 0.5 log, which is the threshold for practical and clinical significance. This finding suggests that a two-minute surgical hand scrub is clinically as effective as a three-minute surgical had scrub. The glove juice technique demonstrated sensitivity and reliability in enumerating bacteria on the hands of perioperative staff members in a clinical setting. PMID:9187454

  16. Microcoupon Assay Of Adhesion And Growth Of Bacterial Films

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Koenig, David W.

    1994-01-01

    Microbiological assay technique facilitates determination of some characteristics of sessile bacteria like those that attach to and coat interior walls of water-purification systems. Biofilms cause sickness and interfere with purification process. Technique enables direct measurement of rate of attachment of bacterial cells, their metabolism, and effects of chemicals on them. Used to quantify effects of both bactericides and growth-stimulating agents and in place of older standard plate-count and tube-dilution techniques.

  17. A Multilevel Latent Growth Curve Approach to Predicting Student Proficiency

    ERIC Educational Resources Information Center

    Choi, Kilchan; Goldschmidt, Pete

    2012-01-01

    Value-added models and growth-based accountability aim to evaluate school's performance based on student growth in learning. The current focus is on linking the results from value-added models to the ones from growth-based accountability systems including Adequate Yearly Progress decisions mandated by No Child Left Behind. We present a new…

  18. Leuconostoc mesenteroides growth kinetics with application to bacterial profile modification

    SciTech Connect

    Lappan, R.E.; Fogler, H.S. . Dept. of Chemical Engineering)

    1994-04-15

    Bacterial profile modification (BPM) is being developed as an oil recovery technique that uses bacteria to selectively plug oil depleted zones within a reservoir to divert displacing fluids into oil-rich zones. Leuconostoc mesenteroides, which produces dextran when supplied with sucrose, is a bacterium that is technically feasible for use in profile modification. However, the technique requires controlled bacterial growth to produce selective plugging. A kinetic model for the production of cells and polysaccharides has been developed for L. mesenteroides bacteria. This model, based on data from batch growth experiments, predicts saccharide utilization, cell generation, and dextran production. The underlying mechanism is the extracellular breakdown of sucrose into glucose and fructose and the subsequent production of polysaccharide. The monosaccharides are then available for growth. Accompanying sucrose consumption is the utilization of yeast extract. The cell requires a complex media that is provided by yeast extract as a source of vitamins and amino acids. Varying the concentration ratio of yeast extract to sucrose in the growth media provides a means of controlling the amount of polymer produced per cell. Consequently, in situ bacteria growth can be controlled by the manipulation of nutrient media composition, thereby providing the ability to create an overall strategy for the use of L. mesenteroides bacteria for profile modification.

  19. Effects of grain growth on the interstellar polarization curve

    NASA Astrophysics Data System (ADS)

    Voshchinnikov, Nikolai V.; Hirashita, Hiroyuki

    2014-11-01

    We apply the time evolution of grain size distributions through accretion and coagulation found in our previous work to the modelling of the wavelength dependence of interstellar linear polarization. We focus in particular on the parameters of the Serkowski curve K and λmax , characterizing the width and maximum wavelength of this curve, respectively. We use aligned silicate and non-aligned carbonaceous spheroidal particles with different aspect ratios a/b. The imperfect alignment of grains with sizes larger than a cut-off size rV, cut is considered. We find that the evolutionary effects on the polarization curve are negligible in the original model with commonly used material parameters (hydrogen number density nH = 103 cm-3, gas temperature Tgas = 10 K and sticking probability for accretion Sacc = 0.3). Therefore, we apply the tuned model, where the coagulation threshold of silicate is removed. In this model, λmax displaces to longer wavelengths and the polarization curve becomes wider (K reduces) on time-scales ˜(30-50)(nH/103cm-3)-1 Myr. The tuned models at T ≲ 30 (n_H/10^3 cm^{-3})^{-1} Myr and different values of the parameters rV, cut can also explain the observed trend between K and λmax . It is significant that the evolutionary effect appears in the perpendicular direction to the effect of rV, cut on the K - λmax diagram. Very narrow polarization curves can be reproduced if we change the type of particles (prolate/oblate) and/or vary a/b.

  20. Mycobacterium massiliense Induces Macrophage Extracellular Traps with Facilitating Bacterial Growth

    PubMed Central

    Yoon, Yina; Na, Yirang; Kim, Bum-Joon; Seok, Seung Hyeok

    2016-01-01

    Human neutrophils have been known to release neutrophil extracellular traps (NETs), antimicrobial DNA structures capable of capturing and killing microbes. Recently, a similar phenomenon has been reported in macrophages infected with various pathogens. However, a role for macrophages extracellular traps (METs) in host defense responses against Mycobacterium massiliense (M. mass) has yet to be described. In this study, we show that M. mass, a rapid growing mycobacterium (RGM), also induces the release of METs from PMA-differentiated THP-1 cells. Intriguingly, this process is not dependent on NADPH oxidase activity, which regulates NET formation. Instead, M. mass-induced MET formation partially depends on calcium influx and requires phagocytosis of high bacterial load. The METs consist of a DNA backbone embedded with microbicidal proteins such as histone, MPO and elastase. Released METs entrap M. mass and prevent their dissemination, but do not have bactericidal activity. Instead, they result in enhanced bacterial growth. In this regard, METs were considered to provide interaction of M. mass with cells and an environment for bacterial aggregation, which may facilitate mycobacterial survival and growth. In conclusion, our results demonstrate METs as an innate defense response against M. mass infection, and suggest that extracellular traps play a multifaceted role in the interplay between host and bacteria. PMID:27191593

  1. Bacterial growth laws reflect the evolutionary importance of energy efficiency

    PubMed Central

    Maitra, Arijit; Dill, Ken A.

    2015-01-01

    We are interested in the balance of energy and protein synthesis in bacterial growth. How has evolution optimized this balance? We describe an analytical model that leverages extensive literature data on growth laws to infer the underlying fitness landscape and to draw inferences about what evolution has optimized in Escherichia coli. Is E. coli optimized for growth speed, energy efficiency, or some other property? Experimental data show that at its replication speed limit, E. coli produces about four mass equivalents of nonribosomal proteins for every mass equivalent of ribosomes. This ratio can be explained if the cell’s fitness function is the the energy efficiency of cells under fast growth conditions, indicating a tradeoff between the high energy costs of ribosomes under fast growth and the high energy costs of turning over nonribosomal proteins under slow growth. This model gives insight into some of the complex nonlinear relationships between energy utilization and ribosomal and nonribosomal production as a function of cell growth conditions. PMID:25548180

  2. On growth and flow: bacterial biofilms in porous media

    NASA Astrophysics Data System (ADS)

    Durham, William; Leombruni, Alberto; Tranzer, Olivier; Stocker, Roman

    2011-11-01

    Bacterial biofilms often occur in porous media, where they play pivotal roles in medicine, industry and the environment. Though flow is ubiquitous in porous media, its effects on biofilm growth have been largely ignored. Using patterned microfluidic devices that simulate unconsolidated soil, we find that the structure of Escherichia coli biofilms undergoes a self-organization mediated by the interaction of growth and flow. Intriguingly, we find that biofilm productivity peaks at intermediate flow rates, when the biofilm is irrigated by a minimum number of preferential flow channels. At larger and smaller flow rates, fluid flows more uniformly through the matrix, but productivity drops due to removal by shear and reduced nutrient transport, respectively. These dynamics are correctly predicted by a simple network model. The observed tradeoff between growth and flow may have important consequences on biofilm-mediated processes such as biochemical cycling, antibiotic resistance and water filtration.

  3. Growing Growth curves using PROC MIXED and PROC NLMIXED

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Being able to describe growth appropriately and succinctly is important in many contexts, including biology, epidemiology, and statistics. Various approaches are used varying from differential equations, deterministic modeling, and statistical approaches like regression. Often, with epidemiologic da...

  4. Bacterial growth, detachment and cell size control on polyethylene terephthalate surfaces

    PubMed Central

    Wang, Liyun; Fan, Daming; Chen, Wei; Terentjev, Eugene M.

    2015-01-01

    In medicine and food industry, bacterial colonisation on surfaces is a common cause of infections and severe illnesses. However, the detailed quantitative information about the dynamics and the mechanisms involved in bacterial proliferation on solid substrates is still lacking. In this study we investigated the adhesion and detachment, the individual growth and colonisation, and the cell size control of Escherichia coli (E. coli) MG1655 on polyethylene terephthalate (PET) surfaces. The results show that the bacterial growth curve on PET exhibits the distinct lag and log phases, but the generation time is more than twice longer than in bulk medium. Single cells in the lag phase are more likely to detach than clustered ones in the log phase; clustered bacteria in micro-colonies have stronger adhesive bonds with surfaces and their neighbours with the progressing colonisation. We show that the cell size is under the density-dependent pathway control: when the adherent cells are at low density, the culture medium is responsible for coordinating cell division and cell size; when the clustered cells are at high population density, we demonstrate that the effect of quorum sensing causes the cell size decrease as the cell density on surfaces increases. PMID:26464114

  5. A new growth curve model for biological growth: some inferential studies on the growth of Cirrhinus mrigala.

    PubMed

    Bhowmick, Amiya Ranjan; Bhattacharya, Sabyasachi

    2014-08-01

    Growth of living organisms is a fundamental biological process. It depicts the physiological development of the species related to the environment. Mathematical development of growth curve models has a long history since its birth. We propose a mathematical model to describe the evolution of relative growth rate as a function of time based on a real life experiment on a major Indian Carp Cirrhinus mrigala. We establish that the proposed model is able to describe the fish growth dynamics more accurately for our experimental data than some existing models e.g. logistic, Gompertz, exponential. Approximate expressions of the points of inflection and the time of achieving the maximum relative growth rate are derived. We study, in detail, the existence of a nonlinear least squares estimator of the model parameters and their consistency properties. Test-statistics is developed to study the equality of points of inflection and equality of the amount of time necessary to achieve the maximum relative growth rate for a species at two different locations. Using the theory of variance stabilizing transformations, we propose a new test statistic to test the effect of the decay parameter for the proposed growth law. The testing procedure is found to be more sensitive in comparison with the test based on nonlinear least squares estimates. Our proposed model provides a general framework to model growth in other disciplines as well. PMID:24933474

  6. A Rhizocarpon geographicum growth curve for the Cascade Range of Washington and northern Oregon, usa

    NASA Astrophysics Data System (ADS)

    O'Neal, Michael A.; Schoenenberger, Katherine R.

    2003-09-01

    Lichen thallus measurements from 22 surfaces of known age on Mount Baker, Mount Hood, and Mount Rainier are used to construct a regional Rhizocarpon geographicum growth curve for the Cascade Range of Washington and northern Oregon. Growth rates determined by measuring the largest thallus diameters on the same surfaces at Mount Rainier in 1976 and 2002 are used for comparison with lichenometric data from Mount Baker and Mount Hood. Similar lichen thallus diameter vs age relationships identified in the data from the three mountains suggest the presence of uniform growth rates over the 400-km range. A regional growth curve developed during our study shows three growth phases of successively slower growth: a rapid phase from 8 to 20 yr, a linear phase from 20 to 145 yr, and a slow phase of unknown duration beyond ca. 145 yr. Uncertainty in lichen growth rates beyond 145 yr limits projection of the curve beyond that age; however, the age range of the constrained growth curve covers an important period of recent climate variability. When applied in appropriate settings, our growth curve can be used to determine numeric ages to ±10 yr for surfaces between 20 and 145 years old in areas where other techniques are not applicable or do not provide unique or well-constrained ages.

  7. Slow Protein Fluctuations Explain the Emergence of Growth Phenotypes and Persistence in Clonal Bacterial Populations

    PubMed Central

    Rocco, Andrea; Kierzek, Andrzej M.; McFadden, Johnjoe

    2013-01-01

    One of the most challenging problems in microbiology is to understand how a small fraction of microbes that resists killing by antibiotics can emerge in a population of genetically identical cells, the phenomenon known as persistence or drug tolerance. Its characteristic signature is the biphasic kill curve, whereby microbes exposed to a bactericidal agent are initially killed very rapidly but then much more slowly. Here we relate this problem to the more general problem of understanding the emergence of distinct growth phenotypes in clonal populations. We address the problem mathematically by adopting the framework of the phenomenon of so-called weak ergodicity breaking, well known in dynamical physical systems, which we extend to the biological context. We show analytically and by direct stochastic simulations that distinct growth phenotypes can emerge as a consequence of slow-down of stochastic fluctuations in the expression of a gene controlling growth rate. In the regime of fast gene transcription, the system is ergodic, the growth rate distribution is unimodal, and accounts for one phenotype only. In contrast, at slow transcription and fast translation, weakly non-ergodic components emerge, the population distribution of growth rates becomes bimodal, and two distinct growth phenotypes are identified. When coupled to the well-established growth rate dependence of antibiotic killing, this model describes the observed fast and slow killing phases, and reproduces much of the phenomenology of bacterial persistence. The model has major implications for efforts to develop control strategies for persistent infections. PMID:23382887

  8. Bacterial Spring Constant in Log-Phase Growth

    NASA Astrophysics Data System (ADS)

    Jain, Deepti; Nanda, H.; Nath, R.; Chitnis, D. S.; Ganesan, V.

    2011-07-01

    Atomic Force Microscopy is a powerful tool in studying bacterial systems too. The turgor pressure studies on well known systems like E-coli and Staphylococcus revealed a fascinating fact that the numbers are in tens of atmosphere depending upon the microbial activity. Hence there is no way that one can destroy them by physical means. This is due to the robust nature of the cell wall. Understanding the cell wall structure requires an estimate of spring constant of the cell wall membrane and its variation upon activity. Here we present an experimental estimate of the spring constant of the cell wall (˜10-2 N/m) using force curve measurements on bacteria using an AFM tip. This has a bearing on measuring turgor pressure of bacterium.

  9. Parent Involvement and Science Achievement: A Latent Growth Curve Analysis

    ERIC Educational Resources Information Center

    Johnson, Ursula Yvette

    2011-01-01

    This study examined science achievement growth across elementary and middle school and parent school involvement using the Early Childhood Longitudinal Study-Kindergarten Class of 1998-1999 (ECLS-K). The ECLS-K is a nationally representative kindergarten cohort of students from public and private schools who attended full-day or half-day…

  10. Lubricating bacteria model for branching growth of bacterial colonies

    NASA Astrophysics Data System (ADS)

    Kozlovsky, Yonathan; Cohen, Inon; Golding, Ido; Ben-Jacob, Eshel

    1999-06-01

    Various bacterial strains (e.g., strains belonging to the genera Bacillus, Paenibacillus, Serratia, and Salmonella) exhibit colonial branching patterns during growth on poor semisolid substrates. These patterns reflect the bacterial cooperative self-organization. A central part of the cooperation is the collective formation of a lubricant on top of the agar which enables the bacteria to swim. Hence it provides the colony means to advance towards the food. One method of modeling the colonial development is via coupled reaction-diffusion equations which describe the time evolution of the bacterial density and the concentrations of the relevant chemical fields. This idea has been pursued by a number of groups. Here we present an additional model which specifically includes an evolution equation for the lubricant excreted by the bacteria. We show that when the diffusion of the fluid is governed by a nonlinear diffusion coefficient, branching patterns evolve. We study the effect of the rates of emission and decomposition of the lubricant fluid on the observed patterns. The results are compared with experimental observations. We also include fields of chemotactic agents and food chemotaxis and conclude that these features are needed in order to explain the observations.

  11. Understanding the Scalability of Bayesian Network Inference Using Clique Tree Growth Curves

    NASA Technical Reports Server (NTRS)

    Mengshoel, Ole J.

    2010-01-01

    One of the main approaches to performing computation in Bayesian networks (BNs) is clique tree clustering and propagation. The clique tree approach consists of propagation in a clique tree compiled from a Bayesian network, and while it was introduced in the 1980s, there is still a lack of understanding of how clique tree computation time depends on variations in BN size and structure. In this article, we improve this understanding by developing an approach to characterizing clique tree growth as a function of parameters that can be computed in polynomial time from BNs, specifically: (i) the ratio of the number of a BN s non-root nodes to the number of root nodes, and (ii) the expected number of moral edges in their moral graphs. Analytically, we partition the set of cliques in a clique tree into different sets, and introduce a growth curve for the total size of each set. For the special case of bipartite BNs, there are two sets and two growth curves, a mixed clique growth curve and a root clique growth curve. In experiments, where random bipartite BNs generated using the BPART algorithm are studied, we systematically increase the out-degree of the root nodes in bipartite Bayesian networks, by increasing the number of leaf nodes. Surprisingly, root clique growth is well-approximated by Gompertz growth curves, an S-shaped family of curves that has previously been used to describe growth processes in biology, medicine, and neuroscience. We believe that this research improves the understanding of the scaling behavior of clique tree clustering for a certain class of Bayesian networks; presents an aid for trade-off studies of clique tree clustering using growth curves; and ultimately provides a foundation for benchmarking and developing improved BN inference and machine learning algorithms.

  12. Effect of bacterial growth stage on resistance to chlorine disinfection.

    PubMed

    Cherchi, C; Gu, A Z

    2011-01-01

    The mechanisms and factors that affect microbial resistance to chlorine disinfection have not been fully elucidated. In this study, we investigated the impact of the cell growth stage on chlorine disinfection efficiency. Specifically, we evaluated the impact of the growth stage on chlorination resistance by comparing the inactivation efficiencies of two indicator bacterial strains (Escherichia coli K12 and Escherichia coli O157:H7) obtained from various growth phases, using Chick-Watson kinetic parameters. For both E. coli strains (K12 and O157:H7), the inactivation rate constants are the lowest at stationary phase (0.19 and 0.32) compared to those at initial lag (0.54 and 0.76) and exponential growth phase (0.63 and 0.69), respectively. These results suggested that the abundance of resistant subpopulations increases at stressed stationary conditions and E. coli cells obtained from the stationary growth phase exhibited more resistance and lower inactivation efficiency compared to those from the lag and exponential phases. This implies that microbes in wastewater treatment process with varying solids retention times (SRTs, which indicate growth rates) may show different extents of chlorine resistance. Comparison of the coefficient of dilution (n) values in both E. coli strains for the various growth phases suggest that cells seem to be more sensitive to disinfectant concentration at the stationary-lag phase than that at the exponential stage. Comparing the two E. coli strains, higher inactivation rates were observed for the pathogenic O157:H7 than for K12 at different stages of growth. The strain-to-strain variability in survivability to chlorine exposure has to be considered when selecting indicator microorganisms for water quality monitoring. PMID:22053451

  13. Oral iron acutely elevates bacterial growth in human serum

    PubMed Central

    Cross, James H.; Bradbury, Richard S.; Fulford, Anthony J.; Jallow, Amadou T.; Wegmüller, Rita; Prentice, Andrew M.; Cerami, Carla

    2015-01-01

    Iron deficiency is the most common nutrient deficiency worldwide and routine supplementation is standard policy for pregnant mothers and children in most low-income countries. However, iron lies at the center of host-pathogen competition for nutritional resources and recent trials of iron administration in African and Asian children have resulted in significant excesses of serious adverse events including hospitalizations and deaths. Increased rates of malaria, respiratory infections, severe diarrhea and febrile illnesses of unknown origin have all been reported, but the mechanisms are unclear. We here investigated the ex vivo growth characteristics of exemplar sentinel bacteria in adult sera collected before and 4 h after oral supplementation with 2 mg/kg iron as ferrous sulfate. Escherichia coli, Yersinia enterocolitica and Salmonella enterica serovar Typhimurium (all gram-negative bacteria) and Staphylococcus epidermidis (gram-positive) showed markedly elevated growth in serum collected after iron supplementation. Growth rates were very strongly correlated with transferrin saturation (p < 0.0001 in all cases). Growth of Staphylococcus aureus, which preferentially scavenges heme iron, was unaffected. These data suggest that even modest oral supplements with highly soluble (non-physiological) iron, as typically used in low-income settings, could promote bacteremia by accelerating early phase bacterial growth prior to the induction of immune defenses. PMID:26593732

  14. Lactic acid bacterial extract as a biogenic mineral growth modifier

    NASA Astrophysics Data System (ADS)

    Borah, Ballav M.; Singh, Atul K.; Ramesh, Aiyagari; Das, Gopal

    2009-04-01

    The formation of minerals and mechanisms by which bacteria could control their formation in natural habitats is now of current interest for material scientists to have an insight of the mechanism of in vivo mineralization, as well as to seek industrial and technological applications. Crystalline uniform structures of calcium and barium minerals formed micron-sized building blocks when synthesized in the presence of an organic matrix consisting of secreted protein extracts from three different lactic acid bacteria (LAB) viz.: Lactobacillus plantarum MTCC 1325, Lactobacillus acidophilus NRRL B4495 and Pediococcus acidilactici CFR K7. LABs are not known to form organic matrix in biological materialization processes. The influence of these bacterial extracts on the crystallization behavior was investigated in details to test the basic coordination behavior of the acidic protein. In this report, varied architecture of the mineral crystals obtained in presence of high molecular weight protein extracts of three different LAB strains has been discussed. The role of native form of high molecular weight bacterial protein extracts in the generation of nucleation centers for crystal growth was clearly established. A model for the formation of organic matrix-cation complex and the subsequent events leading to crystal growth is proposed.

  15. [Osmoregulation--an important parameter of bacterial growth].

    PubMed

    Sochocka, Marta; Boratyński, Janusz

    2011-01-01

    Environmental conditions such as temperature, pH, radiation and osmotic pressure are important factors limiting the growth and multiplication of bacteria. Regular structure and metabolism of bacterial cells are maintained through a stable arrangement of the water-electrolyte system, regulated by osmosis. The rapid changes caused by osmotic shock (dehydration, rehydration) might lead to modifications of the phospholipid structure of the cell membrane and even cell death. Advances disturbing the osmosis, which are a natural part of living cells, may appear for example in colloid systems. The biological identification of the osmotic pressure is connected with an increase or decrease in the environmental osmotic strength of microorganisms' habitat. Cells exposed to osmotic stress, such as an increase in osmotic pressure, initiate mechanisms of active coping with the adverse consequences of its effects. Osmoregulatory processes are designed to maintain cell turgor, hence ensuring proper conditions for bacterial growth. Osmoregulation, which consists of maintaining fluid and electrolyte balance of cells, raising concerns accumulation of specific compatible solutes (osmolytes). Osmolytes are small, soluble organic molecules with a positive influence on membrane stabilization and proteins, without disrupting cellular functions. Storage of compatible solutes takes place by synthesis or by downregulation from the medium by means of special transport systems, activated by mechanical stimuli. Knowledge of the impact of osmotic pressure on microbial cells and the regulation of its activity led to the appropriate use of bacteria in various branches of the biotechnology industry. PMID:22173436

  16. Growth curve analysis for plasma profiles using smoothing splines

    SciTech Connect

    Imre, K.

    1993-05-01

    We are developing a profile analysis code for the statistical estimation of the parametric dependencies of the temperature and density profiles in tokamaks. Our code uses advanced statistical techniques to determine the optimal fit, i.e. the fit which minimized the predictive error. For a forty TFTR Ohmic profile dataset, our preliminary results indicate that the profile shape depends almost exclusively on q[sub a][prime] but that the shape dependencies are not Gaussian. We are now comparing various shape models on the TFTR data. In the first six months, we have completed the core modules of the code, including a B-spline package for variable knot locations, a data-based method to determine the optimal smoothing parameters, self-consistent estimation of the bias errors, and adaptive fitting near the plasma edge. Visualization graphics already include three dimensional surface plots, and discharge by discharge plots of the predicted curves with error bars together with the actual measurements values, and plots of the basis functions with errors.

  17. Body Temperatures in Dinosaurs: What Can Growth Curves Tell Us?

    PubMed Central

    Griebeler, Eva Maria

    2013-01-01

    To estimate the body temperature (BT) of seven dinosaurs Gillooly, Alleen, and Charnov (2006) used an equation that predicts BT from the body mass and maximum growth rate (MGR) with the latter preserved in ontogenetic growth trajectories (BT-equation). The results of these authors evidence inertial homeothermy in Dinosauria and suggest that, due to overheating, the maximum body size in Dinosauria was ultimately limited by BT. In this paper, I revisit this hypothesis of Gillooly, Alleen, and Charnov (2006). I first studied whether BTs derived from the BT-equation of today’s crocodiles, birds and mammals are consistent with core temperatures of animals. Second, I applied the BT-equation to a larger number of dinosaurs than Gillooly, Alleen, and Charnov (2006) did. In particular, I estimated BT of Archaeopteryx (from two MGRs), ornithischians (two), theropods (three), prosauropods (three), and sauropods (nine). For extant species, the BT value estimated from the BT-equation was a poor estimate of an animal’s core temperature. For birds, BT was always strongly overestimated and for crocodiles underestimated; for mammals the accuracy of BT was moderate. I argue that taxon-specific differences in the scaling of MGR (intercept and exponent of the regression line, log-log-transformed) and in the parameterization of the Arrhenius model both used in the BT-equation as well as ecological and evolutionary adaptations of species cause these inaccuracies. Irrespective of the found inaccuracy of BTs estimated from the BT-equation and contrary to the results of Gillooly, Alleen, and Charnov (2006) I found no increase in BT with increasing body mass across all dinosaurs (Sauropodomorpha, Sauropoda) studied. This observation questions that, due to overheating, the maximum size in Dinosauria was ultimately limited by BT. However, the general high inaccuracy of dinosaurian BTs derived from the BT-equation makes a reliable test of whether body size in dinosaurs was ultimately

  18. Teaching the Microbial Growth Curve Concept Using Microalgal Cultures and Flow Cytometry

    ERIC Educational Resources Information Center

    Forget, Nathalie; Belzile, Claude; Rioux, Pierre; Nozais, Christian

    2010-01-01

    The microbial growth curve is widely studied within microbiology classes and bacteria are usually the microbial model used. Here, we describe a novel laboratory protocol involving flow cytometry to assess the growth dynamics of the unicellular microalgae "Isochrysis galbana." The algal model represents an appropriate alternative to bacteria…

  19. Development of Oral Reading Fluency in Children with Speech or Language Impairments: A Growth Curve Analysis

    ERIC Educational Resources Information Center

    Puranik, Cynthia S.; Petscher, Yaacov; Al Otaiba, Stephanie; Catts, Hugh W.; Lonigan, Christopher J.

    2008-01-01

    This longitudinal study used piece-wise growth curve analyses to examine growth patterns in oral reading fluency for 1,991 students with speech impairments (SI) or language impairments (LI) from first through third grade. The main finding of this study was that a diagnosis of SI or LI can have a detrimental and persistent effect on early reading…

  20. Parent Involvement and Science Achievement: A Cross-Classified Multilevel Latent Growth Curve Analysis

    ERIC Educational Resources Information Center

    Johnson, Ursula Y.; Hull, Darrell M.

    2014-01-01

    The authors examined science achievement growth at Grades 3, 5, and 8 and parent school involvement at the same time points using the Early Childhood Longitudinal Study-Kindergarten Class of 1998-1999. Data were analyzed using cross-classified multilevel latent growth curve modeling with time invariant and varying covariates. School-based…

  1. Exploring Gains in Reading and Mathematics Achievement among Regular and Exceptional Students Using Growth Curve Modeling

    ERIC Educational Resources Information Center

    Shin, Tacksoo; Davison, Mark L.; Long, Jeffrey D.; Chan, Chi-Keung; Heistad, David

    2013-01-01

    Using four-wave longitudinal reading and mathematics data (4th to 7th grades) from a large urban school district, growth curve modeling was used as a tool for examining three research questions: Are achievement gaps closing in reading and mathematics? What are the associations between prior-achievement and growth across the reading and mathematics…

  2. Engineered cerium oxide nanoparticles: Effects on bacterial growth and viability

    SciTech Connect

    Pelletier, Dale A; Suresh, Anil K; Holton, Gregory A; McKeown, Catherine K; Wang, Wei; Gu, Baohua; Mortensen, Ninell P; Allison, David P; Joy, David Charles; Allison, Martin R; Brown, Steven D; Phelps, Tommy Joe; Doktycz, Mitchel John

    2010-01-01

    Interest in engineered nanostructures has risen in recent years due to their use in energy conservation strategies and biomedicine. To ensure prudent development and use of nanomaterials, the fate and effects of such engineered structures on the environment should be understood. Interactions of nanomaterials with environmental microorganisms are inevitable, but the general consequences of such interactions remain unclear. Further, standardized methods for assessing such interactions are lacking. Therefore, we have initiated a multianalytical approach to understand the interactions of synthesized nanoparticles with bacterial systems. These efforts are focused initially on cerium oxide nanoparticles and model bacteria in order to evaluate characterization procedures and the possible fate of such materials in the environment. In this study the effects of cerium oxide nanoparticles on the growth and viability of Gram-negative Escherichia coli and Shewanella oneidensis, a metal-reducing bacteria, and Gram-positive Bacillus subtilis were examined relative to particle size, growth media, pH, and dosage. A hydrothermal based synthesis procedure was used to prepare cerium oxide nanoparticles of defined sizes in order to eliminate complications originating from the use of organic solvents and surfactants. Bactericidal effects were determined by minimum inhibitory concentration, colony forming units, disc diffusion tests and Live/Dead assays. In growth inhibition experiments involving E. coli and B. subtilis, a clear strain and size-dependent inhibition was observed. S. oneidensis appeared to be unaffected by the cerium oxide nanoparticles. Transmission electron microscopy along with microarray-based transcriptional profiling have been used to understand the response mechanism of the bacteria. The use of multiple analytical approaches adds confidence to toxicity assessments while the use of different bacterial systems highlights the potential wide-ranging effects of

  3. Effect of a metal alloy fuel catalyst on bacterial growth.

    PubMed

    Ghosh, Ruma; Koerting, Claudia; Suib, Steven L; Best, Michael H; Berlin, Alvin J

    2005-11-01

    Many microorganisms have been demonstrated to utilize petroleum fuel products to fulfill their nutritional requirement for carbon. As a result, the ability of these microbes to degrade fuel has both a deleterious affect as well as beneficial applications. This study focused on the undesired ability of bacteria to grow on fuel and the potential for some metal alloys to inhibit this biodegradation. The objective of this study was to review the pattern of growth of two reference strains of petroleum-degrading bacteria, Pseudomonas oleovorans and Rhodococcus rhodocrous, in a specific hydrocarbon environment in the presence of a commercially available alloy. The alloy formulated and supplied by Advanced Power Systems International Inc. (APSI) is sold for fuel reformulation and other purposes. The components of the alloy used in the study were antimony, tin, lead, and mercury formulated as pellets. Surface characterization also showed the presence of tin oxide and lead amalgam phases. Hydrocarbon used for the study was primarily 87-octane gasoline. The growth of the bacteria in the water and mineral-supplemented gasoline mixture over 6-8 weeks was monitored by the viable plate count method. While an initial increase in bacteria occurred in the first week, overall bacterial growth was found to be suppressed in the presence of the alloy. Results also indicate that the alloy surface characteristics that convey the catalytic activity may also contribute to the observed antibacterial activity. PMID:16262333

  4. Bacterial actin and tubulin homologs in cell growth and division.

    PubMed

    Busiek, Kimberly K; Margolin, William

    2015-03-16

    In contrast to the elaborate cytoskeletal machines harbored by eukaryotic cells, such as mitotic spindles, cytoskeletal structures detectable by typical negative stain electron microscopy are generally absent from bacterial cells. As a result, for decades it was thought that bacteria lacked cytoskeletal machines. Revolutions in genomics and fluorescence microscopy have confirmed the existence not only of smaller-scale cytoskeletal structures in bacteria, but also of widespread functional homologs of eukaryotic cytoskeletal proteins. The presence of actin, tubulin, and intermediate filament homologs in these relatively simple cells suggests that primitive cytoskeletons first arose in bacteria. In bacteria such as Escherichia coli, homologs of tubulin and actin directly interact with each other and are crucial for coordinating cell growth and division. The function and direct interactions between these proteins will be the focus of this review. PMID:25784047

  5. Effects of Low-Level Deuterium Enrichment on Bacterial Growth

    PubMed Central

    Xie, Xueshu; Zubarev, Roman A.

    2014-01-01

    Using very precise (±0.05%) measurements of the growth parameters for bacteria E. coli grown on minimal media, we aimed to determine the lowest deuterium concentration at which the adverse effects that are prominent at higher enrichments start to become noticeable. Such a threshold was found at 0.5% D, a surprisingly high value, while the ultralow deuterium concentrations (≤0.25% D) showed signs of the opposite trend. Bacterial adaptation for 400 generations in isotopically different environment confirmed preference for ultralow (≤0.25% D) enrichment. This effect appears to be similar to those described in sporadic but multiple earlier reports. Possible explanations include hormesis and isotopic resonance phenomena, with the latter explanation being favored. PMID:25033078

  6. Bacterial Growth Phase Influences Methylmercury Production by the Sulfate-Reducing Bacterium Desulfovibrio desulfuricans ND132

    SciTech Connect

    Biswas, Abir; Brooks, Scott C; Miller, Carrie L; Mosher, Jennifer J; Yin, Xiangping Lisa; Drake, Meghan M

    2011-01-01

    The effect of bacterial growth phase is an aspect of mercury (Hg) methylation that previous studies have not investigated in detail. Here we consider the effect of growth phase (mid-log, late-log and late stationary phase) on Hg methylation by the known methylator Desulfovibrio desulfuricans ND132. We tested the addition of Hg alone (chloride-complex), Hg with Suwannee River natural organic matter (SRNOM) (unequilibrated), and Hg equilibrated with SRNOM on monomethylmercury (MMHg) production by ND132 over a growth curve in pyruvate-fumarate media. This NOM did not affect MMHg production even under very low Hg:SRNOM ratios, where Hg binding is predicted to be dominated by high energy sites. Adding Hg or Hg-NOM to growing cultures 24h before sampling (late addition) resulted in {approx}2x greater net fraction of Hg methylated than for comparably aged cultures exposed to Hg from the initial culture inoculation (early addition). Mid- and late-log phase cultures produced similar amounts of MMHg, but late stationary phase cultures (both under early and late Hg addition conditions) produced up to {approx}3x more MMHg, indicating the potential importance of growth phase in studies of MMHg production.

  7. Bacterial Growth Phase Influences Methylmercury Production by the Sulfate-Reducing Bacterium Desulfovibrio desulfuricans ND132

    SciTech Connect

    Biswas, Abir; Brooks, Scott C; Miller, Carrie L; Mosher, Jennifer J; Yin, Xiangping Lisa; Drake, Meghan M

    2011-01-01

    The effect of bacterial growth phase is an aspect of mercury (Hg) methylation that previous studies have not investigated in detail. Here we consider the effect of growth phase (mid-log, late-log and late stationary phase) on Hg methylation by the known methylator Desulfovibrio desulfuricans ND132. We tested the addition of Hg alone (chloride-complex), Hg with Suwannee River natural organic matter (SRNOM) (unequilibrated), and Hg equilibrated with SRNOM on monomethylmercury (MMHg) production by ND132 over a growth curve in pyruvate fumarate media. This NOM did not affect MMHg production even under very low Hg: SRNOM ratios, where Hg binding is predicted to be dominated by high energy sites. Adding Hg or Hg NOM to growing cultures 24 h before sampling (late addition) resulted in ~2 greater net fraction of Hg methylated than for comparably aged cultures exposed to Hg from the initial culture inoculation (early addition). Mid-and late-log phase cultures produced similar amounts of MMHg, but late stationary phase cultures (both under early and late Hg addition conditions) produced up to ~3 more MMHg, indicating the potential importance of growth phase in studies of MMHg production.

  8. Bacterial locomotion, adsorption and growth over chemically patterned surfaces

    NASA Astrophysics Data System (ADS)

    Jalali, Maryam; Molaei, Mehdi; Sheng, Jian

    2013-11-01

    Complex dynamic interactions between bacteria and chemically patched interface that mimics the heterogeneous energy landscape of a real-life interfacial environment are studied in the paper. We explore effects of these spatially varying chemical patches on bacterial locomotion, adsorption, biofilm formation and the film growth rate. Using micro-fabrication and soft-lithography, we have fabricated PDMS microfluidic channels with a solid substrate covered by micro-scale chemical patches. Arrays of 2D geometries of characteristic scales varying from 10 to 50 μm are transferred onto a glass substrate by soft-lithography. The substrate is functionalized to generate alternating hydrophobic and hydrophilic regions and bonded with the channel. The 3D swimming characteristics near these surfaces, such as swimming velocity, linear and angular dispersions, are measured in-situ using 3D digital holographic microscopy. The observations are used to examine the mechanisms involved in adsorption and desorption of swimming bacteria onto the substrate. Long-term experiments are conducted to quantify the growth rate and structures of colony. A correlation between various length scales of the substrate and bacteria motility are observed.

  9. Investigation of growth processes in bacterial colonies by the LASCA technique

    NASA Astrophysics Data System (ADS)

    Ulianova, O. V.; Rebeza, O. S.; Ulyanov, S. S.

    2016-01-01

    The method of analysis of the temporal and spatial contrasts of speckle fields formed during the coherent scattering of radiation in bacterial colonies has been adapted to monitor the growth and structure of bacterial colonies by the example of E. coli. A noticeable change in the spatial structures of colonies during their growth has been demonstrated.

  10. Growth curve analysis of placental and fetal growth influenced by adjacent fetal sex status under crowded uterine conditions in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Intrauterine position and sex of adjacent fetuses in litter bearing species have been implicated in physiological and behavioral differences in males and females. Our objective was to establish growth curves for fetal and placental weight gain as influenced by sex status of flanking fetuses under cr...

  11. Infant Gaze Following and Pointing Predict Accelerated Vocabulary Growth through Two Years of Age: A Longitudinal, Growth Curve Modeling Study

    ERIC Educational Resources Information Center

    Brooks, Rechele; Meltzoff, Andrew N.

    2008-01-01

    We found that infant gaze following and pointing predicts subsequent language development. At ages 0 ; 10 or 0 ; 11, infants saw an adult turn to look at an object in an experimental setting. Productive vocabulary was assessed longitudinally through two years of age. Growth curve modeling showed that infants who gaze followed and looked longer at…

  12. Identifying Longitudinal Growth Trajectories of Learning Domains in Problem-Based Learning: A Latent Growth Curve Modeling Approach Using SEM

    ERIC Educational Resources Information Center

    Wimmers, Paul F.; Lee, Ming

    2015-01-01

    To determine the direction and extent to which medical student scores (as observed by small-group tutors) on four problem-based-learning-related domains change over nine consecutive blocks during a two-year period (Domains: Problem Solving/Use of Information/Group Process/Professionalism). Latent growth curve modeling is used to analyze…

  13. Transcriptome analysis of genetic mechanism of growth curve inflection point using a pig model.

    PubMed

    Shen, Linyuan; Zhang, Shunhua; Zhu, Li

    2015-12-01

    Animal growth curves play an important role for animal breeders to optimize feeding and management strategies (De Lange et al., 2001 [1]; Brossard et al., 2009 [2]; Strathe et al., 2010 [3]). However, the genetic mechanism of the phenotypic difference between the inflection point and noninflection points of the growth curve remains unclear. Here, we report the differentially expressed gene pattern in pig longissimus dorsi among three typical time points of the growth curve, inflection point (IP), before inflection point (BIP) and after inflection point (AIP). The whole genome RNA-seq data was deposited at GenBank under the accession number PRJNA2284587. The RNA-seq libraries generated 117 million reads of 5.89 gigabases in length. Totals of 21,331, 20,996 and 20,139 expressed transcripts were identified in IP, UIP and AIP, respectively. Furthermore, we identified 757 differentially expressed genes (DEGs) between IP and UIP, and 271 DEGs between AIP and IP. Function enrichment analysis of DEGs found that the highly expressed genes in IP were mainly enriched in energy metabolism, global transcriptional activity and bone development intensity. This study contributes to reveal the genetic mechanism of growth curve inflection point. PMID:26697358

  14. Ignoring Individual Differences in Times of Assessment in Growth Curve Modeling

    ERIC Educational Resources Information Center

    Coulombe, Patrick; Selig, James P.; Delaney, Harold D.

    2016-01-01

    Researchers often collect longitudinal data to model change over time in a phenomenon of interest. Inevitably, there will be some variation across individuals in specific time intervals between assessments. In this simulation study of growth curve modeling, we investigate how ignoring individual differences in time points when modeling change over…

  15. Investigation of Mediational Processes Using Parallel Process Latent Growth Curve Modeling.

    ERIC Educational Resources Information Center

    Cheong, JeeWon; MacKinnon, David P.; Khoo, Siek Toon

    2003-01-01

    Investigated a method to evaluate mediational processes using latent growth curve modeling and tested it with empirical data from a longitudinal steroid use prevention program focusing on 1,506 high school football players over 4 years. Findings suggest the usefulness of the approach. (SLD)

  16. Evaluating Model Fit for Growth Curve Models: Integration of Fit Indices from SEM and MLM Frameworks

    ERIC Educational Resources Information Center

    Wu, Wei; West, Stephen G.; Taylor, Aaron B.

    2009-01-01

    Evaluating overall model fit for growth curve models involves 3 challenging issues. (a) Three types of longitudinal data with different implications for model fit may be distinguished: balanced on time with complete data, balanced on time with data missing at random, and unbalanced on time. (b) Traditional work on fit from the structural equation…

  17. Examining the Earnings Trajectories of Community College Students Using a Piecewise Growth Curve Modeling Approach

    ERIC Educational Resources Information Center

    Jaggars, Shanna Smith; Xu, Di

    2016-01-01

    Policymakers have become increasingly concerned with measuring--and holding colleges accountable for--students' labor market outcomes. In this article we introduce a piecewise growth curve approach to analyzing community college students' labor market outcomes, and we discuss how this approach differs from two popular econometric approaches:…

  18. Longitudinal Changes in Physical Fitness Performance in Youth: A Multilevel Latent Growth Curve Modeling Approach

    ERIC Educational Resources Information Center

    Wang, Chee Keng John; Pyun, Do Young; Liu, Woon Chia; Lim, Boon San Coral; Li, Fuzhong

    2013-01-01

    Using a multilevel latent growth curve modeling (LGCM) approach, this study examined longitudinal change in levels of physical fitness performance over time (i.e. four years) in young adolescents aged from 12-13 years. The sample consisted of 6622 students from 138 secondary schools in Singapore. Initial analyses found between-school variation on…

  19. The Dynamics of Self-Esteem: A Growth-Curve Analysis.

    ERIC Educational Resources Information Center

    Baldwin, Scott A.; Hoffmann, John P.

    2002-01-01

    Using 7 years of sequential data from the Family Health Study for 762 subjects aged 11 to 16 years in year 1, estimated a hierarchical growth curve model that emphasized the effects of age, life events, gender, and family cohesion on self-esteem. Results show a curvilinear relationship between age and self-esteem, suggesting that self-esteem is a…

  20. The Performance of Multilevel Growth Curve Models under an Autoregressive Moving Average Process

    ERIC Educational Resources Information Center

    Murphy, Daniel L.; Pituch, Keenan A.

    2009-01-01

    The authors examined the robustness of multilevel linear growth curve modeling to misspecification of an autoregressive moving average process. As previous research has shown (J. Ferron, R. Dailey, & Q. Yi, 2002; O. Kwok, S. G. West, & S. B. Green, 2007; S. Sivo, X. Fan, & L. Witta, 2005), estimates of the fixed effects were unbiased, and Type I…

  1. Career Maturity Growth Curve and Sex-Role Stereotypes of Korean Adolescents

    ERIC Educational Resources Information Center

    Yon, Kyu Jin; Choi, Wonseok; Goh, Michael

    2013-01-01

    This longitudinal study investigated the career maturity growth curve of Korean Adolescents from 4th grade to 12th grade. The participants consisted of 3,241 male and 3,029 female students from the Korea Youth Panel Survey, a nationwide longitudinal study of South Korean adolescents. The present study explored the shape of the career maturity…

  2. Accuracy of Estimates and Statistical Power for Testing Meditation in Latent Growth Curve Modeling

    ERIC Educational Resources Information Center

    Cheong, JeeWon

    2011-01-01

    The latent growth curve modeling (LGCM) approach has been increasingly utilized to investigate longitudinal mediation. However, little is known about the accuracy of the estimates and statistical power when mediation is evaluated in the LGCM framework. A simulation study was conducted to address these issues under various conditions including…

  3. A Latent Growth Curve Analysis of Reading Achievement for an At-Risk Population

    ERIC Educational Resources Information Center

    Beecher, Constance C.

    2011-01-01

    The development of reading skills from age seven until age 19 was investigated for children who were referred for special education preschool intervention using latent growth curve analysis (n=206). Approximately one-third of the study sample did not require special education services after preschool, providing a natural comparison group. Reading…

  4. Sample Sizes for Two-Group Second-Order Latent Growth Curve Models

    ERIC Educational Resources Information Center

    Wanstrom, Linda

    2009-01-01

    Second-order latent growth curve models (S. C. Duncan & Duncan, 1996; McArdle, 1988) can be used to study group differences in change in latent constructs. We give exact formulas for the covariance matrix of the parameter estimates and an algebraic expression for the estimation of slope differences. Formulas for calculations of the required sample…

  5. Aptitude-Treatment Interaction Effects on Explicit Rule Learning: A Latent Growth Curve Analysis

    ERIC Educational Resources Information Center

    Hwu, Fenfang; Pan, Wei; Sun, Shuyan

    2014-01-01

    Finding the match between individuals and educational treatments is the aim of both educators and the aptitude-treatment interaction research paradigm. Using the latent growth curve analysis, the present study investigates the interaction between the type of explicit instructional approaches (deductive vs. explicit-inductive) and the level of…

  6. Mode of physical activity and self-efficacy in older adults: a latent growth curve analysis.

    PubMed

    McAuley, E; Katula, J; Mihalko, S L; Blissmer, B; Duncan, T E; Pena, M; Dunn, E

    1999-09-01

    A randomized controlled trial examined the effect of two physical activity modes on changes in self-efficacy over the course of a 12-month period in older, formerly sedentary adults (N = 174, M age = 65.5 years). Participants were randomized into either an aerobic activity group or a stretching and toning group. Structural equation modeling was employed to conduct multiple sample latent growth curve analyses of individual growth in exercise and physical self-efficacy over time. Results revealed a curvilinear growth pattern for both types of efficacy with increases occurring over the first 6 months followed by declines at the 6-month follow-up. There was a significant treatment by mean level growth interaction for exercise efficacy with both groups increasing over time, but the aerobic group evidenced a twofold increase in growth over the stretching group. Structural analyses indicated that frequency of exercise participation was a significant predictor of overall growth in efficacy, and improvements in fitness were only related to exercise efficacy growth in the stretching group. Findings are discussed in terms of social cognitive theory and further application of latent growth curve modeling to studies of physical activity effects in older adults. PMID:10542821

  7. Bacterial Growth on Chitosan-Coated Polypropylene Textile

    PubMed Central

    Erben, D.; Hola, V.; Jaros, J.; Rahel, J.

    2012-01-01

    Biofouling is a problem common in all systems where microorganisms and aqueous environment meet. Prevention of biofouling is therefore important in many industrial processes. The aim of this study was to develop a method to evaluate the ability of material coating to inhibit biofilm formation. Chitosan-coated polypropylene nonwoven textile was prepared using dielectric barrier discharge plasma activation. Resistance of the textile to biofouling was then tested. First, the textile was submerged into a growth medium inoculated with green fluorescein protein labelled Pseudomonas aeruginosa. After overnight incubation at 33°C, the textile was observed using confocal laser scanning microscopy for bacterial enumeration and biofilm structure characterisation. In the second stage, the textile was used as a filter medium for prefiltered river water, and the pressure development on the in-flow side was measured to quantify the overall level of biofouling. In both cases, nontreated textile samples were used as a control. The results indicate that the chitosan coating exhibits antibacterial properties. The developed method is applicable for the evaluation of the ability to inhibit biofilm formation. PMID:23724330

  8. Bacterial growth on chitosan-coated polypropylene textile.

    PubMed

    Erben, D; Hola, V; Jaros, J; Rahel, J

    2012-01-01

    Biofouling is a problem common in all systems where microorganisms and aqueous environment meet. Prevention of biofouling is therefore important in many industrial processes. The aim of this study was to develop a method to evaluate the ability of material coating to inhibit biofilm formation. Chitosan-coated polypropylene nonwoven textile was prepared using dielectric barrier discharge plasma activation. Resistance of the textile to biofouling was then tested. First, the textile was submerged into a growth medium inoculated with green fluorescein protein labelled Pseudomonas aeruginosa. After overnight incubation at 33°C, the textile was observed using confocal laser scanning microscopy for bacterial enumeration and biofilm structure characterisation. In the second stage, the textile was used as a filter medium for prefiltered river water, and the pressure development on the in-flow side was measured to quantify the overall level of biofouling. In both cases, nontreated textile samples were used as a control. The results indicate that the chitosan coating exhibits antibacterial properties. The developed method is applicable for the evaluation of the ability to inhibit biofilm formation. PMID:23724330

  9. Re-Evaluating Sexual Violence Prevention Through Bystander Education: A Latent Growth Curve Approach.

    PubMed

    Shaw, Jessica; Janulis, Patrick

    2016-10-01

    Recently, there has been a call for more advanced analytic techniques in violence against women research, particularly in community interventions that use longitudinal designs. The current study re-evaluates experimental evaluation data from a sexual violence bystander intervention program. Using an exploratory latent growth curve approach, we were able to model the longitudinal growth trajectories of individual participants over the course of the entire study. Although the results largely confirm the original evaluation findings, the latent growth curve approach better fits the demands of "messy" data (e.g., missing data, varying number of time points per participant, and unequal time spacing within and between participants) that are frequently obtained during a community-based intervention. The benefits of modern statistical techniques to practitioners and researchers in the field of sexual violence prevention, and violence against women more generally, are further discussed. PMID:25888503

  10. Multilevel models for repeated measures research designs in psychophysiology: an introduction to growth curve modeling.

    PubMed

    Kristjansson, Sean D; Kircher, John C; Webb, Andrea K

    2007-09-01

    Psychophysiologists often use repeated measures analysis of variance (RMANOVA) and multivariate analysis of variance (MANOVA) to analyze data collected in repeated measures research designs. ANOVA and MANOVA are nomothetic approaches that focus on group means. Newer multilevel modeling techniques are more informative than ANOVA because they characterize both group-level (nomothetic) and individual-level (idiographic) effects, yielding a more complete understanding of the phenomena under study. This article was written as an introduction to growth curve modeling for applied researchers. A growth model is defined that can be used in place of RMANOVAs and MANOVAs for single-group and mixed repeated measures designs. The model is expanded to test and control for the effects of baseline levels of physiological activity on stimulus-specific responses. Practical, conceptual, and statistical advantages of growth curve modeling are discussed. PMID:17596179

  11. Using growth curves to forecast regional resource recovery: approaches, analytics and consistency tests.

    PubMed

    Sorrell, Steve; Speirs, Jamie

    2014-01-13

    There is growing concern about the depletion of hydrocarbon resources and the risk of near-term peaks in production. These concerns hinge upon contested estimates of the recoverable resources of different regions and the associated forecasts of regional production. Beginning with Hubbert, an influential group of analysts have used growth curves both to estimate recoverable resources and to forecast future production. Despite widespread use, these 'curve-fitting' techniques remain a focus of misunderstanding and dispute. The aim of this paper is to classify and explain these techniques and to identify both their relative suitability in different circumstances and the expected level of confidence in their results. The paper develops a mathematical framework that maps curve-fitting techniques onto the available data for conventional oil and highlights the critical importance of the so-called 'reserve growth'. It then summarizes the historical origins, contemporary application and strengths and weaknesses of each group of curve-fitting techniques and uses illustrative data from a number of oil-producing regions to explore the extent to which these techniques provide consistent estimates of recoverable resources. The paper argues that the applicability of curve-fitting techniques is more limited than adherents claim, the confidence bounds on the results are wider than commonly assumed and the techniques have a tendency to underestimate recoverable resources. PMID:24298074

  12. Growth curves for Turkish Girls with Turner Syndrome: Results of the Turkish Turner Syndrome Study Group

    PubMed Central

    Darendeliler, Feyza; Yeşilkaya, Ediz; Bereket, Abdullah; Baş, Firdevs; Bundak, Rüveyde; Sarı, Erkan; Küçükemre Aydın, Banu; Darcan, Şükran; Dündar, Bumin; Büyükinan, Muammer; Kara, Cengiz; Mazıcıoğlu, Mümtaz M.; Adal, Erdal; Akıncı, Ayşehan; Atabek, Mehmet Emre; Demirel, Fatma; Çelik, Nurullah; Özkan, Behzat; Özhan, Bayram; Orbak, Zerrin; Ersoy, Betül; Doğan, Murat; Ataş, Ali; Turan, Serap; Gökşen, Damla; Tarım, Ömer; Yüksel, Bilgin; Ercan, Oya; Hatun, Şükrü; Şimşek, Enver; Ökten, Ayşenur; Abacı, Ayhan; Döneray, Hakan; Özbek, Mehmet Nuri; Keskin, Mehmet; Önal, Hasan; Akyürek, Nesibe; Bulan, Kezban; Tepe, Derya; Emeksiz, Hamdi Cihan; Demir, Korcan; Kızılay, Deniz; Topaloğlu, Ali Kemal; Eren, Erdal; Özen, Samim; Demirbilek, Hüseyin; Abalı, Saygın; Akın, Leyla; Eklioğlu, Beray Selver; Kaba, Sultan; Anık, Ahmet; Baş, Serpil; Ünüvar, Tolga; Sağlam, Halil; Bolu, Semih; Özgen, Tolga; Doğan, Durmuş; Çakır, Esra Deniz; Şen, Yaşar; Andıran, Nesibe; Çizmecioğlu, Filiz; Evliyaoğlu, Olcay; Karagüzel, Gülay; Pirgon, Özgür; Çatlı, Gönül; Can, Hatice Dilek; Gürbüz, Fatih; Binay, Çiğdem; Baş, Veysel Nijat; Sağlam, Celal; Gül, Davut; Polat, Adem; Açıkel, Cengizhan; Cinaz, Peyami

    2015-01-01

    Objective: Children with Turner syndrome (TS) have a specific growth pattern that is quite different from that of healthy children. Many countries have population-specific growth charts for TS. Considering national and ethnic differences, we undertook this multicenter collaborative study to construct growth charts and reference values for height, weight and body mass index (BMI) from 3 years of age to adulthood for spontaneous growth of Turkish girls with TS. Methods: Cross-sectional height and weight data of 842 patients with TS, younger than 18 years of age and before starting any therapy, were evaluated. Results: The data were processed to calculate the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile values for defined ages and to construct growth curves for height-for-age, weight-for-age and BMI-for-age of girls with TS. The growth pattern of TS girls in this series resembled the growth pattern of TS girls in other reports, but there were differences in height between our series and the others. Conclusion: This study provides disease-specific growth charts for Turkish girls with TS. These disease-specific national growth charts will serve to improve the evaluation of growth and its management with growth-promoting therapeutic agents in TS patients. PMID:26831551

  13. Nanoparticle-Templated Formation and Growth Mechanism of Curved Protein Polymer Fibrils.

    PubMed

    Pham, Thao T H; Rombouts, Wolf H; Fokkink, Remco; Stuart, Marc C A; Cohen Stuart, Martien A; Kleijn, J Mieke

    2016-07-11

    We investigated the growth of biosynthetic protein polymers with templated curvature on pluronic nanospheres. The protein has a central silk-like block containing glutamic residues (S(E)) and collagen-like end-blocks (C). The S(E) blocks stack into filaments when their charge is removed (pH <5). Indeed, at low pH curved and circular fibers are formed at the surface of the nanospheres, which keep their shape after removal of the pluronics. The data reveal the mechanism of the templated fibril-growth: The growth of protein assemblies is nucleated in solution; small protein fibrils adsorb on the nanospheres, presumably due to hydrogen bond formation between the silk-like blocks and the pluronic PEO blocks. The surface of the pluronic particles templates further growth. At relatively low protein/pluronic weight ratios, only a fraction of the nanospheres bears protein fibers, pointing to a limiting amount of nuclei in solution. Because the nanospheres capture fibrils at an early stage of growth, they can be used to separate growth and nucleation rates in protein fibril formation. Moreover, the nanoparticle-templated growth of stable curved fibers opens ways to build proteinaceous nanocapsules from designed protein polymers. PMID:27250876

  14. Effect of flow and active mixing on bacterial growth in a colon-like geometry

    NASA Astrophysics Data System (ADS)

    Cremer, Jonas; Segota, Igor; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

    The large intestine harbors bacteria from hundreds of species, with bacterial densities reaching up to 1012 cells per gram. Many different factors influence bacterial growth dynamics and thus bacterial density and microbiota composition. One dominant force is flow which can in principle lead to a washout of bacteria from the proximal colon. Active mixing by Contractions of the colonic wall together with bacterial growth might counteract such flow-forces and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate Contractions. We investigate growth along the channel under a steady nutrient inflow. In the limits of no or very frequent Contractions, the device behaves like a plug-flow reactor and a chemostat respectively. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term.

  15. Polymer film deposition on agar using a dielectric barrier discharge jet and its bacterial growth inhibition

    NASA Astrophysics Data System (ADS)

    Tsai, T.-C.; Cho, J.; Mcintyre, K.; Jo, Y.-K.; Staack, D.

    2012-08-01

    Polymer film deposition on agar in ambient air was achieved using the helium dielectric barrier discharge jet (DBD jet) fed with polymer precursors, and the bacterial growth inhibition due to the deposited film was observed. The DBD jet with precursor addition was more efficient at sterilization than a helium-only DBD jet. On the areas where polymer films cover the agar the bacterial growth was significantly inhibited. The inhibition efficacy showed dependence on the film thickness. The DBD jet without precursor also created a modified agar layer, which may slow the growth of some bacterial strains.

  16. Divergent selection for shape of growth curve in Japanese quail. 4. Carcase composition and thyroid hormones.

    PubMed

    Hyánková, L; Novotná, B; Darras, V M

    2008-03-01

    1. Changes in the relative weights of carcase, abdominal fat, breast and leg muscles, and plasma thyroid hormone concentrations occurring during the first 6 weeks of postnatal growth were analysed in males of HG and LG lines divergently selected for high and low relative body weight (BW) gain between 11 and 28 d of age, respectively, and constant adult BW. 2. The second week of postnatal life was a critical age at which the HG males exhibited a relatively faster growth in comparison to their LG counterparts and permanently exceeded LG males in the percentage by weight of carcase, breast and leg muscle. A higher production of muscle tissues was associated with lower accumulation of abdominal fat before sexual maturity. 3. In general, the plasma T(3) level of HG quail exceeded that of LG quail. Nevertheless, significant differences were found only at 14, 21 and 28 d of age, that is, in the period during which the highest inter-line differences in relative growth rate were noted. Also the T(3)/T(4) ratio followed a similar trend while plasma T(4) level showed no clear and consistent inter-line differences. 4. The results suggest that the selection for the shape of the growth curve, like the selection for body fat, modifies the carcase quality owing to shortening/prolongation of the acceleration growth phase. Individuals with a short acceleration phase of the growth curve are characterised by low carcase quality during the fattening period. PMID:18409082

  17. A probabilistic neural network approach for modeling and classification of bacterial growth/no-growth data.

    PubMed

    Hajmeer, M; Basheer, I

    2002-10-01

    In this paper, we propose to use probabilistic neural networks (PNNs) for classification of bacterial growth/no-growth data and modeling the probability of growth. The PNN approach combines both Bayes theorem of conditional probability and Parzen's method for estimating the probability density functions of the random variables. Unlike other neural network training paradigms, PNNs are characterized by high training speed and their ability to produce confidence levels for their classification decision. As a practical application of the proposed approach, PNNs were investigated for their ability in classification of growth/no-growth state of a pathogenic Escherichia coli R31 in response to temperature and water activity. A comparison with the most frequently used traditional statistical method based on logistic regression and multilayer feedforward artificial neural network (MFANN) trained by error backpropagation was also carried out. The PNN-based models were found to outperform linear and nonlinear logistic regression and MFANN in both the classification accuracy and ease by which PNN-based models are developed. PMID:12133614

  18. Estimation of the growth curve and heritability of the growth rate for giant panda (Ailuropoda melanoleuca) cubs.

    PubMed

    Che, T D; Wang, C D; Jin, L; Wei, M; Wu, K; Zhang, Y H; Zhang, H M; Li, D S

    2015-01-01

    Giant panda cubs have a low survival rate during the newborn and early growth stages. However, the growth and developmental parameters of giant panda cubs during the early lactation stage (from birth to 6 months) are not well known. We examined the growth and development of giant panda cubs by the Chapman growth curve model and estimated the heritability of the maximum growth rate at the early lactation stage. We found that 83 giant panda cubs reached their maximum growth rate at approximately 75-120 days after birth. The body weight of cubs at 75 days was 4285.99 g. Furthermore, we estimated that the heritability of the maximum growth rate was moderate (h(2) = 0.38). Our study describes the growth and development of giant panda cubs at the early lactation stage and provides valuable growth benchmarks. We anticipate that our results will be a starting point for more detailed research on increasing the survival rate of giant panda cubs. Feeding programs for giant panda cubs need further improvement. PMID:25867378

  19. A Case Study of a Computer Assisted Learning Unit, "The Growth Curve of Microorganisms": Development, Implementation, and Evaluation.

    ERIC Educational Resources Information Center

    Huppert, Jehuda; Lazarovitz, Reuven

    This three-part paper describes the development of a software program called "The Growth Curve of Microorganisms" for a tenth-grade biology class. Designed to improve students' cognitive skills, the program enables them to investigate, through computer simulations, the impact upon the growth curve of a population of three variables: temperature,…

  20. Prediction of stable crack growth and instability using the V sub R-curve method

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1985-01-01

    A methodology is presented for predicting stable crack growth and instability of cracked structural components from results of laboratory tests on metallic materials under plane-stress conditions. The methodology is based on the displacement V sub R at the tip of a stably tearing crack. Basically, the V sub R-curve method is a resistance curve approach, such as K sub R and J sub R, except that the 'crack drive' is written in terms of crack-tip displacement instead of K or J. The relationship between crack-tip-opening displacement, crack length, specimen type, and tensile properties is derived from the Dugdale model for the cracked structure of interest. This report describes the laboratory test procedure and calculations used to obtain the V sub R resistance curve from fracture tests of compact or of middle-crack tension (formally center-crack) specimens. The analysis procedure used to predict stable crack growth and instability of any through-the-thickness crack configuration made of the same material and thickness, and tested under the same environmental conditions, is presented. The various limitations of the present V sub R curve method are given. Four example calculations and predictions are shown.

  1. Theoretical quasar emission-line profiles. I - Curve-of-growth effects on observed profiles

    NASA Technical Reports Server (NTRS)

    Hubbard, E. N.; Puetter, R. C.

    1983-01-01

    Radiative transfer effects are examined in an investigation of the kinematics of quasar and Seyfert emission-line regions with pancake cloud geometries. Consideration is given only to the effects of limb brightening with the aspect angle of pancake clouds, assuming that all lines lie on a single portion of the curve of growth. This effect is coupled with several simple but plausible ensemble geometries and dynamics, and a number of theoretical emission-line profiles have been generated. It is shown that these profiles differ substantially depending on both the ensemble geometry and the portion of the curve of growth considered; for a given ensemble geometry, optically thick line profiles are different from optically thick profiles. It is shown that, for radiatively driven clouds, ensembles of clouds which have maximum velocities approaching the terminal velocity of the acceleration mechanism never produce acceptable profiles unless the cloud luminosity is a strongly decreasing function of radius.

  2. Evaluation of fatigue-crack growth rates by polynomial curve fitting. [Ti alloy plate

    NASA Technical Reports Server (NTRS)

    Davies, K. B.; Feddersen, C. E.

    1973-01-01

    Fundamental characterization of the constant-amplitude fatigue crack propagation is achieved by an analysis of the rate of change of crack length with change in number of applied loading cycles, defining the rate values such that they are consistent with the basic assumption of smoothness and continuity in the fatigue crack growth process. The technique used to satisfy the analytical conditions and minimize the effects of local material anomalies and experimental errors is that of fitting a smooth curve to the entire set of basic data by least square regression. This yields a well-behaved function relating the number of cycles to the crack length. By taking the first derivative of the function, the crack growth rate is obtained for each point. The class of curve fitting functions used in the analysis is the polynomial of degree n.

  3. A GROWTH CURVE MODEL OF LEARNING ACQUISITION AMONG COGNITIVELY NORMAL OLDER ADULTS

    PubMed Central

    Jones, Richard N.; Rosenberg, Adrienne L.; Morris, John N.; Allaire, Jason C.; McCoy, Karin J. M.; Marsiske, Michael; Kleinman, Ken P.; Rebok, George W.; Malloy, Paul F.

    2010-01-01

    The objective of this study was to model recall and learning on the Auditory Verbal Learning Test using latent growth curve techniques. Participants were older adults recruited for the ACTIVE cognitive intervention pilot. A series of nested models revealed that an approximately logarithmic growth curve model provided optimal fit to the data. Although recall and learning factors were statistically uncorrelated, a fitted multivariate model suggested that initial recall was significantly associated with demographic characteristics but unrelated to health factors and cognitive abilities. Individual differences in learning were related to race/ethnicity, speed of processing, verbal knowledge, and global cognitive function level. These results suggest that failing to recognize initial recall and learning as distinct constructs clouds the interpretation of supraspan memory tasks. PMID:16036723

  4. Effect of lag time distribution on the lag phase of bacterial growth - a Monte Carlo analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study is to use Monte Carlo simulation to evaluate the effect of lag time distribution of individual bacterial cells incubated under isothermal conditions on the development of lag phase. The growth of bacterial cells of the same initial concentration and mean lag phase durati...

  5. The Papain Inhibitor (SPI) of Streptomyces mobaraensis Inhibits Bacterial Cysteine Proteases and Is an Antagonist of Bacterial Growth

    PubMed Central

    Zindel, Stephan; Kaman, Wendy E.; Fröls, Sabrina; Pfeifer, Felicitas; Peters, Anna; Hays, John P.

    2013-01-01

    A novel papain inhibitory protein (SPI) from Streptomyces mobaraensis was studied to measure its inhibitory effect on bacterial cysteine protease activity (Staphylococcus aureus SspB) and culture supernatants (Porphyromonas gingivalis, Bacillus anthracis). Further, growth of Bacillus anthracis, Staphylococcus aureus, Pseudomonas aeruginosa, and Vibrio cholerae was completely inhibited by 10 μM SPI. At this concentration of SPI, no cytotoxicity was observed. We conclude that SPI inhibits bacterial virulence factors and has the potential to become a novel therapeutic treatment against a range of unrelated pathogenic bacteria. PMID:23587952

  6. [[sup 3]H] Thymidine incorporation to estimate growth rates of anaerobic bacterial strains

    SciTech Connect

    Winding, A. )

    1992-08-01

    The incorporation of [[sup 3]H] thymidine by axenic cultures of anaerobic bacteria was investigated as a means to measure growth. The three fermentative strains and one of the methanogenic strains tested incorporated [[sup 3]H] thymidine during growth. It is concluded that the [[sup 3]H] thymidine incorporation method underestimates bacterial growth in anaerobic environments.

  7. Research note: Influence of body weight selection on the growth curve of turkeys.

    PubMed

    Anthony, N B; Emmerson, D A; Nestor, K E

    1991-01-01

    The growth curve of a population of turkeys selected for increased 16 wk BW (Line F) and a randombred control population (RBC2) was determined. It was concluded that the Gompertz equation best described the growth pattern of Lines F and RBC2 regardless of sex. Line F had higher BW at hatching, BW and slope at point of inflection (POI), and asymptotic BW than Line RBC2. Age at POI and asymptote were achieved later for Line RBC2 than for Line F. Male turkeys had higher BW and age at POI and BW and age at asymptote than females. Slope at POI was greater for females than for males. PMID:2017414

  8. Effect of Vibration on Bacterial Growth and Antibiotic Resistance

    NASA Technical Reports Server (NTRS)

    Juergensmeyer, Elizabeth A.; Juergensmeyer, Margaret A.

    2004-01-01

    The purpose of this research grant was to provide a fundamental, systematic investigation of the effects of oscillatory acceleration on bacterial proliferation and their responses to antibiotics in a liquid medium.

  9. Growth Curve Models for the Analysis of Phenotype Arrays for a Systems Biology Overview of Yersinia pestis

    SciTech Connect

    Fodor, I K; Holtz-Morris, A E; McCutchen-Maloney, S L

    2005-09-08

    The Phenotype MicroArray technology of Biolog, Inc. (Hayward, CA) measures the respiration of cells as a function of time in thousands of microwells simultaneously, and thus provides a high-throughput means of studying cellular phenotypes. The microwells contain compounds involved in a number of biochemical pathways, as well as chemicals that test the sensitivity of cells against antibiotics and stress. While the PM experimental workflow is completely automated, statistical methods to analyze and interpret the data are lagging behind. To take full advantage of the technology, it is essential to develop efficient analytical methods to quantify the information in the complex datasets resulting from PM experiments. We propose the use of statistical growth-curve models to rigorously quantify observed differences in PM experiments, in the context of the growth and metabolism of Yersinia pestis cells grown under different physiological conditions. The information from PM experiments complement genomic and proteomic results and can be used to identify gene function and in drug development. Successful coupling of phenomics results with genomics and proteomics will lead to an unprecedented ability to characterize bacterial function at a systems biology level.

  10. What is Growth? Concurrent determination of a bacterial population's many shades of growth

    NASA Astrophysics Data System (ADS)

    Lambert, Guillaume; Kussell, Edo

    2013-03-01

    One of the most exciting developments in the study of the physics of microbial life is the ability to precisely monitor stochastic variations of gene expression in individual cells. A fundamental question is whether these variations improve the long-term ability of a population to adapt to new environments. While variations in gene expression in bacteria are easily measured through the use of reporter systems such as green fluorescent proteins and its variants, precise determination of a cell's growth rate, and how it is influenced by its immediate environment, remains challenging. Here, we show that many conflicting and ambiguous definitions of bacterial growth can actually be used interchangeably in E. coli. Indeed, by monitoring small populations of E. coli bacteria inside a microfluidic device, we show that seemingly independent measurements of growth (elongation rate and the average division time, for instance) agree very precisely with one another. We combine these definitions with the population's length and age distribution to very precisely quantify the influence of temperature variations on a population's growth rate. We conclude by using coalescence theory to describe the evolution of a population's genetic structure over time.

  11. Divergent selection for shape of growth curve in Japanese quail. 1. Responses in growth parameters and food conversion.

    PubMed

    Hyánková, L; Knízetová, H; Dĕdková, L; Hort, J

    2001-12-01

    1. HG and LG quail lines selected for high and low relative weight gain between 11 and 28 d of age (RG11-28), respectively, and an unselected C line were compared. Mature body weight of both selected lines was held at that of the C line. Progeny of generation 6 were used for analysis. 2. Divergent selection for RG11-28 brought about opposite changes in the growth rates shortly after hatching. 3. Parameters of the Richards function were used to describe the growth curve. The largest differences between HG and LG lines occurred in age (t+) and body weight (y+) at the inflection point of the growth curve (on average for both sexes 28% and 20%, respectively). For HG quail, the parameter t+ was 5 d later than that for LG quail (18.6 vs 14.1 d for males and 20.6 vs 15.6 d for females, respectively), and consequently the parameter y+ was greater (90.3 vs 84.0 g for males and 104.5 vs 96.1 g for females, respectively). The shape of the growth curve expressed by the y+/A ratio was substantialy different for HG and LG quail (44.8% vs 39.6% for males and 43.5% vs 36.8% for females, respectively). 4. The food/gain ratios for the fattening period (3 to 35 d of age) were 3.21, 3.47 and 3.34 for the HG, LG and C lines, respectively. The HG quail started to utilise food more efficiently than the LG quail as early as 10 to 14 d, that is, at the age when their relative growth rate first became greater. 5. The relative deviations of the HG and LG lines from the C line are discussed. PMID:11811909

  12. Saguaro (Carnegiea gigantea, Cactaceae) age-height relationships and growth: the development of a general growth curve.

    PubMed

    Drezner, Taly Dawn

    2003-06-01

    Because the growth rate of saguaros varies across different environments, past studies on saguaro population structure required extensive data collection (often over many decades) followed by site-specific analysis to estimate age at the sampled locale. However, when height-growth data from different populations are compared, the overall shape of the growth curves is similar. In this study, a formula was developed to establish saguaro age-height relationships (using stepwise regression) that can be applied to any saguaro population and only requires a site-specific factor to adjust the curve to the local growth rate. This adjustment factor can be established more efficiently and requires less data than the full analyses required for previous studies. Saguaro National Park East (SNP-E) was used as the baseline factor, set to 1.0. Results yielded a factor of 0.743 for SNP West. When the formula was applied to 10-yr interval data from Organ Pipe Cactus National Monument (OPCNM) in Arizona, USA, this location had a factor of 0.617 (relative to SNP-E). With this formula and relatively little field sampling, the age of any individual saguaro (whether the individual was sampled or not) in any population can be estimated. PMID:21659186

  13. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    SciTech Connect

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  14. Growth curve by Gompertz nonlinear regression model in female and males in tambaqui (Colossoma macropomum).

    PubMed

    De Mello, Fernanda; Oliveira, Carlos A L; Ribeiro, Ricardo P; Resende, Emiko K; Povh, Jayme A; Fornari, Darci C; Barreto, Rogério V; McManus, Concepta; Streit, Danilo

    2015-01-01

    Was evaluated the pattern of growth among females and males of tambaqui by Gompertz nonlinear regression model. Five traits of economic importance were measured on 145 animals during the three years, totaling 981 morphometric data analyzed. Different curves were adjusted between males and females for body weight, height and head length and only one curve was adjusted to the width and body length. The asymptotic weight (a) and relative growth rate to maturity (k) were different between sexes in animals with ± 5 kg; slaughter weight practiced by a specific niche market, very profitable. However, there was no difference between males and females up to ± 2 kg; slaughter weight established to supply the bigger consumer market. Females showed weight greater than males (± 280 g), which are more suitable for fish farming purposes defined for the niche market to larger animals. In general, males had lower maximum growth rate (8.66 g / day) than females (9.34 g / day), however, reached faster than females, 476 and 486 days growth rate, respectively. The height and length body are the traits that contributed most to the weight at 516 days (P <0.001). PMID:26628036

  15. Control of bacterial adhesion and growth on honeycomb-like patterned surfaces.

    PubMed

    Yang, Meng; Ding, Yonghui; Ge, Xiang; Leng, Yang

    2015-11-01

    It is a great challenge to construct a persistent bacteria-resistant surface even though it has been demonstrated that several surface features might be used to control bacterial behavior, including surface topography. In this study, we develop micro-scale honeycomb-like patterns of different sizes (0.5-10 μm) as well as a flat area as the control on a single platform to evaluate the bacterial adhesion and growth. Bacteria strains, Escherichia coli and Staphylococcus aureus with two distinct shapes (rod and sphere) are cultured on the platforms, with the patterned surface-up and surface-down in the culture medium. The results demonstrate that the 1 μm patterns remarkably reduce bacterial adhesion and growth while suppressing bacterial colonization when compared to the flat surface. The selective adhesion of the bacterial cells on the patterns reveals that the bacterial adhesion is cooperatively mediated by maximizing the cell-substrate contact area and minimizing the cell deformation, from a thermodynamic point of view. Moreover, study of bacterial behaviors on the surface-up vs. surface-down samples shows that gravity does not apparently affect the spatial distribution of the adherent cells although it indeed facilitates bacterial adhesion. Furthermore, the experimental results suggest that two major factors, i.e. the availability of energetically favorable adhesion sites and the physical confinements, contribute to the anti-bacterial nature of the honeycomb-like patterns. PMID:26302067

  16. The combination of different carbon sources enhances bacterial growth efficiency in aquatic ecosystems.

    PubMed

    Fonte, Ellen S; Amado, André M; Meirelles-Pereira, Frederico; Esteves, Francisco A; Rosado, Alexandre S; Farjalla, Vinicius F

    2013-11-01

    The dissolved organic carbon (DOC) pool is composed of several organic carbon compounds from different carbon sources. Each of these sources may support different bacterial growth rates, but few studies have specifically analyzed the effects of the combination of different carbon sources on bacterial metabolism. In this study, we evaluated the response of several metabolic parameters, including bacterial biomass production (BP), bacterial respiration (BR), bacterial growth efficiency (BGE), and bacterial community structure, on the presence of three DOC sources alone and in combination. We hypothesized that the mixture of different DOC sources would increase the efficiency of carbon use by bacteria (BGE). We established a full-factorial substitutive design (seven treatments) in which the effects of the number and identity of DOC sources on bacterial metabolism were evaluated. We calculated the expected metabolic rates of the combined DOC treatments based on the single-DOC treatments and observed a positive interaction on BP, a negative interaction on BR, and, consequently, a positive interaction on BGE for the combinations. The bacterial community composition appeared to have a minor impact on differences in bacterial metabolism among the treatments. Our data indicate that mixtures of DOC sources result in a more efficient biological use of carbon. This study provides strong evidence that the mixture of different DOC sources is a key factor affecting the role of bacteria in the carbon flux of aquatic ecosystems. PMID:23963223

  17. Multi-Trait GWAS and New Candidate Genes Annotation for Growth Curve Parameters in Brahman Cattle.

    PubMed

    Crispim, Aline Camporez; Kelly, Matthew John; Guimarães, Simone Eliza Facioni; Fonseca e Silva, Fabyano; Fortes, Marina Rufino Salinas; Wenceslau, Raphael Rocha; Moore, Stephen

    2015-01-01

    Understanding the genetic architecture of beef cattle growth cannot be limited simply to the genome-wide association study (GWAS) for body weight at any specific ages, but should be extended to a more general purpose by considering the whole growth trajectory over time using a growth curve approach. For such an approach, the parameters that are used to describe growth curves were treated as phenotypes under a GWAS model. Data from 1,255 Brahman cattle that were weighed at birth, 6, 12, 15, 18, and 24 months of age were analyzed. Parameter estimates, such as mature weight (A) and maturity rate (K) from nonlinear models are utilized as substitutes for the original body weights for the GWAS analysis. We chose the best nonlinear model to describe the weight-age data, and the estimated parameters were used as phenotypes in a multi-trait GWAS. Our aims were to identify and characterize associated SNP markers to indicate SNP-derived candidate genes and annotate their function as related to growth processes in beef cattle. The Brody model presented the best goodness of fit, and the heritability values for the parameter estimates for mature weight (A) and maturity rate (K) were 0.23 and 0.32, respectively, proving that these traits can be a feasible alternative when the objective is to change the shape of growth curves within genetic improvement programs. The genetic correlation between A and K was -0.84, indicating that animals with lower mature body weights reached that weight at younger ages. One hundred and sixty seven (167) and two hundred and sixty two (262) significant SNPs were associated with A and K, respectively. The annotated genes closest to the most significant SNPs for A had direct biological functions related to muscle development (RAB28), myogenic induction (BTG1), fetal growth (IL2), and body weights (APEX2); K genes were functionally associated with body weight, body height, average daily gain (TMEM18), and skeletal muscle development (SMN1). Candidate

  18. Multi-Trait GWAS and New Candidate Genes Annotation for Growth Curve Parameters in Brahman Cattle

    PubMed Central

    Crispim, Aline Camporez; Kelly, Matthew John; Guimarães, Simone Eliza Facioni; e Silva, Fabyano Fonseca; Fortes, Marina Rufino Salinas; Wenceslau, Raphael Rocha; Moore, Stephen

    2015-01-01

    Understanding the genetic architecture of beef cattle growth cannot be limited simply to the genome-wide association study (GWAS) for body weight at any specific ages, but should be extended to a more general purpose by considering the whole growth trajectory over time using a growth curve approach. For such an approach, the parameters that are used to describe growth curves were treated as phenotypes under a GWAS model. Data from 1,255 Brahman cattle that were weighed at birth, 6, 12, 15, 18, and 24 months of age were analyzed. Parameter estimates, such as mature weight (A) and maturity rate (K) from nonlinear models are utilized as substitutes for the original body weights for the GWAS analysis. We chose the best nonlinear model to describe the weight-age data, and the estimated parameters were used as phenotypes in a multi-trait GWAS. Our aims were to identify and characterize associated SNP markers to indicate SNP-derived candidate genes and annotate their function as related to growth processes in beef cattle. The Brody model presented the best goodness of fit, and the heritability values for the parameter estimates for mature weight (A) and maturity rate (K) were 0.23 and 0.32, respectively, proving that these traits can be a feasible alternative when the objective is to change the shape of growth curves within genetic improvement programs. The genetic correlation between A and K was -0.84, indicating that animals with lower mature body weights reached that weight at younger ages. One hundred and sixty seven (167) and two hundred and sixty two (262) significant SNPs were associated with A and K, respectively. The annotated genes closest to the most significant SNPs for A had direct biological functions related to muscle development (RAB28), myogenic induction (BTG1), fetal growth (IL2), and body weights (APEX2); K genes were functionally associated with body weight, body height, average daily gain (TMEM18), and skeletal muscle development (SMN1). Candidate

  19. Incorporating Student Mobility in Achievement Growth Modeling: A Cross-Classified Multiple Membership Growth Curve Model

    ERIC Educational Resources Information Center

    Grady, Matthew W.; Beretvas, S. Natasha

    2010-01-01

    Multiple membership random effects models (MMREMs) have been developed for use in situations where individuals are members of multiple higher level organizational units. Despite their availability and the frequency with which multiple membership structures are encountered, no studies have extended the MMREM approach to hierarchical growth curve…

  20. Genetic parameters of traits associated with the growth curve in Segureña sheep.

    PubMed

    Lupi, T M; León, J M; Nogales, S; Barba, C; Delgado, J V

    2016-05-01

    This paper studies the genetic importance of growth curve parameters and their relevance as selection criteria in breeding programmes of Segureño sheep. Logistic and Verhulst growth functions were chosen for their best fit to BW/age in this breed; the first showed the best general fit and the second the best individual fit. Live weights of 41 330 individuals from the historical archives of the National Association of Segureña Sheep Breeders were used in the analysis. The progeny of 1464 rams and 27 048 ewes were used to study the genetic and phenotypic parameters of growth curve parameters and derived traits. Reproductive management in the population consists in controlled natural mating inside every herd, with a minimum of 15% of the females fertilized by artificial insemination with fresh semen; with the purpose being the herd genetic connections, all herd genealogies are screened with DNA markers. Estimates of growth curve parameters from birth to 80 days were obtained for each individual and each function by the non-linear regression procedure using IBM SPSS statistics (version 21) with the Levenberg-Marquart estimation method. (Co)variance components and genetic parameters were estimated by using the REML/Animal model methodology. The heritability of mature weight was estimated as 0.41±0.042 and 0.38±0.021 with the logistic and Verhulst models, respectively, and the heritability of other parameters ranged from 0.41 to 0.62 and 0.37 to 0.61, with the models, respectively. A negative genetic correlation between mature weight and rate of maturing was found. PMID:26696444

  1. Genetic parameter estimates of growth curve and reproduction traits in Japanese quail.

    PubMed

    Narinc, Dogan; Karaman, Emre; Aksoy, Tulin; Firat, Mehmet Ziya

    2014-01-01

    The goal of selection studies in broilers is to obtain genetically superior chicks in terms of major economic traits, which are mainly growth rate, meat yield, and feed conversion ratio. Multiple selection schedules for growth and reproduction are used in selection programs within commercial broiler dam lines. Modern genetic improvement methods have not been applied in experimental quail lines. The current research was conducted to estimate heritabilities and genetic correlations for growth and reproduction traits in a Japanese quail flock. The Gompertz equation was used to determine growth curve parameters. The Gibbs sampling under a multi-trait animal model was applied to estimate the heritabilities and genetic correlations for these traits. A total of 948 quail were used with complete pedigree information to estimate the genetic parameters. Heritability estimates of BW, absolute and relative growth rates at 5 wk of age (AGR and RGR), β0 and β2 parameters, and age at point of inflection (IPT) of Gompertz growth curve, total egg number (EN) from the day of first lay to 24 wk of age were moderate to high, with values ranging from 0.25 to 0.40. A low heritability (0.07) for fertility (FR) and a strong genetic correlation (0.83) between FR and EN were estimated in our study. Body weight exhibited negative genetic correlation with EN, FR, RGR, and IPT. This genetic antagonism among the mentioned traits may be overcome using modern poultry breeding methods such as selection using multi-trait best linear unbiased prediction and crossbreeding. PMID:24570419

  2. The effect of pH and storage on copper speciation and bacterial growth in complex growth media.

    PubMed

    Hasman, Henrik; Bjerrum, Morten J; Christiansen, Lasse E; Bruun Hansen, Hans Christian; Aarestrup, Frank M

    2009-07-01

    In this paper we examine how the bacterial growth is influenced by the availability of copper ions in complex Mueller Hinton growth media. The data shows that the free copper concentration is seven to eight orders of magnitude lower the total copper concentration and that there seems to be a better correlation between the free copper concentration and bacterial growth, than for the total copper concentration and growth. Furthermore, it is shown that the initial pH influences the amount of free copper ions in the media and that this has a direct effect on the ability of bacterial cultures to grow. However, there still remains an effect of pH on bacterial growth which cannot be attributed to the influence of the Cu(2+) concentration alone. The study also shows that the sterilization treatment can have some effect on the availability of copper ions in the media over time. Freshly autoclaved and sterile filtered media contain the same level of free copper ions and perform equally well in the biological assay. However, storage in the refrigerator influences the free copper contents in media, which have been autoclaved, but not in media, which were sterile filtered. Therefore, the latter method is to be recommended, when working with bacterial copper testing. PMID:19341771

  3. Development of luminescent pH sensor films for monitoring bacterial growth through tissue

    PubMed Central

    Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J.; DesJardins, John D.

    2014-01-01

    Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. PMID:23832869

  4. Blue light (470 nm) effectively inhibits bacterial and fungal growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The activity of blue light (470nm) alone on (1) bacterial viability, and (2) with a food grade photosensitizer on filamentous fungal viability, was studied. Suspensions of the bacteria Leuconostoc mesenteroides (LM), Bacillus atrophaeus (BA), and Pseudomonas aeruginosa (PA) were prepared and aliquo...

  5. Monensin inhibits growth of bacterial contaminants from fuel ethanol plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contamination of commercial fermentation cultures by lactic acid bacteria (LAB) is a common and costly problem to the fuel ethanol industry. Virginiamycin (VIR) and penicillin (PEN) are frequently used to control bacterial contamination but extensive use of antibiotics may select for strains with d...

  6. INFLUENCE OF PHOSPHATE CORROSION CONTROL COMPOUNDS ON BACTERIAL GROWTH

    EPA Science Inventory

    The influence of two phosphate corrosion compounds on the growth and survival of coliform and other heterotrophic bacteria was investigated in laboratory, field, and model system studies. Growth of Citrobacter freundii, Enterobacter cloacae, and Klebsiella pneumoniae was not sign...

  7. Effects of Au/Fe and Fe nanoparticles on Serratia bacterial growth and production of biosurfactant.

    PubMed

    Liu, Jia; Vipulanandan, Cumaraswamy

    2013-10-01

    The overall objective of this study was to compare the effects of Au/Fe and Fe nanoparticles on the growth and performance of Serratia Jl0300. The nanoparticle effect was quantified not only by the bacterial growth on agar plate after 1 hour interaction with the nanoparticles, but also by its production of a biosurfactant from used vegetable oil. The nanoparticles were prepared using the foam method. The concentrations of the nanoparticles used for the bacterial interaction study were varied from 1 mg/L to 1 g/L. The test results showed that the effect of nanoparticles on the bacterial growth and biosurfactant production varied with nanoparticle type, concentrations, and interaction time with the bacteria. Au/Fe nanoparticles didn't show toxicity to Serratia after short time (1 h) exposure, while during 8 days fermentation Au/Fe nanoparticles inhibited the growth of Serratia as well as the biosurfactant production when the concentration of the nanoparticles was higher than 10mg/L. Fe nanoparticles showed inhibition effects to bacterial growth both after short time and long time interaction with Serratia, as well as to biosurfactant production when its concentration was higher than 100 mg/L. Based on the trends observed in this study, analytical models have been developed to predict the bacterial growth and biosurfactant production with varying concentrations of nanoparticles. PMID:23910295

  8. Using growth curve analysis to examine challenges in instrumentation in longitudinal measurement in home visiting.

    PubMed

    Goltz, Heather Honoré; Mena, Kristin Cotter; Swank, Paul R

    2014-01-01

    Home visitation programs aim to decrease child maltreatment, yet limited longitudinal data exists concerning their screening and assessment instruments. "At risk" families (N = 2,054) were screened using the Family Stress Checklist and referred to Healthy Families Indiana. The Home Observation Measurement of the Environment Scale (HOME) and Community Life Skills Scale (CLS) were administered at multiple intervals. Growth curve analyses indicate families with lower HOME and CLS scores received more home visits and visits between assessments. However, these instruments may have "ceiling effects" and may be unsuitable for longitudinal assessment and program evaluation. Programmatic changes were made based on evaluation results. PMID:24405137

  9. Diffusion-limited growth in bacterial colony formation

    NASA Astrophysics Data System (ADS)

    Matsushita, Mitsugu; Fujikawa, Hiroshi

    1990-09-01

    Colonies of bacterial species called Bacillus subtilis have been found to grow two-dimensionally and self-similarly on agar plates through diffusion-limited processes in a nutrient concentration field. We obtained a fractal dimension of the colony patterns of D=1.73±0.02, very close to that of the two-dimensional DLA model, and confirmed the existence of the screening effect of protruding main branches against inner ones in a colony, the repulsion between two neighboring colonies and the tendency to grow toward nutrient. These effects are all characteristic of the pattern formation in a Laplacian field. This finding implies the importance of physical properties of the environment for the morphology of bacterial colonies in general.

  10. Logistic growth curve of chickens: a comparison of techniques to estimate parameters.

    PubMed

    Grossman, M; Bohren, B B; Anderson, V L

    1985-01-01

    Parameters of a mathematical function of growth, fit to the body weight curve of two randombred control populations of each sex of chickens from hatching through 45 weeks of age, were estimated. The logistic function was chosen from among growth formulae that express rate of gain as a function of weight at a given time and gain to be made. Two logistic parameters, growth-rate constant and age at the point of inflection, were estimated by the methods of sample quantiles and nonlinear regression from weekly mean body weights of 225 males and 281 females of the Rhode Island Red (RIR) line, and 164 males and 239 females of the White Leghorn (WL) line. Males had a larger growth-rate constant than females of the same line. The RIR line had a larger rate constant than the WL line, for each sex. Age at the point of inflection was similar for males and females in the RIR line, but smaller for males than females in the WL line. Sample quantiles yielded larger, less precise estimates of the growth-rate constant than nonlinear regression. Estimates of age at the point of inflection were usually smaller using sample quantiles. PMID:4056375

  11. Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Mehrübeoglu, Mehrube; Buck, Gregory W.; Livingston, Daniel W.

    2014-09-01

    Detection and identification of bacteria are important for health and safety. Hyperspectral imaging offers the potential to capture unique spectral patterns and spatial information from bacteria which can then be used to detect and differentiate bacterial species. Here, hyperspectral imaging has been used to characterize different bacterial colonies and investigate their growth over time. Six bacterial species (Pseudomonas fluorescens, Escherichia coli, Serratia marcescens, Salmonella enterica, Staphylococcus aureus, Enterobacter aerogenes) were grown on tryptic soy agar plates. Hyperspectral data were acquired immediately after, 24 hours after, and 96 hours after incubation. Spectral signatures from bacterial colonies demonstrated repeatable measurements for five out of six species. Spatial variations as well as changes in spectral signatures were observed across temporal measurements within and among species at multiple wavelengths due to strengthening or weakening reflectance signals from growing bacterial colonies based on their pigmentation. Between-class differences and within-class similarities were the most prominent in hyperspectral data collected 96 hours after incubation.

  12. Description of the growth curve for Angus pasture-fed cows under extensive systems.

    PubMed

    Goldberg, V; Ravagnolo, O

    2015-09-01

    Growth curves are useful for describing the sigmoid shape of an animal's weight pattern over time. The purpose of the present study was to describe, for the first time, a complete growth curve for pasture-fed Angus cows in Uruguay and to analyze the major fixed effects that affect the estimation of mature cow weight (CW). A total of 22,743 records from 5,284 cows belonging to 73 herds were used in the statistical analysis. Five nonlinear models (Brody, Gompertz, Von Bertalanffy, logistic, and Richards) and a 3-knot cubic spline function were fitted to model weight change across age. Body weights were recorded at birth, weaning, and 18 mo and as an adult (at 2.3-3.6, 3.6-4.6, 4.6 to 5.6, 5.6 to 6.6, and 6.6 to 8.1 yr). After preliminary analyses, the fixed effects included in the model to estimate CW were BCS, herd, year and month of measurement, and age of dam. The herd and BCS were the major significant sources of variation. The Richards model had the lowest values for Akaike information criterion, Bayesian information criterion, and -2 log likelihood, with the asymptotic weight being 542 kg. The spline function was the model that fitted the data most closely to the observed weights followed by the Richards function. The Richards model gave better predictions of weights from birth to maturity than the other 4 nonlinear models, because these functions were shown to over- or underestimate weights at different ages in this beef cattle data set. The predicted curve showed that cows reach mature CW after 5 yr of age, which is the age commonly assumed as adult weight in beef cattle. Results form this analysis allowed the estimation of CW and rate of maturing and to take knowledge of the shape of growth curve for Angus females in Uruguay under extensive conditions, helping breeders to take selection decisions. In this way, breeders can optimize the management and efficiency for each production system. PMID:26440328

  13. Determining Cloud Parameters with the Curve-Of-Growth: Application Eta Car

    NASA Technical Reports Server (NTRS)

    Vieira, G. L.; Gull, T. R.; Bruhweiler, F.; Nielsen, K. E.; Verner, E. M.

    2004-01-01

    We have investigated the NUV part of the Eta Car spectrum, using data with high spatial and high spectral resolving power obtained with the HST/STIS under the Treasury Program. The NUV spectrum of Eta Car Shows a great contribution of absorption features from neutral and singly ionized elements along the line-of-sight. A large number of velocity systems have been observed. The two most prominent, with Doppler shifts corresponding to -146 and -513 km/s respectively, are shown to be useful for investigations of the gaseous environments responsible for the absorption. The -146 and the -513 km/s velocity systems display different characteristics regarding the ionization state and spectral line width, which suggest that they originate at different distances from the central object. We have investigated the absorption structures before the spectroscopic minimum, occurring during the summer of 2003, with a standard curve-of-growth. We have independently derived the column density and the b-value for the Fe II (-146 km/s) and Ti II (-513 km/s) velocity systems. The excitation temperature has been determined for the -146 km/s velocity system using the photo-ionization code \\textsc(cloudy). The -146 km/s velocity structure shows noticeable variation over the spectroscopic minimum. The sudden appearance and disappearance of Ti II and V II are astonishing. We have made an attempt to analyze these variations with the curve-of-growth method and will present preliminary results.

  14. Scattering in the atmosphere of Venus. I - Line profiles and curves of growth for isotropic scattering

    NASA Technical Reports Server (NTRS)

    Young, L. D. G.; Kattawar, G. W.

    1976-01-01

    Line profiles and curves of growth were computed for both reflected and transmitted radiation for typical lines in CO2 bands (in the photographic infrared) which occur in the spectrum of Venus. In the model, the pressure variation with altitude was considered, and the base of the cloud deck was set at the 2 bar level. The temperature was held constant at 250 K, and a Voigt profile was used for the line shape. It was also assumed that the scale height of the cloud particles was equal to the scale height of the gas. The calculations were made for four values of the scattering optical thickness (0.1, 1.0, and 100) using a continuum single-scattering albedo of 0.9975 (which gives a Bond albedo of 0.896 for a scattering optical thickness of 100, the value observed for Venus at these wavelengths). Curves of growth are also presented for reflected radiation which has been averaged over the visible disk for three values of the Venus phase angle (0, 86, and 166 deg).

  15. Inhibition of bacterial growth by iron oxide nanoparticles with and without attached drug: Have we conquered the antibiotic resistance problem?

    NASA Astrophysics Data System (ADS)

    Armijo, Leisha M.; Jain, Priyanka; Malagodi, Angelina; Fornelli, F. Zuly; Hayat, Allison; Rivera, Antonio C.; French, Michael; Smyth, Hugh D. C.; Osiński, Marek

    2015-03-01

    Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.

  16. Mode of growth of bacterial pathogens in chronic polymicrobial human osteomyelitis.

    PubMed Central

    Marrie, T J; Costerton, J W

    1985-01-01

    Direct examination of material from two cases of persistent (2 and 60 years) osteomyelitis by morphological and culture techniques showed that the pathogens comprised several bacterial species whose cells grew predominantly in discrete exopolysaccharide-enclosed microcolonies made up of a single bacterial morphotype. Bacterial microcolonies were seen between tissue elements in infected connective tissue, and the microcolonies adherent to bone surfaces coalesced to form extensive biofilms that occluded the surfaces of dead bone in sequestrae. Decalcification techniques were required to examine the interior of infected bone, but recognizable remnants were associated with very large amounts of fibrous, ruthenium red-stained material. All bacterial growth in these persistent infections occurred within an intercellular matrix, and some elements of this matrix, which was fibrous in transmission electron microscopy and amorphous in scanning electron microscopy, were associated with the surfaces of bacterial cells in a manner that suggested their production by these organisms. All of the implications of this microcolony mode of bacterial growth in osteomyelitis, and in other chronic bacterial diseases, have yet to be determined. Images PMID:4066923

  17. Analyzing Exercise Behaviors during the College Years: Results from Latent Growth Curve Analysis

    PubMed Central

    Wittman, Werner

    2016-01-01

    The objective of this study is to analyze changes in the predictors of physical activity behavior among college students. The Theory of Planned Behavior served as its theoretical framework. Methods: Among an initial sample of 417 college students, 195 participants completed a validated questionnaire measuring attitudes, subjective norms, perceived control, intentions and self-reported physical activity, at the beginning and end of each of 3 college semesters. Latent growth curve modeling analyses were conducted to examine the relationships between the trajectories of changes in PA, intentions, attitudes, subjective norms, and perceived control. Results: Good fit indices supported the validity of the proposed longitudinal model (CFI > .97, RMSEA < .05). Changes in perceived control (γ = 0.57) were significantly linked with changes in intentions (p < .05). Perceived control (γ = 0.28) and intention growth (γ = 0.36) predicted behavior changes (p < .05). No gender differences were observed on attitudes, subjective norms and perceived control (p > .10). However, girls tend to have higher growth parameters on intentions and physical activity (p < .05). In summary, intentions and physical activity has significantly increased over 3 college semesters (growth parameters significant at p < .05). Conclusions: This study demonstrated that attitudes and perceived control are key determinants regarding the intentions of being active. On a longer term perspective, future physical activity interventions should focus on the enhancement of students’ perceived control. Such educational context should help in promoting the adoption of an active lifestyle during college. PMID:27124179

  18. Growth curve changes associated with long-term selection for body weight in Japanese quail.

    PubMed

    Marks, H L

    1978-06-01

    Four quail lines were utilized to investigate growth patterns in quail. Three of these lines (P, T and S) had previously undergone long-term selection for high 4-week body weight, while line C was maintained as a nonselected control. Quail progeny from generation 37 and 38 breeders were fed diets containing 28% and 20% protein. Within each trial, the diet/line treatments were replicated 3 times with 12 quail per subclass. Body weight measurements suggested that the growth of all lines was best approximated by the logistic growth curve model. When fed a 28% protein diet the age at maximum growth (point of inflection) of selected lines was 4 to 6 days earlier than the corresponding age of controls. Similar rates of gain after 4 weeks of age between selected and control lines suggested that mechanisms influenced by selection for 4-week body weight in quail operate only during the period prior to the age at selection with little or no residual effect. PMID:680578

  19. Growth curves in short supply: a descriptive study of the availability and utility of growth curve data in adolescents with eating disorders

    PubMed Central

    2013-01-01

    Background Healthy body weight (HBW) determination affects multiple aspects of eating disorder (ED) treatment. For example, it can inform patients and providers as to when return of menses (ROM), an objective determinant of health, can occur. Growth curves (GCs) are sensitive indicators of health in youth and when up to date provide critical information regarding normal and expected trajectories of growth. Although not widely recommended as a first line tool for HBW calculation, a GC guides providers selecting a HBW that is individualized to each patient. The primary aim of this paper was to assess availability and feasibility of utilizing GC data for HBW prediction in adolescents referred for an ED assessment. We also sought to determine how this calculation compared to the standardized HBW calculation that uses mean body mass index (BMI) for age and how each of these numbers compared to the actual weight at ROM. Methods A retrospective chart review was completed on outpatients assessed for EDs between January 2004 and December 2006. A total of 102 patients met inclusion criteria. Demographic information, GC data, HBW predictions, and menstrual history were analyzed. A comparison of predicted HBWs using the aforementioned calculations and weight at ROM was performed using t-test analyses. Results Eighty-one patients (79.4%) had GC data available at assessment although HBW prediction was possible in only 24 patients (23.8%) due to poor GC completion. Of those 24 patients, 9 had ROM data available; no significant difference between our predicted HBW and the weight at ROM was found in these patients. In cases where HBW predictions could be compared using GC data and the BMI method, we found the GC calculation to be overall superior. Conclusions We found overall rates of GC completion to be very low in our patients, which in turn limited the feasibility of relying on a GC for HBW calculation in ED patients. When complete, GCs provide accurate HBWs for most patients

  20. Shaping the Growth Behaviour of Biofilms Initiated from Bacterial Aggregates.

    PubMed

    Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Stephen P; Gordon, Vernita D; Allen, Rosalind J

    2016-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities. PMID:26934187

  1. Shaping the Growth Behaviour of Biofilms Initiated from Bacterial Aggregates

    PubMed Central

    Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Stephen P.; Gordon, Vernita D.; Allen, Rosalind J.

    2016-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities. PMID:26934187

  2. Bacterial growth on a superhydrophobic surface containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Heinonen, S.; Nikkanen, J.-P.; Laakso, J.; Raulio, M.; Priha, O.; Levänen, E.

    2013-12-01

    The antibacterial effect of silver can be exploited in the food and beverage industry and medicinal applications to reduce biofouling of surfaces. Very small amount of silver ions are enough to destructively affect the metabolism of bacteria. Moreover, superhydrophobic properties could reduce bacterial adhesion to the surface. In this study we fabricated superhydrophobic surfaces that contained nanosized silver particles. The superhydrophobic surfaces were manufactured onto stainless steel as combination of ceramic nanotopography and hydrophobication by fluorosilane. Silver nanoparticles were precipitated onto the surface by a chemical method. The dissolution of silver from the surface was tested in an aqueous environment under pH values of 1, 3, 5, 7, 9, 11 and 13. The pH value was adjusted with nitric acid and ammonia. It was found that dissolution rate of silver increased as the pH of the solution altered from the pH of de-ionized water to lower and higher pH values but dissolution occurred also in de-ionized water. The antimicrobial potential of this coating was investigated using bacterial strains isolated from the brewery equipment surfaces. The results showed that the number of bacteria adhering onto steel surface was significantly reduced (88%) on the superhydrophobic silver containing coating.

  3. Bacterial Growth on Distant Naphthalene Diffusing through Water, Air, and Water-Saturated and Nonsaturated Porous Media

    PubMed Central

    Harms, H.

    1996-01-01

    The influence of substrate diffusion on bacterial growth was investigated. Crystalline naphthalene was supplied as the substrate at various distances in the range of centimeters from naphthalene-degrading organisms separated from the substrate by agar-solidified mineral medium. Within 2 weeks, the cells grew to final numbers which were negatively correlated with the distance from the substrate. A mathematical model that combined (i) Monod growth kinetics extended by a term for culture maintenance and (ii) substrate diffusion could explain the observed growth curves. The model could also predict growth on naphthalene that was separated from the bacteria by air. In addition, the bacteria were grown on distant naphthalene that had to diffuse to the cells through water-saturated and unsaturated porous media. The growth of the bacteria could be used to calculate the effective diffusivity of naphthalene in the three-phase system. Diffusion of naphthalene in the pore space containing 80% air was roughly 1 order of magnitude faster than in medium containing only 20% air because of the high Henry's law coefficient of naphthalene. It is proposed that the effective diffusivities of the substrates and the spatial distribution of substrates and bacteria are the main determinants of final cell numbers and, consequently, final degradation rates. PMID:16535349

  4. Growth studies on Mycobacterium BCG: establishment of growth curves and measurement of the oxygen tension of the growth medium.

    PubMed

    Moore, D F; James, A M

    1982-01-01

    Mycobacterium BCG grew exponentially in shallow, static volumes of culture medium for approximately 10 days; the oxygen tension of the medium at all stages of growth was 100% saturation. Higher yields were obtained from Dubos than from glycerol-free medium. In static cultures, the oxygen tension of the culture and consequently the growth rate of BCG was dependent on the depth of the medium; active growth ceased at an oxygen tension of less than 40% saturation. BCG grew actively in a cell sediment, while cells growing in suspension made a negligible contribution to the yield. PMID:6757673

  5. Growth-rate-dependent dynamics of a bacterial genetic oscillator

    NASA Astrophysics Data System (ADS)

    Osella, Matteo; Lagomarsino, Marco Cosentino

    2013-01-01

    Gene networks exhibiting oscillatory dynamics are widespread in biology. The minimal regulatory designs giving rise to oscillations have been implemented synthetically and studied by mathematical modeling. However, most of the available analyses generally neglect the coupling of regulatory circuits with the cellular “chassis” in which the circuits are embedded. For example, the intracellular macromolecular composition of fast-growing bacteria changes with growth rate. As a consequence, important parameters of gene expression, such as ribosome concentration or cell volume, are growth-rate dependent, ultimately coupling the dynamics of genetic circuits with cell physiology. This work addresses the effects of growth rate on the dynamics of a paradigmatic example of genetic oscillator, the repressilator. Making use of empirical growth-rate dependencies of parameters in bacteria, we show that the repressilator dynamics can switch between oscillations and convergence to a fixed point depending on the cellular state of growth, and thus on the nutrients it is fed. The physical support of the circuit (type of plasmid or gene positions on the chromosome) also plays an important role in determining the oscillation stability and the growth-rate dependence of period and amplitude. This analysis has potential application in the field of synthetic biology, and suggests that the coupling between endogenous genetic oscillators and cell physiology can have substantial consequences for their functionality.

  6. Moral Disengagement, Anticipated Social Outcomes and Adolescents' Alcohol Use: Parallel Latent Growth Curve Analyses.

    PubMed

    Quinn, Catherine A; Bussey, Kay

    2015-10-01

    Moral disengagement is a social cognitive process that has been extensively applied to transgressive behaviors, including delinquency, aggression and illicit substance use. However, there has been limited research on moral disengagement as it relates to underage drinking. The current study aimed to examine moral disengagement contextualized to underage drinking and its longitudinal relationship to alcohol use. Moreover, the social context in which adolescent alcohol use typically occurs was also considered, with a specific emphasis on the social sanctions, or social outcomes, that adolescents anticipate receiving from friends for their alcohol use. Adolescents were assessed across three time-points, 8 months apart. The longitudinal sample consisted of 382 (46% female) underage drinkers (12-16 years at T1). Parallel latent growth curve analysis was used to examine the bi-directional influence of initial moral disengagement, anticipated social outcomes, and alcohol use on subsequent growth in moral disengagement, anticipated social outcomes and alcohol use. The interrelation of initial scores and growth curves was also assessed. The findings revealed that, in the binary parallel analyses, initial moral disengagement and anticipated social outcomes both significantly predicted changes in alcohol use across time. Moreover, initial anticipated social outcomes predicted changes in moral disengagement. These findings were not consistently found when all three process analyses were included in a single model. The results emphasize the impact of social context on moral disengagement and suggest that by targeting adolescents' propensity to justify or excuse their drinking, as well as the social outcomes adolescents anticipate for being drunk, it may be possible to reduce their underage drinking. PMID:26318080

  7. Theoretical and Experimental Study of Bacterial Colony Growth in 3D

    NASA Astrophysics Data System (ADS)

    Shao, Xinxian; Mugler, Andrew; Nemenman, Ilya

    2014-03-01

    Bacterial cells growing in liquid culture have been well studied and modeled. However, in nature, bacteria often grow as biofilms or colonies in physically structured habitats. A comprehensive model for population growth in such conditions has not yet been developed. Based on the well-established theory for bacterial growth in liquid culture, we develop a model for colony growth in 3D in which a homogeneous colony of cells locally consume a diffusing nutrient. We predict that colony growth is initially exponential, as in liquid culture, but quickly slows to sub-exponential after nutrient is locally depleted. This prediction is consistent with our experiments performed with E. coli in soft agar. Our model provides a baseline to which studies of complex growth process, such as such as spatially and phenotypically heterogeneous colonies, must be compared.

  8. Essays on the predictability of oil shocks and yield curves for real-time output growth

    NASA Astrophysics Data System (ADS)

    Carlton, Amelie B.

    This dissertation is a collection of three essays that revisits the long-standing puzzle of the apparently disproportionate effect of oil prices in the economy by examining output growth predictability with real-time data. Each study of the predictive content of oil shocks is from a different perspective by using newly developed real-time datasets, which allows for replicating the economic environment faced by policymakers in real time. The first study extends the conventional set of models of output growth determination by investigating predictability of models that incorporate various functional forms of oil prices and real-time data. The results are supportive of the relationship of GDP and oil in the context of Granger causality with real-time data. In the second essay, I use oil shocks to predict the economy is changing direction earlier than would be predicted by solely using initial GDP releases. The model provides compelling evidence of negative GDP growth predictability in response to oil price shocks, which could shorten the "recognition lag" for successful implementation of discretionary counter-cyclical policies. In the third essay, I evaluate short-horizon output growth predictability using real-time data for different sample periods. I find strong evidence of predictability at the one-quarter and four-quarter horizon for the United States. The major result of the paper is that we reject the null hypothesis of no predictability against an alternative hypothesis of predictability with oil shocks that include yield curves in the forecasting regression. This relationship suggests the combination of monetary policy and oil shocks are important for subsequent GDP growth.

  9. Optimization of a new mathematical model for bacterial growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research is to optimize a new mathematical equation as a primary model to describe the growth of bacteria under constant temperature conditions. An optimization algorithm was used in combination with a numerical (Runge-Kutta) method to solve the differential form of the new gr...

  10. Supplemental oxygen attenuates the increase in wound bacterial growth during simulated aeromedical evacuation in goats

    PubMed Central

    Earnest, Ryan E.; Sonnier, Dennis I.; Makley, Amy T.; Campion, Eric M.; Wenke, Joseph C.; Bailey, Stephanie R.; Dorlac, Warren C.; Lentsch, Alex B.; Pritts, Timothy A.

    2012-01-01

    Background Bacterial growth in soft tissue and open fractures is a known risk factor for tissue loss and complications in contaminated musculoskeletal wounds. Current care for battlefield casualties with soft tissue and musculoskeletal wounds includes tactical and strategic aeromedical evacuation (AE). This exposes patients to a hypobaric, hypoxic environment. In the present study, we sought to determine whether exposure to AE alters bacterial growth in contaminated complex musculoskeletal wounds and whether supplemental oxygen had any effect on wound infections during simulated AE. Methods A caprine model of a contaminated complex musculoskeletal wound was employed. Complex musculoskeletal wounds were created and inoculated with bioluminescent Pseudomonas aeruginosa. Goats were divided into three experimental groups: ground control, simulated aeromedical evacuation (AE), and simulated AE with supplemental oxygen (AE+O2). Simulated AE was induced in a hypobaric chamber pressurized to 8800 feet for 7 hours. Bacterial luminescence was measured using a photon counting camera at three timepoints: preflight (20 hours post surgery), postflight (7 hours from preflight and 27 hours post-surgery), and necropsy (24 hours from preflight and 44 hours post surgery). Results There was a significant increase in bacterial growth in the AE group compared to the ground control group measured postflight and at necropsy. Simulated AE induced hypoxia with oxygen saturation less than 93%. Supplemental oxygen corrected the hypoxia and significantly reduced bacterial growth in wounds at necropsy. Conclusions Hypoxia induced during simulated AE enhances bacterial growth in complex musculoskeletal wounds which can be prevented with the application of supplemental oxygen to the host. PMID:22743376

  11. Volatile Emissions from Mycobacterium avium subsp. paratuberculosis Mirror Bacterial Growth and Enable Distinction of Different Strains

    PubMed Central

    Trefz, Phillip; Koehler, Heike; Klepik, Klaus; Moebius, Petra; Reinhold, Petra; Schubert, Jochen K.; Miekisch, Wolfram

    2013-01-01

    Control of paratuberculosis in livestock is hampered by the low sensitivity of established direct and indirect diagnostic methods. Like other bacteria, Mycobacterium avium subsp. paratuberculosis (MAP) emits volatile organic compounds (VOCs). Differences of VOC patterns in breath and feces of infected and not infected animals were described in first pilot experiments but detailed information on potential marker substances is missing. This study was intended to look for characteristic volatile substances in the headspace of cultures of different MAP strains and to find out how the emission of VOCs was affected by density of bacterial growth. One laboratory adapted and four field strains, three of MAP C-type and one MAP S-type were cultivated on Herrold’s egg yolk medium in dilutions of 10-0, 10-2, 10-4 and 10-6. Volatile substances were pre-concentrated from the headspace over the MAP cultures by means of Solid Phase Micro Extraction (SPME), thermally desorbed from the SPME fibers and separated and identified by means of GC-MS. Out of the large number of compounds found in the headspace over MAP cultures, 34 volatile marker substances could be identified as potential biomarkers for growth and metabolic activity. All five MAP strains could clearly be distinguished from blank culture media by means of emission patterns based on these 34 substances. In addition, patterns of volatiles emitted by the reference strain were significantly different from the field strains. Headspace concentrations of 2-ethylfuran, 2-methylfuran, 3-methylfuran, 2-pentylfuran, ethyl acetate, 1-methyl-1-H-pyrrole and dimethyldisulfide varied with density of bacterial growth. Analysis of VOCs emitted from mycobacterial cultures can be used to identify bacterial growth and, in addition, to differentiate between different bacterial strains. VOC emission patterns may be used to approximate bacterial growth density. In a perspective volatile marker substances could be used to diagnose MAP

  12. Accuracy of Estimates and Statistical Power for Testing Meditation in Latent Growth Curve Modeling

    PubMed Central

    Cheong, JeeWon

    2016-01-01

    The latent growth curve modeling (LGCM) approach has been increasingly utilized to investigate longitudinal mediation. However, little is known about the accuracy of the estimates and statistical power when mediation is evaluated in the LGCM framework. A simulation study was conducted to address these issues under various conditions including sample size, effect size of mediated effect, number of measurement occasions, and R2 of measured variables. In general, the results showed that relatively large samples were needed to accurately estimate the mediated effects and to have adequate statistical power, when testing mediation in the LGCM framework. Guidelines for designing studies to examine longitudinal mediation and ways to improve the accuracy of the estimates and statistical power were discussed.

  13. Radiative heat transfer in curved specular surfaces in Czochralski crystal growth furnace

    SciTech Connect

    Guo, Z.; Maruyama, Shigenao; Tsukada, Takao

    1997-11-07

    A numerical investigation of radiative heat transfer constructed by curved surfaces with specular and diffuse reflection components is carried out. The ray tracing method is adopted for the calculation of view factors, in which a new ray emission model is proposed. The second-degree radiation ring elements are introduced, which are of engineering importance and numerical efficiency. The accuracy of the method is analyzed and verified using a simple configuration. The present computation using the proposed ray emission model is in good agreement with the analytical solution. As a numerical example and engineering application, the effects of the specular reflection and the meniscus of the melt surface in Czochralski (CZ) crystal growth are investigated. A marked temperature decrease in the melt surface is found by introducing specular reflection and the meniscus. The combined effects of the specular reflection and the meniscus should be considered in precision heat transfer control of a CZ apparatus.

  14. Determining cloud parameters with the Curve-of-Growth: Application Eta Car

    NASA Astrophysics Data System (ADS)

    Vieira, G. L.; Gull, T. R.; Bruhweiler, F.; Nielsen, K. E.; Verner, E. M.; Eta Car HST Treasury Team

    2003-12-01

    We have investigated the NUV part of the Eta Car spectrum, using data with high spatial and high spectral resolving power obtained with the HST/STIS under the Treasury Program (K. Davidson P.I.). The NUV spectrum of Eta Car shows a great contribution of absorption features from neutral and singly ionized elements along the line-of-sight. A large number of velocity systems have been observed. The two most prominent, with Doppler shifts corresponding to -146 and -513 km/s respectively, are shown to be useful for investigations of the gaseous environments responsible for the absorption. The -146 and the -513 km/s velocity systems display different characteristics regarding the ionization state and spectral line width, which suggest that they originate at different distances from the central object. We have investigated the absorption structures before the spectroscopic minimum, occurring during the summer of 2003, with a standard curve-of-growth. We have independently derived the column density and the b-value for the Fe II (-146 km/s) and Ti II (-513 km/s) velocity systems. The excitation temperature has been determined for the -146 km/s velocity system using the photo-ionization code \\textsc{cloudy} (Ferland 1996, Ferland et al. 2000). The -146 km/s velocity structure shows noticeable variation over the spectroscopic minimum. The sudden appearance and disappearance of Ti II and V II are astonishing. We have made an attempt to analyze these variations with the curve-of-growth method and will present preliminary results.

  15. Tidally Induced Changes in Bacterial Growth and Viability in the Macrotidal Han River Estuary, Yellow Sea

    NASA Astrophysics Data System (ADS)

    Hyun, J.-H.; Choi, J. K.; Chung, K. H.; Yang, E.-J.; Kim, M.-K.

    1999-02-01

    The Han River estuary in the Yellow Sea is a macrotidal (tidal range of 3·5 m at neap tide and 8·0 m at spring tide) eutrophic environment. Changes in bacterial growth and viability at different NaCl concentrations as well as other physico-chemical environmental parameters were investigated at different tidal levels in order to elucidate the major environmental factors controlling the bacterial community. Bacterial growth rates (μ) varied with tidal state; maximum (μ=0·159 h -1) at high tide, and minimum (μ=0·069 h -1) at low tide. Although bacteria play a substantial role in ammonia removal and regeneration, growth was not controlled by the fluctuations of nutrient concentrations in the high nutrient estuary. The low viable cell number recorded with the increased NaCl concentration indicated that the salinity changes with tidal state was a major environmental factor controlling the viability of the freshwater bacterial populations. Portions of freshwater bacterial CFU (colony forming units) during low tide accounted for approximately 30% of the total CFU, and decreased down to 10% during high tide. Overall, the results indicate that the microbial communities in the macrotidal Han River estuary can be divided into two distinct groups according to the variations in salinity and freshwater runoff: (1) autochthonous halotolerant estuarine populations which are nourished by the high nutrient runoff; and (2) allochthonous halophobic freshwater populations which are adversely affected by salinity increase.

  16. Estimation of median growth curves for children up two years old based on biresponse local linear estimator

    NASA Astrophysics Data System (ADS)

    Chamidah, Nur; Rifada, Marisa

    2016-03-01

    There is significant of the coeficient correlation between weight and height of the children. Therefore, the simultaneous model estimation is better than partial single response approach. In this study we investigate the pattern of sex difference in growth curve of children from birth up to two years of age in Surabaya, Indonesia based on biresponse model. The data was collected in a longitudinal representative sample of the Surabaya population of healthy children that consists of two response variables i.e. weight (kg) and height (cm). While a predictor variable is age (month). Based on generalized cross validation criterion, the modeling result based on biresponse model by using local linear estimator for boy and girl growth curve gives optimal bandwidth i.e 1.41 and 1.56 and the determination coefficient (R2) i.e. 99.99% and 99.98%,.respectively. Both boy and girl curves satisfy the goodness of fit criterion i.e..the determination coefficient tends to one. Also, there is difference pattern of growth curve between boy and girl. The boy median growth curves is higher than those of girl curve.

  17. EFFECT OF THE GROWTH REGULATOR PACLOBUTRAZOL ON GROWTH OF THE BACTERIAL PATHOGEN XYLELLA FASTIDIOSA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xyella fastidiosa is a fastidious, xylem-limited, insect transmitted, bacterial plant pathogen that has a wide host range and causes bacterial leaf scorch (BLS) in shade trees. BLS is a chronic disorder characterized by late season leaf scorch and dieback and is common in urban and suburban areas o...

  18. Effects of nitric oxide and nitrogen dioxide on bacterial growth

    NASA Technical Reports Server (NTRS)

    Mancinelli, R. L.; Mckay, C. P.

    1983-01-01

    While it is generally thought that the bactericidal effects of NO and NO2 derive from their reaction with water to form nitrous and nitric acids (Shank et al., 1962), this appears to be true only at high concentrations. The data presented here suggest that at low NO and NO2 concentrations, acids are not present in high enough concentrations to act as toxic agents. Reference is made to a study by Grant et al. (1979), which found that exposing acid forest soil to 1 ppm of NO2 did not cause the soil pH to drop. The results presented here show that at low concentrations of NO and NO2, the NO is bacteriostatic for some organisms and not for others, whereas NO2 may protect some bacteria from the inhibitory effects of NO. Since it has been shown that bacteria can divide while airborne (Dimmick et al., 1979), the present results suggest that NO at the low concentrations found in the atmosphere can select for resistant bacteria in the air and affect the viable airborne bacterial population.

  19. Divergent effects of desferrioxamine on bacterial growth and characteristics.

    PubMed

    Eto, Daisei; Watanabe, Kenta; Saeki, Hisafumi; Oinuma, Ken-ichi; Otani, Ko-ichi; Nobukuni, Megumi; Shiratori-Takano, Hatsumi; Takano, Hideaki; Beppu, Teruhiko; Ueda, Kenji

    2013-04-01

    Desferrioxamines (DF's) are siderophores produced by some groups of bacteria. Previously, we discovered that DFE, produced by Streptomyces griseus, induced divergent developmental phenotypes in various Streptomyces isolates. In this study, we isolated bacteria whose phenotype was affected by the presence of 0.1 mM DFB from soil samples, and studied their phylogenetic position via 16 S rRNA gene-based analysis. Isolates belonging to Microbacterium grew only in the presence of DFB in the medium. DFB promoted growth of some isolates, while significantly inhibiting that of other divergent bacteria. Different groups of isolates were affected, not because of growth-related changes, but because of changes in the colony morphology based on possible stimulation of motility. An isolate affiliated with Janthinobacterium was stimulated for violacein production as well as for pilus formation. The wide and divergent effects of DFB suggest that availability of siderophores significantly affect the structure of microbial community. PMID:23232933

  20. Differential growth responses of soil bacterial taxa to carbon substrates of varying chemical recalcitrance

    SciTech Connect

    Goldfarb, K.C.; Karaoz, U.; Hanson, C.A.; Santee, C.A.; Bradford, M.A.; Treseder, K.K.; Wallenstein, M.D.; Brodie, E.L.

    2011-04-18

    Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin-protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial composition.

  1. Rapid detection of bacterial growth in blood samples by a continuous-monitoring electrical impedance apparatus.

    PubMed Central

    Specter, S; Throm, R; Strauss, R; Friedman, H

    1977-01-01

    A growth detection method utilizing an automated apparatus capable of rapidly detecting bacterial growth by measuring changes of electrical impedance in bacteriological medium was utilized with "mock" blood cultures containing various gram-negative and gram-positive bacteria. Measurement of changes of electrical impedance was found to ba as accurate and comparable for time of growth detection as the radiometric method for detection of the same bacteria using mock blood cultures. In a limited clinical trial the use of the electrical impedance apparatus detected in 1 positive specimen from 40 clinical blood specimens as rapidly as by radiometric measurement. Both methods were considerably faster for detecting bacterial growth as compared with conventional culture methods. The selected species of gram-positive and -negative organisms tested were all detected by the electrical impedance method, including aerobes and anerobes. However, addition of 5% CO2 to the incubation atmosphere enhanced detection of gram-positive organisms. PMID:336642

  2. Stimulation of Lipase Production During Bacterial Growth on Alkanes

    PubMed Central

    Breuil, Colette; Shindler, D. B.; Sijher, J. S.; Kushner, D. J.

    1978-01-01

    Acinetobacter lwoffi strain O16, a facultative psychrophile, can grow on crude oil, hexadecane, octadecane, and most alkanes when tested at 20 but not at 30°C. Growth occurred on a few alkanes at 30°C but after a longer lag than at 20°C. Cells grown on alkanes as sole carbon sources had high levels of cell-bound lipase. In contrast, previous work has shown that those grown on complex medium produced cell-free lipase and those grown on defined medium without alkanes produced little or no lipase. Low concentrations of the detergent Triton X-100 caused the liberation of most of the lipase activity of alkane-grown cells and increased total lipase activity. When ethanol and hexadecane were both present in a mineral medium, diauxic growth occurred; until the ethanol was completely used up, hexadecane was not utilized, and the lipase activity was very low. When growth on hexadecane began, lipase activity increased, reaching a level 50- to 100-fold higher than that of cells growing on ethanol. A similar pattern of lipase formation and hexadecane utilization was observed with Pseudomonas aeruginosa. Whenever A. lwoffi and other bacteria degraded alkanes they exhibited substantial lipase activity. Not all bacteria that produced lipase, however, could attack alkanes. Bacteria that could not produce lipase did not attack alkanes. The results suggest that a correlation may exist between lipase formation and alkane utilization. PMID:627533

  3. Cell Wall Nonlinear Elasticity and Growth Dynamics: How Do Bacterial Cells Regulate Pressure and Growth?

    NASA Astrophysics Data System (ADS)

    Deng, Yi

    In my thesis, I study intact and bulging Escherichia coli cells using atomic force microscopy to separate the contributions of the cell wall and turgor pressure to the overall cell stiffness. I find strong evidence of power--law stress--stiffening in the E. coli cell wall, with an exponent of 1.22±0.12, such that the wall is significantly stiffer in intact cells (E = 23±8 MPa and 49±20 MPa in the axial and circumferential directions) than in unpressurized sacculi. These measurements also indicate that the turgor pressure in living cells E. coli is 29±3 kPa. The nonlinearity in cell elasticity serves as a plausible mechanism to balance the mechanical protection and tension measurement sensitivity of the cell envelope. I also study the growth dynamics of the Bacillus subtilis cell wall to help understand the mechanism of the spatiotemporal order of inserting new cell wall material. High density fluorescent markers are used to label the entire cell surface to capture the morphological changes of the cell surface at sub-cellular to diffraction-limited spatial resolution and sub-minute temporal resolution. This approach reveals that rod-shaped chaining B. subtilis cells grow and twist in a highly heterogeneous fashion both spatially and temporally. Regions of high growth and twisting activity have a typical length scale of 5 μm, and last for 10-40 minutes. Motivated by the quantification of the cell wall growth dynamics, two microscopy and image analysis techniques are developed and applied to broader applications beyond resolving bacterial growth. To resolve densely distributed quantum dots, we present a fast and efficient image analysis algorithm, namely Spatial Covariance Reconstruction (SCORE) microscopy that takes into account the blinking statistics of the fluorescence emitters. We achieve sub-diffraction lateral resolution of 100 nm from 5 to 7 seconds of imaging, which is at least an order of magnitude faster than single-particle localization based methods

  4. Trajectories of Change in Obesity among Tehranian Families: Multilevel Latent Growth Curve Modeling

    PubMed Central

    Akbarzadeh, Mahdi; Mahjub, Hossein; Soltanian, Ali Reza; Daneshpour, Maryam; Morris, Nathan

    2016-01-01

    Objectives. To evaluate the trajectories of change in obesity within and between Tehranian families, who participated in the Tehran Lipid and Glucose Study (TLGS). Methods. This study is a family-based longitudinal design, in four waves. A total of 14761 individuals, within 3980 families, were selected. Three anthropometric measurements, body mass index (BMI), waist circumference (WC), and a body shape index (ABSI), were recorded. Multilevel latent growth curve modeling (MLGCM) approach was used for evaluating the change trajectories in obesity within and between the families. Results. The mean age of the subjects in the present study was 33.28 ± 19.01 (range 3–89 years) and 50.1% were male. Obesity was significantly increased (P < 0.001). Individuals with more fat become obese slower, whereas families with more fat become obese faster (P < 0.001). The initial value and growth rate of WC and ABSI were greater in men than in women, while this result is contrary to BMI (P < 0.001). Conclusions. Our findings demonstrated that there is an alarming increase in the obesity trend in Tehranian families. The important role of the family in the prevention of obesity is highlighted, underlining the need for public health programs, as family centered educations to lifestyle modification, which can address this emerging crisis. PMID:27042349

  5. Dynamic Metabolic Modeling of Denitrifying Bacterial Growth: The Cybernetic Approach

    SciTech Connect

    Song, Hyun-Seob; Liu, Chongxuan

    2015-06-29

    Denitrification is a multistage reduction process converting nitrate ultimately to nitrogen gas, carried out mostly by facultative bacteria. Modeling of the denitrification process is challenging due to the complex metabolic regulation that modulates sequential formation and consumption of a series of nitrogen oxide intermediates, which serve as the final electron acceptors for denitrifying bacteria. In this work, we examined the effectiveness and accuracy of the cybernetic modeling framework in simulating the growth dynamics of denitrifying bacteria in comparison with kinetic models. In four different case studies using the literature data, we successfully simulated diauxic and triauxic growth patterns observed in anoxic and aerobic conditions, only by tuning two or three parameters. In order to understand the regulatory structure of the cybernetic model, we systematically analyzed the effect of cybernetic control variables on simulation accuracy. The results showed that the consideration of both enzyme synthesis and activity control through u- and v-variables is necessary and relevant and that uvariables are of greater importance in comparison to v-variables. In contrast, simple kinetic models were unable to accurately capture dynamic metabolic shifts across alternative electron acceptors, unless an inhibition term was additionally incorporated. Therefore, the denitrification process represents a reasonable example highlighting the criticality of considering dynamic regulation for successful metabolic modeling.

  6. Bacterial growth in a simulated Martian subsurface environment

    NASA Astrophysics Data System (ADS)

    Kronyak, R. E.; Pavlov, A.; House, C. H.

    2013-12-01

    The ability of microorganisms to grow under Martian conditions has implications in both the search for life and habitability of Mars as well as the potential contamination of Mars by landing spacecraft. Factors that inhibit the growth of organisms on Mars include UV radiation, low pressure and temperature, CO2 atmosphere, lack of liquid water, and extreme desiccation. Yet a possible biozone capable of supporting microbial life on Mars exists in the shallow subsurface where there is protection from harsh UV rays. In addition, the presence of widespread subsurface ice, confirmed by the Phoenix Lander, offers a water source as the ice sublimates through the upper soil. Here we will determine the ability of the organism Halomonas desiderata strain SP1 to grow in the simulated Martian subsurface environment. Halomonas was chosen as the bacteria of interest due to its tolerance to extreme environments, including carrying salt concentrations and pH. Experiments were carried out in the Mars Simulation Chamber, where temperatures, pressures, and atmospheric composition can be closely monitored to simulate Martian conditions. A series of stress experiments were conducted to observe Halomonas's ability to withstand exposure to a Mars analog soil, freezing temperatures, anoxic conditions, and low pressures. We have determined that Halomonas is able to survive exposures to low temperatures, pressures, and anoxic conditions. We will report on the survival and growth of Halomonas in the simulated Martian permafrost under low (6-10 mbar) atmospheric pressures.

  7. Growth Curves of Preschool Children in the Northeast of Iran: A Population Based Study Using Quantile Regression Approach

    PubMed Central

    Payande, Abolfazl; Tabesh, Hamed; Shakeri, Mohammad Taghi; Saki, Azadeh; Safarian, Mohammad

    2013-01-01

    Introduction: Growth charts are widely used to assess children’s growth status and can provide a trajectory of growth during early important months of life. The objectives of this study are going to construct growth charts and normal values of weight-for-age for children aged 0 to 5 years using a powerful and applicable methodology. The results compare with the World Health Organization (WHO) references and semi-parametric LMS method of Cole and Green. Methods: A total of 70737 apparently healthy boys and girls aged 0 to 5 years were recruited in July 2004 for 20 days from those attending community clinics for routine health checks as a part of a national survey. Anthropometric measurements were done by trained health staff using WHO methodology. The nonparametric quantile regression method obtained by local constant kernel estimation of conditional quantiles curves using for estimation of curves and normal values. Results: The weight-for-age growth curves for boys and girls aged from 0 to 5 years were derived utilizing a population of children living in the northeast of Iran. The results were similar to the ones obtained by the semi-parametric LMS method in the same data. Among all age groups from 0 to 5 years, the median values of children’s weight living in the northeast of Iran were lower than the corresponding values in WHO reference data. The weight curves of boys were higher than those of girls in all age groups. Conclusion: The differences between growth patterns of children living in the northeast of Iran versus international ones necessitate using local and regional growth charts. International normal values may not properly recognize the populations at risk for growth problems in Iranian children. Quantile regression (QR) as a flexible method which doesn’t require restricted assumptions, proposed for estimation reference curves and normal values. PMID:23618470

  8. Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation

    SciTech Connect

    Zhang Shengli; Zhang Lei; Liang Run; Zhang Erhu; Liu Yachao; Zhao Shumin

    2005-11-01

    In this paper, we study the morphological transition of bacterial colonies exposed to ultraviolet radiation by modifying the bacteria model proposed by Delprato et al. Our model considers four factors: the lubricant fluid generated by bacterial colonies, a chemotaxis initiated by the ultraviolet radiation, the intensity of the ultraviolet radiation, and the bacteria's two-stage destruction rate with given radiation intensities. Using this modified model, we simulate the ringlike pattern formation of the bacterial colony exposed to uniform ultraviolet radiation. The following is shown. (1) Without the UV radiation the colony forms a disklike pattern and reaches a constant front velocity. (2) After the radiation is switched on, the bacterial population migrates to the edge of the colony and forms a ringlike pattern. As the intensity of the UV radiation is increased the ring forms faster and the outer velocity of the colony decreases. (3) For higher radiation intensities the total population decreases, while for lower intensities the total population increases initially at a small rate and then decreases. (4) After the UV radiation is switched off, the bacterial population grows both outward as well as into the inner region, and the colony's outer front velocity recovers to a constant value. All these results agree well with the experimental observations [Phys. Rev. Lett. 87, 158102 (2001)]. Along with the chemotaxis, we find that lubricant fluid and the two-stage destruction rate are critical to the dynamics of the growth of the bacterial colony when exposed to UV radiation, and these were not previously considered.

  9. Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth

    PubMed Central

    Xie, Xueshu; Backman, Daniel; Lebedev, Albert T.; Artaev, Viatcheslav B.; Jiang, Liying; Ilag, Leopold L.; Zubarev, Roman A.

    2015-01-01

    Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms. PMID:26412575

  10. Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth.

    PubMed

    Xie, Xueshu; Backman, Daniel; Lebedev, Albert T; Artaev, Viatcheslav B; Jiang, Liying; Ilag, Leopold L; Zubarev, Roman A

    2015-01-01

    Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms. PMID:26412575

  11. Quantitative spectral light scattering polarimetry for monitoring fractal growth pattern of Bacillus thuringiensis bacterial colonies

    NASA Astrophysics Data System (ADS)

    Banerjee, Paromita; Soni, Jalpa; Ghosh, Nirmalya; Sengupta, Tapas K.

    2013-02-01

    It is of considerable current interest to develop various methods which help to understand and quantify the cellular association in growing bacterial colonies and is also important in terms of detection and identification of a bacterial species. A novel approach is used here to probe the morphological structural changes occurring during the growth of the bacterial colony of Bacillus thuringiensis under different environmental conditions (in normal nutrient agar, in presence of glucose - acting as additional nutrient and additional 3mM arsenate as additional toxic material). This approach combines the quantitative Mueller matrix polarimetry to extract intrinsic polarization properties and inverse analysis of the polarization preserving part of the light scattering spectra to determine the fractal parameter H (Hurst exponent) using Born approximation. Interesting differences are observed in the intrinsic polarization parameters and also in the Hurst exponent, which is a measurement of the fractality of a pattern formed by bacteria while growing as a colony. These findings are further confirmed with optical microscopic studies of the same sample and the results indicate a very strong and distinct dependence on the environmental conditions during growth, which can be exploited to quantify different bacterial species and their growth patterns.

  12. REVERSAL OF d-CYCLOSERINE INHIBITION OF BACTERIAL GROWTH BY ALANINE

    PubMed Central

    Zygmunt, Walter A.

    1962-01-01

    Zygmunt, Walter A. (Mead Johnson & Co., Evansville, Ind.). Reversal of d-cycloserine inhibition of bacterial growth by alanine. J. Bacteriol. 84:154–156. 1962.—Reversal of the antibacterial activity of d-4-amino-3-isoxazolidone by alanine in bacterial cultures actively growing on chemically defined media was compared in cultures requiring exogenous alanine and those capable of its synthesis. dl-Alanine was the most effective reversal agent in Pediococcus cerevisiae, an alanine-requiring organism, and d-alanine was effective in Escherichia coli and Staphylococcus aureus, organisms synthesizing alanine. With all three cultures, l-alanine was the least effective reversal agent. PMID:16561951

  13. Culturable bacterial endophytes isolated from Mangrove tree (Rhizophora apiculata Blume) enhance seedling growth in Rice

    PubMed Central

    Deivanai, Subramanian; Bindusara, Amitraghata Santhanam; Prabhakaran, Guruswamy; Bhore, Subhash Janardhan

    2014-01-01

    Background: Endophytic bacteria do have several potential applications in medicine and in other various sectors of biotechnology including agriculture. Bacterial endophytes need to be explored for their potential applications in agricultural biotechnology. One of the potential applications of bacterial endophytes in agricultural is to enhance the growth of the agricultural crops. Hence, this study was undertaken to explore the plant growth promoting potential application of bacterial endophytes. Objective: The objective of this study was to examine the effect of endophytic bacteria from mangrove tree (Rhizophora apiculata Blume) for their efficacy in promoting seedling growth in rice. Materials and Methods: Eight endophytic bacterial isolates (EBIs) isolated from twig and petiole tissues of the mangrove were identified based on their 16S ribosomal ribonucleic acid (rRNA) gene sequence homology. Separately, surface sterilized paddy seeds were treated with cell-free broth and cell suspension of the EBIs. Rice seedlings were analyzed by various bioassays and data was recorded. Results: The gene sequences of the isolates were closely related to two genera namely, Bacillus and Pantoea. Inoculation of EBIs from R. apiculata with rice seeds resulted in accelerated root and shoot growth with significant increase in chlorophyll content. Among the isolates, Pantoea ananatis (1MSE1) and Bacillus amyloliquefaciens (3MPE1) had shown predominance of activity. Endophytic invasion was recognized by the non-host by rapid accumulation of reactive oxygen species (ROS) and was counteracted by the production of hydrogen peroxide (H2O2) and lipid peroxide. The results demonstrated that EBIs from mangrove tree can increase the fitness of the rice seedlings under controlled conditions. Conclusion: These research findings could be useful to enhance the seedling growth and could serve as foundation in further research on enhancing the growth of the rice crop using endophytic bacteria. PMID

  14. A new method to compare statistical tree growth curves: the PL-GMANOVA model and its application with dendrochronological data.

    PubMed

    Ricker, Martin; Peña Ramírez, Víctor M; von Rosen, Dietrich

    2014-01-01

    Growth curves are monotonically increasing functions that measure repeatedly the same subjects over time. The classical growth curve model in the statistical literature is the Generalized Multivariate Analysis of Variance (GMANOVA) model. In order to model the tree trunk radius (r) over time (t) of trees on different sites, GMANOVA is combined here with the adapted PL regression model Q = A · T+E, where for b ≠ 0 : Q = Ei[-b · r]-Ei[-b · r1] and for b = 0 : Q  = Ln[r/r1], A =  initial relative growth to be estimated, T = t-t1, and E is an error term for each tree and time point. Furthermore, Ei[-b · r]  = ∫(Exp[-b · r]/r)dr, b = -1/TPR, with TPR being the turning point radius in a sigmoid curve, and r1 at t1 is an estimated calibrating time-radius point. Advantages of the approach are that growth rates can be compared among growth curves with different turning point radiuses and different starting points, hidden outliers are easily detectable, the method is statistically robust, and heteroscedasticity of the residuals among time points is allowed. The model was implemented with dendrochronological data of 235 Pinus montezumae trees on ten Mexican volcano sites to calculate comparison intervals for the estimated initial relative growth A. One site (at the Popocatépetl volcano) stood out, with A being 3.9 times the value of the site with the slowest-growing trees. Calculating variance components for the initial relative growth, 34% of the growth variation was found among sites, 31% among trees, and 35% over time. Without the Popocatépetl site, the numbers changed to 7%, 42%, and 51%. Further explanation of differences in growth would need to focus on factors that vary within sites and over time. PMID:25402427

  15. A New Method to Compare Statistical Tree Growth Curves: The PL-GMANOVA Model and Its Application with Dendrochronological Data

    PubMed Central

    Ricker, Martin; Peña Ramírez, Víctor M.; von Rosen, Dietrich

    2014-01-01

    Growth curves are monotonically increasing functions that measure repeatedly the same subjects over time. The classical growth curve model in the statistical literature is the Generalized Multivariate Analysis of Variance (GMANOVA) model. In order to model the tree trunk radius (r) over time (t) of trees on different sites, GMANOVA is combined here with the adapted PL regression model Q = A·T+E, where for and for , A =  initial relative growth to be estimated, , and E is an error term for each tree and time point. Furthermore, Ei[–b·r]  = , , with TPR being the turning point radius in a sigmoid curve, and at is an estimated calibrating time-radius point. Advantages of the approach are that growth rates can be compared among growth curves with different turning point radiuses and different starting points, hidden outliers are easily detectable, the method is statistically robust, and heteroscedasticity of the residuals among time points is allowed. The model was implemented with dendrochronological data of 235 Pinus montezumae trees on ten Mexican volcano sites to calculate comparison intervals for the estimated initial relative growth . One site (at the Popocatépetl volcano) stood out, with being 3.9 times the value of the site with the slowest-growing trees. Calculating variance components for the initial relative growth, 34% of the growth variation was found among sites, 31% among trees, and 35% over time. Without the Popocatépetl site, the numbers changed to 7%, 42%, and 51%. Further explanation of differences in growth would need to focus on factors that vary within sites and over time. PMID:25402427

  16. Spatial Patterning of Newly-Inserted Material during Bacterial Cell Growth

    NASA Astrophysics Data System (ADS)

    Ursell, Tristan

    2012-02-01

    In the life cycle of a bacterium, rudimentary microscopy demonstrates that cell growth and elongation are essential characteristics of cellular reproduction. The peptidoglycan cell wall is the main load-bearing structure that determines both cell shape and overall size. However, simple imaging of cellular growth gives no indication of the spatial patterning nor mechanism by which material is being incorporated into the pre-existing cell wall. We employ a combination of high-resolution pulse-chase fluorescence microscopy, 3D computational microscopy, and detailed mechanistic simulations to explore how spatial patterning results in uniform growth and maintenance of cell shape. We show that growth is happening in discrete bursts randomly distributed over the cell surface, with a well-defined mean size and average rate. We further use these techniques to explore the effects of division and cell wall disrupting antibiotics, like cephalexin and A22, respectively, on the patterning of cell wall growth in E. coli. Finally, we explore the spatial correlation between presence of the bacterial actin-like cytoskeletal protein, MreB, and local cell wall growth. Together these techniques form a powerful method for exploring the detailed dynamics and involvement of antibiotics and cell wall-associated proteins in bacterial cell growth.[4pt] In collaboration with Kerwyn Huang, Stanford University.

  17. GROWTH AND METABOLISM OF INDIVIDUAL BACTERIAL CELLS UTILIZING NANOSIMS

    SciTech Connect

    NEALSON, H. K.

    2007-08-03

    This work involved the use of the Nano-SIMS Instrument at Lawrence Livermore Laboratory, in an effort to utilize this unique tool for experiments in Biology. The work consisted primarily of experiments to measure in real time, C and N fixation in cyanobacteria. The work revealed a number of the difficulties in using the nano-SIMS approach with biological material, but with collaboration from a number of individuals at USC and LLNL, major progress was made. The collaborators from LLNL were from the Chemistry Group (Dr. Peter Weber), and the Biology Group (Dr. Jennifer Pett-Ridge). In addition, there were a number of other scientists involved from LLNL. The USC group consisted of Dr. K.H. Nealson, the PI on the grant, Dr. R. Popa, a postdoctoral fellow and research associate at USC, Professor Douglas Capone, and Juliet Finze, a graduate student in biology. Two major experiments were done, both of which yielded new and exciting data. (1) We studied nitrogen and carbon fixation in Anabaena, demonstrating that fixation ofN occurred rapidly in the heterocysts, and that the fixed N was transported rapidly and completely to the vegetative cells. C fixation occurred in the vegetative cells, with labeled C remaining in these cells in support of their growth and metabolism. This work was accepted in the ISME Journal (Nature Publication), and published last month. (2) We studied nitrogen and carbon fixation in Trichodesmium, a non-heterocystous cyanobacterium that also fixes nitrogen. Interestingly, the nitrogen fixation was confined to regions within the filaments that seem to be identical to the so-called cyanophycaen granules. The fixed N is then transported to other parts of the cyanobacterium, as judged by movement of the heavy N throughout the filaments. On the basis of these very exciting results, we have applied for funding from the NSF to continue the collaboration with LLNL. The results of both studies were presented in the summer of 2007 at the Gordon Research

  18. [In vitro study over statins effects on cellular growth curves and its reversibility with mevalonate].

    PubMed

    Millan Núñez-Cortés, Jesús; Alvarez Rodriguez, Ysmael; Alvarez Novés, Granada; Recarte Garcia-Andrade, Carlos; Alvarez-Sala Walther, Luis

    2014-01-01

    HMG-CoA-Reductase inhibitors, also known as statins, are currently the most powerful cholesterol-lowering drugs available on the market. Clinical trials and experimental evidence suggest that statins have heavy anti-atherosclerotic effects. These are in part consequence of lipid lowering but also result from pleiotropic actions of the drugs. These so-called pleiotropic properties affect various aspects of cell function, inflammation, coagulation, and vasomotor activity. These effects are mediated either indirectly through LDL-c reduction or via a direct effect on cellular functions. Although many of the pleiotropic properties of statins may be a class effect, some may be unique to certain agents and account for differences in their pharmacological activity. So, although statins typically have similar effects on LDL-c levels, differences in chemical structure and pharmacokinetic profile can lead to variations in pleiotropic effects. In this paper we analize the in vitro effects of different statins over different cell lines from cells implicated in atherosclerotic process: endothelial cells, fibroblasts, and vascular muscular cells. In relation with our results we can proof that the effects of different dosis of different statins provides singular effects over growth curves of different cellular lines, a despite of a class-dependent effects. So, pleiotropic effects and its reversibility with mevalonate are different according with the molecule and the dosis. PMID:24126321

  19. Determinants of rate of change in functional disability: An application of latent growth curve modeling.

    PubMed

    Chen, Ya-Mei; Chen, Duan-Rung; Chiang, Tung-Liang; Tu, Yu-Kang; Yu, Hsiao-Wei

    2016-01-01

    Our aim was to identify disablement factors, including predisposing, intra-individual, and extra-individual factors, which predict the rate of change in general functional disability (GFD) in older adults. This study utilized the Taiwan Longitudinal Study on Aging Survey in 1996-2007 (N=3,186). Multiple-indicator latent growth curve modeling was used to examine how 12 disablement factors predicted the rate of change in GFD. GFD trajectories were modeled using Nagi's functional limitations, activities of daily living, and instrumental activities of daily living. Greater age (B=.025), female gender (B=.114), and greater numbers of comorbidities (B=.038) were associated with faster increase in GFD. Education (B=-.005) and participation in physically active leisure time activities (B=-.031) were associated with slower increase in GFD. Our findings add to the understanding of how disablement factors contribute to the rate of change in GFD. Predisposing factors played the main role. However, the factors we found to be associated with the rate of change in GFD in older adults were slightly different from the factors reported in the literature. Decreasing the number of comorbidities and increasing the level of physically active leisure time activity should be considered priorities for preventing disability as people age. PMID:26952373

  20. Monitoring bacterial growth using tunable resistive pulse sensing with a pore-based technique.

    PubMed

    Yu, Allen C S; Loo, Jacky F C; Yu, Samuel; Kong, S K; Chan, Ting-Fung

    2014-01-01

    A novel bacterial growth monitoring method using a tunable resistive pulse sensor (TRPS) system is introduced in this study for accurate and sensitive measurement of cell size and cell concentration simultaneously. Two model bacterial strains, Bacillus subtilis str.168 (BSU168) and Escherichia coli str.DH5α (DH5α), were chosen for benchmarking the growth-monitoring performance of the system. Results showed that the technique of TRPS is sensitive and accurate relative to widely used methods, with a lower detection limit of cell concentration measurement of 5 × 10⁵ cells/ml; at the same time, the mean coefficient of variation from TRPS was within 2 %. The growth of BSU168 and DH5α in liquid cultures was studied by TRPS, optical density (OD), and colony plating. Compared to OD measurement, TRPS-measured concentration correlates better with colony plating (R = 0.85 vs. R = 0.72), which is often regarded as the gold standard of cell concentration determination. General agreement was also observed by comparing TRPS-derived cell volume measurements and those determined from microscopy. We have demonstrated that TRPS is a reliable method for bacterial growth monitoring, where the study of both cell volume and cell concentration are needed to provide further details about the physical aspects of cell dynamics in real time. PMID:24287933

  1. The effects of a low-intensity red laser on bacterial growth, filamentation and plasmid DNA

    NASA Astrophysics Data System (ADS)

    Roos, C.; Santos, J. N.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

    2013-07-01

    Exposure of nonphotosynthesizing microorganisms to light could increase cell division in cultures, a phenomenon denominated as biostimulation. However, data concerning the importance of the genetic characteristics of cells on this effect are as yet scarce. The aim of this work was to evaluate the effects of a low-intensity red laser on the growth, filamentation and plasmids in Escherichia coli cells proficient and deficient in DNA repair. E. coli cultures were exposed to a laser (658 nm, 10 mW, 1 and 8 J cm-2) to study bacterial growth and filamentation. Also, bacterial cultures hosting pBSK plasmids were exposed to the laser to study DNA topological forms from the electrophoretic profile in agarose gels. Data indicate the low-intensity red laser: (i) had no effect on the growth of E. coli wild type and exonuclease III deficient cells; (ii) induced bacterial filamentation, (iii) led to no alteration in the electrophoretic profile of plasmids from exonuclease III deficient cells, but plasmids from wild type cells were altered. A low-intensity red laser at the low fluences used in phototherapy has no effect on growth, but induces filamentation and alters the topological forms of plasmid DNA in E. coli cultures depending on the DNA repair mechanisms.

  2. Diamagnetic levitation enhances growth of liquid bacterial cultures by increasing oxygen availability.

    PubMed

    Dijkstra, Camelia E; Larkin, Oliver J; Anthony, Paul; Davey, Michael R; Eaves, Laurence; Rees, Catherine E D; Hill, Richard J A

    2011-03-01

    Diamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to reproduce aspects of weightlessness, on the Earth. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 h, to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture and reduces the sedimentation rate of the cells. Further experiments and microarray gene analysis show that the increase in growth rate is owing to enhanced oxygen availability. We also demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause convection during the aerobic phases of bacterial growth. We propose that this convection enhances oxygen availability by transporting oxygen around the liquid culture. Since this process results from the strong magnetic field, it is not present in other weightless environments, e.g. in Earth orbit. Hence, these results are of significance and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena. PMID:20667843

  3. Effects of Benzalkonium Chloride on Planktonic Growth and Biofilm Formation by Animal Bacterial Pathogens

    PubMed Central

    Ebrahimi, Azizollah; Hemati, Majid; Shabanpour, Ziba; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Lotfalian, Sharareh; Khubani, Shahin

    2015-01-01

    Background: Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation. Objectives: In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant. Results: The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella. Conclusions: Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation. PMID:25793094

  4. Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae

    PubMed Central

    Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

    2014-01-01

    Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics. PMID:25170896

  5. Growth curves of carcass traits obtained by ultrasonography in three lines of Nellore cattle selected for body weight.

    PubMed

    Coutinho, C C; Mercadante, M E Z; Jorge, A M; Paz, C C P; El Faro, L; Monteiro, F M

    2015-01-01

    The effect of selection for postweaning weight was evaluated within the growth curve parameters for both growth and carcass traits. Records of 2404 Nellore animals from three selection lines were analyzed: two selection lines for high postweaning weight, selection (NeS) and traditional (NeT); and a control line (NeC) in which animals were selected for postweaning weight close to the average. Body weight (BW), hip height (HH), rib eye area (REA), back fat thickness (BFT), and rump fat thickness (RFT) were measured and records collected from animals 8 to 20 (males) and 11 to 26 (females) months of age. The parameters A (asymptotic value) and k (growth rate) were estimated using the nonlinear model procedure of the Statistical Analysis System program, which included fixed effect of line (NeS, NeT, and NeC) in the model, with the objective to evaluate differences in the estimated parameters between lines. Selected animals (NeS and NeT) showed higher growth rates than control line animals (NeC) for all traits. Line effect on curves parameters was significant (P < 0.001) for BW, HH, and REA in males, and for BFT and RFT in females. Selection for postweaning weight was effective in altering growth curves, resulting in animals with higher growth potential. PMID:26535722

  6. Enhancing the Psychological Well-Being of Elderly Individuals through Tai Chi Exercise: A Latent Growth Curve Analysis.

    ERIC Educational Resources Information Center

    Li, Fuzhong; Duncan, Terry E.; Duncan, Susan C.; McAuley, Edward; Chaumeton, Nigel R.; Harmer, Peter

    2001-01-01

    Examined whether a Tai Chi exercise program enhanced the psychological well-being of 98 elderly individuals. Analyzed repeated measures data about participants using latent growth curve analysis. Results indicate the beneficial effects of participation in the Tai Chi program. Discusses implications related to the exercise-psychological health…

  7. The Influence of Input on Connective Acquisition: A Growth Curve Analysis of English "Because" and German "Weil"

    ERIC Educational Resources Information Center

    van Veen, Rosie; Evers-Vermeul, Jacqueline; Sanders, Ted; van den Bergh, Huub

    2013-01-01

    The current study used growth curve analysis to study the role of input during the acquisition of the English causal connective "because" and its German counterpart "weil." The corpora of five German and five English children and their adult caretakers (age range 0;10-4;3) were analyzed for the amount as well as for the type of…

  8. Examining the Earnings Trajectories of Community College Students Using a Piecewise Growth Curve Modeling Approach. A CAPSEE Working Paper

    ERIC Educational Resources Information Center

    Jaggars, Shanna Smith; Xu, Di

    2015-01-01

    Policymakers have become increasingly concerned with measuring--and holding colleges accountable for--students' labor market outcomes. In this paper we introduce a piecewise growth curve approach to analyzing community college students' labor market outcomes, and we discuss how this approach differs from Mincerian and fixed-effects approaches. Our…

  9. Impact of Witnessing Violence on Growth Curves for Problem Behaviors among Early Adolescents in Urban and Rural Settings

    ERIC Educational Resources Information Center

    Farrell, Albert D.; Sullivan, Terri N.

    2004-01-01

    Two studies used latent growth-curve analysis to examine the relation between witnessing violence and changes in problem behaviors (drug use, aggression, and delinquency) and attitudes during early adolescence. In Study 1, six waves of data covering 6th to 8th grades were collected from 731 students in urban schools serving mostly African-American…

  10. Modeling Latent Growth Curves With Incomplete Data Using Different Types of Structural Equation Modeling and Multilevel Software

    ERIC Educational Resources Information Center

    Ferrer, Emilio; Hamagami, Fumiaki; McArdle, John J.

    2004-01-01

    This article offers different examples of how to fit latent growth curve (LGC) models to longitudinal data using a variety of different software programs (i.e., LISREL, Mx, Mplus, AMOS, SAS). The article shows how the same model can be fitted using both structural equation modeling and multilevel software, with nearly identical results, even in…

  11. Self-Esteem Trajectories among Ethnic Minority Adolescents: A Growth Curve Analysis of the Patterns and Predictors of Change

    ERIC Educational Resources Information Center

    Greene, Melissa L.; Way, Niobe

    2005-01-01

    The current study presents a growth curve analysis of self-esteem among Black, Latino, and Asian American high school students. A series of hierarchical linear models were used to examine patterns and predictors of change in self-esteem over time. Results revealed an average increase in self-esteem with age. Although boys and girls experienced…

  12. Exploring the Different Trajectories of Analytical Thinking Ability Factors: An Application of the Second-Order Growth Curve Factor Model

    ERIC Educational Resources Information Center

    Saengprom, Narumon; Erawan, Waraporn; Damrongpanit, Suntonrapot; Sakulku, Jaruwan

    2015-01-01

    The purposes of this study were 1) Compare analytical thinking ability by testing the same sets of students 5 times 2) Develop and verify whether analytical thinking ability of students corresponds to second-order growth curve factors model. Samples were 1,093 eighth-grade students. The results revealed that 1) Analytical thinking ability scores…

  13. Spatial and Temporal Features of the Growth of a Bacterial Species Colonizing the Zebrafish Gut

    PubMed Central

    Jemielita, Matthew; Taormina, Michael J.; Burns, Adam R.; Hampton, Jennifer S.; Rolig, Annah S.; Guillemin, Karen

    2014-01-01

    ABSTRACT The vertebrate intestine is home to microbial ecosystems that play key roles in host development and health. Little is known about the spatial and temporal dynamics of these microbial communities, limiting our understanding of fundamental properties, such as their mechanisms of growth, propagation, and persistence. To address this, we inoculated initially germ-free zebrafish larvae with fluorescently labeled strains of an Aeromonas species, representing an abundant genus in the zebrafish gut. Using light sheet fluorescence microscopy to obtain three-dimensional images spanning the gut, we quantified the entire bacterial load, as founding populations grew from tens to tens of thousands of cells over several hours. The data yield the first ever measurements of the growth kinetics of a microbial species inside a live vertebrate intestine and show dynamics that robustly fit a logistic growth model. Intriguingly, bacteria were nonuniformly distributed throughout the gut, and bacterial aggregates showed considerably higher growth rates than did discrete individuals. The form of aggregate growth indicates intrinsically higher division rates for clustered bacteria, rather than surface-mediated agglomeration onto clusters. Thus, the spatial organization of gut bacteria both relative to the host and to each other impacts overall growth kinetics, suggesting that spatial characterizations will be an important input to predictive models of host-associated microbial community assembly. PMID:25516613

  14. Illumination of growth, division and secretion by metabolic labeling of the bacterial cell surface

    PubMed Central

    Siegrist, M. Sloan; Swarts, Benjamin M.; Fox, Douglas M.; Lim, Shion An; Bertozzi, Carolyn R.

    2015-01-01

    The cell surface is the essential interface between a bacterium and its surroundings. Composed primarily of molecules that are not directly genetically encoded, this highly dynamic structure accommodates the basic cellular processes of growth and division as well as the transport of molecules between the cytoplasm and the extracellular milieu. In this review, we describe aspects of bacterial growth, division and secretion that have recently been uncovered by metabolic labeling of the cell envelope. Metabolite derivatives can be used to label a variety of macromolecules, from proteins to non-genetically-encoded glycans and lipids. The embedded metabolite enables precise tracking in time and space, and the versatility of newer chemoselective detection methods offers the ability to execute multiple experiments concurrently. In addition to reviewing the discoveries enabled by metabolic labeling of the bacterial cell envelope, we also discuss the potential of these techniques for translational applications. Finally, we offer some guidelines for implementing this emerging technology. PMID:25725012

  15. Chlorhexidine Digluconate Effects on Planktonic Growth and Biofilm Formation in Some Field Isolates of Animal Bacterial Pathogens

    PubMed Central

    Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

    2014-01-01

    Background: To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. Objectives: The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Results: Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Conclusions: Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains. PMID:24872940

  16. Bacterial sensing underlies artificial sweetener-induced growth of gut Lactobacillus.

    PubMed

    Daly, Kristian; Darby, Alistair C; Hall, Neil; Wilkinson, Mark C; Pongchaikul, Pisut; Bravo, David; Shirazi-Beechey, Soraya P

    2016-07-01

    Disruption in stable establishment of commensal gut microbiota by early weaning is an important factor in susceptibility of young animals to enteric disorders. The artificial sweetener SUCRAM [consisting of neohesperidin dihydrochalcone (NHDC) and saccharin] included in piglets' feed reduces incidence of enteric disease. Pyrosequencing of pig caecal 16S rRNA gene amplicons identified 25 major families encompassing seven bacterial classes with Bacteroidia, Clostridia and Bacilli dominating the microbiota. There were significant shifts in microbial composition in pigs maintained on a diet containing SUCRAM, establishing SUCRAM as a major influence driving bacterial community dynamics. The most notable change was a significant increase of Lactobacillaceae population abundance, almost entirely due to a single phylotype, designated Lactobacillus 4228. The sweetener-induced increase in Lactobacillaceae was observed in two different breeds of pigs signifying a general effect. We isolated Lactobacillus 4228, sequenced its genome and found it to be related to Lactobacillus amylovorus. In vitro analyses of Lactobacillus 4228 growth characteristics showed that presence of NHDC significantly reduces the lag phase of growth and enhances expression of specific sugar transporters, independently of NHDC metabolism. This study suggests that sensing of NHDC by a bacterial plasma membrane receptor underlies sweetener-induced growth of a health promoting gut bacterium. PMID:26058469

  17. Two bacterial entophytes eliciting both plant growth promotion and plant defense on pepper (Capsicum annuum L.).

    PubMed

    Kang, Seung Hoon; Cho, Hyun-Soo; Cheong, Hoon; Ryu, Choong-Min; Kim, Jihyun F; Park, Seung-Hwan

    2007-01-01

    Plant growth-promoting rhizobacteria (PGPR) have the potential to be used as microbial inoculants to reduce disease incidence and severity and to increase crop yield. Some of the PGPR have been reported to be able to enter plant tissues and establish endophytic populations. Here, we demonstrated an approach to screen bacterial endophytes that have the capacity to promote the growth of pepper seedlings and protect pepper plants against a bacterial pathogen. Initially, out of 150 bacterial isolates collected from healthy stems of peppers cultivated in the Chungcheong and Gyeongsang provinces of Korea, 23 putative endophytic isolates that were considered to be predominating and representative of each pepper sample were selected. By phenotypic characterization and partial 16S rDNA sequence analysis, the isolates were identified as species of Ochrobacterium, Pantoea, Pseudomonas, Sphingomonas, Janthinobacterium, Ralstonia, Arthrobacter, Clavibacter, Sporosarcina, Acidovorax, and Brevundimonas. Among them, two isolates, PS4 and PS27, were selected because they showed consistent colonizing capacity in pepper stems at the levels of 10(6)-10(7) CFU/g tissue, and were found to be most closely related to Pseudomonas rhodesiae and Pantoea ananatis, respectively, by additional analyses of their entire 16S rDNA sequences. Drenching application of the two strains on the pepper seedlings promoted significant growth of peppers, enhancing their root fresh weight by 73.9% and 41.5%, respectively. The two strains also elicited induced systemic resistance of plants against Xanthomonas axonopodis pv. vesicatoria. PMID:18051359

  18. In-depth characterization of wastewater bacterial community in response to algal growth using pyrosequencing.

    PubMed

    Lee, Jangho; Lee, Juyoun; Lee, Tae Kwon; Woo, Sung-Geun; Baek, Gyu Seok; Park, Joonhong

    2013-10-28

    Microalgae have been regarded as a natural resource for sustainable materials and fuels, as well as for removal of nutrients and micropollutants from wastewater, and their interaction with bacteria in wastewater is a critical factor to consider because of the microbial diversity and complexity in a variety of wastewater conditions. Despite their importance, very little is known about the ecological interactions between algae and bacteria in a wastewater environment. In this study, we characterized the wastewater bacterial community in response to the growth of a Selenastrum gracile UTEX 325 population in a real municipal wastewater environment. The Roche 454 GS-FLX Titanium pyrosequencing technique was used for indepth analysis of amplicons of 16S rRNA genes from different conditions in each reactor, with and without the algal population. The algal growth reduced the bacterial diversity and affected the bacterial community structure in the wastewater. The following in-depth analysis of the deep-sequenced amplicons showed that the algal growth selectively stimulated Sphingobacteria class members, especially the Sediminibacterium genus population, in the municipal wastewater environment. PMID:23867704

  19. Stability of Cigarette Consumption Over Time Among Continuing Smokers: A Latent Growth Curve Analysis

    PubMed Central

    Borland, Ron; Thrasher, James F.; Thompson, Mary E.

    2012-01-01

    Objectives: This paper examined the stability over time of daily cigarette consumption of continuing smokers and explored factors that might account for the patterns of change in consumption using a latent growth curve (LGC) analytic approach. Methods: Data come from the first 5 waves of the International Tobacco Control Four-Country Survey, conducted in Canada, the United States, the United Kingdom, and Australia where a cohort of over 2,000 smokers from each country were recruited and followed up annually with replenishment. Results: Raw data revealed that continuing smokers showed a marked steep decline in cigarettes per day during the first 2 waves followed by a gentler linear decline in consumption over the remaining waves of the study period. This pattern of change in cigarette consumption was best modelled using a piecewise linear LGC model. Baseline consumption level was highest in Australia and lowest in the United Kingdom, although the rate of decline was similar across the 4 countries. Being older than 55 years and having made at least 1 quit attempt were related to greater rate of decline in consumption. Conclusions: Continuing smokers who are unwilling or unable to quit smoking can and do attempt to reduce their daily cigarette consumption over time. Factors such as making a quit attempt even if unsuccessful and experiencing smoking bans at work and at homes can contribute to reduced smoking among this group, which suggests that interventions focusing in on these factors, along with providing cessation help, may greatly improve their chances of quitting smoking altogether. PMID:22311963

  20. Evaluation of toxic effects of several carboxylic acids on bacterial growth by toxicodynamic modelling

    PubMed Central

    2011-01-01

    Background Effects of organic acids on microbial fermentation are commonly tested in investigations about metabolic behaviour of bacteria. However, they typically provide only descriptive information without modelling the influence of acid concentrations on bacterial kinetics. Results We developed and applied a mathematical model (secondary model) to capture the toxicological effects of those chemicals on kinetic parameters that define the growth of bacteria in batch cultures. Thus, dose-response kinetics were performed with different bacteria (Leuconostoc mesenteroides, Carnobacterium pisicola, Escherichia coli, Bacillus subtilis and Listonella anguillarum) exposed at increasing concentrations of individual carboxylic acids (formic, acetic, propionic, butyric and lactic). In all bioassays the acids affected the maximum bacterial load (Xm) and the maximum growth rate (vm) but only in specific cases the lag phase (λ) was modified. Significance of the parameters was always high and in all fermentations the toxicodynamic equation was statistically consistent and had good predictability. The differences between D and L-lactic acid effects were significant for the growth of E. coli, L. mesenteroides and C. piscicola. In addition, a global parameter (EC50,τ) was used to compare toxic effects and provided a realistic characterization of antimicrobial agents using a single value. Conclusions The effect of several organic acids on the growth of different bacteria was accurately studied and perfectly characterized by a bivariate equation which combines the basis of dose-response theory with microbial growth kinetics (secondary model). The toxicity of carboxylic acids was lower with the increase of the molecular weight of these chemicals. PMID:22118421

  1. Bacterial growth rates are influenced by cellular characteristics of individual species when immersed in electromagnetic fields.

    PubMed

    Tessaro, Lucas W E; Murugan, Nirosha J; Persinger, Michael A

    2015-03-01

    Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static "puck" magnet upwards of 5000G in intensity; a pair of these magnets rotating opposite one another at ∼30rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250μT were used. Growth rate was discerned by optical density (OD) measurements every hour at 600nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species. PMID:25721476

  2. Inhibitory Effects of Synthetic Peptides Containing Bovine Lactoferrin C-lobe Sequence on Bacterial Growth

    PubMed Central

    Kim, Woan-Sub; Ohashi, Midori; Shimazaki, Kei-ichi

    2016-01-01

    Lactoferrin is a glycoprotein with various biological effects, with antibacterial activity being one of the first effects reported. This glycoprotein suppresses bacterial growth through bacteriostatic or bactericidal action. It also stimulates the growth of certain kinds of bacteria such as lactic acid bacteria and bifidobacteria. In this study, Asn-Leu-Asn-Arg was selected and chemically synthesized based on the partial sequences of bovine lactoferrin tryptic fragments. Synthetic Asn-Leu-Asn-Arg suppressed the growth of Pseudomonas fluorescens, P. syringae and Escherichia coli. P. fluorescens is a major psychrotrophic bacteria found in raw and pasteurized milk, which decreases milk quality. P. syringae is a harmful infectious bacterium that damages plants. However, synthetic Asn-Leu-Asn-Arg did not inhibit the growth of Lactobacillus acidophilus. It is expected that this synthetic peptide would be the first peptide sequence from the bovine lactoferrin C-lobe that shows antibacterial activity. PMID:27621684

  3. Inhibitory Effects of Synthetic Peptides Containing Bovine Lactoferrin C-lobe Sequence on Bacterial Growth.

    PubMed

    Kim, Woan-Sub; Ohashi, Midori; Shimazaki, Kei-Ichi

    2016-01-01

    Lactoferrin is a glycoprotein with various biological effects, with antibacterial activity being one of the first effects reported. This glycoprotein suppresses bacterial growth through bacteriostatic or bactericidal action. It also stimulates the growth of certain kinds of bacteria such as lactic acid bacteria and bifidobacteria. In this study, Asn-Leu-Asn-Arg was selected and chemically synthesized based on the partial sequences of bovine lactoferrin tryptic fragments. Synthetic Asn-Leu-Asn-Arg suppressed the growth of Pseudomonas fluorescens, P. syringae and Escherichia coli. P. fluorescens is a major psychrotrophic bacteria found in raw and pasteurized milk, which decreases milk quality. P. syringae is a harmful infectious bacterium that damages plants. However, synthetic Asn-Leu-Asn-Arg did not inhibit the growth of Lactobacillus acidophilus. It is expected that this synthetic peptide would be the first peptide sequence from the bovine lactoferrin C-lobe that shows antibacterial activity. PMID:27621684

  4. Flotillin-1 (Reggie-2) Contributes to Chlamydia pneumoniae Growth and Is Associated with Bacterial Inclusion

    PubMed Central

    Korhonen, Juha T.; Puolakkainen, Mirja; Häivälä, Reetta; Penttilä, Tuula; Haveri, Anu; Markkula, Eveliina

    2012-01-01

    Chlamydiae are obligate intracellular pathogens replicating only inside the eukaryotic host. Here, we studied the effect of human flotillin-1 protein on Chlamydia pneumoniae growth in human line (HL) and A549 epithelial cell lines. RNA interference was applied to disrupt flotillin-1-mediated endocytosis. Host-associated bacteria were detected by quantitative PCR, and C. pneumoniae growth was evaluated by inclusion counts. C. pneumoniae attachment to host cells was unaffected, but bacterial intracellular growth was attenuated in the flotillin-1-silenced cells. By using confocal microscopy, we detected flotillin-1 colocalized with the inclusion membrane protein A (IncA) in the C. pneumoniae inclusion membranes. In addition, flotillin-1 was associated with IncA in detergent-resistant membrane microdomains (DRMs) in biochemical fractioning. These results suggest that flotillin-1 localizes to the C. pneumoniae inclusion membrane and plays an important role for intracellular growth of C. pneumoniae. PMID:22215737

  5. Tropical freshwater ecosystems have lower bacterial growth efficiency than temperate ones

    PubMed Central

    Amado, André M.; Meirelles-Pereira, Frederico; Vidal, Luciana O.; Sarmento, Hugo; Suhett, Albert L.; Farjalla, Vinicius F.; Cotner, James B.; Roland, Fabio

    2013-01-01

    Current models and observations indicate that bacterial respiration should increase and growth efficiency (BGE) should decrease with increasing temperatures. However, these models and observations are mostly derived from data collected in temperate regions, and the tropics are under-represented. The aim of this work was to compare bacterial metabolism, namely bacterial production (BP) and respiration (BR), bacterial growth efficiency (BGE) and bacterial carbon demand (BCD) between tropical and temperate ecosystems via a literature review and using unpublished data. We hypothesized that (1) tropical ecosystems have higher metabolism than temperate ones and, (2) that BGE is lower in tropical relative to temperate ecosystems. We collected a total of 498 coupled BP and BR observations (Ntotal = 498; Ntemperate = 301; Ntropical = 197), calculated BGE (BP/(BP+BR)) and BCD (BP+BR) for each case and examined patterns using a model II regression analysis and compared each parameter between the two regions using non-parametric Mann–Whitney U test. We observed a significant positive linear regression between BR and BP for the whole dataset, and also for tropical and temperate data separately. We found that BP, BR and BCD were higher in the tropics, but BGE was lower compared to temperate regions. Also, BR rates per BP unit were at least two fold higher in the tropics than in temperate ecosystems. We argue that higher temperature, nutrient limitation, and light exposure all contribute to lower BGE in the tropics, mediated through effects on thermodynamics, substrate stoichiometry, nutrient availability and interactions with photochemically produced compounds. More efforts are needed in this study area in the tropics, but our work indicates that bottom-up (nutrient availability and resource stoichiometry) and top-down (grazer pressure) processes, coupled with thermodynamic constraints, might contribute to the lower BGE in the tropics relative to temperate regions. PMID

  6. Application of Direct Current Potential Drop for the J-integral vs. Crack Growth Resistance Curve Characterization

    SciTech Connect

    Chen, Xiang; Nanstad, Randy K; Sokolov, Mikhail A

    2014-01-01

    The direct current potential drop (DCPD) technique has been applied to derive the J-integral vs. crack growth resistance curve (J-R curve) for fracture toughness characterization of structural materials. The test matrix covered three materials including type 316LN stainless steels, Ni-based alloy 617, and one ferritic-martensitic steel, three specimen configurations including standard compact, single edge bending, and disk-shaped compact specimens, and temperatures ranging from 20 C to 650 C. When compared with baseline J-R curves derived from the ASTM normalization method, the original J-R curves from the DCPD technique yielded much smaller Jq values due to the influence of crack blunting, plastic deformation, etc. on potential drop. To counter these effects, a new procedure for adjusting DCPD J-R curves was proposed. After applying the new adjustment procedure, the average difference in Jq between the DCPD technique and the normalization method was only 5.2% and the difference in tearing modulus was 7.4%. The promising result demonstrates the applicability of the DCPD technique for the J-R curve characterization especially in extreme environments, such as elevated temperatures, where the conventional elastic unloading compliance method faces considerable challenges.

  7. Btcd, a mouse protein that binds to curved DNA, can substitute in Escherichia coli for H-NS, a bacterial nucleoid protein.

    PubMed Central

    Timchenko, T; Bailone, A; Devoret, R

    1996-01-01

    In an Escherichia coli mutant devoid of H-NS, a bacterial nucleoid protein, mouse protein Btcd was able to substitute for H-NS in two tested functions. It restored cell motility and repression of the expression of the bgl operon. Btcd1, a mutant Btcd protein deleted of its zinc finger and thus having reduced DNA binding, failed to substitute for H-NS. Mouse protein Btcd was shown to repress the bgl operon at the level of transcription initiation and to bind preferentially to a curved DNA fragment encompassing the bgl promoter. These effects of Btcd on bacterial gene transcription can be accounted for by the binding of Btcd or H-NS to a curved DNA sequence near a promoter. A few mammalian proteins have been shown to substitute for their Escherichia prototypes involved in DNA and RNA transactions. The efficiency of Btcd protein in substituting for H-NS in Escherichia suggests its possible involvement in regulating gene expression in mouse cells. Images PMID:8670903

  8. Effects of viral enrichment on bacterial production, respiration and growth efficiency

    NASA Astrophysics Data System (ADS)

    Bonilla-Findji, O.; Rochelle-Newall, E.; Weinbauer, M. G.; Gattuso, J.-P.

    2003-04-01

    Viruses are the most common biological agents in the sea. They can influence many ecological processes such as nutrient and carbon cycling, particle size distribution, algal bloom control, species diversity and gene transfer. As they are mainly bacteriophages they not only influence bacterial abundances but also potentially, the bacterial respiration and production, as has been suggested in by Fuhrman’s model in 1992 and a few recent experimental studies. Through their lytic action viruses can influence biogeochemical cycles and so affect the functioning of the whole marine ecosystem. In order to explore this hypothesis and provide some quantitative data we: (1) studied the effects of viruses on bacterial respiration (BR), production (BP) and growth efficiency (BGE) and (2) investigated whether these effects change over time. A viral enrichment experiment was performed in April and May 2002, where the bacterial community isolated from the Bay of Villefranche was exposed to three treatments: Vo (no viral addition), Vm (enrichment of 1-1.5 fold inactivated viruses) and V+ (enrichment of 1-1.5 fold active viruses). No virally induced effects on bacterial metabolism were observed in April but in May after 24 h of incubation, BR was stimulated by ca. 39% in V+ compared to Vo and by 20% relative to Vm. In the presence of active viruses, BP was repressed by ca. 40% compared to Vo and BGE was reduced by 48%. In May, viruses increased the total bacterial carbon demand (17% in V+ compared to Vo, and by 11% relative to Vm). Our results suggest that viruses seem to induce a shift in the specific role of bacterioplankton by reducing the carbon flow to the higher trophic levels and by stimulating the DOM ‡ bacteria ‡ CO2, N, P, Fe pathway.

  9. Rainbow trout resistance to bacterial cold-water disease is moderately heritable and is not adversely correlated with growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to estimate the heritabilities for and genetic correlations among resistance to bacterial cold-water disease and growth traits in a population of rainbow trout. Bacterial cold-water disease, a chronic disease of rainbow trout, is caused by Flavobacterium psychrophilu...

  10. Impact of ZnO and Ag Nanoparticles on Bacterial Growth and Viability

    NASA Astrophysics Data System (ADS)

    Olson, M. S.; Digiovanni, K. A.

    2007-12-01

    Hundreds of consumer products containing nanomaterials are currently available in the U.S., including computers, clothing, cosmetics, sports equipment, medical devices and product packaging. Metallic nanoparticles can be embedded in or coated on product surfaces to provide antimicrobial, deodorizing, and stain- resistant properties. Although these products have the potential to provide significant benefit to the user, the impact of these products on the environment remains largely unknown. The purpose of this project is to study the effect of metallic nanoparticles released to the environment on bacterial growth and viability. Inhibition of bacterial growth was tested by adding doses of suspended ZnO and Ag nanoparticles into luria broth prior to inoculation of Escherichia coli cells. ZnO particles (approximately 40 nm) were obtained commercially and Ag particles (12-14 nm) were fabricated by reduction of silver nitrate with sodium borohydride. Toxicity assays were performed to test the viability of E. coli cells exposed to both ZnO and Ag nanoparticles using the LIVE/DEAD BacLight bacterial viability kit (Invitrogen). Live cells stain green whereas cells with compromised membranes that are considered dead or dying stain red. Cells were first grown, stained, and exposed to varying doses of metallic nanoparticles, and then bacterial viability was measured hourly using fluorescence microscopy. Results indicate that both ZnO and Ag nanoparticles inhibit the growth of E. coli in liquid media. Preliminary results from toxicity assays confirm the toxic effect of ZnO and Ag nanoparticles on active cell cultures. Calculated death rates resulting from analyses of toxicity studies will be presented.

  11. Wheat and Rice Growth Stages and Fertilization Regimes Alter Soil Bacterial Community Structure, But Not Diversity

    PubMed Central

    Wang, Jichen; Xue, Chao; Song, Yang; Wang, Lei; Huang, Qiwei; Shen, Qirong

    2016-01-01

    Maintaining soil fertility and the microbial communities that determine fertility is critical to sustainable agricultural strategies, and the use of different organic fertilizer (OF) regimes represents an important practice in attempts to preserve soil quality. However, little is known about the dynamic response of bacterial communities to fertilization regimes across crop growth stages. In this study, we examined microbial community structure and diversity across eight representative growth stages of wheat-rice rotation under four different fertilization treatments: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic–inorganic mixed fertilizer (OIMF), and OF. Quantitative PCR (QPCR) and high-throughput sequencing of bacterial 16S rRNA gene fragments revealed that growth stage as the best predictor of bacterial community abundance and structure. Additionally, bacterial community compositions differed between wheat and rice rotations. Relative to soils under wheat rotation, soils under rice rotation contained higher relative abundances (RA) of anaerobic and mesophilic microbes and lower RA of aerophilic microbes. With respect to fertilization regime, NNF plots had a higher abundance of nitrogen–fixing Cyanobacteria. OIMF had a lower abundance of ammonia-oxidizing Thaumarchaeota compared with CF. Application of chemical fertilizers (CF and OIMF treatments) significantly increased the abundance of some generally oligotrophic bacteria such those belonging to the Acidobacteria, while more copiotrophic of the phylum Proteobacteria increased with OF application. A high correlation coefficient was found when comparing RA of Acidobacteria based upon QPCR vs. sequence analysis, yet poor correlations were found for the α- and β- Proteobacteria, highlighting the caution required when interpreting these molecular data. In total, crop, fertilization scheme and plant developmental stage all influenced soil microbial community structure, but not total levels of

  12. Wheat and Rice Growth Stages and Fertilization Regimes Alter Soil Bacterial Community Structure, But Not Diversity.

    PubMed

    Wang, Jichen; Xue, Chao; Song, Yang; Wang, Lei; Huang, Qiwei; Shen, Qirong

    2016-01-01

    Maintaining soil fertility and the microbial communities that determine fertility is critical to sustainable agricultural strategies, and the use of different organic fertilizer (OF) regimes represents an important practice in attempts to preserve soil quality. However, little is known about the dynamic response of bacterial communities to fertilization regimes across crop growth stages. In this study, we examined microbial community structure and diversity across eight representative growth stages of wheat-rice rotation under four different fertilization treatments: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic-inorganic mixed fertilizer (OIMF), and OF. Quantitative PCR (QPCR) and high-throughput sequencing of bacterial 16S rRNA gene fragments revealed that growth stage as the best predictor of bacterial community abundance and structure. Additionally, bacterial community compositions differed between wheat and rice rotations. Relative to soils under wheat rotation, soils under rice rotation contained higher relative abundances (RA) of anaerobic and mesophilic microbes and lower RA of aerophilic microbes. With respect to fertilization regime, NNF plots had a higher abundance of nitrogen-fixing Cyanobacteria. OIMF had a lower abundance of ammonia-oxidizing Thaumarchaeota compared with CF. Application of chemical fertilizers (CF and OIMF treatments) significantly increased the abundance of some generally oligotrophic bacteria such those belonging to the Acidobacteria, while more copiotrophic of the phylum Proteobacteria increased with OF application. A high correlation coefficient was found when comparing RA of Acidobacteria based upon QPCR vs. sequence analysis, yet poor correlations were found for the α- and β- Proteobacteria, highlighting the caution required when interpreting these molecular data. In total, crop, fertilization scheme and plant developmental stage all influenced soil microbial community structure, but not total levels of alpha

  13. Growth of 48 built environment bacterial isolates on board the International Space Station (ISS)

    PubMed Central

    Neches, Russell Y.; Lang, Jenna M.; Brown, Wendy E.; Severance, Mark; Cavalier, Darlene

    2016-01-01

    Background. While significant attention has been paid to the potential risk of pathogenic microbes aboard crewed spacecraft, the non-pathogenic microbes in these habitats have received less consideration. Preliminary work has demonstrated that the interior of the International Space Station (ISS) has a microbial community resembling those of built environments on Earth. Here we report the results of sending 48 bacterial strains, collected from built environments on Earth, for a growth experiment on the ISS. This project was a component of Project MERCCURI (Microbial Ecology Research Combining Citizen and University Researchers on ISS). Results. Of the 48 strains sent to the ISS, 45 of them showed similar growth in space and on Earth using a relative growth measurement adapted for microgravity. The vast majority of species tested in this experiment have also been found in culture-independent surveys of the ISS. Only one bacterial strain showed significantly different growth in space. Bacillus safensis JPL-MERTA-8-2 grew 60% better in space than on Earth. Conclusions. The majority of bacteria tested were not affected by conditions aboard the ISS in this experiment (e.g., microgravity, cosmic radiation). Further work on Bacillus safensis could lead to interesting insights on why this strain grew so much better in space. PMID:27019789

  14. Control of bacterial biofilm growth on surfaces by nanostructural mechanics and geometry

    NASA Astrophysics Data System (ADS)

    Epstein, A. K.; Hochbaum, A. I.; Kim, Philseok; Aizenberg, J.

    2011-12-01

    Surface-associated communities of bacteria, called biofilms, pervade natural and anthropogenic environments. Mature biofilms are resistant to a wide range of antimicrobial treatments and therefore pose persistent pathogenic threats. The use of surface chemistry to inhibit biofilm growth has been found to only transiently affect initial attachment. In this work, we investigate the tunable effects of physical surface properties, including high-aspect-ratio (HAR) surface nanostructure arrays recently reported to induce long-range spontaneous spatial patterning of bacteria on the surface. The functional parameters and length scale regimes that control such artificial patterning for the rod-shaped pathogenic species Pseudomonas aeruginosa are elucidated through a combinatorial approach. We further report a crossover regime of biofilm growth on a HAR nanostructured surface versus the nanostructure effective stiffness. When the 'softness' of the hair-like nanoarray is increased beyond a threshold value, biofilm growth is inhibited as compared to a flat control surface. This result is consistent with the mechanoselective adhesion of bacteria to surfaces. Therefore by combining nanoarray-induced bacterial patterning and modulating the effective stiffness of the nanoarray—thus mimicking an extremely compliant flat surface—bacterial mechanoselective adhesion can be exploited to control and inhibit biofilm growth.

  15. Analysis of bacterial growth by UV/Vis spectroscopy and laser reflectometry

    NASA Astrophysics Data System (ADS)

    Peña-Gomar, Mary Carmen; Viramontes-Gamboa, Gonzalo; Peña-Gomar, Grethel; Ortiz Gutiérrez, Mauricio; Hernández Ramírez, Mariano

    2012-10-01

    This work presents a preliminary study on an experimental analysis of the lactobacillus bacterial growth in liquid medium with and without the presence of silver nanoparticles. The study aims to quantify the bactericidal effect of nanoparticles. Quantification of bacterial growth at different times was analyzed by spectroscopy UV/visible and laser reflectometry near the critical angle. From these two techniques the best results were obtained by spectroscopy, showing that as the concentration of silver nanoparticles increases, it inhibits the growth of bacteria, it only grows 63% of the population. Regarding Laser Reflectometry, the variation of reflectance near the critical angle is measured in real time. The observed results at short times are reasonable, since they indicate a gradual growth of the bacteria and the stabilization stage of the population. But at long time, the observed results show abrupt changes caused by temperature effects. The bacteria were isolated from samples taken from commercial yougurth, and cultured in MRS broth at pH 6.5, and controlled with citric acid and constant temperature of 32 °C. Separately, silver nanoparticles were synthesized at 3 °C from aqueous solutions of 1.0 mM silver nitrate and chemically reduced with sodium borohydride to 2.0 mM, with magnetic stirring.

  16. Molecular Mechanisms of Enhanced Bacterial Growth on Hexadecane with Red Clay.

    PubMed

    Jung, Jaejoon; Jang, In-Ae; Ahn, Sungeun; Shin, Bora; Kim, Jisun; Park, Chulwoo; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

    2015-11-01

    Red clay was previously used to enhance bioremediation of diesel-contaminated soil. It was speculated that the enhanced degradation of diesel was due to increased bacterial growth. In this study, we selected Acinetobacter oleivorans DR1, a soil-borne degrader of diesel and alkanes, as a model bacterium and performed transcriptional analysis using RNA sequencing to investigate the cellular response during hexadecane utilization and the mechanism by which red clay promotes hexadecane degradation. We confirmed that red clay promotes the growth of A. oleivorans DR1 on hexadecane, a major component of diesel, as a sole carbon source. Addition of red clay to hexadecane-utilizing DR1 cells highly upregulated β-oxidation, while genes related to alkane oxidation were highly expressed with and without red clay. Red clay also upregulated genes related to oxidative stress defense, such as superoxide dismutase, catalase, and glutaredoxin genes, suggesting that red clay supports the response of DR1 cells to oxidative stress generated during hexadecane utilization. Increased membrane fluidity in the presence of red clay was confirmed by fatty acid methyl ester analysis at different growth phases, suggesting that enhanced growth on hexadecane could be due to increased uptake of hexadecane coupled with upregulation of downstream metabolism and oxidative stress defense. The monitoring of the bacterial community in soil with red clay for a year revealed that red clay stabilized the community structure. PMID:25956940

  17. Growth of 48 built environment bacterial isolates on board the International Space Station (ISS).

    PubMed

    Coil, David A; Neches, Russell Y; Lang, Jenna M; Brown, Wendy E; Severance, Mark; Cavalier, Darlene; Eisen, Jonathan A

    2016-01-01

    Background. While significant attention has been paid to the potential risk of pathogenic microbes aboard crewed spacecraft, the non-pathogenic microbes in these habitats have received less consideration. Preliminary work has demonstrated that the interior of the International Space Station (ISS) has a microbial community resembling those of built environments on Earth. Here we report the results of sending 48 bacterial strains, collected from built environments on Earth, for a growth experiment on the ISS. This project was a component of Project MERCCURI (Microbial Ecology Research Combining Citizen and University Researchers on ISS). Results. Of the 48 strains sent to the ISS, 45 of them showed similar growth in space and on Earth using a relative growth measurement adapted for microgravity. The vast majority of species tested in this experiment have also been found in culture-independent surveys of the ISS. Only one bacterial strain showed significantly different growth in space. Bacillus safensis JPL-MERTA-8-2 grew 60% better in space than on Earth. Conclusions. The majority of bacteria tested were not affected by conditions aboard the ISS in this experiment (e.g., microgravity, cosmic radiation). Further work on Bacillus safensis could lead to interesting insights on why this strain grew so much better in space. PMID:27019789

  18. Characteristics of bacterial and fungal growth in plastic bottled beverages under a consuming condition model.

    PubMed

    Watanabe, Maiko; Ohnishi, Takahiro; Araki, Emiko; Kanda, Takashi; Tomita, Atsuko; Ozawa, Kazuhiro; Goto, Keiichi; Sugiyama, Kanji; Konuma, Hirotaka; Hara-Kudo, Yukiko

    2014-01-01

    Microbial contamination in unfinished beverages can occur when drinking directly from the bottle. Various microorganisms, including foodborne pathogens, are able to grow in these beverages at room temperature or in a refrigerator. In this study, we elucidated the characteristics of microorganism growth in bottled beverages under consuming condition models. Furthermore, we provide insight into the safety of partially consumed bottled beverages with respect to food hygiene. We inoculated microorganisms, including foodborne pathogens, into various plastic bottled beverages and analysed the dynamic growth of microorganisms as well as bacterial toxin production in the beverages. Eight bottled beverage types were tested in this study, namely green tea, apple juice drink, tomato juice, carbonated drink, sport drink, coffee with milk, isotonic water and mineral water, and in these beverages several microorganism types were used: nine bacteria including three toxin producers, three yeasts, and five moulds. Following inoculation, the bottles were incubated at 35°C for 48 h for bacteria, 25°C for 48 h for yeasts, and 25°C for 28 days for moulds. During the incubation period, the number of bacteria and yeasts and visible changes in mould-growth were determined over time. Our results indicated that combinations of the beverage types and microorganism species correlated with the degree of growth. Regarding factors that affect the growth and toxin-productivity of microorganisms in beverages, it is speculated that the pH, static/shaking culture, temperature, additives, or ingredients, such as carbon dioxide or organic matter (especially of plant origin), may be important for microorganism growth in beverages. Our results suggest that various types of unfinished beverages have microorganism growth and can include food borne pathogens and bacterial toxins. Therefore, our results indicate that in terms of food hygiene it is necessary to consume beverages immediately after opening

  19. Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth.

    PubMed

    Klose, Julia; Aistleitner, Karin; Horn, Matthias; Krenn, Liselotte; Dirsch, Verena; Zehl, Martin; Bright, Monika

    2016-01-01

    The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm's trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains. PMID:26730960

  20. Intestinal bacterial community and growth performance of chickens fed diets containing antibiotics.

    PubMed

    Pedroso, A A; Menten, J F M; Lambais, M R; Racanicci, A M C; Longo, F A; Sorbara, J O B

    2006-04-01

    This study was conducted to relate the performance of broiler chickens fed diets containing growth-promoting antibiotics to changes in the intestinal microbiota. The technique of denaturing gradient gel electrophoresis (DGGE) of amplicons of the region V3 of 16S rDNA was used to characterize the microbiota. Two experiments were conducted, one with broilers raised in battery cages and the other with broilers raised in floor pens. Antibiotics improved the performance of the chickens raised in floor pens only. Avilamycin, bacitracin methylene disalicylate, and enramycin induced changes in the composition of the intestinal bacterial community of the birds in both experiments. The number of bacterial genotypes found in the intestinal tract of chickens was not reduced by the antibiotics supplemented in either environment. However, the changes in the composition of the intestinal bacterial community induced by antibiotics may be related to improvement in growth performance. This was indicated by the suppression of 6 amplicons and the presence of 4 amplicons exclusive to the treatment that had the best performance in the floor pen experiment. PMID:16615359

  1. Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth

    PubMed Central

    Klose, Julia; Aistleitner, Karin; Horn, Matthias; Krenn, Liselotte; Dirsch, Verena; Zehl, Martin; Bright, Monika

    2016-01-01

    The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm’s trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains. PMID:26730960

  2. Inhibition of Bacterial Growth and Biofilm Production by Constituents from Hypericum spp

    PubMed Central

    Sarkisian, S.A.; Janssen, M.J.; Matta, H.; Henry, G.E.; LaPlante, K.L.; Rowley, D.C.

    2011-01-01

    Biofilm embedded bacterial pathogens such as Staphylococcus spp., Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii are difficult to eradicate and are major sources of bacterial infections. New drugs are needed to combat these pathogens. Hypericum is a plant genus that contains species known to have antimicrobial properties. However, the specific constituents responsible for the antimicrobial properties are not entirely known, nor have most compounds been tested as inhibitors of biofilm development. The investigation presented here tested seven secondary metabolites isolated from the species Hypericum densiflorum, Hypericumellipticum, Hypericum prolificum and Hypericum punctatum as inhibitors of bacterial growth and biofilm production. Assays were conducted against Staphylococcus epidermidis, Staphylococcusaureus, clinical methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii. Five of the seven compounds demonstrated growth inhibition against the Gram-positive bacteria with minimum inhibitory concentrations (MIC) ranging from 1.95 μg/mL to 7.81 μg/mL. Four of the secondary metabolites inhibited biofilm production by certain Gram-positive strains at sub-MIC concentrations. PMID:22170780

  3. Associated bacterial flora, growth, and toxicity of cultured benthic dinoflagellates Ostreopsis lenticularis and Gambierdiscus toxicus.

    PubMed

    Tosteson, T R; Ballantine, D L; Tosteson, C G; Hensley, V; Bardales, A T

    1989-01-01

    The growth, toxicity, and associated bacterial flora of 10 clonal cultures of the toxic benthic dinoflagellates Ostreopsis lenticularis and Gambierdiscus toxicus isolated from the coastal waters of southwest Puerto Rico have been examined. Clonal cultures of O. lenticularis grew more rapidly and at broader temperature ranges than those of G. toxicus. All five Ostreopsis clones were toxic, while only one of the five Gambierdiscus clones was poisonous. The degree of toxicity among poisonous clones was highly variable. The number of associated bacterial genera and their frequency of occurrence were quite variable among clones of both dinoflagellate genera. Bacterial isolates represented six genera (Nocardia, Pseudomonas, Vibrio, Aeromonas, Flavobacterium, and Moraxella) in addition to coryneform bacteria. Extracts of dinoflagellate-associated bacteria grown in pure culture were not toxic. Gambierdiscus clones were characterized by the frequent presence of Pseudomonas spp. (four of five clones) and the absence of coryneforms. In O. lenticularis, only one of five clones showed the presence of Pseudomonas spp., and Moraxella sp. was absent altogether. Detailed analyses of toxicity and associated microflora in a selected Ostreopsis clone, repeatedly cultivated (four times) over a period of 160 days, showed that peak cell toxicities developed in the late static and early negative culture growth phases. Peak Ostreopsis cell toxicities in the stationary phase of culture growth were correlated with significant increases in the percent total bacteria directly associated with these cells. Changes in the quantity of bacteria directly associated with microalgal cell surfaces and extracellular matrices during culture growth may be related to variability and degree of toxicity in these laboratory-cultured benthic dinoflagellates. PMID:2705766

  4. Conformity of bacterial growth in sputum and contamination free endobronchial samples in patients with cystic fibrosis.

    PubMed Central

    Gilljam, H; Malmborg, A S; Strandvik, B

    1986-01-01

    The use of sputum cultures to guide the antimicrobial treatment of patients with cystic fibrosis has been questioned. Bacterial growth and antibiotic susceptibility patterns of 33 culture pairs from sputum and contamination free endobronchial swabs from 14 patients with cystic fibrosis were compared. As expected, Pseudomonas aeruginosa of the mucoid and non-mucoid type, Staphylococcus aureus, and Haemophilus influenzae were the organisms most frequently found. Absolute or good agreement was found in 73% of the culture pairs. The accuracy of the sputum cultures improved with the duration of antimicrobial treatment. The extra information gained from the endobronchial culture did not change the antimicrobial strategy from that based on the sputum culture alone. It is concluded that sputum cultures provide accurate information about the bacterial colonisation of the lower respiratory tract in patients with cystic fibrosis and therefore can be trusted both at onset of treatment and during the entire treatment period. PMID:3097864

  5. Cationic Pillararenes Potently Inhibit Biofilm Formation without Affecting Bacterial Growth and Viability.

    PubMed

    Joseph, Roymon; Naugolny, Alissa; Feldman, Mark; Herzog, Ido M; Fridman, Micha; Cohen, Yoram

    2016-01-27

    It is estimated that up to 80% of bacterial infections are accompanied by biofilm formation. Since bacteria in biofilms are less susceptible to antibiotics than are bacteria in the planktonic state, biofilm-associated infections pose a major health threat, and there is a pressing need for antibiofilm agents. Here we report that water-soluble cationic pillararenes differing in the quaternary ammonium groups efficiently inhibited the formation of biofilms by clinically important Gram-positive pathogens. Biofilm inhibition did not result from antimicrobial activity; thus, the compounds should not inhibit growth of natural bacterial flora. Moreover, none of the cationic pillararenes caused detectable membrane damage to red blood cells or toxicity to human cells in culture. The results indicate that cationic pillararenes have potential for use in medical applications in which biofilm formation is a problem. PMID:26745311

  6. Continuous monitoring of bacterial biofilm growth using uncoated Thickness-Shear Mode resonators

    NASA Astrophysics Data System (ADS)

    Castro, P.; Resa, P.; Durán, C.; Maestre, J. R.; Mateo, M.; Elvira, L.

    2012-12-01

    Quartz Crystal Microbalances (QCM) were used to nondestructively monitor in real time the microbial growth of the bacteria Staphylococcus epidermidis (S. epidermidis) in a liquid broth. QCM, sometimes referred to as Thickness-Shear Mode (TSM) resonators, are highly sensitive sensors not only able to measure very small mass, but also non-gravimetric contributions of viscoelastic media. These devices can be used as biosensors for bacterial detection and are employed in many applications including their use in the food industry, water and environment monitoring, pharmaceutical sciences and clinical diagnosis. In this work, three strains of S. epidermidis (which differ in the ability to produce biofilm) have been continuously monitored using an array of piezoelectric TSM resonators, at 37 °C in a selective culturing media. Microbial growth was followed by measuring the changes in the crystal resonant frequency and bandwidth at several harmonics. It was shown that microbial growth can be monitored in real time using multichannel and multiparametric QCM sensors.

  7. Individual growth detection of bacterial species in an in vitro oral polymicrobial biofilm model.

    PubMed

    Tabenski, L; Maisch, T; Santarelli, F; Hiller, K-A; Schmalz, G

    2014-11-01

    Most in vitro studies on the antibacterial effects of antiseptics have used planktonic bacteria in monocultures. However, this study design does not reflect the in vivo situation in oral cavities harboring different bacterial species that live in symbiotic relationships in biofilms. The aim of this study was to establish a simple in vitro polymicrobial model consisting of only three bacterial strains of different phases of oral biofilm formation to simulate in vivo oral conditions. Therefore, we studied the biofilm formation of Actinomyces naeslundii (An), Fusobacterium nucleatum (Fn), and Enterococcus faecalis (Ef) on 96-well tissue culture plates under static anaerobic conditions using artificial saliva according to the method established by Pratten et al. that was supplemented with 1 g l(-1) sucrose. Growth was separately determined for each bacterial strain after incubation periods of up to 72 h by means of quantitative real-time polymerase chain reaction and live/dead staining. Presence of an extracellular polymeric substance (EPS) was visualized by Concanavalin A staining. Increasing incubation times of up to 72 h showed adhesion and propagation of the bacterial strains with artificial saliva formulation. An and Ef had significantly higher growth rates than Fn. Live/dead staining showed a median of 49.9 % (range 46.0-53.0 %) of living bacteria after 72 h of incubation, and 3D fluorescence microscopy showed a three-dimensional structure containing EPS. An in vitro oral polymicrobial biofilm model was established to better simulate oral conditions and had the advantage of providing the well-controlled experimental conditions of in vitro testing. PMID:25119373

  8. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria

    PubMed Central

    Zaka, Abha; Imran, Asma; Zahid, Muhammad Awais; Yousaf, Sumaira; Rasul, Ghulam; Arif, Muhammad; Mirza, Muhammad Sajjad

    2016-01-01

    The present study was conducted to evaluate the potential of rice rhizosphere associated antagonistic bacteria for growth promotion and disease suppression of bacterial leaf blight (BLB). A total of 811 rhizospheric bacteria were isolated and screened against 3 prevalent strains of BLB pathogen Xanthomonas oryzae pv. oryzae (Xoo) of which five antagonistic bacteria, i.e., Pseudomonas spp. E227, E233, Rh323, Serratia sp. Rh269 and Bacillus sp. Rh219 showed antagonistic potential (zone of inhibition 1–19 mm). Production of siderophores was found to be the common biocontrol determinant and all the strains solubilized inorganic phosphate (82–116 μg mL-1) and produced indole acetic acid (0.48–1.85 mg L-1) in vitro. All antagonistic bacteria were non-pathogenic to rice, and their co-inoculation significantly improved plant health in terms of reduced diseased leaf area (80%), improved shoot length (31%), root length (41%) and plant dry weight (60%) as compared to infected control plants. Furthermore, under pathogen pressure, bacterial inoculation resulted in increased activity of defense related enzymes including phenylalanine ammonia-lyase and polyphenol oxidase, along with 86% increase in peroxidase and 53% increase in catalase enzyme activities in plants inoculated with Pseudomonas sp. Rh323 as well as co-inoculated plants. Bacterial strains showed good colonization potential in the rice rhizosphere up to 21 days after seed inoculation. Application of bacterial consortia in the field resulted in an increase of 31% in grain yield and 10% in straw yield over non-inoculated plots. Although, yield increase was statistically non-significant but was accomplished with overall saving of 20% chemical fertilizers. The study showed that Pseudomonas sp. Rh323 can be used to develop dual-purpose inoculum which can serve not only to suppress BLB but also to promote plant growth in rice. PMID:27532545

  9. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria.

    PubMed

    Yasmin, Sumera; Zaka, Abha; Imran, Asma; Zahid, Muhammad Awais; Yousaf, Sumaira; Rasul, Ghulam; Arif, Muhammad; Mirza, Muhammad Sajjad

    2016-01-01

    The present study was conducted to evaluate the potential of rice rhizosphere associated antagonistic bacteria for growth promotion and disease suppression of bacterial leaf blight (BLB). A total of 811 rhizospheric bacteria were isolated and screened against 3 prevalent strains of BLB pathogen Xanthomonas oryzae pv. oryzae (Xoo) of which five antagonistic bacteria, i.e., Pseudomonas spp. E227, E233, Rh323, Serratia sp. Rh269 and Bacillus sp. Rh219 showed antagonistic potential (zone of inhibition 1-19 mm). Production of siderophores was found to be the common biocontrol determinant and all the strains solubilized inorganic phosphate (82-116 μg mL-1) and produced indole acetic acid (0.48-1.85 mg L-1) in vitro. All antagonistic bacteria were non-pathogenic to rice, and their co-inoculation significantly improved plant health in terms of reduced diseased leaf area (80%), improved shoot length (31%), root length (41%) and plant dry weight (60%) as compared to infected control plants. Furthermore, under pathogen pressure, bacterial inoculation resulted in increased activity of defense related enzymes including phenylalanine ammonia-lyase and polyphenol oxidase, along with 86% increase in peroxidase and 53% increase in catalase enzyme activities in plants inoculated with Pseudomonas sp. Rh323 as well as co-inoculated plants. Bacterial strains showed good colonization potential in the rice rhizosphere up to 21 days after seed inoculation. Application of bacterial consortia in the field resulted in an increase of 31% in grain yield and 10% in straw yield over non-inoculated plots. Although, yield increase was statistically non-significant but was accomplished with overall saving of 20% chemical fertilizers. The study showed that Pseudomonas sp. Rh323 can be used to develop dual-purpose inoculum which can serve not only to suppress BLB but also to promote plant growth in rice. PMID:27532545

  10. Thermal design and turbidity sensor for autonomous bacterial growth measurements in spaceflight.

    PubMed

    van Benthem, Roel; Krooneman, Janneke; de Grave, Wubbo; Hammenga-Dorenbos, Hilma

    2009-04-01

    For application of biological air filters in manned spacecraft, research on bacterial growth is carried out under microgravity conditions. For the BIOFILTER experiment, flown in 2005 on FOTON M2, eight turbidity sensors to measure the growth rate of the bacterium Xanthobacter autotrophicus GJ10 were used. Also thermal management provisions were implemented to control the internal temperature. The design and performance of the BIOFILTER equipment as well as results of the biological ground reference experiments performed in 2006 are discussed. High-performance thermal (vacuum) insulation (lambda= 0.7 mW/mK) and phase change material were implemented, keeping the BIOFILTER internal temperature below 16 degrees C during the 4-day integration period between transport and launch. After launch, in microgravity, the growth of X. autotrophicus GJ10 was successfully triggered by a temperature increase by using an internal heater to 26 degrees C. Although the operation of the sensor electronics was not fully satisfying, the bacterial growth was measured with the sensors, revealing growth rates between 0.046 and 0.077 h(-1) in microgravity, that is, approximately 1.5-2.5 times slower than routinely measured on Earth under optimal laboratory conditions. For the ground-reference experiments the equipment box, containing the eight sensors, was placed on a random positioning machine performing random rotations at 0.5 degrees /min (settling compensation) and 90 degrees /min (microgravity simulation) while the environment was controlled, accurately repeating the BIOFILTER internal temperature profile. Despite the rotation speed differences, growth rates of 0.115 h(-1) were confirmed by both the ground reference experiments. Biological interpretation of the measurements is, however, compromised owing to poor mixing and other unknown physical and biological phenomena that need to be addressed for further space experiments using these kinds of systems. PMID:19426313

  11. Scaling laws governing stochastic growth and division of single bacterial cells

    PubMed Central

    Iyer-Biswas, Srividya; Wright, Charles S.; Henry, Jonathan T.; Lo, Klevin; Burov, Stanislav; Lin, Yihan; Crooks, Gavin E.; Crosson, Sean; Dinner, Aaron R.; Scherer, Norbert F.

    2014-01-01

    Uncovering the quantitative laws that govern the growth and division of single cells remains a major challenge. Using a unique combination of technologies that yields unprecedented statistical precision, we find that the sizes of individual Caulobacter crescentus cells increase exponentially in time. We also establish that they divide upon reaching a critical multiple (≈1.8) of their initial sizes, rather than an absolute size. We show that when the temperature is varied, the growth and division timescales scale proportionally with each other over the physiological temperature range. Strikingly, the cell-size and division-time distributions can both be rescaled by their mean values such that the condition-specific distributions collapse to universal curves. We account for these observations with a minimal stochastic model that is based on an autocatalytic cycle. It predicts the scalings, as well as specific functional forms for the universal curves. Our experimental and theoretical analysis reveals a simple physical principle governing these complex biological processes: a single temperature-dependent scale of cellular time governs the stochastic dynamics of growth and division in balanced growth conditions. PMID:25349411

  12. Scaling laws governing stochastic growth and division of single bacterial cells.

    PubMed

    Iyer-Biswas, Srividya; Wright, Charles S; Henry, Jonathan T; Lo, Klevin; Burov, Stanislav; Lin, Yihan; Crooks, Gavin E; Crosson, Sean; Dinner, Aaron R; Scherer, Norbert F

    2014-11-11

    Uncovering the quantitative laws that govern the growth and division of single cells remains a major challenge. Using a unique combination of technologies that yields unprecedented statistical precision, we find that the sizes of individual Caulobacter crescentus cells increase exponentially in time. We also establish that they divide upon reaching a critical multiple (≈ 1.8) of their initial sizes, rather than an absolute size. We show that when the temperature is varied, the growth and division timescales scale proportionally with each other over the physiological temperature range. Strikingly, the cell-size and division-time distributions can both be rescaled by their mean values such that the condition-specific distributions collapse to universal curves. We account for these observations with a minimal stochastic model that is based on an autocatalytic cycle. It predicts the scalings, as well as specific functional forms for the universal curves. Our experimental and theoretical analysis reveals a simple physical principle governing these complex biological processes: a single temperature-dependent scale of cellular time governs the stochastic dynamics of growth and division in balanced growth conditions. PMID:25349411

  13. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  14. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    PubMed Central

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-01-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction. PMID:25008009

  15. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli.

    PubMed

    Martino, Daniele De; Capuani, Fabrizio; Martino, Andrea De

    2016-01-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity. PMID:27232645

  16. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli

    NASA Astrophysics Data System (ADS)

    De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

    2016-06-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity.

  17. A new model for the spectral induced polarization signature of bacterial growth in porous media

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Revil, A.; Atekwana, E. A.; Jardani, A.; Smith, S.

    2012-12-01

    Recent biogeophysics studies demonstrated the sensitivity of complex conductivity to bacterial growth and microbial mediated mineral transformations in porous media. Frequency-domain induced polarization is a minimally invasive manner to measure the complex conductivity of a material over a broad range of frequencies. The real component of complex conductivity is associated with electromigration of the charge carriers, and the imaginary component represents reversible energy storage of charge carriers at polarization length scales. Quantitative relationship between frequency-domain induced polarization responses and bacterial growth and decay in porous media is analyzed in this study using a new developed model. We focus on the direct contribution of bacteria themselves to the complex conductivity in porous media in the absence of biomineralization. At low frequencies, the induced polarization of bacteria (α-polarization) is related to the properties of the electrical double layer surrounding the membrane surface of bacteria. Surface conductivity and α-polarization are due to the Stern layer of the counterions occurring in a brush of polymers coating the surface of the bacteria, and can be related to the cation exchange capacity of the bacteria. From the modeling results, at low frequencies (< 10 Hz), the mobility of the counterions (K+) in the Stern layer of bacteria is found to be extremely small (4.7×10-10 m2s-1 V-1 at 25°C), and is close to the mobility of the same counterions along the surface of clay minerals (Na+, 1.5×10-10 m2s-1 V-1 at 25°C). This result is in agreement with experimental observations and it indicates a very low relaxation frequency for the α-polarization of the bacteria cells (typically around 0.1 to 5 Hertz). By coupling this new model with reactive transport modeling in which the evolution of bacterial populations are usually described by Monod kinetics, we show that the changes in imaginary conductivity with time can be used to

  18. Zinc-Triggered Hydrogelation of Self-assembled Small Molecules to Inhibit Bacterial Growth

    NASA Astrophysics Data System (ADS)

    Xu, Chao; Cai, Yanbin; Ren, Chunhua; Gao, Jie; Hao, Jihui

    2015-01-01

    There is a significant need to develop antibacterial materials that could be applied locally and directly to the places surrounded by large amount of bacteria, in order to address the problems of bacterial antibiotic-resistance or irreversible biofilm formation. Hydrogels are thought to be suitable candidates due to their versatile applications in biomedical field. Among them, small molecular hydrogels have been paid lots of attention because they are easy to design and fabricate and often sensitive to external stimuli. Meanwhile, the antibacterial activity of metal ions are attracting more and more attention because resistance to them are not yet found within bacteria. We therefore designed the zinc ion binding peptide of Nap-GFFYGGGHGRGD, who can self-assemble into hydrogels after binds Zn2+ and inhibit the growth of bacteria due to the excellent antibacterial activity of Zn2+. Upon the addition of zinc ions, solutions containing Nap-GFFYGGGHGRGD transformed into supramolecular hydrogels composed of network of long nano-fibers. Bacterial tests revealed an antibacterial effect of the zinc triggered hydrogels on E. coli. The studied small molecular hydrogel shows great potential in locally addressing bacterial infections.

  19. Growth and location of bacterial colonies within dairy foods using microscopy techniques: a review

    PubMed Central

    Hickey, Cian D.; Sheehan, Jeremiah J.; Wilkinson, Martin G.; Auty, Mark A. E.

    2015-01-01

    The growth, location, and distribution of bacterial colonies in dairy products are important factors for the ripening and flavor development of cheeses, yogurts, and soured creams. Starter, non-starter, spoilage, and pathogenic bacteria all become entrapped in the developing casein matrix of dairy foods. In order to visualize these bacterial colonies and the environments surrounding them, microscopy techniques are used. The use of various microscopy methods allow for the rapid detection, enumeration, and distribution of starter, non-starter and pathogenic bacteria in dairy foods. Confocal laser scanning microscopy is extensively utilized to identify bacteria location via the use of fluorescent dyes. Further study is needed in relation to the development of micro- gradients and localized ripening parameters in dairy products due to the location of bacteria at the protein–fat interface. Development in the area of bacterial discrimination using microscopy techniques and fluorescent dyes/tags is needed as the benefits of rapidly identifying spoilage/pathogenic bacteria early in product manufacture would be of huge benefit in relation to both safety and financial concerns. PMID:25741328

  20. Gyramides Prevent Bacterial Growth by Inhibiting DNA Gyrase and Altering Chromosome Topology

    PubMed Central

    2015-01-01

    Antibiotics targeting DNA gyrase have been a clinical success story for the past half-century, and the emergence of bacterial resistance has fueled the search for new gyrase inhibitors. In this paper we demonstrate that a new class of gyrase inhibitors, the gyramides, are bacteriostatic agents that competitively inhibit the ATPase activity of Escherichia coli gyrase and produce supercoiled DNA in vivo. E. coli cells treated with gyramide A have abnormally localized, condensed chromosomes that blocks DNA replication and interrupts chromosome segregation. The resulting alterations in DNA topology inhibit cell division through a mechanism that involves the SOS pathway. Importantly, gyramide A is a specific inhibitor of gyrase and does not inhibit the closely related E. coli enzyme topoisomerase IV. E. coli mutants with reduced susceptibility to gyramide A do not display cross-resistance to ciprofloxacin and novobiocin. The results demonstrate that the gyramides prevent bacterial growth by a mechanism in which the topological state of chromosomes is altered and halts DNA replication and segregation. The specificity and activity of the gyramides for inhibiting gyrase makes these compounds important chemical tools for studying the mechanism of gyrase and the connection between DNA topology and bacterial cell division. PMID:24712739

  1. Zinc-Triggered Hydrogelation of Self-assembled Small Molecules to Inhibit Bacterial Growth

    PubMed Central

    Xu, Chao; Cai, Yanbin; Ren, Chunhua; Gao, Jie; Hao, Jihui

    2015-01-01

    There is a significant need to develop antibacterial materials that could be applied locally and directly to the places surrounded by large amount of bacteria, in order to address the problems of bacterial antibiotic-resistance or irreversible biofilm formation. Hydrogels are thought to be suitable candidates due to their versatile applications in biomedical field. Among them, small molecular hydrogels have been paid lots of attention because they are easy to design and fabricate and often sensitive to external stimuli. Meanwhile, the antibacterial activity of metal ions are attracting more and more attention because resistance to them are not yet found within bacteria. We therefore designed the zinc ion binding peptide of Nap-GFFYGGGHGRGD, who can self-assemble into hydrogels after binds Zn2+ and inhibit the growth of bacteria due to the excellent antibacterial activity of Zn2+. Upon the addition of zinc ions, solutions containing Nap-GFFYGGGHGRGD transformed into supramolecular hydrogels composed of network of long nano-fibers. Bacterial tests revealed an antibacterial effect of the zinc triggered hydrogels on E. coli. The studied small molecular hydrogel shows great potential in locally addressing bacterial infections. PMID:25583430

  2. The Mammalian Neuroendocrine Hormone Norepinephrine Supplies Iron for Bacterial Growth in the Presence of Transferrin or Lactoferrin

    PubMed Central

    Freestone, Primrose P. E.; Lyte, Mark; Neal, Christopher P.; Maggs, Anthony F.; Haigh, Richard D.; Williams, Peter H.

    2000-01-01

    Norepinephrine stimulates the growth of a range of bacterial species in nutritionally poor SAPI minimal salts medium containing 30% serum. Addition of size-fractionated serum components to SAPI medium indicated that transferrin was required for norepinephrine stimulation of growth of Escherichia coli. Since bacteriostasis by serum is primarily due to the iron-withholding capacity of transferrin, we considered the possibility that norepinephrine can overcome this effect by supplying transferrin-bound iron for growth. Incubation with concentrations of norepinephrine that stimulated bacterial growth in serum-SAPI medium resulted in loss of bound iron from iron-saturated transferrin, as indicated by the appearance of monoferric and apo- isoforms upon electrophoresis in denaturing gels. Norepinephrine also caused the loss of iron from lactoferrin. The pharmacologically inactive metabolite norepinephrine 3-O-sulfate, by contrast, did not result in iron loss from transferrin or lactoferrin and did not stimulate bacterial growth in serum-SAPI medium. Norepinephrine formed stable complexes with transferrin, lactoferrin, and serum albumin. Norepinephrine-transferrin and norepinephrine-lactoferrin complexes, but not norepinephrine-apotransferrin or norepinephrine-albumin complexes, stimulated bacterial growth in serum-SAPI medium in the absence of additional norepinephrine. Norepinephrine-stimulated growth in medium containing 55Fe complexed with transferrin or lactoferrin resulted in uptake of radioactivity by bacterial cells. Moreover, norepinephrine-stimulated growth in medium containing [3H]norepinephrine indicated concomitant uptake of norepinephrine. In each case, addition of excess iron did not affect growth but significantly reduced levels of radioactivity (55Fe or 3H) associated with bacterial cells. A role for catecholamine-mediated iron supply in the pathophysiology of infectious diseases is proposed. PMID:11029429

  3. Asynchrony in the growth and motility responses to environmental changes by individual bacterial cells

    SciTech Connect

    Umehara, Senkei; Hattori, Akihiro; Inoue, Ippei; Yasuda, Kenji . E-mail: yasuda.bmi@tmd.ac.jp

    2007-05-04

    Knowing how individual cells respond to environmental changes helps one understand phenotypic diversity in a bacterial cell population, so we simultaneously monitored the growth and motility of isolated motile Escherichia coli cells over several generations by using a method called on-chip single-cell cultivation. Starved cells quickly stopped growing but remained motile for several hours before gradually becoming immotile. When nutrients were restored the cells soon resumed their growth and proliferation but remained immotile for up to six generations. A flagella visualization assay suggested that deflagellation underlies the observed loss of motility. This set of results demonstrates that single-cell transgenerational study under well-characterized environmental conditions can provide information that will help us understand distinct functions within individual cells.

  4. Cloning of human epidermal growth factor as a bacterial secretory protein, its properties and mutagenesis

    SciTech Connect

    Engler, D.A.; Matsunami, R.K.; Campion, S.R.; Foote, R.S.; Mural, R.J.; Larimer, F.W.; Stevens, A.; Niyogi, S.K.

    1987-05-01

    A chimeric gene, containing the DNA coding for the human epidermal growth factor (EGF) and that for the signal peptide of E. coli alkaline phosphatase, was constructed by the annealing and subsequent ligation of appropriate DNA oligonucleotides synthesized in an automated DNA synthesizer. The gene was then cloned into a bacterial plasmid under the transcriptional control of the E. coli trp-lac (tac) promoter, and then transformed into E. coli. Following induction with isopropylthiogalactoside, the secretion of EGF into the E. coli periplasmic space and some into the growth medium was confirmed by its specific binding to the EGF receptor and stimulation of the EGF receptor tyrosine kinase activity. The size and physicochemical properties of the purified protein mimicked those of authentic human EGF. Studies of structure/function relationships by specific alterations of targeted amino acid residues in the EGF molecule have been initiated by utilizing site-directed mutagenesis.

  5. Application of a Microcomputer-Based System to Control and Monitor Bacterial Growth

    PubMed Central

    Titus, Jeffrey A.; Luli, Gregory W.; Dekleva, Michael L.; Strohl, William R.

    1984-01-01

    A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO2, and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations. PMID:16346462

  6. Application of a microcomputer-based system to control and monitor bacterial growth.

    PubMed

    Titus, J A; Luli, G W; Dekleva, M L; Strohl, W R

    1984-02-01

    A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO(2), and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations. PMID:16346462

  7. Effect of humic substance photodegradation on bacterial growth and respiration in lake water.

    PubMed

    Anesio, Alexandre M; Granéli, Wilhelm; Aiken, George R; Kieber, David J; Mopper, Kenneth

    2005-10-01

    This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-microm-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by approximately 18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed approximately 10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates. PMID:16204548

  8. Effect of Humic Substance Photodegradation on Bacterial Growth and Respiration in Lake Water

    PubMed Central

    Anesio, Alexandre M.; Granéli, Wilhelm; Aiken, George R.; Kieber, David J.; Mopper, Kenneth

    2005-01-01

    This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-μm-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by ∼18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed ∼10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates. PMID:16204548

  9. Effect of humic substance photodegradation on bacterial growth and respiration in lake water

    USGS Publications Warehouse

    Anesio, A.M.; Graneli, W.; Aiken, G.R.; Kieber, D.J.; Mopper, K.

    2005-01-01

    This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-??m-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H 2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by ???18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed ???10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates. Copyright ?? 2005, American Society for Microbiology. All Rights Reserved.

  10. Inhibition of Pseudogymnoascus destructans growth from conidia and mycelial extension by bacterially produced volatile organic compounds.

    PubMed

    Cornelison, Christopher T; Gabriel, Kyle T; Barlament, Courtney; Crow, Sidney A

    2014-02-01

    The recently identified causative agent of white-nose syndrome (WNS), Pseudogymnoascus destructans, has been implicated in the mortality of an estimated 5.5 million North American bats since its initial documentation in 2006 (Frick et al. in Science 329:679-682, 2010). In an effort to identify potential biological and chemical control options for WNS, 6 previously described bacterially produced volatile organic compounds (VOCs) were screened for anti-P. destructans activity. The compounds include decanal; 2-ethyl-1-hexanol; nonanal; benzothiazole; benzaldehyde; andN,N-dimethyloctylamine. P. destructans conidia and mycelial plugs were exposed to the VOCs in a closed air space at 15 and 4 °C and then evaluated for growth inhibition. All VOCs inhibited growth from conidia as well as inhibiting radial mycelial extension, with the greatest effect at 4 °C. Studies of the ecology of fungistatic soils and the natural abundance of the fungistatic VOCs present in these environments suggest a synergistic activity of select VOCs may occur. The evaluation of formulations of two or three VOCs at equivalent concentrations was supportive of synergistic activity in several cases. The identification of bacterially produced VOCs with anti-P. destructans activity indicates disease-suppressive and fungistatic soils as a potentially significant reservoir of biological and chemical control options for WNS and provides wildlife management personnel with tools to combat this devastating disease. PMID:24190516

  11. Sweet scents from good bacteria: Case studies on bacterial volatile compounds for plant growth and immunity.

    PubMed

    Chung, Joon-hui; Song, Geun Cheol; Ryu, Choong-Min

    2016-04-01

    Beneficial bacteria produce diverse chemical compounds that affect the behavior of other organisms including plants. Bacterial volatile compounds (BVCs) contribute to triggering plant immunity and promoting plant growth. Previous studies investigated changes in plant physiology caused by in vitro application of the identified volatile compounds or the BVC-emitting bacteria. This review collates new information on BVC-mediated plant-bacteria airborne interactions, addresses unresolved questions about the biological relevance of BVCs, and summarizes data on recently identified BVCs that improve plant growth or protection. Recent explorations of bacterial metabolic engineering to alter BVC production using heterologous or endogenous genes are introduced. Molecular genetic approaches can expand the BVC repertoire of beneficial bacteria to target additional beneficial effects, or simply boost the production level of naturally occurring BVCs. The effects of direct BVC application in soil are reviewed and evaluated for potential large-scale field and agricultural applications. Our review of recent BVC data indicates that BVCs have great potential to serve as effective biostimulants and bioprotectants even under open-field conditions. PMID:26177913

  12. Kinetics of substrate utilization and bacterial growth of crude oil degraded by Pseudomonas aeruginosa.

    PubMed

    Talaiekhozani, Amirreza; Jafarzadeh, Nematollah; Fulazzaky, Mohamad Ali; Talaie, Mohammad Reza; Beheshti, Masoud

    2015-01-01

    Pollution associated with crude oil (CO) extraction degrades the quality of waters, threatens drinking water sources and may ham air quality. The systems biology approach aims at learning the kinetics of substrate utilization and bacterial growth for a biological process for which very limited knowledge is available. This study uses the Pseudomonas aeruginosa to degrade CO and determines the kinetic parameters of substrate utilization and bacterial growth modeled from a completely mixed batch reactor. The ability of Pseudomonas aeruginosa can remove 91 % of the total petroleum hydrocarbons and 83 % of the aromatic compounds from oily environment. The value k of 9.31 g of substrate g(-1) of microorganism d(-1) could be far higher than the value k obtained for petrochemical wastewater treatment and that for municipal wastewater treatment. The production of new cells of using CO as the sole carbon and energy source can exceed 2(3) of the existing cells per day. The kinetic parameters are verified to contribute to improving the biological removal of CO from oily environment. PMID:26413306

  13. Growth performance and carcase quality in broiler chickens fed on bacterial protein grown on natural gas.

    PubMed

    Øverland, M; Schøyen, H F; Skrede, A

    2010-10-01

    1. The effects of increasing concentrations (0, 40, 80 or 120 g/kg) of bacterial protein meal (BPM) and bacterial protein autolysate (BPA) grown on natural gas on growth performance and carcase quality in broiler chickens were examined. 2. Adding BPM to diets reduced feed intake and improved gain: feed from 0 to 21 d and overall to 35 d, but did not significantly affect weight gain compared to the soybean meal based control diet. 3. Increasing concentrations of BPA significantly reduced growth rate, feed intake, gain: feed, carcase weight and dressing percentage, but significantly increased carcase dry matter, fat and energy content. 4. Adding BPM to diets had no effect on viscosity of diets and jejunal digesta, and minor effects on litter quality, whereas BPA increased the viscosity of diets and jejunal digesta, improved litter quality at 21 d, but decreased litter quality at 32 d. 5. To conclude, broiler chickens performed better on a BPM product with intact proteins than on an autolysate with ruptured cell walls and a high content of free amino acids and low molecular-weight peptides. PMID:21058073

  14. Red and infrared laser therapy inhibits in vitro growth of major bacterial species that commonly colonize skin ulcers.

    PubMed

    de Sousa, Natanael Teixeira Alves; Gomes, Rosana Caetano; Santos, Marcos Ferracioli; Brandino, Hugo Evangelista; Martinez, Roberto; de Jesus Guirro, Rinaldo Roberto

    2016-04-01

    Low-level laser therapy (LLLT) is used in chronic wounds due to its healing effects. However, bacterial species may colonize these wounds and the optimal parameters for effective bacterial inhibition are not clear. The aim of this study was to analyze the effect of LLLT on bacterial growth in vitro. Bacterial strains including Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were suspended in saline solution at a concentration of 10(3) cells/ml and exposed to laser irradiation at wavelengths of 660, 830, and 904 nm at fluences of 0 (control), 3, 6, 12, 18, and 24 J/cm(2). An aliquot of the irradiated suspension was spread on the surface of petri plates and incubated at 37 °C for quantification of colony-forming unit after 24, 48, and 72 h. Laser irradiation inhibited the growth of S. aureus at all wavelengths and fluences higher than 12 J/cm(2), showing a strong correlation between increase in fluence and bacterial inhibition. However, for P. aeruginosa, LLLT inhibited growth at all wavelengths only at a fluence of 24 J/cm(2). E. coli had similar growth inhibition at a wavelength of 830 nm at fluences of 3, 6, 12, and 24 J/cm(2). At wavelengths of 660 and 904 nm, growth inhibition was only observed at fluences of 12 and 18 J/cm(2), respectively. LLLT inhibited bacterial growth at all wavelengths, for a maximum of 72 h after irradiation, indicating a correlation between bacterial species, fluence, and wavelength. PMID:26886585

  15. The receptor for advanced glycation end products promotes bacterial growth at distant body sites in Staphylococcus aureus skin infection.

    PubMed

    Achouiti, Ahmed; Van't Veer, Cornelis; de Vos, Alex F; van der Poll, Tom

    2015-09-01

    The receptor for advanced glycation endproducts (RAGE) has been implicated in the regulation of skin inflammation. We here sought to study the role of RAGE in host defense during skin infection caused by Staphylococcus (S.) aureus, the most common pathogen in this condition. Wild-type (Wt) and RAGE deficient (rage(-/-)) mice were infected subcutaneously with S. aureus and bacterial loads and local inflammation were quantified at regular intervals up to 8 days after infection. While bacterial burdens were similar in both mouse strains at the primary site of infection, rage(-/-) mice had lower bacterial counts in lungs and liver. Skin cytokine and chemokine levels did not differ between groups. In accordance with the skin model, direct intravenous infection with S. aureus was associated with lower bacterial loads in lungs and liver of rage(-/-) mice. Together these data suggest that RAGE does not impact local host defense during S. aureus skin infection, but facilitates bacterial growth at distant body sites. PMID:26086798

  16. Pump-free gradient-based micro-device enables quantitative and high-throughput bacterial growth inhibition analysis.

    PubMed

    Ran, Min; Wang, Ying; Wang, Sida; Luo, Chunxiong

    2015-08-01

    Antibiotic susceptibility testing is very important in antibiotic therapy. Traditional methods to determine antibiotic susceptibility include disk diffusion and broth dilution. However, these tests are always labor intensive, time-consuming, and need large amounts of reagents. In this paper, we demonstrated a novel pump-free micro-device that enables quantitative and high-throughput bacterial growth inhibition analysis. This device consists of a series of wells and diffusion-based antibiotic gradient channels. The wells serve as antibiotic sources and buffer sinks, and we could easily observe the bacterial growth in the gradient channels .The design of the multi-wells is adapted to the commercialized multi-channel pipette, which makes it very convenient for loading reagents into the wells. For each assay, only about 20 μL antibiotic solution is needed. As a demonstration, we used both fluorescence images and dark-field images to quantify the bacterial growth inhibition effect under different antibiotics. The quantitative data of bacterial growth inhibition under different antibiotics can be obtained within 3 to 4 h. Considering the simple operation process and the high-throughput and quantitative result this device can offer, it has great potential to be widely used in clinics and may be useful for the study of the kinetics of bacterial growth. PMID:26044203

  17. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    PubMed Central

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-01-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

  18. Combining prebiotics with probiotic bacteria can enhance bacterial growth and secretion of bacteriocins.

    PubMed

    Pranckutė, Raminta; Kaunietis, Arnoldas; Kuisienė, Nomeda; Čitavičius, Donaldas J

    2016-08-01

    There is a growing interest in supporting human health by using prebiotics, such as oligosaccharides, and beneficial bacteria, also called probiotics. Combining these two components we can develop synbiotics. In order to create successful combination of synbiotic it is very important to evaluate the influence of prebiotic oligosaccharides to probiotic bacteria and their behavior, such as growth and secretion of health related biomolecules, including bacteriocins. In this study seven type strains of probiotic bacteria (five Lactobacillus sp. and two Lactococcus sp.) and two Lactobacillus sp. strains, isolated from probiotic yoghurt, were cultivated with various commercially available and extracted oligosaccharides (OS). The aim of this study was to evaluate the influence of these OS on type and isolated bacterial strains growth and antibacterial activity. Obtained results suggest that combination of certain OS with probiotic strains may considerably improve their growth and/or antibacterial activity. We also determined the antibacterial activity spectrum of investigated strains with combination of OS against common food borne pathogens. Results of this work show that prebiotic OS can be useful for modulating probiotic bacteria growth, antibacterial activity and even specificity of this activity. PMID:27181578

  19. Bacterial endophyte Sphingomonas sp. LK11 produces gibberellins and IAA and promotes tomato plant growth.

    PubMed

    Khan, Abdul Latif; Waqas, Muhammad; Kang, Sang-Mo; Al-Harrasi, Ahmed; Hussain, Javid; Al-Rawahi, Ahmed; Al-Khiziri, Salima; Ullah, Ihsan; Ali, Liaqat; Jung, Hee-Young; Lee, In-Jung

    2014-08-01

    Plant growth promoting endophytic bacteria have been identified as potential growth regulators of crops. Endophytic bacterium, Sphingomonas sp. LK11, was isolated from the leaves of Tephrosia apollinea. The pure culture of Sphingomonas sp. LK11 was subjected to advance chromatographic and spectroscopic techniques to extract and isolate gibberellins (GAs). Deuterated standards of [17, 17-(2)H2]-GA4, [17, 17-(2)H2]-GA9 and [17, 17-(2)H2]-GA20 were used to quantify the bacterial GAs. The analysis of the culture broth of Sphingomonas sp. LK11 revealed the existence of physiologically active gibberellins (GA4: 2.97 ± 0.11 ng/ml) and inactive GA9 (0.98 ± 0.15 ng/ml) and GA20 (2.41 ± 0.23). The endophyte also produced indole acetic acid (11.23 ± 0.93 μM/ml). Tomato plants inoculated with endophytic Sphingomonas sp. LK11 showed significantly increased growth attributes (shoot length, chlorophyll contents, shoot, and root dry weights) compared to the control. This indicated that such phyto-hormones-producing strains could help in increasing crop growth. PMID:24994010

  20. Nonlinear estimation of Monod growth kinetic parameters from a single substrate depletion curve.

    PubMed Central

    Robinson, J A; Tiedje, J M

    1983-01-01

    Monod growth kinetic parameters were estimated by fitting sigmoidal substrate depletion data to the integrated Monod equation, using nonlinear least-squares analysis. When the initial substrate concentration was in the mixed-order region, nonlinear estimation of simulated data sets containing known measurement errors provided accurate estimates of the mu max, Ks, and Y values used to create these data. Nonlinear regression analysis of sigmoidal substrate depletion data was also evaluated for H2-limited batch growth of Desulfovibrio sp. strain G11. The integrated Monod equation can be more convenient for the estimation of growth kinetic parameters, particularly for gaseous substrates, but it must be recognized that the estimates of mu max, Ks, and Y obtained may be influenced by the growth rate history of the inoculum. PMID:6870238

  1. Study on Growth Curves of Longissimus dorsi Muscle Area, Backfat Thickness and Body Conformation for Hanwoo (Korean Native) Cows

    PubMed Central

    Lee, J. H.; Oh, S.-H.; Lee, Y. M.; Kim, Y. S.; Son, H. J.; Jeong, D. J.; Whitley, N. C.; Kim, J. J.

    2014-01-01

    The objective of this study was to estimate the parameters of Gompertz growth curves with the measurements of body conformation, real-time ultrasound longissimus dorsi muscle area (LMA) and backfat thickness (BFT) in Hanwoo cows. The Hanwoo cows (n = 3,373) were born in 97 Hanwoo commercial farms in the 17 cities or counties of Gyeongbuk province, Korea, between 2000 and 2007. A total of 5,504 ultrasound measurements were collected for the cows at the age of 13 to 165 months in 2007 and 2008. Wither height (HW), rump height (HR), the horizontal distance between the top of the hips (WH), and girth of chest (GC) were also measured. Analysis of variance was conducted to investigate variables affecting LMA and BFT. The effect of farm nested in location was included in the statistical model, as well as the effects of HW, HR, WH, and GC as covariates. All of the effects were significant in the analysis of variance for LMA and BFT (p<0.01), except for the HR effect for LMA. The two ultrasound measures and the four body conformation traits were fitted to a Gompertz growth curve function to estimate parameters. Upper asymptotic weights were estimated as 54.0 cm2, 7.67 mm, 125.6 cm, 126.4 cm, 29.3 cm, and 184.1 cm, for LMA, BFT, HW, HR, WH, and GC, respectively. Results of ultrasound measurements showed that Hanwoo cows had smaller LMA and greater BFT than other western cattle breeds, suggesting that care must be taken to select for thick BFT rather than an increase of only beef yield. More ultrasound records per cow are needed to get accurate estimates of growth curve, which, thus, helps producers select animals with high accuracy. PMID:25178367

  2. Stool consistency is strongly associated with gut microbiota richness and composition, enterotypes and bacterial growth rates

    PubMed Central

    Vandeputte, Doris; Falony, Gwen; Vieira-Silva, Sara; Tito, Raul Y; Joossens, Marie; Raes, Jeroen

    2016-01-01

    Objective The assessment of potentially confounding factors affecting colon microbiota composition is essential to the identification of robust microbiome based disease markers. Here, we investigate the link between gut microbiota variation and stool consistency using Bristol Stool Scale classification, which reflects faecal water content and activity, and is considered a proxy for intestinal colon transit time. Design Through 16S rDNA Illumina profiling of faecal samples of 53 healthy women, we evaluated associations between microbiome richness, Bacteroidetes:Firmicutes ratio, enterotypes, and genus abundance with self-reported, Bristol Stool Scale-based stool consistency. Each sample’s microbiota growth potential was calculated to test whether transit time acts as a selective force on gut bacterial growth rates. Results Stool consistency strongly correlates with all known major microbiome markers. It is negatively correlated with species richness, positively associated to the Bacteroidetes:Firmicutes ratio, and linked to Akkermansia and Methanobrevibacter abundance. Enterotypes are distinctly distributed over the BSS-scores. Based on the correlations between microbiota growth potential and stool consistency scores within both enterotypes, we hypothesise that accelerated transit contributes to colon ecosystem differentiation. While shorter transit times can be linked to increased abundance of fast growing species in Ruminococcaceae-Bacteroides samples, hinting to a washout avoidance strategy of faster replication, this trend is absent in Prevotella-enterotyped individuals. Within this enterotype adherence to host tissue therefore appears to be a more likely bacterial strategy to cope with washout. Conclusions The strength of the associations between stool consistency and species richness, enterotypes and community composition emphasises the crucial importance of stool consistency assessment in gut metagenome-wide association studies. PMID:26069274

  3. Mining the phytomicrobiome to understand how bacterial coinoculations enhance plant growth

    PubMed Central

    Maymon, Maskit; Martínez-Hidalgo, Pilar; Tran, Stephen S.; Ice, Tyler; Craemer, Karena; Anbarchian, Teni; Sung, Tiffany; Hwang, Lin H.; Chou, Minxia; Fujishige, Nancy A.; Villella, William; Ventosa, Jérôme; Sikorski, Johannes; Sanders, Erin R.; Faull, Kym F.; Hirsch, Ann M.

    2015-01-01

    In previous work, we showed that coinoculating Rhizobium leguminosarum bv. viciae 128C53 and Bacillus simplex 30N-5 onto Pisum sativum L. roots resulted in better nodulation and increased plant growth. We now expand this research to include another alpha-rhizobial species as well as a beta-rhizobium, Burkholderia tuberum STM678. We first determined whether the rhizobia were compatible with B. simplex 30N-5 by cross-streaking experiments, and then Medicago truncatula and Melilotus alba were coinoculated with B. simplex 30N-5 and Sinorhizobium (Ensifer) meliloti to determine the effects on plant growth. Similarly, B. simplex 30N-5 and Bu. tuberum STM678 were coinoculated onto Macroptilium atropurpureum. The exact mechanisms whereby coinoculation results in increased plant growth are incompletely understood, but the synthesis of phytohormones and siderophores, the improved solubilization of inorganic nutrients, and the production of antimicrobial compounds are likely possibilities. Because B. simplex 30N-5 is not widely recognized as a Plant Growth Promoting Bacterial (PGPB) species, after sequencing its genome, we searched for genes proposed to promote plant growth, and then compared these sequences with those from several well studied PGPB species. In addition to genes involved in phytohormone synthesis, we detected genes important for the production of volatiles, polyamines, and antimicrobial peptides as well as genes for such plant growth-promoting traits as phosphate solubilization and siderophore production. Experimental evidence is presented to show that some of these traits, such as polyamine synthesis, are functional in B. simplex 30N-5, whereas others, e.g., auxin production, are not. PMID:26442090

  4. Effects of Assimilable Organic Carbon and Free Chlorine on Bacterial Growth in Drinking Water

    PubMed Central

    Liu, Tingting; Kong, Weiwen; He, Xiaoqing; Jin, Yi; Zhang, Bolin

    2015-01-01

    Assimilable organic carbon (AOC) is one of the most important factors affecting the re-growth of microorganisms in drinking water. High AOC concentrations result in biological instability, but disinfection kills microbes to ensure the safety of drinking water. Free chlorine is an important oxidizing agent used during the disinfection process. Therefore, we explored the combined effects of AOC and free chlorine on bacterial growth in drinking water using flow cytometry (FCM). The initial AOC concentration was 168 μg.L-1 in all water samples. Without free chlorine, the concentrations of intact bacteria increased but the level of AOC decreased. The addition of sodium hypochlorite caused an increase and fluctuation in AOC due to the oxidation of organic carbon. The concentrations of intact bacteria decreased from 1.1×105 cells.mL-1 to 2.6×104 cells.mL-1 at an initial free chlorine dose of 0.6 mg.L-1 to 4.8×104 cells.mL-1 at an initial free chlorine dose of 0.3 mg.L-1 due to free chlorine originating from sodium hypochlorite. Additionally, free chlorine might be more obviously affected AOC concentrations than microbial growth did. These results suggested that AOC and free chlorine might have combined effects on microbial growth. In this study, our results showed concentrations determined by FCM were higher than those by HPC, which indicated that some E. coli detected by FCM might not be detected using HPC in drinking water. The level of free chlorine might restrain the consumption of AOC by inhibiting the growth of E. coli; on the other hand, chlorination might increase the level of AOC, thereby increase the potential for microbial growth in the drinking water network. PMID:26034988

  5. Analysis of a Stochastic Model for Bacterial Growth and the Lognormality of the Cell-Size Distribution

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ken; Wakita, Jun-ichi

    2016-07-01

    This paper theoretically analyzes a phenomenological stochastic model for bacterial growth. This model comprises cell division and the linear growth of cells, where growth rates and cell cycles are drawn from lognormal distributions. We find that the cell size is expressed as a sum of independent lognormal variables. We show numerically that the quality of the lognormal approximation greatly depends on the distributions of the growth rate and cell cycle. Furthermore, we show that actual parameters of the growth rate and cell cycle take values that give a good lognormal approximation; thus, the experimental cell-size distribution is in good agreement with a lognormal distribution.

  6. Growth curve analyses of the relationship between early maternal age and children's mathematics and reading performance.

    PubMed

    Torres, D Diego

    2015-03-01

    Regarding the methods used to examine the early maternal age-child academic outcomes relationship, the extant literature has tended to examine change using statistical analyses that fail to appreciate that individuals vary in their rates of growth. Of the one study I have been able to find that employs a true growth model to estimate this relationship, the authors only controlled for characteristics of the maternal household after family formation; confounding background factors of mothers that might select them into early childbearing, a possible source of bias, were ignored. The authors' findings nonetheless suggested an inverse relationship between early maternal age, i.e., a first birth between the ages of 13 and 17, and Canadian adolescents' mean math performance at age 10. Early maternal age was not related to the linear slope of age. To elucidate whether the early maternal age-child academic outcomes association, treated in a growth context, is consistent with this finding, the present study built on it using US data and explored children's mathematics and reading trajectories from age 5 on. Its unique contribution is that it further explicitly controlled for maternal background factors and employed a three-level growth model with repeated measures of children nested within their mothers. Though the strength of the relationship varied between mean initial academic performance and mean academic growth, results confirmed that early maternal age was negatively related to children's mathematics and reading achievement, net of post-teen first birth child-specific and maternal household factors. Once maternal background factors were included, there was no statistically significant relationship between early maternal age and either children's mean initial mathematics and reading scores or their mean mathematics and reading growth. PMID:25592941

  7. Growth of Goertler vortices in compressible boundary layers along curved surfaces

    NASA Technical Reports Server (NTRS)

    El-Hady, N. M.; Verma, A. K.

    1983-01-01

    An investigation of the growth of the three-dimensional, counter-rotating, longitudinal type vortices is considered in two-dimensional laminar compressible boundary-layer flow. The basic approximation of the disturbance equations that includes the terms due to boundary layer growth is considered and solved numerically. These terms are shown to have large local effects near the neutral stability region. The study shows that the instability of the boundary layer with respect to the three-dimensional vortices sets in at higher Goertler number as Mach number increases. Also the maximum amplitude ratio of the vortices is reduced by about 20 percent as Mach number increases from 0 to 5.

  8. Divergent selection for shape of growth curve in Japanese quail. 5. Growth pattern and low protein level in starter diet.

    PubMed

    Hyankova, L; Knizetova, H

    2009-07-01

    1. The effect of crude protein (CP) concentration in starter diet (259 or 216 g CP and 11.7 MJ ME/kg, fed from 0 to 21 d of age) on postnatal growth pattern (from hatching to 70 d of age) was analysed in Japanese quail lines divergently selected for high (HG) and low (LG) relative gain of body weight (BW) between 11 and 28 d of age, and constant BW at 49 d of age. 2. Males and females of both lines fed on the low CP diet showed a transient BW retardation between 7 and 28 d of age, and 7 and 35 d of age, respectively, when compared with their counterparts receiving the standard CP diet. 3. Although the negative effect of low CP concentration on growth rate was observed in both lines, a lower tolerance of young HG vs. LG quail to the reduction of CP level in food was evident from their (i) stronger BW retardation at 14 d of age (16 vs. 7%), (ii) more delayed onset of compensatory growth (21 vs. 7 d of age) and (iii) greater prolongation of the acceleration growth phase (3 vs. 1 d of age) following insufficient dietary CP. 4. The line differences in early growth rate were accompanied by significant differences in food intake. The LG line consumed more food than the HG line on both CP diets and consumption was not influenced by food quality. In contrast, HG quail reduced food intake with the decrease of dietary CP concentration. On both CP diets, this was associated with a higher body fatness of LG vs. HG quail. 5. The protein-deficient food could thus represent an important factor contributing to the selection advantage of developmentally accelerated genotypes during the selection for high BW in young age categories. PMID:19735014

  9. Changes in bacterial flora of Japanese cabbage during growth and potential source of flora.

    PubMed

    Izumi, Hidemi; Sera, Kaori

    2011-04-01

    Bacterial flora of cabbage were identified and enumerated during various stages of growth, and the potential sources of contamination in the field were determined. Bacterial counts increased from below the level of detection (2.4 log CFU/g) on seeds to 2.5 to 5.7 log CFU/g on seedlings. After transplanting, the counts of mesophilic aerobic bacteria on leaves decreased and then increased to 5.7 log CFU/g on outer leaves, 5.0 log CFU/g on middle leaves, and 3.0 log CFU/g on inner leaves at the harvesting stage. Counts of coliforms were below the level of detection during the growing period of the leaves. Bacteria isolated from cabbage seeds, seedlings, and leaves were soilborne organisms such as Bacillus, Curtobacterium, and Delftia and phytopathogenic organisms such as Pseudomonas, Pantoea, and Stenotrophomonas. These bacteria were found frequently in seeding machines, potting soil mix, soil, agricultural water, pesticide solutions mixed with the agricultural water, liquid fertilizers, and chemical fertilizers. Contamination from these environmental sites occurred throughout the cabbage growing period rather than only at the harvesting stage. These results indicate that use of clean water for irrigation and for mixing with pesticides and amendments from seeding to the harvesting stage is an important part of a good agricultural practices program for cabbage in Japan. PMID:21477482

  10. Agarose particle-templated porous bacterial cellulose and its application in cartilage growth in vitro.

    PubMed

    Yin, Na; Stilwell, Matthew D; Santos, Thiago M A; Wang, Huaping; Weibel, Douglas B

    2015-01-01

    Bacterial cellulose (BC) is a biocompatible hydrogel with a three-dimensional (3-D) structure formed by a dense network of cellulose nanofibers. A limitation of using BC for applications in tissue engineering is that the pore size of the material (∼0.02-10μm) is smaller than the dimensions of mammalian cells and prevents cells from penetrating into the material and growing into 3-D structures that mimic tissues. This paper describes a new route to porous bacterial cellulose (pBC) scaffolds by cultivating Acetobacter xylinum in the presence of agarose microparticles deposited on the surface of a growing BC pellicle. Monodisperse agarose microparticles with a diameter of 300-500μm were created using a microfluidic technique, layered on growing BC pellicles and incorporated into the polymer as A. xylinum cells moved upward through the growing pellicle. Removing the agarose microparticles by autoclaving produced BC gels containing a continuous, interconnected network of pores with diameters ranging from 300 to 500μm. Human P1 chondrocytes seeded on the scaffolds, replicated, invaded the 3-D porous network and distributed evenly throughout the substrate. Chondrocytes grown on pBC substrates displayed a higher viability compared to growth on the surface of unmodified BC substrates. The approach described in this paper introduces a new method for creating pBC substrates with user-defined control over the physical dimensions of the pore network, and demonstrates the application of these materials for tissue engineering. PMID:25449918

  11. Effects of Gypsophila saponins on bacterial growth kinetics and on selection of subterranean clover rhizosphere bacteria.

    PubMed

    Fons, F; Amellal, N; Leyval, C; Saint-Martin, N; Henry, M

    2003-06-01

    Plant secondary metabolites, such as saponins, have a considerable impact in agriculture because of their allelopathic effects. They also affect the growth of soil microorganisms, especially fungi. We investigated the influence of saponins on rhizosphere bacteria in vitro and in soil conditions. The effects of gypsophila saponins on the growth kinetics of rhizosphere bacteria were studied by monitoring the absorbance of the cultures in microtiter plates. Gypsophila saponins (1%) increased the lag phase of bacterial growth. The impact of gypsophila saponins on subterranean clover rhizosphere was also investigated in a pot experiment. The addition of gypsophila saponins did not modify clover biomass but significantly increased (twofold with 1% saponins) the weight of adhering soil. The number of culturable heterotrophic bacteria of the clover rhizosphere was not affected by the addition of gypsophila saponins. Nevertheless, the phenotypical characterization of the dominant Gram-negative strains of the clover rhizosphere, using the Biolog system, showed qualitative and quantitative differences induced by 1% saponins. With the addition of saponins, the populations of Chryseomonas spp. and Acinetobacter spp., the two dominant culturable genera of control clover, were no longer detectable or were significantly decreased, while that of Aquaspirillum dispar increased and Aquaspirillum spp. became the major genus. Aquaspirillum dispar and Aquaspirillum spp. were also the dominant rhizosphere bacteria of Gypsophila paniculata, which greatly accumulates these saponins in its roots. These results suggest that saponins may control rhizosphere bacteria in soil through rhizodeposition mechanisms. PMID:14569290

  12. Response of the bacterial symbiont Holospora caryophila to different growth conditions of its host.

    PubMed

    Castelli, Michele; Lanzoni, Olivia; Fokin, Sergei I; Schrallhammer, Martina; Petroni, Giulio

    2015-02-01

    Previous studies on bacterial symbionts of ciliates have shown that some symbionts can be maintained relatively well under standard laboratory conditions whereas others are frequently lost, especially when the host is cultivated at a high division rate. In this study, the variation in infection level by the endosymbiont Holospora caryophila within its host population Paramecium octaurelia was investigated in response to three alimentary treatments and a subsequent starvation phase. The response of the ciliates was determined as a nearly exponential growth rate with different slopes in each treatment, proportional to the amount of food received. The initial infection level was higher than 90%. After 24 days of exponential host's growth, the prevalence remained stable at approximately 90% in all treatments, even after a subsequent starvation phase of 20 days. However, at intermediate time-points in both the feeding and the starvation phase, fluctuations in the presence of the intracellular bacteria were observed. These results show that H. caryophila is able to maintain its infection under the tested range of host growth conditions, also due to the possibility of an effective re-infection in case of partial loss. PMID:25635695

  13. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

    PubMed Central

    Forte, Elena; Borisov, Vitaliy B.; Falabella, Micol; Colaço, Henrique G.; Tinajero-Trejo, Mariana; Poole, Robert K.; Vicente, João B.; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  14. Quantitative Genetic Analysis of Latent Growth Curve Models of Cognitive Abilities in Adulthood

    ERIC Educational Resources Information Center

    Reynolds, Chandra A.; Finkel, Deborah; McArdle, John J.; Gatz, Margaret; Berg, Stig; Pedersen, Nancy L.

    2005-01-01

    Though many cognitive abilities exhibit marked decline over the adult years, individual differences in rates of change have been observed. In the current study, biometrical latent growth models were used to examine sources of variability for ability level (intercept) and change (linear and quadratic effects) for verbal, fluid, memory, and…

  15. Level and Change of Bullying Behavior during High School: A Multilevel Growth Curve Analysis

    ERIC Educational Resources Information Center

    Nocentini, Annalaura; Menesini, Ersilia; Salmivalli, Christina

    2013-01-01

    The development of bullying behavior was examined across three years in a sample of 515 adolescents (46% females) from 41 classrooms. At time 1, the students were in grades 9 and 10 (mean age = 14.5 years; SD = 0.54). Results of a multilevel growth model showed that both baseline level and change of bullying varied significantly across individuals…

  16. CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS

    SciTech Connect

    McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L.; D'Alessio, P.; Espaillat, C.; Sargent, B.; Watson, D. M.; Hernández, J. E-mail: ncalvet@umich.edu E-mail: lingleby@umich.edu E-mail: cespaillat@cfa.harvard.edu E-mail: dmw@pas.rochester.edu

    2013-10-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10{sup –8} to 10{sup –10} M{sub ☉} yr{sup –1}, the maximum grain size in the lower layer decreases from ∼3 to 0.5 μm. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 × 10{sup –4} of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 μm silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system.

  17. Molecular mechanisms for the evolution of bacterial morphologies and growth modes

    PubMed Central

    Randich, Amelia M.; Brun, Yves V.

    2015-01-01

    Bacteria exhibit a rich diversity of morphologies. Within this diversity, there is a uniformity of shape for each species that is replicated faithfully each generation, suggesting that bacterial shape is as selectable as any other biochemical adaptation. We describe the spatiotemporal mechanisms that target peptidoglycan synthesis to different subcellular zones to generate the rod-shape of model organisms Escherichia coli and Bacillus subtilis. We then demonstrate, using the related genera Caulobacter and Asticcacaulis as examples, how the modularity of the core components of the peptidoglycan synthesis machinery permits repositioning of the machinery to achieve different growth modes and morphologies. Finally, we highlight cases in which the mechanisms that underlie morphological evolution are beginning to be understood, and how they depend upon the expansion and diversification of the core components of the peptidoglycan synthesis machinery. PMID:26106381

  18. Sevoflurane Contamination: Water Accumulation in Sevoflurane Vaporizers Can Allow Bacterial Growth in the Vaporizer.

    PubMed

    Wallace, Arthur W

    2016-06-15

    Sevoflurane vaporizers (GE Tec 7) were difficult to fill with "slow flow" and a need to "burp." Evaluation of the bottle of sevoflurane (AbbVie Ultane) demonstrated a contaminant. Four of the facilities' 13 sevoflurane vaporizers had the contaminant. Unopened sevoflurane bottles did not have evidence of contamination. The contaminant was found to be water at pH 6.0 growing Staphylococcus epidermidis. Gas chromatography revealed the production of multiple metabolites of sevoflurane, including primarily urea and 1,3,5-triazine-2,4,6(1H,3H,5H)-trione (83% and 9.6% of volatiles) in addition to multiple other organic molecules. Sevoflurane contains water that can accumulate in vaporizers allowing bacterial growth. PMID:27301057

  19. Convexity of the Photosynthetic Light-Response Curve in Relation to Intensity and Direction of Light during Growth.

    PubMed Central

    Ogren, E.

    1993-01-01

    Photosynthesis in the intermediate light range is most efficient when the convexity of the photosynthetic light-response curve is high. Factors determining the convexity were examined for intact leaves using Salix sp. and for a plant cell culture using the green microalga Coccomyxa sp. It was found that the leaf had lower convexity than diluted plant cells because the light gradient through the leaf was not fully matched by a corresponding gradient in photosynthetic capacity. The degree to which the leaf gradients were matched was quantified by measuring photosynthesis at both leaf surfaces using modulated fluorescence. Two principal growth conditions were identified as those causing mismatch of leaf gradients and lowering of the convexity relative to cells. The first was growth under low light, where leaves did not develop any noteworthy gradient in photosynthetic capacity. This led to decreased convexity, particularly in old leaves with high chlorophyll content and, hence, steep light gradients. Second and less conspicuous was growth under high light conditions when light was given bilaterally rather than unilaterally, which yielded leaves of high photosynthetic capacity at both surfaces. Two situations were also identified that caused the convexity to decrease at the chloroplast level: (a) increased light during growth, for both leaves and cells, and (b) increased CO2 concentration during measurement of high-light-grown leaves. These changes of the intrinsic convexity were interpreted to indicate that the convexity declines with increased capacity of ribulose-1,5-bisphosphate carboxylase/oxygenase relative to the capacity of electron transport. PMID:12231754

  20. Response of leaf endophytic bacterial community to elevated CO2 at different growth stages of rice plant

    PubMed Central

    Ren, Gaidi; Zhang, Huayong; Lin, Xiangui; Zhu, Jianguo; Jia, Zhongjun

    2015-01-01

    Plant endophytic bacteria play an important role in plant growth and health. In the context of climate change, the response of plant endophytic bacterial communities to elevated CO2 at different rice growing stages is poorly understood. Using 454 pyrosequencing, we investigated the response of leaf endophytic bacterial communities to elevated CO2 (eCO2) at the tillering, filling, and maturity stages of the rice plant under different nitrogen fertilization conditions [low nitrogen fertilization (LN) and high nitrogen fertilization (HN)]. The results revealed that the leaf endophytic bacterial community was dominated by Gammaproteobacteria-affiliated families, such as Enterobacteriaceae and Xanthomonadaceae, which represent 28.7–86.8% and 2.14–42.6% of the total sequence reads, respectively, at all tested growth stages. The difference in the bacterial community structure between the different growth stages was greater than the difference resulting from the CO2 and nitrogen fertilization treatments. The eCO2 effect on the bacterial communities differed greatly under different nitrogen application conditions and at different growth stages. Specifically, eCO2 revealed a significant effect on the community structure under both LN and HN levels at the tillering stage; however, the significant effect of eCO2 was only observed under HN, rather than under the LN condition at the filling stage; no significant effect of eCO2 on the community structure at both the LN and HN fertilization levels was found at the maturity stage. These results provide useful insights into the response of leaf endophytic bacterial communities to elevated CO2 across rice growth stages. PMID:26379635

  1. Using Reactive Transport Modeling to Understand Changes in Electrical Conductivity Associated with Bacterial Growth and Respiration

    NASA Astrophysics Data System (ADS)

    Regberg, A. B.; Singha, K.; Picardal, F.; Brantley, S. L.

    2011-12-01

    Previous research has linked measured changes in the bulk electrical conductivity (σb) of water-saturated sediments to the respiration and growth of anaerobic bacteria. If the mechanism causing this signal is understood and characterized it could be used to identify and monitor zones of bacterial activity in the subsurface. The 1-D reactive transport model PHREEQC was used to understand σb signals by modeling chemical gradients within two column reactors and corresponding changes in effluent chemistry. The flow-through column reactors were packed with Fe(III)-bearing sediment from Oyster, VA and inoculated with an environmental consortia of microorganisms. Influent in the first reactor was amended with 1mM Na-acetate to encourage the growth of iron-reducing bacteria. Influent in the second reactor was amended with 0.1mM Na-Acetate and 2mM NaNO3 to encourage the growth of nitrate-reducing bacteria. While effluent concentrations of acetate, Fe(II), NO3-, NO2-, and NH4+ remained at steady state, we measured a 3-fold increase (0.055 S/m - 0.2 S/m) in σb in the iron-reducing column and a 10-fold increase in σb (0.07 S/m - 0.8 S/m) in the nitrate-reducing column over 198 days. The ionic strength in both reactors remained constant through time indicating that the measured increases in σb were not caused by changing effluent concentrations. PHREEQC successfully matched the measured changes in effluent concentrations for both columns when the reaction database was modified in the following manner. For the iron-reducing column, kinetic expressions governing the rate of iron reduction, the rate of bacterial growth, and the production of methane were added to the reaction database. Additionally, surface adsorption and cation exchange reactions were added so that the model was consistent with measured effluent chemistry. For the nitrate-reducing column, kinetic expressions governing nitrate reduction and bacterial growth were added to the reaction database. Additionally

  2. Simultaneous Assessment of Acidogenesis-Mitigation and Specific Bacterial Growth-Inhibition by Dentifrices.

    PubMed

    Forbes, Sarah; Latimer, Joe; Sreenivasan, Prem K; McBain, Andrew J

    2016-01-01

    Dentifrices can augment oral hygiene by inactivating bacteria and at sub-lethal concentrations may affect bacterial metabolism, potentially inhibiting acidogenesis, the main cause of caries. Reported herein is the development of a rapid method to simultaneously measure group-specific bactericidal and acidogenesis-mitigation effects of dentifrices on oral bacteria. Saliva was incubated aerobically and anaerobically in Tryptone Soya Broth, Wilkins-Chalgren Broth with mucin, or artificial saliva and was exposed to dentifrices containing triclosan/copolymer (TD); sodium fluoride (FD); stannous fluoride and zinc lactate (SFD1); or stannous fluoride, zinc lactate and stannous chloride (SFD2). Minimum inhibitory concentrations (MIC) were determined turbidometrically whilst group-specific minimum bactericidal concentrations (MBC) were assessed using growth media and conditions selective for total aerobes, total anaerobes, streptococci and Gram-negative anaerobes. Minimum acid neutralization concentration (MNC) was defined as the lowest concentration of dentifrice at which acidification was inhibited. Differences between MIC and MNC were calculated and normalized with respect to MIC to derive the combined inhibitory and neutralizing capacity (CINC), a cumulative measure of acidogenesis-mitigation and growth inhibition. The overall rank order for growth inhibition potency (MIC) under aerobic and anaerobic conditions was: TD> SFD2> SFD1> FD. Acidogenesis-mitigation (MNC) was ordered; TD> FD> SFD2> SFD1. CINC was ordered TD> FD> SFD2> SFD1 aerobically and TD> FD> SFD1> SFD2 anaerobically. With respect to group-specific bactericidal activity, TD generally exhibited the greatest potency, particularly against total aerobes, total anaerobes and streptococci. This approach enables the rapid simultaneous evaluation of acidity mitigation, growth inhibition and specific antimicrobial activity by dentifrices. PMID:26882309

  3. Simultaneous Assessment of Acidogenesis-Mitigation and Specific Bacterial Growth-Inhibition by Dentifrices

    PubMed Central

    Forbes, Sarah; Latimer, Joe; Sreenivasan, Prem K.; McBain, Andrew J.

    2016-01-01

    Dentifrices can augment oral hygiene by inactivating bacteria and at sub-lethal concentrations may affect bacterial metabolism, potentially inhibiting acidogenesis, the main cause of caries. Reported herein is the development of a rapid method to simultaneously measure group-specific bactericidal and acidogenesis-mitigation effects of dentifrices on oral bacteria. Saliva was incubated aerobically and anaerobically in Tryptone Soya Broth, Wilkins-Chalgren Broth with mucin, or artificial saliva and was exposed to dentifrices containing triclosan/copolymer (TD); sodium fluoride (FD); stannous fluoride and zinc lactate (SFD1); or stannous fluoride, zinc lactate and stannous chloride (SFD2). Minimum inhibitory concentrations (MIC) were determined turbidometrically whilst group-specific minimum bactericidal concentrations (MBC) were assessed using growth media and conditions selective for total aerobes, total anaerobes, streptococci and Gram-negative anaerobes. Minimum acid neutralization concentration (MNC) was defined as the lowest concentration of dentifrice at which acidification was inhibited. Differences between MIC and MNC were calculated and normalized with respect to MIC to derive the combined inhibitory and neutralizing capacity (CINC), a cumulative measure of acidogenesis-mitigation and growth inhibition. The overall rank order for growth inhibition potency (MIC) under aerobic and anaerobic conditions was: TD> SFD2> SFD1> FD. Acidogenesis-mitigation (MNC) was ordered; TD> FD> SFD2> SFD1. CINC was ordered TD> FD> SFD2> SFD1 aerobically and TD> FD> SFD1> SFD2 anaerobically. With respect to group-specific bactericidal activity, TD generally exhibited the greatest potency, particularly against total aerobes, total anaerobes and streptococci. This approach enables the rapid simultaneous evaluation of acidity mitigation, growth inhibition and specific antimicrobial activity by dentifrices. PMID:26882309

  4. Growth curves for school children from Kuching, Sarawak: a methodological development.

    PubMed

    Bong, Yii Bonn; Shariff, Asma Ahmad; Mohamed, Abdul Majid; Merican, Amir Feisal

    2015-03-01

    In this article, the authors propose reference curves for height and weight for school children in the Kuching area, Sarawak. The school children were from primary to secondary schools (aged 6.5 to 17 years old) and comprised both genders. Anthropometric measurements and demographic information for 3081 school-aged children were collected (1440 boys and 1641 girls). Fitted line plots and percentiles for height and weight (3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles) were obtained. The height of school boys and school girls were almost similar at the start of their school-going age. For school girls, height and weight values stabilized when they reached 16 or 17 years old but kept increasing for school boys. School boys were taller than school girls as they entered adolescence. Height differences between school boys and school girls became significantly wider as they grew older. Chinese school children were taller and heavier than those of other ethnic groups. PMID:22652249

  5. Growth curve analysis for plasma profiles using smoothing splines. Annual progress report, June 1992--June 1993

    SciTech Connect

    Imre, K.

    1993-05-01

    We are developing a profile analysis code for the statistical estimation of the parametric dependencies of the temperature and density profiles in tokamaks. Our code uses advanced statistical techniques to determine the optimal fit, i.e. the fit which minimized the predictive error. For a forty TFTR Ohmic profile dataset, our preliminary results indicate that the profile shape depends almost exclusively on q{sub a}{prime} but that the shape dependencies are not Gaussian. We are now comparing various shape models on the TFTR data. In the first six months, we have completed the core modules of the code, including a B-spline package for variable knot locations, a data-based method to determine the optimal smoothing parameters, self-consistent estimation of the bias errors, and adaptive fitting near the plasma edge. Visualization graphics already include three dimensional surface plots, and discharge by discharge plots of the predicted curves with error bars together with the actual measurements values, and plots of the basis functions with errors.

  6. Production of fungal and bacterial growth modulating secondary metabolites is widespread among mycorrhiza-associated streptomycetes

    PubMed Central

    2012-01-01

    Background Studies on mycorrhiza associated bacteria suggest that bacterial-fungal interactions play important roles during mycorrhiza formation and affect plant health. We surveyed Streptomyces Actinobacteria, known as antibiotic producers and antagonists of fungi, from Norway spruce mycorrhizas with predominantly Piloderma species as the fungal partner. Results Fifteen Streptomyces isolates exhibited substantial variation in inhibition of tested mycorrhizal and plant pathogenic fungi (Amanita muscaria, Fusarium oxysporum, Hebeloma cylindrosporum, Heterobasidion abietinum, Heterobasidion annosum, Laccaria bicolor, Piloderma croceum). The growth of the mycorrhiza-forming fungus Laccaria bicolor was stimulated by some of the streptomycetes, and Piloderma croceum was only moderately affected. Bacteria responded to the streptomycetes differently than the fungi. For instance the strain Streptomyces sp. AcM11, which inhibited most tested fungi, was less inhibitory to bacteria than other tested streptomycetes. The determined patterns of Streptomyces-microbe interactions were associated with distinct patterns of secondary metabolite production. Notably, potentially novel metabolites were produced by strains that were less antagonistic to fungi. Most of the identified metabolites were antibiotics (e.g. cycloheximide, actiphenol) and siderophores (e.g. ferulic acid, desferroxiamines). Plant disease resistance was activated by a single streptomycete strain only. Conclusions Mycorrhiza associated streptomycetes appear to have an important role in inhibiting the growth of fungi and bacteria. Additionally, our study indicates that the Streptomyces strains, which are not general antagonists of fungi, may produce still un-described metabolites. PMID:22852578

  7. BIODEGRADATION DURING CONTAMINANT TRANSPORT IN POROUS MEDIA. 4. IMPACT OF MICROBIAL LAG AND BACTERIAL CELL GROWTH. (R825415)

    EPA Science Inventory

    Abstract

    Miscible-displacement experiments were conducted to examine the impact of microbial lag and bacterial cell growth on the transport of salicylate, a model hydrocarbon compound. The impacts of these processes were examined separately, as well as jointly, to dete...

  8. Bacterial and fungal growth for monitoring the impact of wildfire combined or not with different soil stabilization treatments

    NASA Astrophysics Data System (ADS)

    Barreiro, Ana; Baath, Erland; Díaz-Raviña, Montserrat

    2015-04-01

    Soil stabilization techniques are rapidly gaining acceptance as efficient tool for reducing post-fire erosion. However, despite its interest, information concerning their impact on soil biota is scarce. We examined, under field conditions, the bacterial and fungal medium-term responses in a hillslope area located in Laza (NW Spain) affected by a high severity wildfire with the following treatments established by triplicate (4 x 20 m plots): unburnt control soil, burnt control soil, burnt soil with rye seeding and burnt soil with straw mulch. The bacterial and fungal growth, as well as respiration, were measured 4 years after fire and application of treatments using leucine incorporation for bacterial growth and acetate-in-ergosterol incorporation for fungal growth. The results showed that soil respiration and fungal biomass were negatively affected by fire, in the top layer (0-5 cm), while bacterial and fungal growth was stimulated. These microbial changes induced by fire were associated with modifications in organic matter (50% reduction in C content) and soil pH (increase of 0.5-0.9 units). Thus, the results suggested that under acid environment (pH in water 3.5) post-fire conditions might have favoured both microbial groups, which is supported by the fact that estimated bacterial and fungal growth were positive and significant correlated with soil pH (range of 3.5-4.5). This contrast with the well-known reported investigations showing that bacteria rather than fungi proliferation occurred after prescribed fire or wildfire; it should be noticed, however, that soils with a higher pH than that in the present study were used. Our data also indicated that bacterial and fungal communities were not significantly affected by seeding and mulching treatments. The results highlighted the importance of pre-fire soil pH as key factor in determining the microbial response after fire. Acknowledgements. A. Barreiro is recipient of FPU grant from Spanish Ministry of Education

  9. Self-Esteem and Delinquency Revisited (Again): A Test of Kaplan's Self-Derogation Theory of Delinquency Using Latent Growth Curve Modeling.

    ERIC Educational Resources Information Center

    Mason, W. Alex

    2001-01-01

    Studied the relationship between self-esteem and delinquency using latent growth curve modeling. Analyses of panel data for 2,213 adolescent boys from the Youth in Transition Study supported Kaplan's self-derogation theory of delinquency (H. Kaplan, 1978) by showing that delinquency was positively associated with growth in self-esteem among…

  10. A Latent Growth Curve Analysis of Early and Increasing Peer Victimization as Predictors of Mental Health Across Elementary School

    PubMed Central

    Rudolph, Karen D.; Troop-Gordon, Wendy; Hessel, Elenda T.; Schmidt, Jennifer D.

    2011-01-01

    Peer victimization has been implicated as a traumatic stressor that compromises children’s long-term mental health, yet a dearth of prospective research specifically demonstrates lasting effects of early victimization. This research examined whether early (2nd grade) victimization and increasing (2nd – 5th grade) victimization independently predicted depressive symptoms and aggressive behavior (overt and relational) in 5th grade. Participants included 433 children (238 girls, 195 boys). Children reported on peer victimization and depressive symptoms; teachers reported on peer victimization and aggressive behavior. Latent growth curve analysis revealed that both early and increasing victimization made unique contributions to subsequent depressive symptoms and aggressive behavior. Relational aggression was particularly likely to follow victimization in girls. PMID:21229448

  11. A high-throughput system for two-hybrid screening based on growth curve analysis in microtiter plates.

    PubMed

    Diaz-Camino, Claudia; Risseeuw, Eddy P; Liu, Enwu; Crosby, William L

    2003-05-15

    The yeast two-hybrid system is a powerful tool for identifying novel protein-protein interactions. In general, biochemical marker genes such as lacZ are exploited for indirect quantification of the interaction, and commonly involve the conduct of rather laborious beta-galactosidase assays. This paper describes a simple alternative method based on growth curve analysis of yeast cultures that is amenable to microtiter plate format, and therefore allows the quantification of large numbers of yeast two-hybrid combinations. The analyzed results of yeast cultures grown in microtiter plates were compared with those obtained from the classical beta-galactosidase assay. We conclude that the method presented here is reproducible, of equal or greater sensitivity than the beta-galactosidase assay, and can be further adapted for application to the conduct of large-scale, automated yeast two-hybrid experiments. PMID:12711337

  12. Short- and Mid-Term Effects of Violent Victimization on Delinquency: A Multilevel Growth-Curve Modeling Approach.

    PubMed

    Kim, Young S; Lo, Celia C

    2016-10-01

    The present study investigates how adolescents' experiences of violent victimization exert short- and mid-term effects on their involvement in delinquency. The study compares and contrasts delinquency trajectories of youths whose experiences of violent victimization differ. A multilevel growth-curve modeling approach is applied to analyze data from five waves of the National Youth Survey. The results show that, although delinquency involvement increases as youths experience violent victimization, delinquency trajectories differ with the type of violent victimization, specifically, parental versus non-parental victimization. Violent victimization by parents produced a sharp initial decline in delinquency (short-term effect) followed by a rapid acceleration (mid-term effect). In turn, non-parental violence showed a stable trend over time. The findings have important implications for prevention and treatment services. PMID:25888502

  13. Examination of Bacterial Characteristics of Anaerobic Membrane Bioreactors in Three Pilot-Scale Plants for Treating Low-Strength Wastewater by Application of the Colony-Forming-Curve Analysis Method

    PubMed Central

    Kataoka, Naoaki; Tokiwa, Yutaka; Tanaka, Yasuo; Fujiki, Kiichi; Taroda, Hiroyuki; Takeda, Kiyoshi

    1992-01-01

    Characteristic sludge ecosystems arising in anaerobic membrane bioreactors of three pilot-scale plants treating low-strength (less than 1 g of biological oxygen demand per liter) sewage or soybean-processing wastewater were examined by analysis of the colony-forming-curves (CFC) obtained by counting colonies at suitable intervals. The wastewaters, containing high amounts of suspended solids (SS) (SS/chemical oxygen demand ratio, 0.51 to 0.80), were treated by using two types of bioreactors: (i) a hydrolyzation reactor for solubilization and acidification of SS in wastewater and (ii) a methane fermentation reactor for producing methane. The colony counts for the two sewage treatment plants continued to increase even after 3 weeks of incubation, whereas those for soybean-processing wastewater reached an approximately constant level within 3 weeks of incubation. The CFCs were analyzed by correlating the rate of colony appearance on roll tubes with the physiological types of bacteria present in the bioreactors. It was found that there were large numbers of slow-colony-forming anaerobic bacteria within the bioreactors and that the viable populations consisted of a few groups with different growth rates. It is considered that the slow-growing colonies appearing after 10 days of incubation were the dominant microflora in the sewage treated by hydrolyzation reactors. In particular, highly concentrated sludge (30.0 g of mixed-liquor volatile SS per liter) retained by the membrane separation module contained a large number of such bacteria. Slow-growing colonies of these bacteria could be counted by using a sludge extract medium prepared from only the supernatant of autoclaved sludge. In addition, the highest colony counts were almost always obtained with the sludge extract medium, meaning that most of the anaerobic bacteria in these sludges have complex nutrient requirements for growth. This report also indicates the usefulness of application of the CFC analysis method to

  14. N-acetyl-L-cysteine affects growth, extracellular polysaccharide production, and bacterial biofilm formation on solid surfaces.

    PubMed

    Olofsson, Ann-Cathrin; Hermansson, Malte; Elwing, Hans

    2003-08-01

    N-Acetyl-L-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Using 10 different bacterial strains isolated from a paper mill, we found that the mode of action of NAC is chemical, as well as biological, in the case of bacterial adhesion to stainless steel surfaces. The initial adhesion of bacteria is dependent on the wettability of the substratum. NAC was shown to bind to stainless steel, increasing the wettability of the surface. Moreover, NAC decreased bacterial adhesion and even detached bacteria that were adhering to stainless steel surfaces. Growth of various bacteria, as monocultures or in a multispecies community, was inhibited at different concentrations of NAC. We also found that there was no detectable degradation of extracellular polysaccharides (EPS) by NAC, indicating that NAC reduced the production of EPS, in most bacteria tested, even at concentrations at which growth was not affected. Altogether, the presence of NAC changes the texture of the biofilm formed and makes NAC an interesting candidate for use as a general inhibitor of formation of bacterial biofilms on stainless steel surfaces. PMID:12902275

  15. Indoor Heating Drives Water Bacterial Growth and Community Metabolic Profile Changes in Building Tap Pipes during the Winter Season

    PubMed Central

    Zhang, Hai-Han; Chen, Sheng-Nan; Huang, Ting-Lin; Shang, Pan-Lu; Yang, Xiao; Ma, Wei-Xing

    2015-01-01

    The growth of the bacterial community harbored in indoor drinking water taps is regulated by external environmental factors, such as indoor temperature. However, the effect of indoor heating on bacterial regrowth associated with indoor drinking water taps is poorly understood. In the present work, flow cytometry and community-level sole-carbon-source utilization techniques were combined to explore the effects of indoor heating on water bacterial cell concentrations and community carbon metabolic profiles in building tap pipes during the winter season. The results showed that the temperature of water stagnated overnight (“before”) in the indoor water pipes was 15–17 °C, and the water temperature decreased to 4–6 °C after flushing for 10 min (“flushed”). The highest bacterial cell number was observed in water stagnated overnight, and was 5–11 times higher than that of flushed water. Meanwhile, a significantly higher bacterial community metabolic activity (AWCD590nm) was also found in overnight stagnation water samples. The significant “flushed” and “taps” values indicated that the AWCD590nm, and bacterial cell number varied among the taps within the flushed group (p < 0.01). Heatmap fingerprints and principle component analyses (PCA) revealed a significant discrimination bacterial community functional metabolic profiles in the water stagnated overnight and flushed water. Serine, threonine, glucose-phosphate, ketobutyric acid, phenylethylamine, glycerol, putrescine were significantly used by “before” water samples. The results suggested that water stagnated at higher temperature should be treated before drinking because of bacterial regrowth. The data from this work provides useful information on reasonable utilization of drinking water after stagnation in indoor pipes during indoor heating periods. PMID:26516885

  16. Ex Vivo - Growth Response of Porcine Small Intestinal Bacterial Communities to Pharmacological Doses of Dietary Zinc Oxide

    PubMed Central

    Starke, Ingo C.; Zentek, Jürgen; Vahjen, Wilfried

    2013-01-01

    Piglets were fed diets containing 57 (low) or 2425 (high) mg zinc from analytical grade zinc oxide (ZnO) ·kg−1 feed. Digesta samples from the stomach and jejuna of 32, 39, 46 and 53 d old animals (n  = 6 per group) were incubated in media containing 80, 40, 20 and 0 µg·mL−1 soluble zinc from ZnO. Turbidity was recorded for 16 h and growth parameters were calculated. Additionally, DNA extracts of selected samples were analyzed via qPCR for different bacterial groups. Samples from animals fed the low dietary zinc concentration always showed highest rate of growth and lowest lag times in media without added zinc. However, media supplemented with zinc displayed highest growth rates and lowest lag time in the high dietary zinc group. Specific growth rates and lag time showed significant differences on day 32 and 39 of age, but rarely on days 46 and 53 of age. Bacterial growth in digesta samples from the high dietary zinc group was less influenced by zinc and recovered growth more rapidly than in the low dietary zinc group. Specific growth rates and bacterial cell numbers from qPCR results showed that lactobacilli were most susceptible to zinc, while bifidobacteria, enterobacteria and enterococci exhibited increased growth rates in samples of animals from the high dietary zinc treatment. No treatment related differences were observed for clostridial cluster IV and the Bacteroides-Prevotella-Porphyromonas cluster. The diversity of enterobacteria after incubation was always higher in the high dietary zinc treatment or in medium supplemented with 80 µg·mL−1 soluble ZnO. This study has shown that a pharmacological dosage of ZnO leads to a reduced ex vivo- bacterial growth rate of bacteria from the stomach and jejunum of weaned piglets. In view of the rapid bacterial adaptation to dietary zinc, the administration of ZnO in feeds for weaned piglets might only be beneficial in a short period after weaning. PMID:23441186

  17. Ex vivo-growth response of porcine small intestinal bacterial communities to pharmacological doses of dietary zinc oxide.

    PubMed

    Starke, Ingo C; Zentek, Jürgen; Vahjen, Wilfried

    2013-01-01

    Piglets were fed diets containing 57 (low) or 2425 (high) mg zinc from analytical grade zinc oxide (ZnO) ·kg(-1) feed. Digesta samples from the stomach and jejuna of 32, 39, 46 and 53 d old animals (n = 6 per group) were incubated in media containing 80, 40, 20 and 0 µg·mL(-1) soluble zinc from ZnO. Turbidity was recorded for 16 h and growth parameters were calculated. Additionally, DNA extracts of selected samples were analyzed via qPCR for different bacterial groups. Samples from animals fed the low dietary zinc concentration always showed highest rate of growth and lowest lag times in media without added zinc. However, media supplemented with zinc displayed highest growth rates and lowest lag time in the high dietary zinc group. Specific growth rates and lag time showed significant differences on day 32 and 39 of age, but rarely on days 46 and 53 of age. Bacterial growth in digesta samples from the high dietary zinc group was less influenced by zinc and recovered growth more rapidly than in the low dietary zinc group. Specific growth rates and bacterial cell numbers from qPCR results showed that lactobacilli were most susceptible to zinc, while bifidobacteria, enterobacteria and enterococci exhibited increased growth rates in samples of animals from the high dietary zinc treatment. No treatment related differences were observed for clostridial cluster IV and the Bacteroides-Prevotella-Porphyromonas cluster. The diversity of enterobacteria after incubation was always higher in the high dietary zinc treatment or in medium supplemented with 80 µg·mL(-1) soluble ZnO. This study has shown that a pharmacological dosage of ZnO leads to a reduced ex vivo-bacterial growth rate of bacteria from the stomach and jejunum of weaned piglets. In view of the rapid bacterial adaptation to dietary zinc, the administration of ZnO in feeds for weaned piglets might only be beneficial in a short period after weaning. PMID:23441186

  18. Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment

    PubMed Central

    Jeanson, Sophie; Floury, Juliane; Gagnaire, Valérie; Lortal, Sylvie; Thierry, Anne

    2015-01-01

    Bacteria, either indigenous or added, are immobilized in solid foods where they grow as colonies. Since the 80's, relatively few research groups have explored the implications of bacteria growing as colonies and mostly focused on pathogens in large colonies on agar/gelatine media. It is only recently that high resolution imaging techniques and biophysical characterization techniques increased the understanding of the growth of bacterial colonies, for different sizes of colonies, at the microscopic level and even down to the molecular level. This review covers the studies on bacterial colony growth in agar or gelatine media mimicking the food environment and in model cheese. The following conclusions have been brought to light. Firstly, under unfavorable conditions, mimicking food conditions, the immobilization of bacteria always constrains their growth in comparison with planktonic growth and increases the sensibility of bacteria to environmental stresses. Secondly, the spatial distribution describes both the distance between colonies and the size of the colonies as a function of the initial level of population. By studying the literature, we concluded that there systematically exists a threshold that distinguishes micro-colonies (radius < 100–200 μm) from macro-colonies (radius >200 μm). Micro-colonies growth resembles planktonic growth and no pH microgradients could be observed. Macro-colonies growth is slower than planktonic growth and pH microgradients could be observed in and around them due to diffusion limitations which occur around, but also inside the macro-colonies. Diffusion limitations of milk proteins have been demonstrated in a model cheese around and in the bacterial colonies. In conclusion, the impact of immobilization is predominant for macro-colonies in comparison with micro-colonies. However, the interaction between the colonies and the food matrix itself remains to be further investigated at the microscopic scale. PMID:26648910

  19. Bacterial growth and biofilm formation in household-stored groundwater collected from public wells.

    PubMed

    Burkowska-But, Aleksandra; Kalwasińska, Agnieszka; Swiontek Brzezinska, Maria

    2015-06-01

    The research was aimed at assessing changes in the number of bacteria and evaluating biofilm formation in groundwater collected from public wells, both aspects directly related to the methods of household storage. In the research, water collected from Cretaceous aquifer wells in Toruń (Poland) was stored in a refrigerator and at room temperature. Microbiological parameters of the water were measured immediately after the water collection, and then after 3 and 7 days of storage under specified conditions. The microbiological examination involved determining the number of heterotrophic bacteria capable of growth at 22 and 37 °C, the number of spore-forming bacteria, and the total number of bacteria on membrane filters. The storage may affect water quality to such an extent that the water, which initially met the microbiological criteria for water intended for human consumption, may pose a health risk. The repeated use of the same containers for water storage results in biofilm formation containing live and metabolically active bacterial cells. PMID:26042968

  20. In vitro evaluation of Pseudomonas bacterial isolates from rice phylloplane for biocontrol of Rhizoctonia solani and plant growth promoting traits.

    PubMed

    Akter, Shamima; Kadir, Jugah; Juraimi, Abdul Shukor; Saud, Halimi Mohd

    2016-07-01

    The ability for biocontrol and plant growth promotion of three Pseudomonas bacterial isolates namely Pseudomonas fluorescens (UMB20), Pseudomonas aeruginosa (KMB25) and Pseudomonas asplenii (BMB42) obtained from rice plants was investigated. Fungal growth inhibition by the isolates ranged from 86.85 to 93.15% in volatile and 100% in diffusible metabolites test. Among the isolates, BMB42 showed fungal growth inhibition significantly in the volatile metabolite test. Isolates UMB20 and BMB42 were able to synthesis chitinase with chitinolytic indices of 13.66 and 13.50, respectively. In case of -1,3-glucanase, all the isolates showed activity to produce this enzyme at varied levels and isolate KMB25 showed significantly highest activity (53.53 ppm). Among the three isolates, KMB25 showed positive response to protease production and all of them were negative to pectinase and lipase and positive to the production of siderophore, and HCN, and were able to solubilize tricalcium phosphate. All the three bacterial isolates were capable of forming biofilm at different levels. Above results suggest that phylloplane Pseudomonas bacterial isolates have potential for antifungal activities and plant growth promotion. PMID:27498507

  1. Illustration of year-to-year variation in wheat spectral profile crop growth curves. [Kansas, Oklahoma, North Dakota and South Dakota

    NASA Technical Reports Server (NTRS)

    Gonzalez, P.; Jones, C. (Principal Investigator)

    1980-01-01

    Data previously compiled on the year to year variability of spectral profile crop growth parameters for spring and winter wheat in Kansas, Oklahoma, and the Dakotas were used with a profile model to develop graphs illustrating spectral profile crop growth curves for a number of years and a number of spring and winter wheat segments. These curves show the apparent variability in spectral profiles for wheat from one year to another within the same segment and from one segment to another within the same year.

  2. Predicting bacterial growth in raw, salted, and cooked chicken breast fillets during storage.

    PubMed

    Galarz, Liane Aldrighi; Fonseca, Gustavo Graciano; Prentice, Carlos

    2016-09-01

    Growth curves were evaluated for aerobic mesophilic and psychrotrophic bacteria, Pseudomonas spp. and Staphylococcus spp., grown in raw, salted, and cooked chicken breast at 2, 4, 7, 10, 15, and 20 ℃, respectively, using the modified Gompertz and modified logistic models. Shelf life was determined based on microbiological counts and sensory analysis. Temperature increase reduced the shelf life, which varied from 10 to 26 days at 2 ℃, from nine to 21 days at 4 ℃, from six to 12 days at 7 ℃, from four to eight days at 10 ℃, from two to four days at 15 ℃, and from one to two days at 20 ℃. In most cases, cooked chicken breast showed the highest microbial count, followed by raw breast and lastly salted breast. The data obtained here were useful for the generation of mathematical models and parameters. The models presented high correlation and can be used for predictive purposes in the poultry meat supply chain. PMID:26683484

  3. Gut Commensal E. coli Proteins Activate Host Satiety Pathways following Nutrient-Induced Bacterial Growth.

    PubMed

    Breton, Jonathan; Tennoune, Naouel; Lucas, Nicolas; Francois, Marie; Legrand, Romain; Jacquemot, Justine; Goichon, Alexis; Guérin, Charlène; Peltier, Johann; Pestel-Caron, Martine; Chan, Philippe; Vaudry, David; do Rego, Jean-Claude; Liénard, Fabienne; Pénicaud, Luc; Fioramonti, Xavier; Ebenezer, Ivor S; Hökfelt, Tomas; Déchelotte, Pierre; Fetissov, Sergueï O

    2016-02-01

    The composition of gut microbiota has been associated with host metabolic phenotypes, but it is not known if gut bacteria may influence host appetite. Here we show that regular nutrient provision stabilizes exponential growth of E. coli, with the stationary phase occurring 20 min after nutrient supply accompanied by bacterial proteome changes, suggesting involvement of bacterial proteins in host satiety. Indeed, intestinal infusions of E. coli stationary phase proteins increased plasma PYY and their intraperitoneal injections suppressed acutely food intake and activated c-Fos in hypothalamic POMC neurons, while their repeated administrations reduced meal size. ClpB, a bacterial protein mimetic of α-MSH, was upregulated in the E. coli stationary phase, was detected in plasma proportional to ClpB DNA in feces, and stimulated firing rate of hypothalamic POMC neurons. Thus, these data show that bacterial proteins produced after nutrient-induced E. coli growth may signal meal termination. Furthermore, continuous exposure to E. coli proteins may influence long-term meal pattern. PMID:26621107

  4. Listeria monocytogenes virulence factor Listeriolysin O favors bacterial growth in co-culture with the ciliate Tetrahymena pyriformis, causes protozoan encystment and promotes bacterial survival inside cysts

    PubMed Central

    2010-01-01

    Background The gram-positive pathogenic bacterium Listeria monocytogenes is widely spread in the nature. L. monocytogenes was reported to be isolated from soil, water, sewage and sludge. Listeriolysin O (LLO) is a L. monocytogenes major virulence factor. In the course of infection in mammals, LLO is required for intracellular survival and apoptosis induction in lymphocytes. In this study, we explored the potential of LLO to promote interactions between L. monocytogenes and the ubiquitous inhabitant of natural ecosystems bacteriovorous free-living ciliate Tetrahymena pyriformis. Results Wild type L. monocytogenes reduced T. pyriformis trophozoite counts and stimulated encystment. The effects were observed starting from 48 h of co-incubation. On the day 14, trophozoites were eliminated from the co-culture while about 5 × 104 cells/ml remained in the axenic T. pyriformis culture. The deficient in the LLO-encoding hly gene L. monocytogenes strain failed to cause mortality among protozoa and to trigger protozoan encystment. Replenishment of the hly gene in the mutant strain restored toxicity towards protozoa and induction of protozoan encystment. The saprophytic non-haemolytic species L. innocua transformed with the LLO-expressing plasmid caused extensive mortality and encystment in ciliates. During the first week of co-incubation, LLO-producing L. monocytogenes demonstrated higher growth rates in association with T. pyriformis than the LLO-deficient isogenic strain. At latter stages of co-incubation bacterial counts were similar for both strains. T. pyriformis cysts infected with wild type L. monocytogenes caused listerial infection in guinea pigs upon ocular and oral inoculation. The infection was proved by bacterial plating from the internal organs. Conclusions The L. monocytogenes virulence factor LLO promotes bacterial survival and growth in the presence of bacteriovorous ciliate T. pyriformis. LLO is responsible for L. monocytogenes toxicity for protozoa and

  5. Treatment of “Bacterial Cystitis” in Fully Automatic Mechanical Models Simulating Conditions of Bacterial Growth in the Urinary Bladder

    PubMed Central

    O'Grady, F.; Mackintosh, I. P.; Greenwood, D.; Watson, B. W.

    1973-01-01

    Two fully automatic models are described in which growing cultures can be continuously diluted and periodically discharged producing conditions of growth resembling those of the infected urinary bladder. Both models generate a continuous record of the opacity of the growing culture and the second model also generates a record of the Eh. The effect of adding ampicillin to a sensitive strain of Escherichia coli growing in these conditions is described and the relation of the results to human therapy is discussed. ImagesFig. 1 PMID:4577943

  6. Bacterial Growth at the High Concentrations of Magnesium Sulfate Found in Martian Soils

    PubMed Central

    Crisler, J.D.; Newville, T.M.; Chen, F.; Clark, B.C.

    2012-01-01

    Abstract The martian surface environment exhibits extremes of salinity, temperature, desiccation, and radiation that would make it difficult for terrestrial microbes to survive. Recent evidence suggests that martian soils contain high concentrations of MgSO4 minerals. Through warming of the soils, meltwater derived from subterranean ice-rich regolith may exist for an extended period of time and thus allow the propagation of terrestrial microbes and create significant bioburden at the near surface of Mars. The current report demonstrates that halotolerant bacteria from the Great Salt Plains (GSP) of Oklahoma are capable of growing at high concentrations of MgSO4 in the form of 2 M solutions of epsomite. The epsotolerance of isolates in the GSP bacterial collection was determined, with 35% growing at 2 M MgSO4. There was a complex physiological response to mixtures of MgSO4 and NaCl coupled with other environmental stressors. Growth also was measured at 1 M concentrations of other magnesium and sulfate salts. The complex responses may be partially explained by the pattern of chaotropicity observed for high-salt solutions as measured by agar gelation temperature. Select isolates could grow at the high salt concentrations and low temperatures found on Mars. Survival during repetitive freeze-thaw or drying-rewetting cycles was used as other measures of potential success on the martian surface. Our results indicate that terrestrial microbes might survive under the high-salt, low-temperature, anaerobic conditions on Mars and present significant potential for forward contamination. Stringent planetary protection requirements are needed for future life-detection missions to Mars. Key Words: Analogue—Mars—Planetary protection—Salts—Life in extreme environments. Astrobiology 12, 98–106. PMID:22248384

  7. Effects of High Hydrostatic Pressure on Bacterial Growth on Human Ossicles Explanted from Cholesteatoma Patients

    PubMed Central

    Ostwald, Jürgen; Lindner, Tobias; Zautner, Andreas Erich; Arndt, Kathleen; Pau, Hans Wilhelm; Podbielski, Andreas

    2012-01-01

    Background High hydrostatic pressure (HHP) treatment can eliminate cholesteatoma cells from explanted human ossicles prior to re-insertion. We analyzed the effects of HHP treatment on the microbial flora on ossicles and on the planktonic and biofilm states of selected isolates. Methodology Twenty-six ossicles were explanted from cholesteatoma patients. Five ossicles were directly analyzed for microbial growth without further treatment. Fifteen ossicles were cut into two pieces. One piece was exposed to HHP of 350 MPa for 10 minutes. Both the treated and untreated (control) pieces were then assessed semi-quantitatively. Three ossicles were cut into two pieces and exposed to identical pressure conditions with or without the addition of one of two different combinations of antibiotics to the medium. Differential effects of 10-minute in vitro exposure of planktonic and biofilm bacteria to pressures of 100 MPa, 250 MPa, 400 MPa and 540 MPa in isotonic and hypotonic media were analyzed using two patient isolates of Staphylococcus epidermidis and Neisseria subflava. Bacterial cell inactivation and biofilm destruction were assessed by colony counting and electron microscopy. Principal Findings A variety of microorganisms were isolated from the ossicles. Irrespective of the medium, HHP treatment at 350 MPa for 10 minutes led to satisfying but incomplete inactivation especially of Gram-negative bacteria. The addition of antibiotics increased the efficacy of elimination. A comparison of HHP treatment of planktonic and biofilm cells showed that the effects of HPP were reduced by about one decadic logarithmic unit when HPP was applied to biofilms. High hydrostatic pressure conditions that are suitable to inactivate cholesteatoma cells fail to completely sterilize ossicles even if antibiotics are added. As a result of the reduced microbial load and the viability loss of surviving bacteria, however, there is a lower risk of re-infection after re-insertion. PMID:22291908

  8. Common Components of Industrial Metal-Working Fluids as Sources of Carbon for Bacterial Growth

    PubMed Central

    Foxall-VanAken, S.; Brown, J. A.; Young, W.; Salmeen, I.; McClure, T.; Napier, S.; Olsen, R. H.

    1986-01-01

    Water-based metal-working fluids used in large-scale industrial operations consist of many components, but in the most commonly used formulations only three classes of components are present in high enough concentrations that they could, in principle, provide enough carbon to support the high bacterial densities (109 CFU/ml) often observed in contaminated factory fluids. These components are petroleum oil (1 to 5%), petroleum sulfonates (0.1 to 0.5%), and fatty acids (less than 0.1%, mainly linoleic and oleic acids supplied as tall oils). We isolated pure strains of predominating bacteria from contaminated reservoirs of two metal-working systems and randomly selected 12 strains which we tested in liquid culture for growth with each of the metal-working fluid components as the sole source of carbon. Of the 12 strains, 7 reached high density (109 CFU/ml from an initial inoculum of less than 2 × 103) in 24 h, and 1 strain did the same in 48 h with 0.05% oleic or linoleic acid as the carbon source. These same strains also grew on 1% naphthenic petroleum oil but required up to 72 h to reach densities near 108 CFU/ml. One strain grew slightly and the others not at all on the petroleum sulfonates. The four remaining strains did not grow on any of the components, even though they were among the predominating bacteria in the contaminated system. Of the seven strains that grew best on the fatty acids and on the naphthenic petroleum oil, five were tentatively identified as Acinetobacter species and two were identified as Pseudomonas species. Four of the bacteria that did not grow were tentatively identified as species of Pseudomonas, and one could not be identified. PMID:16347072

  9. Bacterial growth at the high concentrations of magnesium sulfate found in martian soils.

    PubMed

    Crisler, J D; Newville, T M; Chen, F; Clark, B C; Schneegurt, M A

    2012-02-01

    The martian surface environment exhibits extremes of salinity, temperature, desiccation, and radiation that would make it difficult for terrestrial microbes to survive. Recent evidence suggests that martian soils contain high concentrations of MgSO₄ minerals. Through warming of the soils, meltwater derived from subterranean ice-rich regolith may exist for an extended period of time and thus allow the propagation of terrestrial microbes and create significant bioburden at the near surface of Mars. The current report demonstrates that halotolerant bacteria from the Great Salt Plains (GSP) of Oklahoma are capable of growing at high concentrations of MgSO₄ in the form of 2 M solutions of epsomite. The epsotolerance of isolates in the GSP bacterial collection was determined, with 35% growing at 2 M MgSO₄. There was a complex physiological response to mixtures of MgSO₄ and NaCl coupled with other environmental stressors. Growth also was measured at 1 M concentrations of other magnesium and sulfate salts. The complex responses may be partially explained by the pattern of chaotropicity observed for high-salt solutions as measured by agar gelation temperature. Select isolates could grow at the high salt concentrations and low temperatures found on Mars. Survival during repetitive freeze-thaw or drying-rewetting cycles was used as other measures of potential success on the martian surface. Our results indicate that terrestrial microbes might survive under the high-salt, low-temperature, anaerobic conditions on Mars and present significant potential for forward contamination. Stringent planetary protection requirements are needed for future life-detection missions to Mars. PMID:22248384

  10. Growth of Tl2Ba2CaCu2O7 thin films on curved substrates for metamaterial applications

    NASA Astrophysics Data System (ADS)

    Speller, S. C.; Hao, T.; Stevens, C. J.; Edwards, D. J.; Grovenor, C. R. M.

    2008-02-01

    Recent developments in the field of magnetic metamaterials have shown that coupled split-ring resonator (SRR) structures can manipulate magnetic fields on a scale shorter than the wavelength of the electromagnetic radiation [1]. In particular, stacks of copper/dielectic SRR structures can be used as high Q filters or as waveguides in near field imaging applications [2]. However, major improvements in the sensitivity of such devices would be achieved by fabricating the SRR elements from high temperature superconducting (HTS) films on appropriate dielectric substrates. In order to produce a stack of superconducting/dielectric SRR structures, the ideal method involves patterning them into an HTS film grown on the curved surface of a dielectric cylinder. To our knowledge this has not previously been attempted on the small scale required for these applications. The desired feature sizes range from a few millimetres for filter applications down to about 10μm for high resolution imaging applications. We report here our initial attempts at the growth of Tl2Ba2CaCu2O7 (Tl-2212) thin films on the surface of LaAlO3 and MgO single crystal cylinders of diameter 3mm and length 5mm. Scanning Electron Microscopy, Electron Backscatter Diffraction and a novel X-ray Diffraction technique have been used to study the microstructure and analyse the growth morphology of the Tl-2212 films in this unusual geometry. Simulations have been carried out on an axial array of SRR structures that could be fabricated from these HTS/dielectric cylinders.

  11. Diversity of culturable bacterial populations associated to Tuber borchii ectomycorrhizas and their activity on T. borchii mycelial growth.

    PubMed

    Sbrana, Cristiana; Agnolucci, Monica; Bedini, Stefano; Lepera, Annamaria; Toffanin, Annita; Giovannetti, Manuela; Nuti, Marco P

    2002-06-01

    Isolation and physiological and molecular characterisation of culturable bacterial strains belonging to actinomycetes, pseudomonads and aerobic spore-forming bacteria were carried out on mycorrhizal root tips of Quercus robur var. peduncolata infected by Tuber borchii. Cellular density of the three bacterial groups in ectomycorrhizal root tips was estimated to be 1.3+/-0.11 x 10(6) cfu g(-1) dry weight for total heterotrophic bacteria and 1.08+/-0.6 x 10(5) (mean+/-S.E.), 1.3+/-0.3 x 10(5) and 1.4+/-0.2 x 10(5) cfu g(-1) dry weight for pseudomonads, actinomycetes and spore-forming bacteria respectively. Identification of pseudomonads by the Biolog system indicated, besides the most represented species Pseudomonas fluorescens (biotypes B, F and G), the occurrence of strains belonging to Pseudomonas corrugata. Amplified ribosomal DNA restriction analysis of actinomycetes and spore formers revealed at least three and six different groups of patterns, respectively. Many bacterial isolates were able to induce variations in growth rates of T. borchii mycelium; among these, 101 strains showed antifungal activity, whereas 17 isolates, belonging to spore formers, were able to increase mycelial growth up to 78% when compared to uninoculated mycelial growth. The potential role of these populations in the development and establishment of mycorrhizas is discussed. PMID:12076812

  12. Mycelium-Like Networks Increase Bacterial Dispersal, Growth, and Biodegradation in a Model Ecosystem at Various Water Potentials.

    PubMed

    Worrich, Anja; König, Sara; Miltner, Anja; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin; Harms, Hauke; Kästner, Matthias; Wick, Lukas Y

    2016-05-15

    Fungal mycelia serve as effective dispersal networks for bacteria in water-unsaturated environments, thereby allowing bacteria to maintain important functions, such as biodegradation. However, poor knowledge exists on the effects of dispersal networks at various osmotic (Ψo) and matric (Ψm) potentials, which contribute to the water potential mainly in terrestrial soil environments. Here we studied the effects of artificial mycelium-like dispersal networks on bacterial dispersal dynamics and subsequent effects on growth and benzoate biodegradation at ΔΨo and ΔΨm values between 0 and -1.5 MPa. In a multiple-microcosm approach, we used a green fluorescent protein (GFP)-tagged derivative of the soil bacterium Pseudomonas putida KT2440 as a model organism and sodium benzoate as a representative of polar aromatic contaminants. We found that decreasing ΔΨo and ΔΨm values slowed bacterial dispersal in the system, leading to decelerated growth and benzoate degradation. In contrast, dispersal networks facilitated bacterial movement at ΔΨo and ΔΨm values between 0 and -0.5 MPa and thus improved the absolute biodegradation performance by up to 52 and 119% for ΔΨo and ΔΨm, respectively. This strong functional interrelationship was further emphasized by a high positive correlation between population dispersal, population growth, and degradation. We propose that dispersal networks may sustain the functionality of microbial ecosystems at low osmotic and matric potentials. PMID:26944849

  13. Stimulated bacterioplankton growth and selection for certain bacterial taxa in the vicinity of the ctenophore Mnemiopsis leidyi

    PubMed Central

    Dinasquet, Julie; Granhag, Lena; Riemann, Lasse

    2012-01-01

    Episodic blooms of voracious gelatinous zooplankton, such as the ctenophore Mnemiopsis leidyi, affect pools of inorganic nutrients and dissolved organic carbon by intensive grazing activities and mucus release. This will potentially influence bacterioplankton activity and community composition, at least at local scales; however, available studies on this are scarce. In the present study we examined effects of M. leidyi on bacterioplankton growth and composition in incubation experiments. Moreover, we examined community composition of bacteria associated with the surface and gut of M. leidyi. High release of ammonium and high bacterial growth was observed in the treatments with M. leidyi relative to controls. Deep 454 pyrosequencing of 16 S rRNA genes showed specific bacterial communities in treatments with M. leidyi as well as specific communities associated with M. leidyi tissue and gut. In particular, members of Flavobacteriaceae were associated with M. leidyi. Our study shows that M. leidyi influences bacterioplankton activity and community composition in the vicinity of the jellyfish. In particular during temporary aggregations of jellyfish, these local zones of high bacterial growth may contribute significantly to the spatial heterogeneity of bacterioplankton activity and community composition in the sea. PMID:22912629

  14. Maintaining convex interface shapes during electrodynamic gradient freeze growth of cadmium zinc telluride using a dynamic, bell-curve furnace profile

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Yeckel, Andrew; Derby, Jeffrey J.

    2012-09-01

    A novel, bell-curve furnace temperature profile is presented and predicted to achieve macroscopically convex solid-liquid interface shapes during melt growth of CZT in an EDG furnace. A strategy is also presented to dynamically adapt this furnace profile so that uniform, convex interface shapes are maintained through an entire growth run. This approach represents a significant advance over traditional gradient-freeze profiles, which always yield concave interface shapes, and static heat transfer designs, such as pedestal design, that achieve convex interfaces over only a small portion of the growth run. Importantly, this strategy may be applied to any Bridgman configuration that utilizes multiple, controllable heating zones. Realizing a convex solidification interface via this adaptive bell-curve furnace profile is postulated to result in better crystallinity and higher yields than conventional CZT growth techniques.

  15. The Interactive Effects of Impulsivity and Negative Emotions on Adolescent Nonsuicidal Self-injury: A Latent Growth Curve Analysis.

    PubMed

    You, Jianing; Deng, Baoping; Lin, Min-Pei; Leung, Freedom

    2016-06-01

    This study employed latent growth curve analysis to evaluate the interactive effects of two specific facets of impulsivity (i.e., negative urgency [NU] and premeditation [PRE]) and negative emotions (NE) on the developmental trajectory of nonsuicidal self-injury (NSSI) among 3,453 (57% females) Chinese community adolescents. Participants completed questionnaires assessing NSSI, NU, PRE, and NE (i.e., depression, anxiety, and stress) at three waves of time. The initial levels of NE and NU significantly predicted the initial level of NSSI. Changes in NE and NU significantly predicted change in NSSI. Moreover, the initial levels of NU and PRE significantly moderated the relationship between the initial levels of NE and NSSI, such that among individuals with higher NU or less PRE, the three NE were associated with a higher level of NSSI. Additionally, among individuals with a faster increase in NU, depression and anxiety were associated with a faster increase in NSSI. These findings suggest that adolescents with trait impulsivity, especially in the form of NU, are more vulnerable to the engagement in NSSI. PMID:26436464

  16. Do children orphaned by AIDS experience distress over time? A latent growth curve analysis of depressive symptoms.

    PubMed

    Chi, Peilian; Li, Xiaoming; Barnett, Douglas; Zhao, Junfeng; Zhao, Guoxiang

    2014-01-01

    This longitudinal study aimed to examine the enduring effects of parental HIV/AIDS on children's psychological well-being in Asia. A sample of 1625 children aged from 6 to 18 years old were assessed annually for their depressive symptoms over three years. Latent growth curve modeling (LGCM) was used to examine the trajectories of depressive symptoms among AIDS orphans and vulnerable children in comparison with children from HIV-free families. AIDS orphans demonstrated the highest initial level of depressive symptoms among the three groups. On average, children's depressive symptoms' scores can be expected to realize an approximate 25% decrease for AIDS orphans, 19% decrease for vulnerable children, and 15% decrease for comparison children over a three-year period. Individual differences within the groups showed that children with higher initial level of depressive symptoms can be expected to decrease slower over time. Multiple group LGCM showed that the three groups of children demonstrated significantly different trajectories of depressive symptoms. Among the key demographic factors, only age exerted an effect on the trajectory of depressive symptoms of vulnerable children, indicating that the younger children showed higher level of initial depressive symptoms and lower rate of decrease than the older children. The current study enriched our knowledge on the longitudinal effect of parental HIV/AIDS on children's emotional distress. Future psychological support might take the children's developmental stages and cultural appropriateness into consideration and deliver service for the most vulnerable group of children affected by HIV/AIDS. PMID:24090100

  17. Influence of Asthma on the Longitudinal Trajectories of Cigarette Use Behaviors From Adolescence to Adulthood Using Latent Growth Curve Models

    PubMed Central

    Bae, Jisuk

    2015-01-01

    Objectives: While epidemiologic research indicates that the prevalence of risk-taking behaviors including cigarette smoking among young people with asthma is substantial, the longitudinal patterns of cigarette smoking in this vulnerable population have received little attention. The aim of this study was to evaluate differences in the longitudinal trajectories of cigarette use behaviors from adolescence to adulthood between young people with and without asthma. Methods: Data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) during the years 1994 to 1995 (Wave I, adolescence), 2001 to 2002 (Wave III, young adulthood), and 2007 to 2008 (Wave IV, adulthood) were analyzed (n=12 244). Latent growth curve models were used to examine the longitudinal trajectories of cigarette use behaviors during the transition to adulthood according to asthma status. Results: Regardless of asthma status, the trajectory means of cigarette use behaviors were found to increase, and then slightly decrease from adolescence to adulthood. In total participants, there were no statistically significant differences in initial levels and changes in cigarette use behaviors according to asthma status. However, in select sex and race subgroups (i.e., females and non-whites), former asthmatics showed greater escalation in cigarette use behaviors than did non-asthmatics or current asthmatics. Conclusions: This study indicated that the changing patterns of cigarette use behaviors during the transition to adulthood among young people with asthma are comparable to or even more drastic than those among young people without asthma. PMID:25857649

  18. Some triple-filament lead isotope ratio measurements and an absolute growth curve for single-stage leads

    USGS Publications Warehouse

    Stacey, J.S.; Delevaux, M.E.; Ulrych, T.J.

    1969-01-01

    Triple-filament analyses of three standard lead samples are used to calibrate a mass spectrometer in an absolute sense. The bias we measure is 0.0155 percent per mass unit, and the precision (for 95% confidence limits) is ??0.13% or less for all ratios relative to 204Pb. Although its precision is not quite so good as that of the lead-tetramethyl method in the analysis of large samples, the triple-filament method is less complex and is an attractive alternative for smaller sample sizes down to 500 ??g. Triple-filament data are presented for six possibly single-stage lead ores and one feldspar. These new data for ores are combined with corrected tetramethyl data for stratiform lead deposits to compute absolute parameters for a universal single-stage lead isotope growth curve. Absolute isotopic ratios for primeval lead have been determined by Oversby and because all the previous data for both meteorites and lead ores were similarly fractionated, the absolute value of 238U 204Pb = 9.09 ?? 0.06 for stratiform leads is little different from the value 8.99 ?? 0.05 originally computed by Ostic, Russell and Stanton. Absolute values for lead isotope ratios for all interlaboratory standard samples presently available from the literature are tabulated. ?? 1969.

  19. High-throughput phenotypic profiling of gene-environment interactions by quantitative growth curve analysis in Saccharomyces cerevisiae.

    PubMed

    Weiss, Andrew; Delproposto, James; Giroux, Craig N

    2004-04-01

    Cell-based assays are widely used in high-throughput screening to determine the effects of toxicants and drugs on their biological targets. To enable a functional genomics modeling of gene-environment interactions, quantitative assays are required both for gene expression and for the phenotypic responses to environmental challenge. To address this need, we describe an automated high-throughput methodology that provides phenotypic profiling of the cellular responses to environmental stress in Saccharomyces cerevisiae. Standardized assay conditions enable the use of a single metric value to quantify yeast microculture growth curves. This assay format allows precise control of both genetic and environmental determinants of the cellular responses to oxidative stress, a common mechanism of environmental insult. These yeast-cell-based assays are validated with hydrogen peroxide, a simple direct-acting oxidant. Phenotypic profiling of the oxidative stress response of a yap1 mutant strain demonstrates the mechanistic analysis of genetic susceptibility to oxidative stress. As a proof of concept for analysis of more complex gene-environment interactions, we describe a combinatorial assay design for phenotypic profiling of the cellular responses to tert-butyl hydroperoxide, a complex oxidant that is actively metabolized by its target cells. Thus, the yeast microculture assay format supports comprehensive applications in toxicogenomics. PMID:15033507

  20. Latent growth curve analysis of fear during a speech task before and after treatment for social phobia.

    PubMed

    Price, Matthew; Anderson, Page L

    2011-11-01

    Models of social phobia highlight the importance of anticipatory anxiety in the experience of fear during a social situation. Anticipatory anxiety has been shown to be highly correlated with performance anxiety for a variety of social situations. A few studies show that average ratings of anxiety during the anticipation and performance phases of a social situation decline following treatment. Evidence also suggests that the point of confrontation with the feared stimulus is the peak level of fear. No study to date has evaluated the pattern of anxious responding across the anticipation, confrontation, and performance phases before and after treatment, which is the focus of the current study. Socially phobic individuals (N = 51) completed a behavioral avoidance task before and after two types of manualized cognitive behavioral therapy, and gave ratings of fear during the anticipation and performance phases. Results from latent growth curve analysis were the same for the two treatments and suggested that before treatment, anxiety sharply increased during the anticipation phase, was highly elevated at the confrontation, and gradually increased during the performance phase. After treatment, anxiety increased during the anticipation phase, although at a much slower rate than at pretreatment, peaked at confrontation, and declined during the performance phase. The findings suggest that anticipatory experiences are critical to the experience of fear for public speaking and should be incorporated into exposures. PMID:21907972

  1. A Model to Explain Plant Growth Promotion Traits: A Multivariate Analysis of 2,211 Bacterial Isolates

    PubMed Central

    da Costa, Pedro Beschoren; Granada, Camille E.; Ambrosini, Adriana; Moreira, Fernanda; de Souza, Rocheli; dos Passos, João Frederico M.; Arruda, Letícia; Passaglia, Luciane M. P.

    2014-01-01

    Plant growth-promoting bacteria can greatly assist sustainable farming by improving plant health and biomass while reducing fertilizer use. The plant-microorganism-environment interaction is an open and complex system, and despite the active research in the area, patterns in root ecology are elusive. Here, we simultaneously analyzed the plant growth-promoting bacteria datasets from seven independent studies that shared a methodology for bioprospection and phenotype screening. The soil richness of the isolate's origin was classified by a Principal Component Analysis. A Categorical Principal Component Analysis was used to classify the soil richness according to isolate's indolic compound production, siderophores production and phosphate solubilization abilities, and bacterial genera composition. Multiple patterns and relationships were found and verified with nonparametric hypothesis testing. Including niche colonization in the analysis, we proposed a model to explain the expression of bacterial plant growth-promoting traits according to the soil nutritional status. Our model shows that plants favor interaction with growth hormone producers under rich nutrient conditions but favor nutrient solubilizers under poor conditions. We also performed several comparisons among the different genera, highlighting interesting ecological interactions and limitations. Our model could be used to direct plant growth-promoting bacteria bioprospection and metagenomic sampling. PMID:25542031

  2. A model to explain plant growth promotion traits: a multivariate analysis of 2,211 bacterial isolates.

    PubMed

    da Costa, Pedro Beschoren; Granada, Camille E; Ambrosini, Adriana; Moreira, Fernanda; de Souza, Rocheli; dos Passos, João Frederico M; Arruda, Letícia; Passaglia, Luciane M P

    2014-01-01

    Plant growth-promoting bacteria can greatly assist sustainable farming by improving plant health and biomass while reducing fertilizer use. The plant-microorganism-environment interaction is an open and complex system, and despite the active research in the area, patterns in root ecology are elusive. Here, we simultaneously analyzed the plant growth-promoting bacteria datasets from seven independent studies that shared a methodology for bioprospection and phenotype screening. The soil richness of the isolate's origin was classified by a Principal Component Analysis. A Categorical Principal Component Analysis was used to classify the soil richness according to isolate's indolic compound production, siderophores production and phosphate solubilization abilities, and bacterial genera composition. Multiple patterns and relationships were found and verified with nonparametric hypothesis testing. Including niche colonization in the analysis, we proposed a model to explain the expression of bacterial plant growth-promoting traits according to the soil nutritional status. Our model shows that plants favor interaction with growth hormone producers under rich nutrient conditions but favor nutrient solubilizers under poor conditions. We also performed several comparisons among the different genera, highlighting interesting ecological interactions and limitations. Our model could be used to direct plant growth-promoting bacteria bioprospection and metagenomic sampling. PMID:25542031

  3. Growth curves of crossbred cows sired by Hereford, Angus, Belgian Blue, Brahman, Boran, and Tuli bulls, and the fraction of mature weight and height at puberty

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate the growth curves of females to determine if mature size and relative rates of maturing amongst breeds differed. Body weight and hip height data were fit to the nonlinear function: BW = f(t) = A – Bek(age) where A is an estimate of mature BW and k determi...

  4. A Growth Curve Analysis of the Joint Influences of Parenting Affect, Child Characteristics and Deviant Peers on Adolescent Illicit Drug Use

    ERIC Educational Resources Information Center

    Pires, Paulo; Jenkins, Jennifer M.

    2007-01-01

    This study purports that parental rejection and warmth are critical to the development of adolescent drug use, and investigates a model that also considers children's vulnerability and deviant peer affiliations. It tests mediation through the proximal risk factor of deviant peers. Poisson growth curve modeling was used to examine participants from…

  5. Modeling C-Curves for the Growth Rate of Widmanstätten and Bainitic Ferrite in Fe-C Alloys

    NASA Astrophysics Data System (ADS)

    Leach, Lindsay; Hillert, Mats; Borgenstam, Annika

    2016-01-01

    When Zener formulated his maximum growth rate criterion for predicting the coarseness of various metallographic objects, he simplified the growth rate equations and predicted that the optimum coarseness should be twice the critical value for which all the driving force would be absorbed by interfacial energy. It is now emphasized that a composition dependence of the diffusion coefficient has a considerable influence and can result in a ratio much larger than two. Various approximations have now been removed from the growth rate equation. When applied to acicular ferrite in the Fe-C system, a C-curve for the growth rate is obtained that resembles the unusually wide C-curve obtained experimentally when information on Widmanstätten ferrite and bainite is combined. It is not necessary to explain that shape as a combination of separate curves for Widmanstätten ferrite and bainite. The main reason for the wide C-curve is the direct effect of the composition dependence of the diffusivity of carbon in austenite.

  6. Effects of Bacillus subtilis KN-42 on Growth Performance, Diarrhea and Faecal Bacterial Flora of Weaned Piglets

    PubMed Central

    Hu, Yuanliang; Dun, Yaohao; Li, Shenao; Zhao, Shumiao; Peng, Nan; Liang, Yunxiang

    2014-01-01

    This research focused on the effects of different doses of Bacillus subtilis KN-42 on the growth performance, diarrhea incidence, faecal bacterial flora, and the relative number of Lactobacillus and Escherichia coli in faeces of weaned piglets to determine whether the strain can serve as a candidate antimicrobial growth promoter. A total of 360 piglets (initial body weight 7.14±0.63 kg) weaned at 26±2 days of age were randomly allotted to 5 treatment groups (4 pens per treatment with 18 pigs per pen) for a 28-day trial. Dietary treatments were basal diet without any antimicrobial (negative control; NC), basal diet supplemented with 120 mg/kg feed of neomycin sulfate (positive control; PC) and basal diet supplemented with 2×109 (L), 4×109 (M) and 20×109 (H) CFU/kg feed of B. subtilis KN-42. During the overall period, average daily gain and feed efficiency of piglets were higher in groups PC, M, and H than those in group NC (p<0.05), and all probiotics and antibiotics groups had a lower diarrhea index than group NC (p<0.05). The 16S rDNA gene-based methods were used to analyze faecal bacterial flora on day 28 of experiment. The result of denaturing gradient gel electrophoresis analysis showed that supplementation of B. subtilis KN-42 to the diet changed the bacterial communities, with a higher bacterial diversity and band number in group M than in the other four groups. Real-time polymerase chain reaction analysis showed that the relative number of Lactobacillus were higher in groups PC and H than in group NC (p<0.05), and the supplemented B. subtilis KN-42 to the diet also reduced the relative number of E. coli (p<0.05). These results suggest that dietary addition of B. subtilis KN-42 can improve the growth performance and gastrointestinal health of piglets. PMID:25083107

  7. Root ethylene signalling is involved in Miscanthus sinensis growth promotion by the bacterial endophyte Herbaspirillum frisingense GSF30T

    PubMed Central

    Ludewig, Uwe

    2013-01-01

    The bacterial endophyte Herbaspirillum frisingense GSF30T is a colonizer of several grasses grown in temperate climates, including the highly nitrogen-efficient perennial energy grass Miscanthus. Inoculation of Miscanthus sinensis seedlings with H. frisingense promoted root and shoot growth but had only a minor impact on nutrient concentrations. The bacterium affected the root architecture and increased fine-root structures. Although H. frisingense has the genetic requirements to fix nitrogen, only minor changes in nitrogen concentrations were observed. Herbaspirillum agglomerates were identified primarily in the root apoplast but also in the shoots. The short-term (3h) and long-term (3 weeks) transcriptomic responses of the plant to bacterial inoculation revealed that H. frisingense induced rapid changes in plant hormone signalling, most prominent in jasmonate signalling. Ethylene signalling pathways were also affected and persisted after 3 weeks in the root. Growth stimulation of the root by the ethylene precursor 1-aminocyclopropane 1-carboxylic acid was dose dependent and was affected by H. frisingense inoculation. Minor changes in the proteome were identified after 3 weeks. This study suggests that H. frisingense improves plant growth by modulating plant hormone signalling pathways and provides a framework to understand the beneficial effects of diazotrophic plant-growth-promoting bacteria, such as H. frisingense, on the biomass grass Miscanthus. PMID:24043849

  8. Effects of Eyjafjallajökull Volcanic Ash on Innate Immune System Responses and Bacterial Growth in Vitro

    PubMed Central

    Baltrusaitis, Jonas; Powers, Linda S.; Borcherding, Jennifer A.; Caraballo, Juan C.; Mudunkotuwa, Imali; Peate, David W.; Walters, Katherine; Thompson, Jay M.; Grassian, Vicki H.; Gudmundsson, Gunnar; Comellas, Alejandro P.

    2013-01-01

    Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20–100 µg/cm2), primary rat and human alveolar macrophages (5–20 µg/cm2), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals. PMID:23478268

  9. Population dynamics of a Salmonella lytic phage and its host: implications of the host bacterial growth rate in modelling.

    PubMed

    Santos, Sílvio B; Carvalho, Carla; Azeredo, Joana; Ferreira, Eugénio C

    2014-01-01

    The prevalence and impact of bacteriophages in the ecology of bacterial communities coupled with their ability to control pathogens turn essential to understand and predict the dynamics between phage and bacteria populations. To achieve this knowledge it is essential to develop mathematical models able to explain and simulate the population dynamics of phage and bacteria. We have developed an unstructured mathematical model using delay-differential equations to predict the interactions between a broad-host-range Salmonella phage and its pathogenic host. The model takes into consideration the main biological parameters that rule phage-bacteria interactions likewise the adsorption rate, latent period, burst size, bacterial growth rate, and substrate uptake rate, among others. The experimental validation of the model was performed with data from phage-interaction studies in a 5 L bioreactor. The key and innovative aspect of the model was the introduction of variations in the latent period and adsorption rate values that are considered as constants in previous developed models. By modelling the latent period as a normal distribution of values and the adsorption rate as a function of the bacterial growth rate it was possible to accurately predict the behaviour of the phage-bacteria population. The model was shown to predict simulated data with a good agreement with the experimental observations and explains how a lytic phage and its host bacteria are able to coexist. PMID:25051248

  10. Population Dynamics of a Salmonella Lytic Phage and Its Host: Implications of the Host Bacterial Growth Rate in Modelling

    PubMed Central

    Santos, Sílvio B.; Carvalho, Carla; Azeredo, Joana; Ferreira, Eugénio C.

    2014-01-01

    The prevalence and impact of bacteriophages in the ecology of bacterial communities coupled with their ability to control pathogens turn essential to understand and predict the dynamics between phage and bacteria populations. To achieve this knowledge it is essential to develop mathematical models able to explain and simulate the population dynamics of phage and bacteria. We have developed an unstructured mathematical model using delay-differential equations to predict the interactions between a broad-host-range Salmonella phage and its pathogenic host. The model takes into consideration the main biological parameters that rule phage-bacteria interactions likewise the adsorption rate, latent period, burst size, bacterial growth rate, and substrate uptake rate, among others. The experimental validation of the model was performed with data from phage-interaction studies in a 5 L bioreactor. The key and innovative aspect of the model was the introduction of variations in the latent period and adsorption rate values that are considered as constants in previous developed models. By modelling the latent period as a normal distribution of values and the adsorption rate as a function of the bacterial growth rate it was possible to accurately predict the behaviour of the phage-bacteria population. The model was shown to predict simulated data with a good agreement with the experimental observations and explains how a lytic phage and its host bacteria are able to coexist. PMID:25051248

  11. Severity of Prenatal Cocaine Exposure and Child Language Functioning Through Age Seven Years: A Longitudinal Latent Growth Curve Analysis

    PubMed Central

    Bandstra, Emmalee S.; Vogel, April L.; Morrow, Connie E.; Xue, Lihua; Anthony, James C.

    2009-01-01

    The current study estimates the longitudinal effects of severity of prenatal cocaine exposure on language functioning in an urban sample of full-term African-American children (200 cocaine-exposed, 176 noncocaine-exposed) through age 7 years. The Miami Prenatal Cocaine Study sample was enrolled prospectively at birth, with documentation of prenatal drug exposure status through maternal interview and toxicology assays of maternal and infant urine and infant meconium. Language functioning was measured at ages 3 and 5 years using the Clinical Evaluation of Language Fundamentals–Preschool (CELF-P) and at age 7 years using the Core Language Domain of the NEPSY: A Developmental Neuropsychological Assessment. Longitudinal latent growth curve analyses were used to examine two components of language functioning, a more stable aptitude for language performance and a time-varying trajectory of language development, across the three time points and their relationship to varying levels of prenatal cocaine exposure. Severity of prenatal cocaine exposure was characterized using a latent construct combining maternal self-report of cocaine use during pregnancy by trimesters and maternal and infant bioassays, allowing all available information to be taken into account. The association between severity of exposure and language functioning was examined within a model including factors for fetal growth, gestational age, and IQ as intercorrelated response variables and child’s age, gender, and prenatal alcohol, tobacco, and marijuana exposure as covariates. Results indicated that greater severity of prenatal cocaine exposure was associated with greater deficits within the more stable aptitude for language performance (D = −0.071, 95% CI = −0.133, −0.009; p = 0.026). There was no relationship between severity of prenatal cocaine exposure and the time-varying trajectory of language development. The observed cocaine-associated deficit was independent of multiple alternative

  12. Growth promotion and colonization of switchgrass (Panicum virgatum) cv. Alamo by bacterial endophyte Burkholderia phytofirmans strain PsJN

    PubMed Central

    2012-01-01

    Background Switchgrass is one of the most promising bioenergy crop candidates for the US. It gives relatively high biomass yield and can grow on marginal lands. However, its yields vary from year to year and from location to location. Thus it is imperative to develop a low input and sustainable switchgrass feedstock production system. One of the most feasible ways to increase biomass yields is to harness benefits of microbial endophytes. Results We demonstrate that one of the most studied plant growth promoting bacterial endophytes, Burkholderia phytofirmans strain PsJN, is able to colonize and significantly promote growth of switchgrass cv. Alamo under in vitro, growth chamber, and greenhouse conditions. In several in vitro experiments, the average fresh weight of PsJN-inoculated plants was approximately 50% higher than non-inoculated plants. When one-month-old seedlings were grown in a growth chamber for 30 days, the PsJN-inoculated Alamo plants had significantly higher shoot and root biomass compared to controls. Biomass yield (dry weight) averaged from five experiments was 54.1% higher in the inoculated treatment compared to non-inoculated control. Similar results were obtained in greenhouse experiments with transplants grown in 4-gallon pots for two months. The inoculated plants exhibited more early tillers and persistent growth vigor with 48.6% higher biomass than controls. We also found that PsJN could significantly promote growth of switchgrass cv. Alamo under sub-optimal conditions. However, PsJN-mediated growth promotion in switchgrass is genotype specific. Conclusions Our results show B. phytofirmans strain PsJN significantly promotes growth of switchgrass cv. Alamo under different conditions, especially in the early growth stages leading to enhanced production of tillers. This phenomenon may benefit switchgrass establishment in the first year. Moreover, PsJN significantly stimulated growth of switchgrass cv. Alamo under sub-optimal conditions

  13. [Qualitative and quantitative determination of bacterial populations in an aquatic environment. 7. Development of bacterial growth on raw materials exposed to potable water].

    PubMed

    Dott, W; Schoenen, D

    1985-05-01

    Refined steel plates coated with different materials that contained available organic compounds led to a microbial growth on the surface. Even plastics and bitumen which were used in the sphere of drinking water showed after an exposure time of three months up to 192 ml slime per square meter. The number of viable bacteria within the Aufwuchs was in the range of 10(7) cfu/ml. The production of slime increased with time. The relation of carbohydrate and protein content significantly changed from 2 at the beginning to 30 after 12 months of incubation the bitumen coating test plates. This indicates an increase synthesis of carbohydrate containing extracellular polymeric substances during the late phase of growth. The bacteria isolated from the Aufwuchs mainly belonged to the genera Pseudomonas, Flavobacterium, Acinetobacter, Caulobacter, sheated bacteria and other gramnegative physiologically nonreactiv roads. During exposure of the plates the relation changed within the bacterial communities of the main groups. Comparing the bacteria communities of inlet and outflow water it became evident that the later one was influenced by bacteria of the Aufwuchs. PMID:4024773

  14. Bacterial growth state distinguished by single-cell protein profiling: Does chlorination kill coliforms in municipal effluent?

    SciTech Connect

    Rockabrand, D.; Austin, T.; Kaiser, R.; Blum, P.

    1999-09-01

    Municipal effluent is the largest reservoir of human enteric bacteria. Its public health significance, however, depends upon the physiological status of the wastewater bacterial community. A novel immunofluorescence assay was developed and used to examine the bacterial growth state during wastewater disinfection. Quantitative levels of three highly conserved cytosolic proteins (DnaK, Dps, and Fis) were determined by using enterobacterium-specific antibody fluorochrome-coupled probes. Enterobacterial Fis homologs were abundant in growing cells and nearly undetectable in stationary-phase cells. In contrast, enterobacterial Dps homologs were abundant in stationary-phase cells but virtually undetectable in growing cells. The range of variation in the abundance of both proteins was at least 100-fold as determined by Western blotting and immunofluorescence analysis. Enterobacterial DnaK homologs were nearly invariant with growth state, enabling their use as permeabilization controls. The cellular growth states of individual enterobacteria in wastewater samples were determined by measurement of Fis, Dps, and DnaK abundance (protein profiling). Intermediate levels of Fis and Dps were evident and occurred in response to physiological transitions. The results indicate that chlorination failed to kill coliforms but rather elicited nutrient starvation and a reversible nonculturable state. These studies suggest that the current standard procedures for wastewater analysis which rely on detection of culturable cells likely underestimate fecal coliform content.

  15. Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

    PubMed

    Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

    2015-01-01

    The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil. PMID:25867954

  16. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    PubMed Central

    Liu, Yiwen; Ni, Bing-Jie

    2015-01-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d−1 compared to 0.118 d−1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment. PMID:25644239

  17. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    NASA Astrophysics Data System (ADS)

    Liu, Yiwen; Ni, Bing-Jie

    2015-02-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d-1 compared to 0.118 d-1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment.

  18. Effects of Interactions of Auxin-Producing Bacteria and Bacterial-Feeding Nematodes on Regulation of Peanut Growths

    PubMed Central

    Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

    2015-01-01

    The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil. PMID:25867954

  19. Asynchronous magnetic bead rotation (AMBR) micro-viscometer for rapid, sensitive and label-free studies of bacterial growth and drug sensitivity

    PubMed Central

    Sinn, Irene; Albertson, Theodore; Kinnunen, Paivo; Breslauer, David N.; McNaughton, Brandon H.; Burns, Mark A.; Kopelman, Raoul

    2012-01-01

    The long turnaround time in antimicrobial susceptibility testing (AST) endangers patients and encourages the administration of wide spectrum antibiotics, thus resulting in alarming increases of multi-drug resistant pathogens. A method for faster detection of bacterial proliferation presents one avenue towards addressing this global concern. We report on a label-free asynchronous magnetic bead rotation (AMBR) based viscometry method that rapidly detects bacterial growth and determines drug sensitivity by measuring changes in the suspension’s viscosity. With this platform, we observed the growth of a uropathogenic Escherichia coli isolate, with an initial concentration of 50 cells per drop, within 20 minutes; in addition, we determined the gentamicin minimum inhibitory concentration (MIC) of the E. coli isolate within 100 minutes. We thus demonstrated a label-free, micro-viscometer platform that can measure bacterial growth and drug susceptibility more rapidly, with lower initial bacterial counts than existing commercial systems, and potentially with any microbial strains. PMID:22507307

  20. Microbial Biogeography along an Estuarine Salinity Gradient: Combined Influences of Bacterial Growth and Residence Time

    PubMed Central

    Crump, Byron C.; Hopkinson, Charles S.; Sogin, Mitchell L.; Hobbie, John E.

    2004-01-01

    Shifts in bacterioplankton community composition along the salinity gradient of the Parker River estuary and Plum Island Sound, in northeastern Massachusetts, were related to residence time and bacterial community doubling time in spring, summer, and fall seasons. Bacterial community composition was characterized with denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA. Average community doubling time was calculated from bacterial production ([14C]leucine incorporation) and bacterial abundance (direct counts). Freshwater and marine populations advected into the estuary represented a large fraction of the bacterioplankton community in all seasons. However, a unique estuarine community formed at intermediate salinities in summer and fall, when average doubling time was much shorter than water residence time, but not in spring, when doubling time was similar to residence time. Sequencing of DNA in DGGE bands demonstrated that most bands represented single phylotypes and that matching bands from different samples represented identical phylotypes. Most river and coastal ocean bacterioplankton were members of common freshwater and marine phylogenetic clusters within the phyla Proteobacteria, Bacteroidetes, and Actinobacteria. Estuarine bacterioplankton also belonged to these phyla but were related to clones and isolates from several different environments, including marine water columns, freshwater sediments, and soil. PMID:15006771

  1. Addition of Selenium Nanoparticles to Electrospun Silk Scaffold Improves the Mammalian Cell Activity While Reducing Bacterial Growth

    PubMed Central

    Chung, Stanley; Ercan, Batur; Roy, Amit K.; Webster, Thomas J.

    2016-01-01

    Silk possesses many beneficial wound healing properties, and electrospun scaffolds are especially applicable for skin applications, due to their smaller interstices and higher surface areas. However, purified silk promotes microbial growth. Selenium nanoparticles have shown excellent antibacterial properties and are a novel antimicrobial chemistry. Here, electrospun silk scaffolds were doped with selenium nanoparticles to impart antibacterial properties to the silk scaffolds. Results showed significantly improved bacterial inhibition and mild improvement in human dermal fibroblast metabolic activity. These results suggest that the addition of selenium nanoparticles to electrospun silk is a promising approach to improve wound healing with reduced infection, without relying on antibiotics. PMID:27471473

  2. In vitro bacterial growth and in vivo ruminal microbiota populations associated with bloat in steers grazing wheat forage.

    PubMed

    Min, B R; Pinchak, W E; Anderson, R C; Hume, M E

    2006-10-01

    The role of ruminal bacteria in the frothy bloat complex common to cattle grazing winter wheat has not been previously determined. Two experiments, one in vitro and another in vivo, were designed to elucidate the effects of fresh wheat forage on bacterial growth, biofilm complexes, rumen fermentation end products, rumen bacterial diversity, and bloat potential. In Exp. 1, 6 strains of ruminal bacteria (Streptococcus bovis strain 26, Prevotella ruminicola strain 23, Eubacterium ruminantium B1C23, Ruminococcus albus SY3, Fibrobacter succinogenes ssp. S85, and Ruminococcus flavefaciens C94) were used in vitro to determine the effect of soluble plant protein from winter wheat forage on specific bacterial growth rate, biofilm complexes, VFA, and ruminal H2 and CH4 in mono or coculture with Methanobrevibacter smithii. The specific growth rate in plant protein medium containing soluble plant protein (3.27% nitrogen) was measured during a 24-h incubation at 39 degrees C in Hungate tubes under a CO2 gas phase. A monoculture of M. smithii was grown similarly, except under H2:CO2 (1:1), in a basal methanogen growth medium supplemented likewise with soluble plant protein. In Exp. 2, 6 ruminally cannulated steers grazing wheat forage were used to evaluate the influence of bloat on the production of biofilm complexes, ruminal microbial biodiversity patterns, and ruminal fluid protein fractions. In Exp. 1, cultures of R. albus (P < 0.01) and R. flavefaciens (P < 0.05) produced the most H2 among strains and resulted in greater (P < 0.01) CH4 production when cocultured with M. smithii than other coculture combinations. Cultures of S. bovis and E. ruminantium + M. smithii produced the most biofilm mass among strains. In Exp. 2, when diets changed from bermudagrass hay to wheat forage, biofilm production increased (P < 0.01). Biofilm production, concentrations of whole ruminal content (P < 0.01), and cheesecloth filtrate protein fractions (P < 0.05) in the ruminal fluid were greater

  3. CONSEQUENCES OF PROTIST-STIMULATED BACTERIAL PRODUCTION FOR ESTIMATING PROTIST GROWTH EFFICIENCIES

    EPA Science Inventory

    The trophic link between bacteria and bacterivorous protists is a complex interaction that involves feedback of inorganic nutrients and growth substrates that are immediately available for prey growth. These interactions were examined in the laboratory and in incubations of conce...

  4. Evaluation of free-stall mattress bedding treatments to reduce mastitis bacterial growth

    SciTech Connect

    Kristula, M.A.; Dou, Z.; Toth, J.D.; Smith, B.I.; Harvey, N.; Sabo, M.

    2008-05-15

    Bacterial counts were compared in free-stall mattresses and teat ends exposed to 5 treatments in a factorial study design on 1 dairy farm. Mattresses in five 30-cow groups were subjected to 1 of 5 bedding treatments every other day: 0.5 kg of hydrated limestone, 120 mL of commercial acidic conditioner, 1 kg of coal fly ash, 1 kg of kiln-dried wood shavings, and control (no bedding). Counts of coliforms, Klebsiella spp., Escherichia coli, and Streptococcus spp. were lowest on mattresses bedded with lime. Mattresses bedded with the commercial acidic conditioner had the next lowest counts for coliforms, Klebsiella spp., and Streptococcus spp. Wood shavings and the no-bedding control had the highest counts for coliform and Klebsiella spp. Compared with wood shavings or control, fly ash reduced the counts of coliforms, whereas for the other 3 bacterial groups, the reduction was not always significant. Streptococcus spp. counts were greatest in the control group and did not differ among the shavings and fly ash groups. Teat swab results indicated that hydrated lime was the only bedding treatment that significantly decreased the counts of both coliforms and Klebsiella spp. There were no differences in Streptococcus spp. numbers on the teats between any of the bedding treatments. Bacterial populations grew steadily on mattresses and were generally higher at 36 to 48 h than at 12 to 24 h, whereas bacterial populations on teats grew rapidly by 12 h and then remained constant. Hydrated lime was the only treatment that significantly reduced bacterial counts on both mattresses and teat ends, but it caused some skin irritation.

  5. Evaluation of free-stall mattress bedding treatments to reduce mastitis bacterial growth.

    PubMed

    Kristula, M A; Dou, Z; Toth, J D; Smith, B I; Harvey, N; Sabo, M

    2008-05-01

    Bacterial counts were compared in free-stall mattresses and teat ends exposed to 5 treatments in a factorial study design on 1 dairy farm. Mattresses in five 30-cow groups were subjected to 1 of 5 bedding treatments every other day: 0.5 kg of hydrated limestone, 120 mL of commercial acidic conditioner, 1 kg of coal fly ash, 1 kg of kiln-dried wood shavings, and control (no bedding). Counts of coliforms, Klebsiella spp., Escherichia coli, and Streptococcus spp. were lowest on mattresses bedded with lime. Mattresses bedded with the commercial acidic conditioner had the next lowest counts for coliforms, Klebsiella spp., and Streptococcus spp. Wood shavings and the no-bedding control had the highest counts for coliform and Klebsiella spp. Compared with wood shavings or control, fly ash reduced the counts of coliforms, whereas for the other 3 bacterial groups, the reduction was not always significant. Streptococcus spp. counts were greatest in the control group and did not differ among the shavings and fly ash groups. Teat swab results indicated that hydrated lime was the only bedding treatment that significantly decreased the counts of both coliforms and Klebsiella spp. There were no differences in Streptococcus spp. numbers on the teats between any of the bedding treatments. Bacterial populations grew steadily on mattresses and were generally higher at 36 to 48 h than at 12 to 24 h, whereas bacterial populations on teats grew rapidly by 12 h and then remained constant. Hydrated lime was the only treatment that significantly reduced bacterial counts on both mattresses and teat ends, but it caused some skin irritation. PMID:18420619

  6. Plant Growth Promotion Potential Is Equally Represented in Diverse Grapevine Root-Associated Bacterial Communities from Different Biopedoclimatic Environments

    PubMed Central

    Fusi, Marco; Cherif, Ameur; Abou-Hadid, Ayman; El-Bahairy, Usama; Sorlini, Claudia; Daffonchio, Daniele

    2013-01-01

    Plant-associated bacteria provide important services to host plants. Environmental factors such as cultivar type and pedoclimatic conditions contribute to shape their diversity. However, whether these environmental factors may influence the plant growth promoting (PGP) potential of the root-associated bacteria is not widely understood. To address this issue, the diversity and PGP potential of the bacterial assemblage associated with the grapevine root system of different cultivars in three Mediterranean environments along a macrotransect identifying an aridity gradient were assessed by culture-dependent and independent approaches. According to 16S rRNA gene PCR-DGGE, the structure of endosphere and rhizosphere bacterial communities was highly diverse (P = 0.03) and was associated with a cultivar/latitudinal/climatic effect. Despite being diverse, the bacterial communities associated with Egyptian grapevines shared a higher similarity with the Tunisian grapevines than those cultivated in North Italy. A similar distribution, according to the cultivar/latitude/aridity gradients, was observed for the cultivable bacteria. Many isolates (23%) presented in vitro multiple stress resistance capabilities and PGP activities, the most frequent being auxin synthesis (82%), insoluble phosphate solubilisation (61%), and ammonia production (70%). The comparable numbers and types of potential PGP traits among the three different environmental settings indicate a strong functional homeostasis of beneficial bacteria associated with grape root. PMID:23878810

  7. Synthesis of fluorescent D-amino acids (FDAAs) and their use for probing peptidoglycan synthesis and bacterial growth in situ

    PubMed Central

    Kuru, Erkin; Tekkam, Srinivas; Hall, Edward

    2015-01-01

    Fluorescent D-amino acids (FDAAs) are efficiently incorporated into the peptidoglycan of diverse bacterial species at the sites of active peptidoglycan biosynthesis, allowing specific and covalent probing of bacterial growth with minimal perturbation. Here, we provide a protocol for the synthesis of four FDAAs emitting light in blue, green or red and for their use in peptidoglycan labeling of live bacteria. Our modular synthesis protocol gives easy access to a library of different FDAAs made with commercially available fluorophores. FDAAs can be synthesized in a typical chemistry laboratory in 2–3 days. The simple labeling procedure involves addition of the FDAAs to the bacterial sample for the desired labeling duration and stopping further label incorporation by fixation or by washing away excess dye. We discuss several scenarios for the use of these labels including short or long labeling durations, and the combination of different labels in pure culture or complex environmental samples. Depending on the experiment, FDAA labeling can take as little as 30 s for a rapidly growing species such as Escherichia coli. PMID:25474031

  8. Plant growth promotion potential is equally represented in diverse grapevine root-associated bacterial communities from different biopedoclimatic environments.

    PubMed

    Marasco, Ramona; Rolli, Eleonora; Fusi, Marco; Cherif, Ameur; Abou-Hadid, Ayman; El-Bahairy, Usama; Borin, Sara; Sorlini, Claudia; Daffonchio, Daniele

    2013-01-01

    Plant-associated bacteria provide important services to host plants. Environmental factors such as cultivar type and pedoclimatic conditions contribute to shape their diversity. However, whether these environmental factors may influence the plant growth promoting (PGP) potential of the root-associated bacteria is not widely understood. To address this issue, the diversity and PGP potential of the bacterial assemblage associated with the grapevine root system of different cultivars in three Mediterranean environments along a macrotransect identifying an aridity gradient were assessed by culture-dependent and independent approaches. According to 16S rRNA gene PCR-DGGE, the structure of endosphere and rhizosphere bacterial communities was highly diverse (P = 0.03) and was associated with a cultivar/latitudinal/climatic effect. Despite being diverse, the bacterial communities associated with Egyptian grapevines shared a higher similarity with the Tunisian grapevines than those cultivated in North Italy. A similar distribution, according to the cultivar/latitude/aridity gradients, was observed for the cultivable bacteria. Many isolates (23%) presented in vitro multiple stress resistance capabilities and PGP activities, the most frequent being auxin synthesis (82%), insoluble phosphate solubilisation (61%), and ammonia production (70%). The comparable numbers and types of potential PGP traits among the three different environmental settings indicate a strong functional homeostasis of beneficial bacteria associated with grape root. PMID:23878810

  9. A curve of growth determination of the f-values for the fourth positive system of CO and the Lyman-Birge-Hopfield system of N2.

    NASA Technical Reports Server (NTRS)

    Pilling, M. J.; Bass, A. M.; Braun, W.

    1971-01-01

    The curve of growth method has been employed to determine f-values for the fourth positive system of CO and the magnetic dipole and electric quadrupole components of the Lyman-Birge-Hopfield system of N2. No significant dependence on r-centroid was found. The mean value of the ratio of the electric quadrupole to magnetic dipole f-values was 0.076.

  10. Mouse hepatitis virus strain UAB infection enhances resistance to Salmonella typhimurium in mice by inducing suppression of bacterial growth.

    PubMed Central

    Fallon, M T; Benjamin, W H; Schoeb, T R; Briles, D E

    1991-01-01

    We have previously shown that intranasal infection of mice with mouse hepatitis virus (MHV) strain UAB (MHV-UAB) increases their resistance to Salmonella typhimurium injected intravenously 6 days later. To study how salmonella resistance was induced, BALB/cAnNCr mice were infected with salmonella strains carrying specific genetic alterations. One set of studies compared the effect of MHV infection on subsequent salmonella infections with AroA- (avirulent) and Aro+ (virulent) salmonellae. Unlike its effect on Aro+ salmonellae, MHV failed to reduce the number of AroA- salmonellae recovered from mice. Because AroA- S. typhimurium shows almost no growth in vivo, this failure indicated that the effect of MHV on salmonella resistance required growth of the infecting salmonellae. In other studies, the effect of MHV infection on both growth and killing were monitored simultaneously in mice with growing salmonellae carrying a single copy of the temperature-sensitive pHSG422 plasmid, which is unable to replicate in vivo. MHV infection reduced salmonella growth but caused no increase in salmonella killing. MHV infection of mice given wild-type salmonellae also resulted in no increase in salmonella killing 4 h after salmonella challenge. These studies demonstrate that MHV-UAB infection increases host resistance to salmonellae by enhancing suppression of bacterial growth instead of by increasing the amount of salmonella killing. PMID:1847697

  11. Heterotic and maternal effects on body weight and the parameters of a logistic growth curve of LL and SS rats and their F1 offspring.

    PubMed

    Kasser, T G; Mabry, J W; Benyshek, L L; Campion, D J; Martin, R J

    1983-01-01

    Differences in growth curve parameters were evaluated on two growth strains of rats and their reciprocal crosses. Least squares analysis indicated differences (p less than .05) in asymptotic weight, age and weight at the inflection point, the rate parameter, and absolute growth rate. Significant paternal, maternal, and sex influences were evident for each of the four derived traits. Positive significant heterosis was exhibited for each of the parameters of the growth function. Analysis of least square means of body weight also indicated significant differences at all ages from 4 to 15 weeks. Significant line of sire, line of dam and sex effects were expressed for each week body weight was recorded. Although negative, significant heterosis was expressed for body weight at weeks 5 and 6. There was a tendency for heterosis in all other weekly body weight measurements to be positive. PMID:6642246

  12. Divergent selection for shape of growth curve in Japanese quail. 3. Onset of sexual maturity and basic characteristics of early lay.

    PubMed

    Hyánková, L; Novotná, B

    2007-10-01

    1. The onset of lay, quality of eggs during early lay and gonadal development of both sexes were analysed in meat-type lines of Japanese quail, HG and LG divergently selected for high and low relative weight gain between 11 and 28 d of age, respectively, and constant body weight (BW) at 49 d of age. 2. The LG line was sexually mature at an earlier age and lower BW than the HG line. This corresponded with the trend during embryonic and early postnatal development. 3. Analysis of gonads also confirmed earlier sexual development in the LG than in the HG line. In both lines, the growth of testes was detected about one week earlier than the growth of ovary. 4. Despite the different age and BW at onset of lay, HG and LG quail commenced lay at the same degree of maturity (about 90% of adult BW). This implied that the onset of sexual maturity could be identified as a point on the growth curve which terminates the linear phase. 5. When compared with the LG line, the HG line was characterised by a longer acceleration and shorter retardation phase of the growth curve. This difference is seen as an important determinant of line differences in growth and reproductive performance. PMID:17952726

  13. Effects of monofunctional platinum agents on bacterial growth: a retrospective study.

    PubMed

    Johnstone, Timothy C; Alexander, Sarah M; Lin, Wei; Lippard, Stephen J

    2014-01-01

    The effect of the novel and potent monofunctional platinum(II) agent phenanthriplatin on Escherichia coli and bacteriophage λ lysogens is reported. E. coli filamentation was observed by light microscopy when cells were grown in the presence of phenanthriplatin, cis-[Pt(NH3)2(Am)Cl](+) where Am is phenanthridine. Treatment of lysogenic bacteria with this compound resulted in lysis and the production of viral particles, as indicated by plaque formation in a bacterial lawn. The results obtained with phenanthriplatin are contextualized by comparison with those obtained using cisplatin as well as other, less active, monofunctional compounds such as [Pt(NH3)3Cl](+) and cis-[Pt(NH3)2(py)Cl](+), where py is pyridine. The ability of phenanthriplatin to induce bacterial filamentation and initiate lysis in lysogenic bacteria corroborates the hypothesis that the biological activity of this complex is mediated by its interaction with DNA. PMID:24364388

  14. Characterization of culturable bacterial endophytes and their capacity to promote plant growth from plants grown using organic or conventional practices.

    PubMed

    Xia, Ye; DeBolt, Seth; Dreyer, Jamin; Scott, Delia; Williams, Mark A

    2015-01-01

    Plants have a diverse internal microbial biota that has been shown to have an important influence on a range of plant health attributes. Although these endophytes have been found to be widely occurring, few studies have correlated agricultural production practices with endophyte community structure and function. One agricultural system that focuses on preserving and enhancing soil microbial abundance and biodiversity is organic farming, and numerous studies have shown that organically managed system have increased microbial community characteristics. Herein, the diversity and specificity of culturable bacterial endophytes were evaluated in four vegetable crops: corn, tomato, melon, and pepper grown under organic or conventional practices. Endophytic bacteria were isolated from surface-sterilized shoot, root, and seed tissues and sequence identified. A total of 336 bacterial isolates were identified, and grouped into 32 species and five phyla. Among these, 239 isolates were from organically grown plants and 97 from those grown conventionally. Although a diverse range of bacteria were documented, 186 were from the Phylum Firmicutes, representing 55% of all isolates. Using the Shannon diversity index, we observed a gradation of diversity in tissues, with shoots and roots having a similar value, and seeds having the least diversity. Importantly, endophytic microbial species abundance and diversity was significantly higher in the organically grown plants compared to those grown using conventional practices, potentially indicating that organic management practices may increase endophyte presence and diversity. The impact that these endophytes could have on plant growth and yield was evaluated by reintroducing them into tomato plants in a greenhouse environment. Of the bacterial isolates tested, 61% were found to promote tomato plant growth and 50-64% were shown to enhance biomass accumulation, illustrating their potential agroecosystem application. PMID:26217348

  15. Characterization of culturable bacterial endophytes and their capacity to promote plant growth from plants grown using organic or conventional practices

    PubMed Central

    Xia, Ye; DeBolt, Seth; Dreyer, Jamin; Scott, Delia; Williams, Mark A.

    2015-01-01

    Plants have a diverse internal microbial biota that has been shown to have an important influence on a range of plant health attributes. Although these endophytes have been found to be widely occurring, few studies have correlated agricultural production practices with endophyte community structure and function. One agricultural system that focuses on preserving and enhancing soil microbial abundance and biodiversity is organic farming, and numerous studies have shown that organically managed system have increased microbial community characteristics. Herein, the diversity and specificity of culturable bacterial endophytes were evaluated in four vegetable crops: corn, tomato, melon, and pepper grown under organic or conventional practices. Endophytic bacteria were isolated from surface-sterilized shoot, root, and seed tissues and sequence identified. A total of 336 bacterial isolates were identified, and grouped into 32 species and five phyla. Among these, 239 isolates were from organically grown plants and 97 from those grown conventionally. Although a diverse range of bacteria were documented, 186 were from the Phylum Firmicutes, representing 55% of all isolates. Using the Shannon diversity index, we observed a gradation of diversity in tissues, with shoots and roots having a similar value, and seeds having the least diversity. Importantly, endophytic microbial species abundance and diversity was significantly higher in the organically grown plants compared to those grown using conventional practices, potentially indicating that organic management practices may increase endophyte presence and diversity. The impact that these endophytes could have on plant growth and yield was evaluated by reintroducing them into tomato plants in a greenhouse environment. Of the bacterial isolates tested, 61% were found to promote tomato plant growth and 50–64% were shown to enhance biomass accumulation, illustrating their potential agroecosystem application. PMID:26217348

  16. Group A Streptococcus transcriptome dynamics during growth in human blood reveals bacterial adaptive and survival strategies.

    PubMed

    Graham, Morag R; Virtaneva, Kimmo; Porcella, Stephen F; Barry, William T; Gowen, Brian B; Johnson, Claire R; Wright, Fred A; Musser, James M

    2005-02-01

    The molecular basis for bacterial responses to host signals during natural infections is poorly understood. The gram-positive bacterial pathogen group A Streptococcus (GAS) causes human mucosal, skin, and life-threatening systemic infections. During the transition from a throat or skin infection to an invasive infection, GAS must adapt to changing environments and host factors. To better understand how GAS adapts, we used transcript profiling and functional analysis to investigate the transcriptome of a wild-type serotype M1 GAS strain in human blood. Global changes in GAS gene expression occur rapidly in response to human blood exposure. Increased transcription was observed for many genes that likely enhance bacterial survival, including those encoding superantigens and host-evasion proteins regulated by a multiple gene activator called Mga. GAS also coordinately expressed genes involved in proteolysis, transport, and catabolism of oligopeptides to obtain amino acids in this protein-rich host environment. Comparison of the transcriptome of the wild-type strain to that of an isogenic deletion mutant (DeltacovR) mutated in the two-component regulatory system designated CovR-CovS reinforced the hypothesis that CovR-CovS has an important role linking key biosynthetic, catabolic, and virulence functions during transcriptome restructuring. Taken together, the data provide crucial insights into strategies used by pathogenic bacteria for thwarting host defenses and surviving in human blood. PMID:15681829

  17. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

  18. Multilevel Growth Curve Analyses of Treatment Effects of a Web-Based Intervention for Stress Reduction: Randomized Controlled Trial

    PubMed Central

    Raeder, Sabine; Kraft, Pål; Bjørkli, Cato Alexander

    2013-01-01

    Background Stress is commonly experienced by many people and it is a contributing factor to many mental and physical health conditions, However, few efforts have been made to develop and test the effects of interventions for stress. Objective The aim of this study was to examine the effects of a Web-based stress-reduction intervention on stress, investigate mindfulness and procrastination as potential mediators of any treatment effects, and test whether the intervention is equally effective for females as males, all ages, and all levels of education. Methods We employed a randomized controlled trial in this study. Participants were recruited online via Facebook and randomly assigned to either the stress intervention or a control condition. The Web-based stress intervention was fully automated and consisted of 13 sessions over 1 month. The controls were informed that they would get access to the intervention after the final data collection. Data were collected at baseline and at 1, 2, and 6 months after intervention onset by means of online questionnaires. Outcomes were stress, mindfulness, and procrastination, which were all measured at every measurement occasion. Results A total of 259 participants were included and were allocated to either the stress intervention (n=126) or the control condition (n=133). Participants in the intervention and control group were comparable at baseline; however, results revealed that participants in the stress intervention followed a statistically different (ie, cubic) developmental trajectory in stress levels over time compared to the controls. A growth curve analysis showed that participants in the stress intervention (unstandardized beta coefficient [B]=–3.45, P=.008) recovered more quickly compared to the control group (B=–0.81, P=.34) from baseline to 1 month. Although participants in the stress intervention did show increases in stress levels during the study period (B=2.23, P=.008), long-term stress levels did decrease

  19. Inhibition of bacterial, fungal and plant growth by testa extracts of Citrullus genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watermelon (Citrullus lanatus var. lanatus (Thunb.) Matsum & Nakai) seed exudates inhibit germination and seedling growth of several plant species and growth of pathogenic fungi and bacteria. This study was conducted to determine if extractable components in testae contribute to the inhibition. T...

  20. Validity of the tritiated thymidine method for estimating bacterial growth rates: measurement of isotope dilution during DNA synthesis

    SciTech Connect

    Pollard, P.C.; Moriarty, D.J.W.

    1984-12-01

    The rate of tritiated thymidine incorporation into DNA was used to estimate bacterial growth rates in aquatic environments. To be accurate, the calculation of growth rates has to include a factor for the dilution of isotope before incorporation. The validity of an isotope dilution analysis to determine this factor was verified in experiments reported here with cultures of a marine bacterium growing in a chemostat. Growth rates calculated from data on chemostat dilution rates and cell density agreed well with rates calculated by tritiated thymidine incorporation into DNA and isotope dilution analysis. With sufficiently high concentrations of exogenous thymidine, de novo synthesis of deoxythymidine monophosphate was inhibited, thereby preventing the endogenous dilution of isoope. The thymidine technique was also shown to be useful for measuring growth rates of mixed suspensions of bacteria growing anaerobically. Thymidine was incorporated into the DNA of a range of marine pseudomonads that were investigated. Three species did not take up thymidine. The common marine cyanobacterium Synechococcus species did not incorporate thymidine into DNA.

  1. Transcriptome Analysis of Liangshan Pig Muscle Development at the Growth Curve Inflection Point and Asymptotic Stages Using Digital Gene Expression Profiling

    PubMed Central

    Du, Jingjing; Liu, Chendong; Wu, Xiaoqian; Pu, Qiang; Fu, Yuhua; Tang, Qianzi; Liu, Yuanrui; Li, Qiang; Yang, Runlin; Li, Xuewei; Tang, Guoqing; Jiang, Yanzhi; Li, Mingzhou; Zhang, Shunhua; Zhu, Li

    2015-01-01

    Animal growth curves can provide essential information for animal breeders to optimize feeding and management strategies. However, the genetic mechanism underlying the phenotypic differentiation between the inflection point and asymptotic stages of the growth curve is not well characterized. Here, we employed Liangshan pigs in stages of growth at the inflection point (under inflection point: UIP) and the two asymptotic stages (before the inflection point: BIP, after the inflection point: AIP) as models to survey global gene expression in the longissimus dorsi muscle using digital gene expression (DGE) tag profiling. We found Liangshan pigs reached maximum growth rate (UIP) at 163.6 days of age and a weight of 134.6 kg. The DGE libraries generated 117 million reads of 5.89 gigabases in length. 21,331, 20,996 and 20,139 expressed transcripts were identified BIP, UIP and AIP, respectively. Among them, we identified 757 differentially expressed genes (DEGs) between BIP and UIP, and 271 DEGs between AIP and UIP. An enrichment analysis of DEGs proved the immune system was strengthened in the AIP stage. Energy metabolism rate, global transcriptional activity and bone development intensity were highest UIP. Meat from Liangshan pigs had the highest intramuscular fat content and most favorable fatty acid composition in the AIP. Three hundred eighty (27.70%) specific expression genes were highly enriched in QTL regions for growth and meat quality traits. This study completed a comprehensive analysis of diverse genetic mechanisms underlying the inflection point and asymptotic stages of growth. Our findings will serve as an important resource in the understanding of animal growth and development in indigenous pig breeds. PMID:26292092

  2. Transcriptome Analysis of Liangshan Pig Muscle Development at the Growth Curve Inflection Point and Asymptotic Stages Using Digital Gene Expression Profiling.

    PubMed

    Shen, Linyuan; Luo, Jia; Du, Jingjing; Liu, Chendong; Wu, Xiaoqian; Pu, Qiang; Fu, Yuhua; Tang, Qianzi; Liu, Yuanrui; Li, Qiang; Yang, Runlin; Li, Xuewei; Tang, Guoqing; Jiang, Yanzhi; Li, Mingzhou; Zhang, Shunhua; Zhu, Li

    2015-01-01

    Animal growth curves can provide essential information for animal breeders to optimize feeding and management strategies. However, the genetic mechanism underlying the phenotypic differentiation between the inflection point and asymptotic stages of the growth curve is not well characterized. Here, we employed Liangshan pigs in stages of growth at the inflection point (under inflection point: UIP) and the two asymptotic stages (before the inflection point: BIP, after the inflection point: AIP) as models to survey global gene expression in the longissimus dorsi muscle using digital gene expression (DGE) tag profiling. We found Liangshan pigs reached maximum growth rate (UIP) at 163.6 days of age and a weight of 134.6 kg. The DGE libraries generated 117 million reads of 5.89 gigabases in length. 21,331, 20,996 and 20,139 expressed transcripts were identified BIP, UIP and AIP, respectively. Among them, we identified 757 differentially expressed genes (DEGs) between BIP and UIP, and 271 DEGs between AIP and UIP. An enrichment analysis of DEGs proved the immune system was strengthened in the AIP stage. Energy metabolism rate, global transcriptional activity and bone development intensity were highest UIP. Meat from Liangshan pigs had the highest intramuscular fat content and most favorable fatty acid composition in the AIP. Three hundred eighty (27.70%) specific expression genes were highly enriched in QTL regions for growth and meat quality traits. This study completed a comprehensive analysis of diverse genetic mechanisms underlying the inflection point and asymptotic stages of growth. Our findings will serve as an important resource in the understanding of animal growth and development in indigenous pig breeds. PMID:26292092

  3. The importance of growth kinetic analysis in determining bacterial susceptibility against antibiotics and silver nanoparticles

    PubMed Central

    Theophel, Karsten; Schacht, Veronika J.; Schlüter, Michael; Schnell, Sylvia; Stingu, Catalina-Suzana; Schaumann, Reiner; Bunge, Michael

    2014-01-01

    Routine antibiotics susceptibility testing still relies on standardized cultivation-based analyses, including measurement of inhibition zones in conventional agar diffusion tests and endpoint turbidity-based measurements. Here, we demonstrate that common off-line monitoring and endpoint determination after 18–24 h could be insufficient for reliable growth-dependent evaluation of antibiotic susceptibility. Different minimal inhibitory concentrations were obtained in 20- and 48 h microdilution plate tests using an Enterococcus faecium clinical isolate (strain UKI-MB07) as a model organism. Hence, we used an on-line kinetic assay for simultaneous cultivation and time-resolved growth analysis in a 96-well format instead of off-line susceptibility testing. Growth of the Enterococcus test organism was delayed up to 30 h in the presence of 0.25 μg mL-1 of vancomycin and 8 μg mL-1 of fosfomycin, after which pronounced growth was observed. Despite the delayed onset of growth, treatment with fosfomycin, daptomycin, fusidic acid, cefoxitin, or gentamicin resulted in higher maximum growth rates and/or higher final optical density values compared with antibiotic-free controls, indicating that growth stimulation and hormetic effects may occur with extended exposure to sublethal antibiotic concentrations. Whereas neither maximum growth rate nor final cell density correlated with antibiotic concentration, the lag phase duration for some antibiotics was a more meaningful indicator of dose-dependent growth inhibition. Our results also reveal that non-temporal growth profiles are only of limited value for cultivation-based antimicrobial silver nanoparticle susceptibility testing. The exposure to Ag(0) nanoparticles led to plasma membrane damage in a concentration-dependent manner and induced oxidative stress in Enterococcus faecium UKI-MB07, as shown by intracellular ROS accumulation. PMID:25426104

  4. Noninvasive Quantitative Measurement of Bacterial Growth in Porous Media under Unsaturated-Flow Conditions †

    PubMed Central

    Yarwood, R. R.; Rockhold, M. L.; Niemet, M. R.; Selker, J. S.; Bottomley, P. J.

    2002-01-01

    Glucose-dependent growth of the luxCDABE reporter bacterium Pseudomonas fluorescens HK44 was monitored noninvasively in quartz sand under unsaturated-flow conditions within a 45- by 56- by 1-cm two-dimensional light transmission chamber. The spatial and temporal development of growth were mapped daily over 7 days by quantifying salicylate-induced bioluminescence. A nonlinear model relating the rate of increase in light emission after salicylate exposure to microbial density successfully predicted growth over 4 orders of magnitude (r2 = 0.95). Total model-predicted growth agreed with growth calculated from the mass balance of the system by using previously established growth parameters of HK44 (predicted, 1.2 × 1012 cells; calculated, 1.7 × 1012 cells). Colonization expanded in all directions from the inoculation region, including upward migration against the liquid flow. Both the daily rate of expansion of the colonized zone and the population density of the first day's growth in each newly colonized region remained relatively constant throughout the experiment. Nonetheless, substantial growth continued to occur on subsequent days in the older regions of the colonized zone. The proportion of daily potential growth that remained within the chamber declined progressively between days 2 and 7 (from 97 to 13%). A densely populated, anoxic region developed in the interior of the colonized zone even though the sand was unsaturated and fresh growth medium continued to flow through the colonized zone. These data illustrate the potential of a light transmission chamber, bioluminescent bacteria, and sensitive digital camera technology to noninvasively study real-time hydrology-microbiology interactions associated with unsaturated flow in porous media. PMID:12089048

  5. Noninvasive Quantitative Measurement of Bacterial Growth in Porous Media Under Unsaturated-Flow Conditions

    SciTech Connect

    Yarwood, Rocky; Rockhold, Mark L. ); Niemet, Mike; Selker, John S.; Bottomley, Peter J.

    2002-07-01

    Glucose-dependent growth of the luxCDABE reporter bacterium Pseudomonas fluorescens HK44 was monitored noninvasively in quartz sand under unsaturated-flow conditions within a 45- by 56- by 1-cm two-dimensional light transmission chamber. The spatial and temporal development of growth were mapped daily over 7 days by quantifying salicylate-induced bioluminescence. A nonlinear model relating the rate of increase in light emission after salicylate exposure to microbial density successfully predicted growth over 4 orders of magnitude (r{sup 2}=0.95). Total model-predicted growth agreed with growth calculated from the mass balance of the system by using previously determined growth parameters of HK44 (predicted, 1.2 x 10{sup 12} cells; calculated, 1.7 x 10{sup 12} cells). Colonization expanded in all directions from the inoculation region, including upward migration against the liquid flow. Both the daily rate of expansion of the colonized zone and the population density of the first day's growth in each newly colonized region remained relatively constant throughout the experiment. Nonetheless, substantial growth continued to occur on subsequent days in the older regions of the colonized zone. The proportion of daily potential growth that remained within the chamber declined progressively between days 2 and 7 (from 97 to 13%). A densely populated, anoxic region developed in the interior of the colonized zone even though the sand was unsaturated and fresh growth medium continued to flow through the colonized zone. These data illustrate the potential of a light transmission chamber, bioluminescent bacteria, and sensitive digital camera technology to noninvasively study real-time hydrology-microbiology interactions associated with unsaturated flow in porous media.

  6. A multiphasic approach for the identification of endophytic bacterial in strawberry fruit and their potential for plant growth promotion.

    PubMed

    de Melo Pereira, Gilberto Vinícius; Magalhães, Karina Teixeira; Lorenzetii, Emi Rainildes; Souza, Thiago Pereira; Schwan, Rosane Freitas

    2012-02-01

    This study used a multiphasic approach, characterized by the simultaneous use of culture-dependent and culture-independent methods, to investigate endophytic bacterial communities in strawberry (Fragaria ananassa) fruit. A total of 92 bacterial endophytes were isolated and initially grouped by their repetitive extragenic palindromic (rep)-PCR banding pattern and biochemical features. Phylogenetic analysis of the 16S rRNA gene sequences of 45 representatives showed that the isolates belonged to the species Bacillus subtilis (eight isolates), Bacillus sp. (seven isolates), Enterobacter sp. (seven isolates), Enterobacter ludwigii (six isolates), Lactobacillus plantarum (six isolates), Pseudomonas sp. (five isolates), Pantoea punctata (three isolates), and Curtobacterium citreum (three isolates). Nucleic acids were extracted from the strawberry fruit and subjected to 16S rRNA gene directed polymerase chain reaction denaturing gradient gel electrophoresis (16S rRNA PCR-DGGE). The species B. subtilis, Enterobacter sp., and Pseudomonas sp. were detected both by isolation and DGGE. The DGGE fingerprints of total bacterial DNA did not exhibit bands corresponding to several of the representative species isolated in the extinction dilution (L. plantarum, C. citreum, and P. punctata). In contrast, bands in the DGGE profile that were identified as relatives of Arthrobacter sp. and one uncultivable Erythrobacter sp. were not recovered by cultivation techniques. After isolation, the nitrogen fixation ability and the in vitro production of indole-3-acetic acid (IAA) equivalents and siderophores were evaluated. A high percentage of isolates were found to possess the ability to produce siderophores and IAA equivalents; however, only a few isolates belonging to the genera Pseudomonas and Enterobacter showed the ability to fix nitrogen. Plant growth promotion was evaluated under greenhouse conditions and revealed the ability of the Bacillus strains to enhance the number of leaves

  7. Genetic variances, heritabilities and maternal effects on body weight, breast meat yield, meat quality traits and the shape of the growth curve in turkey birds

    PubMed Central

    2011-01-01

    Background Turkey is an important agricultural species and is largely used as a meat bird. In 2004, turkey represented 6.5% of the world poultry meat production. The world-wide turkey population has rapidly grown due to increased commercial farming. Due to the high demand for turkey meat from both consumers and industry global turkey stocks increased from 100 million in 1970 to over 276 million in 2004. This rapidly increasing importance of turkeys was a reason to design this study for the estimation of genetic parameters that control body weight, body composition, meat quality traits and parameters that shape the growth curve in turkey birds. Results The average heritability estimate for body weight traits was 0.38, except for early weights that were strongly affected by maternal effects. This study showed that body weight traits, upper asymptote (a growth curve trait), percent breast meat and redness of meat had high heritability whereas heritabilities of breast length, breast width, percent drip loss, ultimate pH, lightness and yellowness of meat were medium to low. We found high positive genetic and phenotypic correlations between body weight, upper asymptote, most breast meat yield traits and percent drip loss but percent drip loss was found strongly negatively correlated with ultimate pH. Percent breast meat, however, showed genetic correlations close to zero with body weight traits and upper asymptote. Conclusion The results of this analysis and the growth curve from the studied population of turkey birds suggest that the turkey birds could be selected for breeding between 60 and 80 days of age in order to improve overall production and the production of desirable cuts of meat. The continuous selection of birds within this age range could promote high growth rates but specific attention to meat quality would be needed to avoid a negative impact on the quality of meat. PMID:21266032

  8. Effects of space flight and mixing on bacterial growth in low volume cultures

    NASA Technical Reports Server (NTRS)

    Kacena, M. A.; Manfredi, B.; Todd, P.

    1999-01-01

    Previous investigations have shown that liquid suspension bacterial cultures grow to higher cell concentrations in spaceflight than on Earth. None of these studies included ground-control experiments designed to evaluate the fluid effects potentially responsible for the reported increases. Therefore, the emphasis of this research was to both confirm differences in final cell concentration between 1g and microgravity cultures, and to examine the effects of mixing as a partial explanation for this difference. Flight experiments were performed in the Fluid Processing Apparatus (FPA), aboard Space Shuttle Missions STS-63 and STS-69, with simultaneous 1g static and agitated controls. Additional static 1g, agitated, and clino-rotated controls were performed in 9-ml culture tubes. This research revealed that both E. coli and B. subtilis samples cultured in space flight grew to higher final cell densities (120-345% increase) than simultaneous static 1g controls. The final cell concentration of E. coli cells cultured under agitation was 43% higher than in static 1g cultures and was 102% higher with clino-rotation. However, for B. subtilis cultures grown while being agitated on a shaker or clino-rotated, the final cell concentrations were nearly identical to those of the simultaneous static 1g controls. Therefore, these data suggest that the unique fluid quiescence in the microgravity environment (lack of sedimentation, creating unique transfer of nutrients and waste products), was responsible for the enhanced bacterial proliferation reported in this and other studies.

  9. PRODUCTION OF PLANT GROWTH PROMOTING SUBSTANCES IN BACTERIAL ISOLATES FROM THE SEAGRASS RHIZOSPHERE

    EPA Science Inventory

    Plants and rhizosphere bacteria have evolved chemical signals that enable their mutual growth. These relationships have been well investigated with agriculturally important plants, but not in seagrasses, which are important to the stability of estuaries. Seagrasses are rooted in ...

  10. Consideration of probability of bacterial growth for Jovian planets and their satellites

    NASA Technical Reports Server (NTRS)

    Taylor, D. M.; Berkman, R. M.; Divine, N.

    1974-01-01

    Environmental parameters affecting growth of bacteria are compared with current atmospheric models for Jupiter and Saturn, and with the available physical data for their satellites. Different zones of relative probability of growth are identified for Jupiter and Saturn. Of the more than two dozen satellites, only the largest (Io, Europa, Ganymede, Callisto, and Titan) are found to be interesting biologically. Titan's atmosphere may produce a substantial greenhouse effect providing increased surface temperatures. Models predicting a dense atmosphere are compatible with microbial growth for a range of pressures at Titan's surface. For Titan's surface the probability of growth would be enhanced if: (1) the surface is entirely or partially liquid; (2) volcanism is present; or (3) access to internal heat sources is significant.

  11. Comparison of bacterial growth in sonication fluid cultures with periprosthetic membranes and with cultures of biopsies for diagnosing periprosthetic joint infection.

    PubMed

    Hischebeth, Gunnar T R; Randau, Thomas M; Molitor, Ernst; Wimmer, Matthias D; Hoerauf, Achim; Bekeredjian-Ding, Isabelle; Gravius, Sascha

    2016-02-01

    Total joint arthroplasty is a common operation worldwide with infection rates between 1% and 3%. In cases of suspected periprosthetic joint infection, it is very challenging to rule out the causative microorganisms. In this study, we compared the appearance of periprosthetic membranes with the microbiological results obtained from cultures of sonication fluid and the correlation between classical microbiological cultures and cultures of sonication fluid. The results confirmed a strong correlation of bacterial growth in sonication fluid cultures with bacterial growth in classical microbiological cultures. Most importantly, however, our study documented a highly significant correlation of periprosthetic membranes typical for periprosthetic joint infection (PJI) with bacterial growth in sonication fluid. Sonication fluid cultures yielded a better sensitivity than tissue cultures (72.34-60.87%). These 3 methods are useful tools in diagnosing PJIs, and even more, sonication fluid cultures should be included in the diagnostic path of PJI. PMID:26584961

  12. Growth kinetics of a diesel-degrading bacterial strain from petroleum-contaminated soil.

    PubMed

    Dahalan, S F A; Yunus, I; Johari, W L W; Shukor, M Y; Halmi, M I E; Shamaan, N A; Syed, M A

    2014-03-01

    A diesel-degrading bacterium was isolated from a diesel-contaminated site in Selangor, Malaysia. The isolate was tentatively identified as Acinetobacter sp. strain DRY12 based on partial 16S rDNA molecular phylogeny and Biolog GN microplate panels and Microlog database. Optimum growth occurred from 3 to 5% diesel and the strain was able to tolerate as high as 8% diesel. The optimal pH that supported growth of the bacterium was between pH 7.5 to 8.0. The isolate exhibited optimal growth in between 30 and 35 degrees C. The best nitrogen source was potassium nitrate (between 0.6 and 0.9% (w/v)) followed by ammonium chloride, sodium nitrite and ammonium sulphate in descending order. An almost complete removal of diesel components was seen from the reduction in hydrocarbon peaks observed using Solid Phase Microextraction Gas Chromatography analysis after 10 days of incubation. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibiting growth with a correlation coefficient value of 0.97. The maximum growth rate- micromax was 0.039 hr(-1) while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.387% and 4.46%, respectively. MATH assays showed that 75% of the bacterium was found in the hexadecane phase indicating that the bacterium was hydrophobic. The characteristics of this bacterium make it useful for bioremediation works in the Tropics. PMID:24665769

  13. Effects of novobiocin, coumermycin A1, clorobiocin, and their analogs on Escherichia coli DNA gyrase and bacterial growth.

    PubMed Central

    Hooper, D C; Wolfson, J S; McHugh, G L; Winters, M B; Swartz, M N

    1982-01-01

    Novobiocin, coumermycin A1, and clorobiocin, structurally related compounds that antagonize the B subunit of the essential bacterial enzyme DNA gyrase, were compared with 18 of their analogs for the inhibition of Escherichia coli DNA gyrase supertwisting activity in vitro and of bacterial multiplication. This family of compounds has a 4-hydroxy-8-methylcoumarin core substituted in the 7 and 3 positions. Important for enzyme inhibition in vitro is a 7 ether linkage to a 3'-substituted noviose sugar. The 3'-ester-linked 5-methylpyrrole, found in the coumermycin series, conferred at least 10-fold more inhibitory activity than did the similarly linked amide, found in the novobiocin series; lack of the pyrrole and amide results in the loss of inhibitory activity. Of many aryl and alkyl substituents linked as an amide at the 3 position, the 4-hydroxyl-3-(3-methyl-2-butenyl)benzoic acid moiety, found in novobiocin and clorobiocin, and the reduplication of the coumarin-noviose-5-methylpyrrole, found in coumermycin A1, were most effective in gyrase inhibition. In vivo, the ability of these compounds to inhibit the growth of E. coli varied greatly. The enhanced inhibition of gyrase in vitro conferred by a 5-methylpyrrole relative to an amide in the 3'-noviose position was reflected in inhibition of bacterial multiplication. Several substitutions at the 3 position of the coumarin core conferring similar antagonism of gyrase in vitro resulted in substantially different inhibitory activities for E. coli, suggesting that these moieties at the 3 position affect drug access to the intracellular target. This target was shown for isobutyryl PNC-NH2 (PNC-NH2 is 3-amino-4-hydroxy-8-methyl-7-[3-O-(5-methyl-2-pyrrolylcarbonyl)noviosyloxy] coumarin) and confirmed for novobiocin, coumermycin A1, and clorobiocin to be in the B subunit of DNA gyrase. Images PMID:6295263

  14. A possible mechanism of action of plant growth-promoting rhizobacteria (PGPR) strain Bacillus pumilus WP8 via regulation of soil bacterial community structure.

    PubMed

    Kang, Yijun; Shen, Min; Wang, Huanli; Zhao, Qingxin

    2013-01-01

    According to the traditional view, establishment and maintenance of critical population densities in the rhizosphere was the premise of PGPR to exert growth-promoting effects. In light of the facts that soil bacterial community structures can be changed by some PGPR strains including Bacillus pumilus WP8, we hypothesize that regulation of soil bacterial community structure is one of the plant growth-promoting mechanisms of B. pumilus WP8, rather than depending on high-density cells in soil. In this study, denaturing gradient gel electrophoresis (PCR-DGGE) was performed to evaluate the relationship between changes in soil bacterial community structure and growth-promoting effect on the seedling growth of fava beans (Vicia faba L.) during three successive cultivations. We found that B. pumilus WP8 lacks capacity to reproduce in large enough numbers to survive in bulk soil more than 40 days, yet the bacterial community structures were gradually influenced by inoculation of WP8, especially on dominant populations. Despite WP8 being short-lived, it confers the ability of steadily promoting fava bean seedling growth on soil during the whole growing period for at least 90 days. Pseudomonas chlororaphis RA6, another tested PGPR strain, exists in large numbers for at least 60 days but less than 90 days, whilst giving rise to slight influence on bacterial community structure. In addition, along with the extinction of RA6 cells in bulk soils, the effect of growth promotion disappeared simultaneously. Furthermore, the increment of soil catalase activity from WP8 treatment implied the ability to stimulate soil microbial activity, which may be the reason why the dominant population changed and increased as time passed. Our study suggests that regulation of treated soil bacterial community structure may be another possible action mechanism. PMID:24005176

  15. Stimulated bacterial growth under elevated p CO₂: results from an off-shore mesocosm study.

    PubMed

    Endres, Sonja; Galgani, Luisa; Riebesell, Ulf; Schulz, Kai-Georg; Engel, Anja

    2014-01-01

    Marine bacteria are the main consumers of freshly produced organic matter. Many enzymatic processes involved in the bacterial digestion of organic compounds were shown to be pH sensitive in previous studies. Due to the continuous rise in atmospheric CO2 concentration, seawater pH is presently decreasing at a rate unprecedented during the last 300 million years but the consequences for microbial physiology, organic matter cycling and marine biogeochemistry are still unresolved. We studied the effects of elevated seawater pCO2 on a natural plankton community during a large-scale mesocosm study in a Norwegian fjord. Nine Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS) were adjusted to different pCO2 levels ranging initially from ca. 280 to 3000 µatm and sampled every second day for 34 days. The first phytoplankton bloom developed around day 5. On day 14, inorganic nutrients were added to the enclosed, nutrient-poor waters to stimulate a second phytoplankton bloom, which occurred around day 20. Our results indicate that marine bacteria benefit directly and indirectly from decreasing seawater pH. During the first phytoplankton bloom, 5-10% more transparent exopolymer particles were formed in the high pCO2 mesocosms. Simultaneously, the efficiency of the protein-degrading enzyme leucine aminopeptidase increased with decreasing pH resulting in up to three times higher values in the highest pCO2/lowest pH mesocosm compared to the controls. In general, total and cell-specific aminopeptidase activities were elevated under low pH conditions. The combination of enhanced enzymatic hydrolysis of organic matter and increased availability of gel particles as substrate supported up to 28% higher bacterial abundance in the high pCO2 treatments. We conclude that ocean acidification has the potential to stimulate the bacterial community and facilitate the microbial recycling of freshly produced organic matter, thus strengthening the role of the microbial loop in the

  16. Viral effects on bacterial respiration, production and growth efficiency: Consistent trends in the Southern Ocean and the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Bonilla-Findji, Osana; Malits, Andrea; Lefèvre, Dominique; Rochelle-Newall, Emma; Lemée, Rodolphe; Weinbauer, Markus G.; Gattuso, Jean-Pierre

    2008-03-01

    To investigate the potential effects of viruses on bacterial respiration (BR), production (BP) and growth efficiency (BGE), experiments were performed using natural microbial communities from the coastal Mediterranean Sea, from a typical high-nutrient low-chlorophyll (HNLC) region in the Southern Ocean and from a naturally iron (Fe)-fertilized algal bloom above the Kerguelen Plateau (Southern Ocean). Seawater was sequentially filtered and concentrated to produce a bacterial concentrate, a viral concentrate and a virus-free ultrafiltrate. The combination of all three fractions served as treatments with active viruses. Heating or microwaving was used to inactivate viruses for the control treatments. Despite the differences in the initial trophic state and community composition of the study sites, consistent trends were found. In the presence of active viruses, BR was stimulated (up to 113%), whereas BP and BGE were reduced (up to 51%). Our results suggest that viruses enhance the role of bacteria as oxidizers of organic matter, hence as producers of CO 2, and remineralizers of CO 2, N, P and Fe. In the context of Fe-fertilization, this has important implications for the final fate of organic carbon in marine systems.

  17. Superoxide anions produced by Streptococcus pyogenes group A-stimulated keratinocytes are responsible for cellular necrosis and bacterial growth inhibition.

    PubMed

    Regnier, Elodie; Grange, Philippe A; Ollagnier, Guillaume; Crickx, Etienne; Elie, Laetitia; Chouzenoux, Sandrine; Weill, Bernard; Plainvert, Céline; Poyart, Claire; Batteux, Frédéric; Dupin, Nicolas

    2016-02-01

    Gram-positive Streptococcus pyogenes (group A Streptococcus or GAS) is a major skin pathogen and interacts with keratinocytes in cutaneous tissues. GAS can cause diverse suppurative and inflammatory infections, such as cellulitis, a common acute bacterial dermo-hypodermitis with a high morbidity. Bacterial isolation yields from the lesions are low despite the strong local inflammation observed, raising numerous questions about the pathogenesis of the infection. Using an in vitro model of GAS-infected keratinocytes, we show that the major ROS produced is the superoxide anion ([Formula: see text]), and that its production is time- and dose-dependent. Using specific modulators of ROS production, we show that [Formula: see text] is mainly synthesized by the cytoplasmic NADPH oxidase. Superoxide anion production leads to keratinocyte necrosis but incomplete inhibition of GAS growth, suggesting that GAS may be partially resistant to the oxidative burst. In conclusion, GAS-stimulated keratinocytes are able to develop an innate immune response based on the production of ROS. This local immune response limits GAS development and induces keratinocyte cell death, resulting in the skin lesions observed in patients with cellulitis. PMID:26621818

  18. Effect of autochthonous bacteriocin-producing Lactococcus lactis on bacterial population dynamics and growth of halotolerant bacteria in Brazilian charqui.

    PubMed

    Biscola, Vanessa; Abriouel, Hikmate; Todorov, Svetoslav Dimitrov; Capuano, Verena Sant'Anna Cabral; Gálvez, Antonio; Franco, Bernadette Dora Gombossy de Melo

    2014-12-01

    Charqui is a fermented, salted and sun-dried meat product, widely consumed in Brazil and exported to several countries. Growth of microorganisms in this product is unlikely due to reduced Aw, but halophilic and halotolerant bacteria may grow and cause spoilage. Charqui is a good source of lactic acid bacteria able to produce antimicrobial bacteriocins. In this study, an autochthonous bacteriocinogenic strain (Lactococcus lactis subsp. lactis 69), isolated from charqui, was added to the meat used for charqui manufacture and evaluated for its capability to prevent the growth of spoilage bacteria during storage up to 45 days. The influence of L. lactis 69 on the bacterial diversity during the manufacturing of the product was also studied, using denaturing gradient gel electrophoresis (DGGE). L. lactis 69 did not affect the counts and diversity of lactic acid bacteria during manufacturing and storage, but influenced negatively the populations of halotolerant microorganisms, reducing the spoilage potential. The majority of tested virulence genes was absent, evidencing the safety and potential technological application of this strain as an additional hurdle to inhibit undesirable microbial growth in this and similar fermented meat products. PMID:25084676

  19. Statistical optimization of medium components and physicochemical parameters to simultaneously enhance bacterial growth and esterase production by Bacillus thuringiensis.

    PubMed

    Mazzucotelli, Cintia Anabela; Moreira, María del Rosario; Ansorena, María Roberta

    2016-01-01

    Bacillus thuringiensis is a genus extensively studied because of its high potential for biotechnological application, principally in biocontrol techniques. However, the optimization of esterase production by this strain has been scarcely studied. The aim of this work was to select and optimize the physicochemical and nutritional parameters that significantly influence the growth and esterase production of B. thuringiensis. To this purpose, 6 nutritional factors and 2 physicochemical parameters were evaluated using a Plackett-Burman design. Significant variables were optimized using a Box-Behnken design and through the desirability function to select the levels of the variables that simultaneously maximize microbial growth and esterase production. The optimum conditions resulting from simultaneous optimization of the responses under study were found to be 1 g/L glucose, 15 g/L peptone, and 3.25 g/L NaCl. Under these optimal conditions, it was possible to achieve a 2.5 log CFU/mL increase in bacterial growth and a 113-fold increase in esterase productivity, compared with minimal medium without agitation. PMID:26529589

  20. Diversity and distribution of the endophytic bacterial community at different stages of Eucalyptus growth.

    PubMed

    Miguel, Paulo Sérgio Balbino; de Oliveira, Marcelo Nagem Valério; Delvaux, Júlio César; de Jesus, Guilherme Luiz; Borges, Arnaldo Chaer; Tótola, Marcos Rogério; Neves, Júlio César Lima; Costa, Maurício Dutra

    2016-06-01

    The relationships between plants and endophytic bacteria significantly contribute to plant health and yield. However, the microbial diversity in leaves of Eucalyptus spp. is still poorly characterized. Here, we investigated the endophytic diversity in leaves of hybrid Eucalyptus grandis x E. urophylla (Eucalyptus "urograndis") by using culture-independent and culture-dependent approaches, to better understand their ecology in leaves at different stages of Eucalyptus development, including bacteria with N2 fixation potential. Firmicutes, Proteobacteria (classes alpha-, beta- and gamma-) and Actinobacteria were identified in the Eucalyptus "urograndis" endophytic bacterial community. Within this community, the species Novosphingobium barchaimii, Rhizobium grahamii, Stenotrophomonas panacihumi, Paenibacillus terrigena, P. darwinianus and Terrabacter lapilli represent the first report these bacteria as endophytes. The diversity of the total endophytic bacteria was higher in the leaves from the 'field' (the Shannon-Wiener index, 2.99), followed by the indices obtained in the 'clonal garden' (2.78), the 'recently out from under shade (2.68), 'under shade' (2.63) and 'plants for dispatch' (2.51). In contrast, for diazotrophic bacteria, the highest means of these indices were obtained from the leaves of plants in the 'under shade' (2.56), 'recently out from under shade (2.52)' and 'field' stages (2.54). The distribution of the endophytic bacterial species in Eucalyptus was distinct and specific to the development stages under study, and many of the species had the potential for nitrogen fixation, raising the question of whether these bacteria could contribute to overall nitrogen metabolism of Eucalyptus. PMID:27010209

  1. Correlation between PLD repair capacity and the survival curve of human fibroblasts in exponential growth phase: analysis in terms of several parameters

    SciTech Connect

    Fertil, B.; Deschavanne, P.J.; Debieu, D.; Malaise, E.P.

    1988-10-01

    Published data on the in vitro radiosensitivity of 46 nontransformed fibroblasts of different genetic origins studied in plateau phase with immediate or delayed plating were used to investigate to what extent potentially lethal damage repair capacity is related to intrinsic radiosensitivity (i.e., irradiated in exponential growth phase). While most of the survival curve analysis is conducted in terms of D0, Dq, and the mean inactivation dose D, some of the data are also discussed in terms of the linear-quadratic model parameter alpha. Using D it is shown that: (i) the radiosensitivity of human fibroblasts in exponential growth phase does not significantly differ from that of plateau-phase fibroblasts with immediate plating; (ii) the radiosensitivity of plateau-phase cells with delayed plating is correlated to the radiosensitivity of cells with immediate plating: the more radioresistant the cell strain in exponential growth phase, the higher its repair capacity; (iii) the repair capacity of the cell strains is related to their genetic origin. In conclusion, we suggest that the survival curve of growing cells depends on the repair capacity of the cells.

  2. The rpoE gene of Escherichia coli, which encodes sigma E, is essential for bacterial growth at high temperature.

    PubMed Central

    Hiratsu, K; Amemura, M; Nashimoto, H; Shinagawa, H; Makino, K

    1995-01-01

    In vitro transcription analysis has shown that only RNA polymerase containing an alternative sigma subunit, sigma E, activates transcription from one of the rpoH promoters and the htrA promoter. The location of the rpoE gene encoding sigma E on the Escherichia coli chromosome has recently been established, but no rpoE mutant has yet become available for phenotypic testing. We cloned the rpoE gene from the lambda-ordered clones of the E. coli genome and confirmed that the reconstituted RNA polymerase containing the gene product (E sigma E) can transcribe htrA in vitro. We constructed an rpoE-defective strain by gene disruption using the cloned rpoE gene. We demonstrate that expression of htrA is completely dependent on the rpoE gene in vivo and that the rpoE gene is essential for bacterial growth at high temperature. PMID:7751307

  3. In vitro mechanism of inhibition of bacterial cell growth by allicin.

    PubMed Central

    Feldberg, R S; Chang, S C; Kotik, A N; Nadler, M; Neuwirth, Z; Sundstrom, D C; Thompson, N H

    1988-01-01

    Diallyl thiosulfinate (allicin) is the agent found in garlic which is responsible for the antibacterial and antifungal activity of extracts of this plant. The effect of bacteriostatic concentrations of allicin (0.2 to 0.5 mM) on the growth of Salmonella typhimurium revealed a pattern of inhibition characterized by: (i) a lag of approximately 15 min between addition of allicin and onset of inhibition, (ii) a transitory inhibition phase whose duration was proportional to allicin concentration and inversely proportional to culture density, (iii) a resumed growth phase which showed a lower rate of growth than in uninhibited controls, and (iv) an entry into stationary phase at a lower culture density. Whereas DNA and protein syntheses showed a delayed and partial inhibition by allicin, inhibition of RNA synthesis was immediate and total, suggesting that this is the primary target of allicin action. PMID:2469386

  4. Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor

    NASA Technical Reports Server (NTRS)

    Myers, Charles R.; Nealson, Kenneth H.

    1988-01-01

    Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

  5. Simultaneous determination and stability studies of linezolid, meropenem and vancomycin in bacterial growth medium by high-performance liquid chromatography.

    PubMed

    Wicha, Sebastian G; Kloft, Charlotte

    2016-08-15

    For pharmacokinetic/pharmacodynamic (PK/PD) assessment of antibiotics combinations in in vitro infection models, accurate and precise quantification of drug concentrations in bacterial growth medium is crucial for derivation of valid PK/PD relationships. We aimed to (i) develop a high-performance liquid chromatography (HPLC) assay to simultaneously quantify linezolid (LZD), vancomycin (VAN) and meropenem (MER), as typical components of broad-spectrum antibiotic combination therapy, in bacterial growth medium cation-adjusted Mueller-Hinton broth (CaMHB) and (ii) determine the stability profiles of LZD, VAN and MER under conditions in in vitro infection models. To separate sample matrix components, the final method comprised the pretreatment of 100μL sample with 400μL methanol, the evaporation of supernatant and its reconstitution in water. A low sample volume of 2μL processed sample was injected onto an Accucore C-18 column (2.6μm, 100×2.1mm) coupled to a Dionex Ultimate 3000 HPLC+ system. UV detection at 251, 240 and 302nm allowed quantification limits of 0.5, 2 and 0.5μg/mL for LZD, VAN and MER, respectively. The assay was successfully validated according to the relevant EMA guideline. The rapid method (14min) was successfully applied to quantify significant degradation of LZD, VAN and MER in in vitro infection models: LZD was stable, VAN degraded to 90.6% and MER to 62.9% within 24h compared to t=0 in CaMHB at 37°C, which should be considered when deriving PK/PD relationships in in vitro infection models. Inclusion of further antibiotics into the flexible gradient-based HPLC assay seems promising. PMID:27414982

  6. Selenium hyperaccumulators harbor a diverse endophytic bacterial community characterized by high selenium resistance and plant growth promoting properties

    PubMed Central

    Sura-de Jong, Martina; Reynolds, Ray J. B.; Richterova, Klara; Musilova, Lucie; Staicu, Lucian C.; Chocholata, Iva; Cappa, Jennifer J.; Taghavi, Safiyh; van der Lelie, Daniel; Frantik, Tomas; Dolinova, Iva; Strejcek, Michal; Cochran, Alyssa T.; Lovecka, Petra; Pilon-Smits, Elizabeth A. H.

    2015-01-01

    Selenium (Se)-rich plants may be used to provide dietary Se to humans and livestock, and also to clean up Se-polluted soils or waters. This study focused on endophytic bacteria of plants that hyperaccumulate selenium (Se) to 0.5–1% of dry weight. Terminal restriction fragment length polymorphism (T-RFLP) analysis was used to compare the diversity of endophytic bacteria of hyperaccumulators Stanleya pinnata (Brassicaceae) and Astragalus bisulcatus (Fabaceae) with those from related non-accumulators Physaria bellii (Brassicaceae) and Medicago sativa (Fabaceae) collected on the same, seleniferous site. Hyperaccumulators and non-accumulators showed equal T-RF diversity. Parsimony analysis showed that T-RFs from individuals of the same species were more similar to each other than to those from other species, regardless of plant Se content or spatial proximity. Cultivable endophytes from hyperaccumulators S. pinnata and A. bisulcatus were further identified and characterized. The 66 bacterial morphotypes were shown by MS MALDI-TOF Biotyper analysis and 16S rRNA gene sequencing to include strains of Bacillus, Pseudomonas, Pantoea, Staphylococcus, Paenibacillus, Advenella, Arthrobacter, and Variovorax. Most isolates were highly resistant to selenate and selenite (up to 200 mM) and all could reduce selenite to red elemental Se, reduce nitrite and produce siderophores. Seven isolates were selected for plant inoculation and found to have plant growth promoting properties, both in pure culture and when co-cultivated with crop species Brassica juncea (Brassicaceae) or M. sativa. There were no effects on plant Se accumulation. We conclude that Se hyperaccumulators harbor an endophytic bacterial community in their natural seleniferous habitat that is equally diverse to that of comparable non-accumulators. The hyperaccumulator endophytes are characterized by high Se resistance, capacity to produce elemental Se and plant growth promoting properties. PMID:25784919

  7. Inhibition of bacterial growth in sweet cheese whey by carbon dioxide as determined by culture-independent community profiling.

    PubMed

    Lo, Raquel; Xue, Tian; Weeks, Mike; Turner, Mark S; Bansal, Nidhi

    2016-01-18

    Whey is a valuable co-product from cheese making that serves as a raw material for a wide range of products. Its rich nutritional content lends itself to rapid spoilage, thus it typically needs to be pasteurised and refrigerated promptly. Despite the extensive literature on milk spoilage bacteria, little is known about the spoilage bacteria of whey. The utility of carbon dioxide (CO2) to extend the shelf-life of raw milk and cottage cheese has been well established, but its application in whey preservation has not yet been explored. This study aims to characterise the microbial populations of fresh and spoiled sweet whey by culture-independent community profiling using 454 pyrosequencing of 16S rRNA gene amplicons and to determine whether carbonation is effective in inhibiting bacterial growth in sweet whey. The microbiota of raw Cheddar and Mozzarella whey was dominated by cheese starter bacteria. After pasteurisation, two out of the three samples studied became dominated by diverse environmental bacteria from various phyla, with Proteobacteria being the most dominant. Diverse microbial profiles were maintained until spoilage occurred, when the entire population was dominated by just one or two genera. Whey spoilage bacteria were found to be similar to those of milk. Pasteurised Cheddar and Mozzarella whey was spoiled by Bacillus sp. or Pseudomonas sp., and raw Mozzarella whey was spoiled by Pseudomonas sp., Serratia sp., and other members of the Enterobacteriaceae family. CO2 was effective in inhibiting bacterial growth of pasteurised Cheddar and Mozzarella whey stored at 15°C and raw Mozzarella whey stored at 4°C. The spoilage bacteria of the carbonated samples were similar to those of the non-carbonated controls. PMID:26476573

  8. Selenium hyperaccumulators harbor a diverse endophytic bacterial community characterized by high selenium resistance and plant growth promoting properties.

    PubMed

    Sura-de Jong, Martina; Reynolds, Ray J B; Richterova, Klara; Musilova, Lucie; Staicu, Lucian C; Chocholata, Iva; Cappa, Jennifer J; Taghavi, Safiyh; van der Lelie, Daniel; Frantik, Tomas; Dolinova, Iva; Strejcek, Michal; Cochran, Alyssa T; Lovecka, Petra; Pilon-Smits, Elizabeth A H

    2015-01-01

    Selenium (Se)-rich plants may be used to provide dietary Se to humans and livestock, and also to clean up Se-polluted soils or waters. This study focused on endophytic bacteria of plants that hyperaccumulate selenium (Se) to 0.5-1% of dry weight. Terminal restriction fragment length polymorphism (T-RFLP) analysis was used to compare the diversity of endophytic bacteria of hyperaccumulators Stanleya pinnata (Brassicaceae) and Astragalus bisulcatus (Fabaceae) with those from related non-accumulators Physaria bellii (Brassicaceae) and Medicago sativa (Fabaceae) collected on the same, seleniferous site. Hyperaccumulators and non-accumulators showed equal T-RF diversity. Parsimony analysis showed that T-RFs from individuals of the same species were more similar to each other than to those from other species, regardless of plant Se content or spatial proximity. Cultivable endophytes from hyperaccumulators S. pinnata and A. bisulcatus were further identified and characterized. The 66 bacterial morphotypes were shown by MS MALDI-TOF Biotyper analysis and 16S rRNA gene sequencing to include strains of Bacillus, Pseudomonas, Pantoea, Staphylococcus, Paenibacillus, Advenella, Arthrobacter, and Variovorax. Most isolates were highly resistant to selenate and selenite (up to 200 mM) and all could reduce selenite to red elemental Se, reduce nitrite and produce siderophores. Seven isolates were selected for plant inoculation and found to have plant growth promoting properties, both in pure culture and when co-cultivated with crop species Brassica juncea (Brassicaceae) or M. sativa. There were no effects on plant Se accumulation. We conclude that Se hyperaccumulators harbor an endophytic bacterial community in their natural seleniferous habitat that is equally diverse to that of comparable non-accumulators. The hyperaccumulator endophytes are characterized by high Se resistance, capacity to produce elemental Se and plant growth promoting properties. PMID:25784919

  9. Modeling Change in Effort across a Low-Stakes Testing Session: A Latent Growth Curve Modeling Approach

    ERIC Educational Resources Information Center

    Barry, Carol L.; Finney, Sara J.

    2016-01-01

    We examined change in test-taking effort over the course of a three-hour, five test, low-stakes testing session. Latent growth modeling results indicated that change in test-taking effort was well-represented by a piecewise growth form, wherein effort increased from test 1 to test 4 and then decreased from test 4 to test 5. There was significant…

  10. Body size change in various nematodes depending on bacterial food, sex and growth temperature.

    PubMed

    So, Shuhei; Garan, Yohei; Miyahara, Kohji; Ohshima, Yasumi

    2012-04-01

    We previously reported significant body size change in the nematode Caenorhabditis elegans, depending on the food strain of E. coli. Here, we examined this body size change in 11 other nematode species as well, and found that it is common to most of these nematodes. Furthermore, this food-dependent body size change is influenced by sex and growth temperature. PMID:24058830

  11. Body size change in various nematodes depending on bacterial food, sex and growth temperature

    PubMed Central

    So, Shuhei; Garan, Yohei; Miyahara, Kohji; Ohshima, Yasumi

    2012-01-01

    We previously reported significant body size change in the nematode Caenorhabditis elegans, depending on the food strain of E. coli. Here, we examined this body size change in 11 other nematode species as well, and found that it is common to most of these nematodes. Furthermore, this food-dependent body size change is influenced by sex and growth temperature. PMID:24058830

  12. Consideration of probability of bacterial growth for Jovian planets and their satellites

    NASA Technical Reports Server (NTRS)

    Taylor, D. M.; Berkman, R. M.; Divine, N.

    1975-01-01

    Environmental parameters affecting growth of bacteria (e.g., moisture, temperature, pH, and chemical composition) were compared with current atmospheric models for Jupiter and Saturn, and with the available physical data for their satellites. Different zones of relative probability of growth were identified for Jupiter and Saturn, with the highest in pressure regions of 1-10 million N/sq m (10 to 100 atmospheres) and 3-30 million N/sq m (30 to 300 atmospheres), respectively. Of the more than two dozen satellites, only the largest (Io, Europa, Ganymede, Callisto, and Titan) were found to be interesting biologically. Titan's atmosphere may produce a substantial greenhouse effect providing increased surface temperatures. Models predicting a dense atmosphere are compatible with microbial growth for a range of pressures at Titan's surface. For Titan's surface the probability of growth would be enhanced if (1) the surface is entirely or partially liquid (water), (2) volcanism (in an ice-water-steam system) is present, or (3) access to internal heat sources is significant.

  13. Induction of Purple Sulfur Bacterial Growth in Dairy Wastewater Lagoons by Circulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: To determine if circulation of diary wastewater induces the growth of phototrophic purple sulfur bacteria (PSB). Methods and Results: Two dairy wastewater lagoons that were similar in size, geographic location, number and type of cattle loading the lagoons were chosen. The only obvious diffe...

  14. Growth rates made easy.

    PubMed

    Hall, Barry G; Acar, Hande; Nandipati, Anna; Barlow, Miriam

    2014-01-01

    In the 1960s-1980s, determination of bacterial growth rates was an important tool in microbial genetics, biochemistry, molecular biology, and microbial physiology. The exciting technical developments of the 1990s and the 2000s eclipsed that tool; as a result, many investigators today lack experience with growth rate measurements. Recently, investigators in a number of areas have started to use measurements of bacterial growth rates for a variety of purposes. Those measurements have been greatly facilitated by the availability of microwell plate readers that permit the simultaneous measurements on up to 384 different cultures. Only the exponential (logarithmic) portions of the resulting growth curves are useful for determining growth rates, and manual determination of that portion and calculation of growth rates can be tedious for high-throughput purposes. Here, we introduce the program GrowthRates that uses plate reader output files to automatically determine the exponential portion of the curve and to automatically calculate the growth rate, the maximum culture density, and the duration of the growth lag phase. GrowthRates is freely available for Macintosh, Windows, and Linux. We discuss the effects of culture volume, the classical bacterial growth curve, and the differences between determinations in rich media and minimal (mineral salts) media. This protocol covers calibration of the plate reader, growth of culture inocula for both rich and minimal media, and experimental setup. As a guide to reliability, we report typical day-to-day variation in growth rates and variation within experiments with respect to position of wells within the plates. PMID:24170494

  15. Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

    USGS Publications Warehouse

    Schwarz, L.K.; Runge, M.C.

    2009-01-01

    Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

  16. The effects of a hydrocolloid dressing on bacterial growth and the healing process of leg ulcers.

    PubMed

    Annoni, F; Rosina, M; Chiurazzi, D; Ceva, M

    1989-01-01

    Thirty patients with lower extremity ulcers of different aetiologies, although mainly of venous origin, were treated with an occlusive hydrocolloid dressing twice a week for a maximum period of 12 weeks. No antibacterial chemotherapy was utilized. A culture was taken of the exudate of the ulcer before commencement of treatment and weekly or bi-weekly thereafter. The results showed a mixed flora with prevalence of Staphylococcus aureus. The average duration of the treatment period was 67 +/- 11 days with a total of 26 patients being healed by the end of this period. The average interval between dressing changes was 4.1 days. Subsequent bacterial cultures showed a persistence of the original flora, but there was no correlation between the type of flora present and clinical evidence of infection or between the type of flora present and the rate of healing of the ulcer. Clinical evaluation of the results obtained with the hydrocolloid dressing was favourable in respect to reduced risk of contamination of the ulcer, lower pain perception and less trauma to the granulation tissue during dressing changes. PMID:2634718

  17. Evaluation and simplification of the assimilable organic carbon nutrient bioassay for bacterial growth in drinking water.

    PubMed

    Kaplan, L A; Bott, T L; Reasoner, D J

    1993-05-01

    A modified assimilable organic carbon (AOC) bioassay is proposed. We evaluated all aspects of the AOC bioassay technique, including inoculum, incubation water, bioassay vessel, and enumeration technique. Other concerns included eliminating the need to prepare organic carbon-free glassware and minimizing the risks of bacterial and organic carbon contamination. Borosilicate vials (40 ml) with Teflon-lined silicone septa are acceptable incubation vessels. Precleaned vials are commercially available, and the inoculum can be injected directly through the septa. Both bioassay organisms, Pseudomonas fluorescens P-17 and Spirillum sp. strain NOX, are available from the American Type Culture Collection and grow well on R2A agar, making this a convenient plating medium. Turbid raw waters need to be filtered prior to an AOC analysis. Glass fiber filters used with either a peristaltic pump or a syringe-type filter holder are recommended for this purpose. A sampling design that emphasizes replication of the highest experimental level, individual batch cultures, is the most efficacious way to reduce the total variance associated with the AOC bioassay. Quality control for the AOC bioassay includes an AOC blank and checks for organic carbon limitation and inhibition of the bioassay organisms. PMID:8517748

  18. Conserved rates and patterns of transcription errors across bacterial growth states and lifestyles.

    PubMed

    Traverse, Charles C; Ochman, Howard

    2016-03-22

    Errors that occur during transcription have received much less attention than the mutations that occur in DNA because transcription errors are not heritable and usually result in a very limited number of altered proteins. However, transcription error rates are typically several orders of magnitude higher than the mutation rate. Also, individual transcripts can be translated multiple times, so a single error can have substantial effects on the pool of proteins. Transcription errors can also contribute to cellular noise, thereby influencing cell survival under stressful conditions, such as starvation or antibiotic stress. Implementing a method that captures transcription errors genome-wide, we measured the rates and spectra of transcription errors in Escherichia coli and in endosymbionts for which mutation and/or substitution rates are greatly elevated over those of E. coli Under all tested conditions, across all species, and even for different categories of RNA sequences (mRNA and rRNAs), there were no significant differences in rates of transcription errors, which ranged from 2.3 × 10(-5) per nucleotide in mRNA of the endosymbiont Buchnera aphidicola to 5.2 × 10(-5) per nucleotide in rRNA of the endosymbiont Carsonella ruddii The similarity of transcription error rates in these bacterial endosymbionts to that in E. coli (4.63 × 10(-5) per nucleotide) is all the more surprising given that genomic erosion has resulted in the loss of transcription fidelity factors in both Buchnera and Carsonella. PMID:26884158

  19. Bacterial cellulose as a support for the growth of retinal pigment epithelium.

    PubMed

    Gonçalves, Sara; Padrão, Jorge; Rodrigues, Inês Patrício; Silva, João Pedro; Sencadas, Vítor; Lanceros-Mendez, Senentxu; Girão, Henrique; Dourado, Fernando; Rodrigues, Lígia R

    2015-04-13

    The feasibility of bacterial cellulose (BC) as a novel substrate for retinal pigment epithelium (RPE) culture was evaluated. Thin (41.6 ± 2.2 μm of average thickness) and heat-dried BC substrates were surface-modified via acetylation and polysaccharide adsorption, using chitosan and carboxymethyl cellulose. All substrates were characterized according to their surface chemistry, wettability, energy, topography, and also regarding their permeability, dimensional stability, mechanical properties, and endotoxin content. Then, their ability to promote RPE cell adhesion and proliferation in vitro was assessed. All surface-modified BC substrates presented similar permeation coefficients with solutes of up to 300 kDa. Acetylation of BC decreased it's swelling and the amount of endotoxins. Surface modification of BC greatly enhanced the adhesion and proliferation of RPE cells. All samples showed similar stress-strain behavior; BC and acetylated BC showed the highest elastic modulus, but the latter exhibited a slightly smaller tensile strength and elongation at break as compared to pristine BC. Although similar proliferation rates were observed among the modified substrates, the acetylated ones showed higher initial cell adhesion. This difference may be mainly due to the moderately hydrophilic surface obtained after acetylation. PMID:25748276

  20. Oxa, Thia, Heterocycle, and Carborane Analogues of SQ109: Bacterial and Protozoal Cell Growth Inhibitors

    PubMed Central

    Li, Kai; Wang, Yang; Yang, Gyongseon; Byun, Sooyoung; Rao, Guodong; Shoen, Carolyn; Yang, Hongliang; Gulati, Anmol; Crick, Dean C.; Cynamon, Michael; Huang, Guozhong; Docampo, Roberto; No, Joo Hwan; Oldfield, Eric

    2015-01-01

    We synthesized a library of 48 analogs of the Mycobacterium tuberculosis cell growth inhibitor SQ109 in which the ethylene diamine linker was replaced by oxa-, thia- or heterocyclic species, and in some cases, the adamantyl group was replaced by a 1,2-carborane or the N-geranyl group by another hydrophobic species. Compounds were tested against Mycobacterium tuberculosis (H37Rv and/or Erdman), Mycobacterium smegmatis, Bacillus subtilis, Escherichia coli, Saccharomyces cerevisiae, Trypanosoma brucei and two human cell lines (human embryonic kidney, HEK293T, and the hepatocellular carcinoma, HepG2). Most potent activity was found against T. brucei, the causative agent of human African trypanosomiasis, and involved targeting of the mitochondrial membrane potential with 15 SQ109 analogs being more active than was SQ109 in cell growth inhibition, having IC50 values as low as 12 nM (5.5 ng/mL) and a selectivity index of ~300. PMID:26258172

  1. Plant growth promotion by inoculation with selected bacterial strains versus mineral soil supplements.

    PubMed

    Wernitznig, S; Adlassnig, W; Sprocati, A R; Turnau, K; Neagoe, A; Alisi, C; Sassmann, S; Nicoara, A; Pinto, V; Cremisini, C; Lichtscheidl, I

    2014-01-01

    In the process of remediation of mine sites, the establishment of a vegetation cover is one of the most important tasks. This study tests two different approaches to manipulate soil properties in order to facilitate plant growth. Mine waste from Ingurtosu, Sardinia, Italy rich in silt, clay, and heavy metals like Cd, Cu, and Zn was used in a series of greenhouse experiments. Bacteria with putative beneficial properties for plant growth were isolated from this substrate, propagated and consortia of ten strains were used to inoculate the substrate. Alternatively, sand and volcanic clay were added. On these treated and untreated soils, seeds of Helianthus annuus, of the native Euphorbia pithyusa, and of the grasses Agrostis capillaris, Deschampsia flexuosa and Festuca rubra were germinated, and the growth of the seedlings was monitored. The added bacteria established well under all experimental conditions and reduced the extractability of most metals. In association with H. annuus, E. pithyusa and D. flexuosa bacteria improved microbial activity and functional diversity of the original soil. Their effect on plant growth, however, was ambiguous and usually negative. The addition of sand and volcanic clay, on the other hand, had a positive effect on all plant species except E. pithyusa. Especially the grasses experienced a significant benefit. The effects of a double treatment with both bacteria and sand and volcanic clay were rather negative. It is concluded that the addition of mechanical support has great potential to boost revegetation of mining sites though it is comparatively expensive. The possibilities offered by the inoculation of bacteria, on the other hand, appear rather limited. PMID:23990253

  2. Measurement of bacterial growth rates in subsurface sediments using the incorporation of tritiated thymidine into DNA.

    PubMed

    Thorn, P M; Ventullo, R M

    1988-07-01

    Microbial growth rates in subsurface sediment from three sites were measured using incorporation of tritiated thymidine into DNA. Sampling sites included Lula, Oklahoma, Traverse City, Michigan, and Summit Lake, Wisconsin. Application of the thymidine method to subsurface sediments required (1) thymidine concentrations greater than 125 nM, (2) incubation periods of less than 4 hours, (3) addition of SDS and EDTA for optimum macromolecular extraction, and (4) DNA purification, in order to accurately measure the rate of thymidine incorporation into DNA. Macromolecule extraction recoveries, as well as the percentage of tritium label incorporated into the DNA fraction, were variable and largely dependent upon sediment composition. In general, sandy sediments yielded higher extraction recoveries and demonstrated a larger percentage of label incorporated into DNA than sediments that contained a high silt-clay component. Reported results also indicate that the acid-base hydrolysis procedure routinely used for macromolecular fractionation in water samples may not be routinely applicable to the modified sediment procedure where addition of SDS and EDTA are required for macromolecule extraction. Growth rates exhibited by subsurface communities are relatively slow, ranging from 5.1 to 10.2×10(5) cells g(-1) day(-1). These rates are 2-1,000-fold lower than growth rates measured in surface sediments. These data lend support to the supposition that subsurface microbial communities are nutritionally stressed. PMID:24201529

  3. Toxicity of four spill-treating agents on bacterial growth and sea urchin embryogenesis.

    PubMed

    Rial, Diego; Murado, Miguel A; Beiras, Ricardo; Vázquez, José A

    2014-06-01

    The toxicity of spill-treating agents (STAs) is a topic that needs to be assessed prior to their potential application in environmental disasters. The aim of the present work was to study the effects of four commercial STAs (CytoSol, Finasol OSR 51, Agma OSD 569 and OD4000) on the growth of marine (Phaeobacter sp., Pseudomonas sp.) and terrestrial (Leuconostoc mesenteroides) bacteria, and sea urchin (Paracentrotus lividus) embryolarval development. In general, STA did not inhibit significantly the biomass production of the tested marine bacteria. Finasol OSR 51 and OD4000 clearly inhibited the growth of L. mesenteroides and an accurate description of the kinetics was provided by a proposed bivariate equation. For this species, a global parameter (EC50,τ) was defined to summarize the set of growth kinetics. Using this parameter Finasol OSR 51 was found to be less toxic (754μL L(-1)) than OD4000 (129μL L(-1)). For the sea urchin embryo assay, the ranking of toxicity as EC50 (μL L(-1)) was Agma OSD 569 (34.0)

  4. Bacterial Metabolism in the Host Environment: Pathogen Growth and Nutrient Assimilation in the Mammalian Upper Respiratory Tract.

    PubMed

    Armstrong, Sandra K

    2015-06-01

    Pathogens evolve in specific host niches and microenvironments that provide the physical and nutritional requirements conducive to their growth. In addition to using the host as a source of food, bacterial pathogens must avoid the immune response to their presence. The mammalian upper respiratory tract is a site that is exposed to the external environment, and is readily colonized by bacteria that live as resident flora or as pathogens. These bacteria can remain localized, descend to the lower respiratory tract, or traverse the epithelium to disseminate throughout the body. By virtue of their successful colonization of the respiratory epithelium, these bacteria obtain the nutrients needed for growth, either directly from host resources or from other microbes. This chapter describes the upper respiratory tract environment, including its tissue and mucosal structure, prokaryotic biota, and biochemical composition that would support microbial life. Neisseria meningitidis and the Bordetella species are discussed as examples of bacteria that have no known external reservoirs but have evolved to obligately colonize the mammalian upper respiratory tract. PMID:26185081

  5. Evolution of cooperation in microbial biofilms - A stochastic model for the growth and survival of bacterial mats

    NASA Astrophysics Data System (ADS)

    Knebel, Johannes; Cremer, Jonas; Melbinger, Anna; Frey, Erwin

    2012-02-01

    Cooperative behavior is essential for microbial biofilms. The structure and composition of a biofilm change over time and thereby influence the evolution of cooperation within the system. In turn, the level of cooperation affects the growth dynamics of the biofilm. Here, we investigate this coupling for an experimentally well-defined situation in which mutants of the Pseudomonas fluorescens strain form a mat at the liquid-air interface by the production of an extra-cellular matrix [1]. We model the occurrence of cooperation in this bacterial population by taking into account the formation of the mat. The presence of cooperators enhances the growth of the mat, but at the same time cheaters can infiltrate the population and put the viability of the mat at risk. We find that the survival time of the mat crucially depends on its initial dynamics which is subject to demographic fluctuations [2]. More generally, our work provides conceptual insights into the requirements and mechanisms for the evolution of cooperation.[1] P. Rainey et al., Nature 425, 72 (2003).[2] A. Melbinger et al., PRL 105, 178101 (2010).

  6. An Ancient Bacterial Signaling Pathway Regulates Chloroplast Function to Influence Growth and Development in Arabidopsis[OPEN

    PubMed Central

    Sugliani, Matteo; Ke, Hang; Bouveret, Emmanuelle; Robaglia, Christophe; Caffarri, Stefano

    2016-01-01

    The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained elusive. Using the model plant Arabidopsis thaliana, we show that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We then go on to demonstrate that the antagonistic functions of different plant RelA SpoT homologs together modulate ppGpp levels to regulate chloroplast function and show that they are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Therefore, our results show that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development. PMID:26908759

  7. Career Education: An Application of Latent Growth Curve Modelling to Career Information-Seeking Behaviour of School Pupils

    ERIC Educational Resources Information Center

    Shevlin, Mark; Millar, Rob

    2006-01-01

    Background: This study applied the theory of planned behaviour (TPB) in an attempt to predict longitudinal growth of career exploratory behaviour in school pupils. The importance of information for making considered career decisions is indicated in theories of career development and choice, career education programmes, and concepts of career…

  8. A Growth Curve Analysis of Literacy Performance among Second-Grade, Spanish-Speaking, English-Language Learners

    ERIC Educational Resources Information Center

    Gutiierrez, Gabriel; Vanderwood, Mike L.

    2013-01-01

    The literacy growth of 260 second-grade English learners (ELs) with varying degrees of English language proficiency (e.g., Beginning, Early Intermediate, Intermediate, Early Advanced and Advanced English language proficiency) was assessed with English literacy skill assessments. Dynamic Indicators of Basic Early Literacy Skills measures were…

  9. Combination of therapeutic ultrasound with antibiotics interfere with the growth of bacterial culture that colonizes skin ulcers: An in-vitro study.

    PubMed

    Guirro, Elaine Caldeira de Oliveira; Angelis, Dejanira de Franceschi de; Sousa, Natanael Teixeira Alves de; Guirro, Rinaldo Roberto de Jesus

    2016-09-01

    Staphylococcus aureus and Escherichia coli are among the major bacterial species that colonize skin ulcers. Therapeutic ultrasound (TUS) produces biophysical effects that are relevant to wound healing; however, its application over a contaminated injury is not evidence-based. The objective of this research was to analyze the effect of TUS on in vitro-isolated S. aureus and E. coli, including the combination of ultrasound and antibiotics, in order to assess their antibiotic action on bacterial susceptibility. For the experiments, the bacterial strains were suspended in saline, then diluted (10(4)CFU/mL) for irradiation (at 1 and 3MHz, 0.5 and 0.8W/cm(2) for 0 and 15min) and the combination treatment of ultrasonication and antibiotics was administered by adding nalidixic acid (S. aureus) and tetracycline (E. coli) at concentrations equivalent to 50% of the minimum inhibitory concentration (MIC). The experiments were carried out in duplicate with six repetitions. The suspensions were inoculated on to Petri plates and incubated at 37°C and the colony forming units (CFUs) were counted after 24h. The results were subjected to the Shapiro-Wilk normality test, followed by parametric ANOVA and Tukey's post hoc test at a significance level of 1%. The results demonstrated that the action of TUS at 1MHz inhibited bacterial growth while at 3MHz, bacterial growth was observed in both species. However, the synergistic combination of ultrasound and antibiotics was able to inhibit the growth of both bacteria completely after 15min of ultrasonication. The results suggest that the action of ultrasound on S. aureus and E. coli are dependent on the oscillation frequency as well as the intensity and time of application. The combination of ultrasound with antibiotics was able to inhibit bacterial growth fully at all frequencies and doses in both species. PMID:27150772

  10. Effect of bacterial inoculation of strains of Pseudomonas aeruginosa, Alcaligenes feacalis and Bacillus subtilis on germination, growth and heavy metal (Cd, Cr, and Ni) uptake of Brassica juncea.

    PubMed

    Ndeddy Aka, Robinson Junior; Babalola, Olubukola Oluranti

    2016-01-01

    Bacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg(-1) of NiCl2, 100 mg kg(-1) of CdCl2, and 150 mg kg(-1) of K2Cr2O7, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction. PMID:26503637

  11. A New Method for Re-Analyzing Evaluation Bias: Piecewise Growth Curve Modeling Reveals an Asymmetry in the Evaluation of Pro and Con Arguments

    PubMed Central

    Jirschitzka, Jens; Kimmerle, Joachim; Cress, Ulrike

    2016-01-01

    In four studies we tested a new methodological approach to the investigation of evaluation bias. The usage of piecewise growth curve modeling allowed for investigation into the impact of people’s attitudes on their persuasiveness ratings of pro- and con-arguments, measured over the whole range of the arguments’ polarity from an extreme con to an extreme pro position. Moreover, this method provided the opportunity to test specific hypotheses about the course of the evaluation bias within certain polarity ranges. We conducted two field studies with users of an existing online information portal (Studies 1a and 2a) as participants, and two Internet laboratory studies with mostly student participants (Studies 1b and 2b). In each of these studies we presented pro- and con-arguments, either for the topic of MOOCs (massive open online courses, Studies 1a and 1b) or for the topic of M-learning (mobile learning, Studies 2a and 2b). Our results indicate that using piecewise growth curve models is more appropriate than simpler approaches. An important finding of our studies was an asymmetry of the evaluation bias toward pro- or con-arguments: the evaluation bias appeared over the whole polarity range of pro-arguments and increased with more and more extreme polarity. This clear-cut result pattern appeared only on the pro-argument side. For the con-arguments, in contrast, the evaluation bias did not feature such a systematic picture. PMID:26840219

  12. A New Method for Re-Analyzing Evaluation Bias: Piecewise Growth Curve Modeling Reveals an Asymmetry in the Evaluation of Pro and Con Arguments.

    PubMed

    Jirschitzka, Jens; Kimmerle, Joachim; Cress, Ulrike

    2016-01-01

    In four studies we tested a new methodological approach to the investigation of evaluation bias. The usage of piecewise growth curve modeling allowed for investigation into the impact of people's attitudes on their persuasiveness ratings of pro- and con-arguments, measured over the whole range of the arguments' polarity from an extreme con to an extreme pro position. Moreover, this method provided the opportunity to test specific hypotheses about the course of the evaluation bias within certain polarity ranges. We conducted two field studies with users of an existing online information portal (Studies 1a and 2a) as participants, and two Internet laboratory studies with mostly student participants (Studies 1b and 2b). In each of these studies we presented pro- and con-arguments, either for the topic of MOOCs (massive open online courses, Studies 1a and 1b) or for the topic of M-learning (mobile learning, Studies 2a and 2b). Our results indicate that using piecewise growth curve models is more appropriate than simpler approaches. An important finding of our studies was an asymmetry of the evaluation bias toward pro- or con-arguments: the evaluation bias appeared over the whole polarity range of pro-arguments and increased with more and more extreme polarity. This clear-cut result pattern appeared only on the pro-argument side. For the con-arguments, in contrast, the evaluation bias did not feature such a systematic picture. PMID:26840219

  13. Brief report: Examining children's disruptive behavior in the wake of trauma - A two-piece growth curve model before and after a school shooting.

    PubMed

    Liao, Yue; Shonkoff, Eleanor T; Barnett, Elizabeth; Wen, C K Fred; Miller, Kimberly A; Eddy, J Mark

    2015-10-01

    School shootings may have serious negative impacts on children years after the event. Previous research suggests that children exposed to traumatic events experience heightened fear, anxiety, and feelings of vulnerability, but little research has examined potential aggressive and disruptive behavioral reactions. Utilizing a longitudinal dataset in which a local school shooting occurred during the course of data collection, this study sought to investigate whether the trajectory of disruptive behaviors was affected by the shooting. A two-piece growth curve model was used to examine the trajectory of disruptive behaviors during the pre-shooting years (i.e., piece one) and post-shooting years (i.e., piece two). Results indicated that the two-piece growth curve model fit the data better than the one-piece model and that the school shooting precipitated a faster decline in aggressive behaviors. This study demonstrated a novel approach to examining effects of an unexpected traumatic event on behavioral trajectories using an existing longitudinal data set. PMID:26298676

  14. Analysis of the relationship between economic growth and industrial pollution in Zaozhuang, China-based on the hypothesis of the environmental Kuznets curve.

    PubMed

    Liu, Xiao-Hui; Wang, Wei-Liang; Lu, Shao-Yong; Wang, Yu-Fan; Ren, Zongming

    2016-08-01

    In Zaozhuang, economic development affects the discharge amount of industrial wastewater, chemical oxygen demand (COD), and ammonia nitrogen (NH3-N). To reveal the trend of water environmental quality related to the economy in Zaozhuang, this paper simulated the relationships between industrial wastewater discharge, COD, NH3-N load, and gross domestic product (GDP) per capita for Zaozhuang (2002-2012) using environmental Kuznets curve (EKC) models. The results showed that the added value of industrial GDP, the per capita GDP, and wastewater emission had average annual growth rates of 16.62, 16.19, and 17.89 %, respectively, from 2002 to 2012, while COD and NH3-N emission in 2012, compared with 2002, showed average annual decreases of 10.70 and 31.12 %, respectively. The export of EKC models revealed that industrial wastewater discharge had a typical inverted-U-shaped relationship with per capita GDP. However, both COD and NH3-N showed the binding curve of the left side of the "U" curve and left side U-shaped curve. The economy in Zaozhuang had been at the "fast-growing" stage, with low environmental pollution according to the industrial pollution level. In recent years, Zaozhuang has abated these heavy-pollution industries emphatically, so pollutants have been greatly reduced. Thus, Zaozhuang industrial wastewater treatment has been quite effective, with water quality improved significantly. The EKC models provided scientific evidence for estimating industrial wastewater discharge, COD, and NH3-N load as well as their changeable trends for Zaozhuang from an economic perspective. PMID:27155838

  15. Valorization of lubricant-based wastewater for bacterial neutral lipids production: Growth-linked biosynthesis.

    PubMed

    Da Silva, Pedro D M P; Lima, Filipa; Alves, Maria Madalena; Bijmans, Martijn F M; Pereira, Maria Alcina

    2016-09-15

    Lipids produced by microorganisms are currently of great interest as raw material for either biofuels or oleochemicals production. Significant biosynthesis of neutral lipids, such as triacylglycerol (TAG) and wax esters (WE) are thought to be limited to a few strains. Hydrocarbonoclastic bacteria (HCB), key players in bioremediation of hydrocarbon contaminated ecosystems, are among this group of strains. Hydrocarbon rich wastewaters have been overlooked concerning their potential as raw material for microbial lipids production. In this study, lubricant-based wastewater was fed, as sole carbon source, to two HCB representative wild strains: Alcanivorax borkumensis SK2, and Rhodococcus opacus PD630. Neutral lipid production was observed with both strains cultivated under uncontrolled conditions of pH and dissolved oxygen. A. borkumensis SK2 was further investigated in a pH- and OD-controlled fermenter. Different phases were assessed separately in terms of lipids production and alkanes removal. The maximum TAG production rate occurred during stationary phase (4 mg-TAG/L h). The maximum production rate of WE-like compounds was 15 mg/L h, and was observed during exponential growth phase. Hydrocarbons removal was 97% of the gas chromatography (GC) resolved straight-chain alkanes. The maximum removal rate was observed during exponential growth phase (6 mg-alkanes/L h). This investigation proposes a novel approach for the management of lubricant waste oil, aiming at its conversion into valuable lipids. The feasibility of the concept is demonstrated under low salt (0.3%) and saline (3.3%) conditions, and presents clues for its technological development, since growth associated oil production opens the possibility for establishing continuous fermentation processes. PMID:27244293

  16. Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken.

    PubMed

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-08-01

    Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2 S producing bacteria were characterized based on maximum growth rates (μmax ), maximal microbial concentration (Nmax ) and at the moment of microbial shelf life (Svalues ), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax . The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C2 ) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2 ) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C2 as rapid evaluation for poultry quality testing using SPME-GC-MS. PMID:27332555

  17. Inhibitors of bacterial growth in urine: what is the role of betaines?

    PubMed

    Chambers, S T; Peddie, B A; Randall, K; Lever, M

    1999-05-01

    It has long been recognised that some individuals produce urine that is inhibitory to uropathogens. This may be partly explained by inhibitors. Several inhibitors have been identified in urine including urea and organic acids. Bacteria adapt to high osmolarity by activating osmoregulated betaine porters and accumulating organic osmolytes intracellularly. The preferred substrate is glycine betaine, which is present in urine, and promotes rapid growth by balancing osmotic forces and stabilising macromolecular structures against the toxicity of urea and low pH. Other dietary betaines such as trigonelline may also be taken but enhance urea toxicity. The importance of such compounds in vivo is unknown. PMID:10394986

  18. Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions

    PubMed Central

    Griebeler, Eva Maria; Klein, Nicole; Sander, P. Martin

    2013-01-01

    Information on aging, maturation, and growth is important for understanding life histories of organisms. In extinct dinosaurs, such information can be derived from the histological growth record preserved in the mid-shaft cortex of long bones. Here, we construct growth models to estimate ages at death, ages at sexual maturity, ages at which individuals were fully-grown, and maximum growth rates from the growth record preserved in long bones of six sauropod dinosaur individuals (one indeterminate mamenchisaurid, two Apatosaurus sp., two indeterminate diplodocids, and one Camarasaurus sp.) and one basal sauropodomorph dinosaur individual (Plateosaurus engelhardti). Using these estimates, we establish allometries between body mass and each of these traits and compare these to extant taxa. Growth models considered for each dinosaur individual were the von Bertalanffy model, the Gompertz model, and the logistic model (LGM), all of which have inherently fixed inflection points, and the Chapman-Richards model in which the point is not fixed. We use the arithmetic mean of the age at the inflection point and of the age at which 90% of asymptotic mass is reached to assess respectively the age at sexual maturity or the age at onset of reproduction, because unambiguous indicators of maturity in Sauropodomorpha are lacking. According to an AIC-based model selection process, the LGM was the best model for our sauropodomorph sample. Allometries established are consistent with literature data on other Sauropodomorpha. All Sauropodomorpha reached full size within a time span similar to scaled-up modern mammalian megaherbivores and had similar maximum growth rates to scaled-up modern megaherbivores and ratites, but growth rates of Sauropodomorpha were lower than of an average mammal. Sauropodomorph ages at death probably were lower than that of average scaled-up ratites and megaherbivores. Sauropodomorpha were older at maturation than scaled-up ratites and average mammals, but

  19. Autoinducer 2: A concentration-dependent signal for mutualistic bacterial biofilm growth

    USGS Publications Warehouse

    Rickard, A.H.; Palmer, R.J., Jr.; Blehert, D.S.; Campagna, S.R.; Semmelhack, M.F.; Egland, P.G.; Bassler, B.L.; Kolenbrander, P.E.

    2006-01-01

    4,5-dihydroxy-2,3-pentanedione (DPD), a product of the LuxS enzyme in the catabolism of S-ribosylhomocysteine, spontaneously cyclizes to form autoinducer 2 (AI-2). AI-2 is proposed to be a universal signal molecule mediating interspecies communication among bacteria. We show that mutualistic and abundant biofilm growth in flowing saliva of two human oral commensal bacteria, Actinomyces naeslundii T14V and Streptococcus oralis 34, is dependent upon production of AI-2 by S. oralis 34. A luxS mutant of S. oralis 34 was constructed which did not produce AI-2. Unlike wild-type dual-species biofilms, A. naeslundii T14V and an S. oralis 34 luxS mutant did not exhibit mutualism and generated only sparse biofilms which contained a 10-fold lower biomass of each species. Restoration of AI-2 levels by genetic or chemical (synthetic AI-2 in the form of DPD) complementation re-established the mutualistic growth and high biomass characteristic for the wild-type dual-species biofilm. Furthermore, an optimal concentration of DPD was determined, above and below which biofilm formation was suppressed. The optimal concentration was 100-fold lower than the detection limit of the currently accepted AI-2 assay. Thus, AI-2 acts as an interspecies signal and its concentration is critical for mutualism between two species of oral bacteria grown under conditions that are representative of the human oral cavity. ?? 2006 Blackwell Publishing Ltd.

  20. SutA is a bacterial transcription factor expressed during slow growth in Pseudomonas aeruginosa

    PubMed Central

    Babin, Brett M.; Bergkessel, Megan; Sweredoski, Michael J.; Moradian, Annie; Hess, Sonja; Newman, Dianne K.; Tirrell, David A.

    2016-01-01

    Microbial quiescence and slow growth are ubiquitous physiological states, but their study is complicated by low levels of metabolic activity. To address this issue, we used a time-selective proteome-labeling method [bioorthogonal noncanonical amino acid tagging (BONCAT)] to identify proteins synthesized preferentially, but at extremely low rates, under anaerobic survival conditions by the opportunistic pathogen Pseudomonas aeruginosa. One of these proteins is a transcriptional regulator that has no homology to any characterized protein domains and is posttranscriptionally up-regulated during survival and slow growth. This small, acidic protein associates with RNA polymerase, and chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing suggests that the protein associates with genomic DNA through this interaction. ChIP signal is found both in promoter regions and throughout the coding sequences of many genes and is particularly enriched at ribosomal protein genes and in the promoter regions of rRNA genes. Deletion of the gene encoding this protein affects expression of these and many other genes and impacts biofilm formation, secondary metabolite production, and fitness in fluctuating conditions. On the basis of these observations, we have designated the protein SutA (survival under transitions A). PMID:26787849

  1. Novel Bacterial and Archaeal Lineages from an In Situ Growth Chamber Deployed at a Mid-Atlantic Ridge Hydrothermal Vent

    PubMed Central

    Reysenbach, Anna-Louise; Longnecker, Krista; Kirshtein, Julie

    2000-01-01

    The phylogenetic diversity was determined for a microbial community obtained from an in situ growth chamber placed on a deep-sea hydrothermal vent on the Mid-Atlantic Ridge (23°22′ N, 44°57′ W). The chamber was deployed for 5 days, and the temperature within the chamber gradually decreased from 70 to 20°C. Upon retrieval of the chamber, the DNA was extracted and the small-subunit rRNA genes (16S rDNA) were amplified by PCR using primers specific for the Archaea or Bacteria domain and cloned. Unique rDNA sequences were identified by restriction fragment length polymorphisms, and 38 different archaeal and bacterial phylotypes were identified from the 85 clones screened. The majority of the archaeal sequences were affiliated with the Thermococcales (71%) and Archaeoglobales (22%) orders. A sequence belonging to the Thermoplasmales confirms that thermoacidophiles may have escaped enrichment culturing attempts of deep-sea hydrothermal vent samples. Additional sequences that represented deeply rooted lineages in the low-temperature eurarchaeal (marine group II) and crenarchaeal clades were obtained. The majority of the bacterial sequences obtained were restricted to the Aquificales (18%), the ɛ subclass of the Proteobacteria (ɛ-Proteobacteria) (40%), and the genus Desulfurobacterium (25%). Most of the clones (28%) were confined to a monophyletic clade within the ɛ-Proteobacteria with no known close relatives. The prevalence of clones related to thermophilic microbes that use hydrogen as an electron donor and sulfur compounds (S0, SO4, thiosulfate) indicates the importance of hydrogen oxidation and sulfur metabolism at deep-sea hydrothermal vents. The presence of sequences that are related to sequences from hyperthermophiles, moderate thermophiles, and mesophiles suggests that the diversity obtained from this analysis may reflect the microbial succession that occurred in response to the shift in temperature and possible associated changes in the chemistry of the

  2. Bacterial structure and characterization of plant growth promoting and oil degrading bacteria from the rhizospheres of mangrove plants.

    PubMed

    do Carmo, Flávia Lima; dos Santos, Henrique Fragoso; Martins, Edir Ferreira; van Elsas, Jan Dirk; Rosado, Alexandre Soares; Peixoto, Raquel Silva

    2011-08-01

    Most oil from oceanic spills converges on coastal ecosystems, such as mangrove forests, which are threatened with worldwide disappearance. Particular bacteria that inhabit the rhizosphere of local plant species can stimulate plant development through various mechanisms; it would be advantageous if these would also be capable of degrading oil. Such bacteria may be important in the preservation or recuperation of mangrove forests impacted by oil spills. This study aimed to compare the bacterial structure, isolate and evaluate bacteria able to degrade oil and stimulate plant growth, from the rhizospheres of three mangrove plant species. These features are particularly important taking into account recent policies for mangrove bioreme-diation, implying that oil degradation as well as plant maintenance and health are key targets. Fifty-seven morphotypes were isolated from the mangrove rhizospheres on Bushneil-Haas (BH) medium supplemented with oil as the sole carbon source and tested for plant growth promotion. Of this strains, 60% potentially fixed nitrogen, 16% showed antimicrobial activity, 84% produced siderophores, 51% had the capacity to solubilize phosphate, and 33% produced the indole acetic acid hormone. Using gas chromatography, we evaluated the oil-degrading potential of ten selected strains that had different morphologies and showed Plant Growth Promoting Rhizobacteria (PGPR) features. The ten tested strains showed a promising degradation profile for at least one compound present in the oil. Among degrader strains, 46% had promising PGPR potential, having at least three of the above capacities. These strains might be used as a consortium, allowing the concomitant degradation of oil and stimulation of mangrove plant survival and maintenance. PMID:21887634

  3. Growth curves and age-related changes in carcass characteristics, organs, serum parameters, and intestinal transporter gene expression in domestic pigeon (Columba livia).

    PubMed

    Gao, C Q; Yang, J X; Chen, M X; Yan, H C; Wang, X Q

    2016-04-01

    Two experiments were conducted to fit growth curves, and determine age-related changes in carcass characteristics, organs, serum biochemical parameters, and gene expression of intestinal nutrient transporters in domestic pigeon (Columba livia). In experiment 1, body weight (BW) of 30 pigeons was respectively determined at 1, 3, 7, 14, 21, 28, and 35 days old to fit growth curves and to describe the growth of pigeons. In experiment 2, eighty-four 1-day-old squabs were grouped by weight into 7 groups. On d 1, 3, 7, 14, 21, 28, and 35, twelve birds from each group were randomly selected for slaughter and post-slaughter analysis. The results showed that BW of pigeons increased rapidly from d 1 to d 28 (a 25.7-fold increase), and then had little change until d 35. The Logistic, Gompertz, and Von Bertalanffy functions can all be well fitted with the growth curve of domestic pigeons (R2>0.90) and the Gompertz model showed the highest R2value among the models (R2=0.9997). The equation of Gompertz model was Y=507.72×e-(3.76exp(-0.17t))(Y=BW of pigeon (g); t=time (day)). In addition, breast meat yield (%) increased with age throughout the experiment, whereas the leg meat yield (%) reached to the peak on d 14. Serum total protein, albumin, globulin, and glucose concentration were increased with age, whereas serum uric acid concentration was decreased (P<0.05). Furthermore, the gene expressions of nutrient transporters (y+LAT2, LAT1, B0AT1, PepT1, and NHE2) in jejunum of pigeon were increased with age. The results of correlation analysis showed the gene expressions of B0AT1, PepT1, and NHE2 had positive correlations with BW (0.73

  4. Synergistic effects of the Lactobacillus acidophilus surface layer and nisin on bacterial growth.

    PubMed

    Prado-Acosta, Mariano; Ruzal, Sandra M; Allievi, Mariana C; Palomino, María Mercedes; Sanchez Rivas, Carmen

    2010-02-01

    We have previously described a murein hydrolase activity for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356. Here we show that, in combination with nisin, this S-layer acts synergistically to inhibit the growth of pathogenic Gram-negative Salmonella enterica and potential pathogenic Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus. In addition, bacteriolytic effects were observed for the Gram-positive species tested. We postulate that the S-layer enhances the access of nisin into the cell membrane by enabling it to cross the cell wall, while nisin provides the sudden ion-nonspecific dissipation of the proton motive force required to enhance the S-layer murein hydrolase activity. PMID:19948852

  5. Product formation from thiophene by a mixed bacterial culture. Influence of benzene as growth substrate.

    PubMed

    Rivas, Isabelle M; Mosbaek, Hans; Arvin, Erik

    2003-07-01

    The influence of benzene as a growth substrate on the cometabolic conversion of thiophene was investigated in batch systems with microorganisms originating from an creosote contaminated site. Benzene was shown to stimulate the conversion of thiophene with a first-order rate, during the initial phase of transformation. The microorganisms were able to transform thiophene in the absence of benzene at a zero-order rate. Thiophene was converted to five oxidation products, regardless of the presence of benzene. Benzene had no influence on the distribution of these oxidation products. The main oxidation product, a thiophene sulphoxide dimer, represented 78+/-12% of the transformed thiophene, while the second most important product, also a thiophene sulphoxide dimer, represented 20+/-2% of the converted thiophene. PMID:12767308

  6. Arabidopsis growth and defense are modulated by bacterial quorum sensing molecules

    PubMed Central

    Schenk, Sebastian T.; Stein, Elke; Kogel, Karl-Heinz; Schikora, Adam

    2012-01-01

    N-acyl-homoserine lactones (AHLs) play an important role in the communication within the rhizosphere; they serve as a chemical base for interactions within and between different species of Gram-negative bacteria. Not only bacteria, also plants perceive and react to AHLs with diverse responses. Here we describe a negative correlation between the length of AHLs’ lipid chains and the observed growth promotion in Arabidopsis thaliana. Moreover, we speculate on a positive correlation between the reinforcement of defense mechanisms and the length of the lipid moieties. Observation presented here may be of great importance for understanding of the complex interplay between plants and their environment, as well as for agronomic applications. PMID:22307043

  7. Pressate from peat dewatering as a substrate for bacterial growth. [Rhizopus arrhizus; Xanthomonas campestris; Aureobasidium

    SciTech Connect

    Mulligan, C.N.; Cooper, D.G.

    1985-07-01

    This study considered the possibility of using water expressed during the drying of fuel-grade peat as a substrate for microbial growth. Highly humified peat pressed for 2.5 min at 1.96 MPa produced water with a chemical oxygen demand of 690 mg/liter. Several biological compounds could be produced by using the organic matter inexpressed peat water as a substrate. These included polymers such as chitosan, contained in the cell wall of Rhizopus arrhizus, and two extracellular polysaccharides, xanthan gum and pullulan, produced by Bacillus subtilis grown in the expressed water. Small additions of nutrients to the peat pressate were necessary to obtain substantial yields of products. The addition of peptone, yeast extract, and glucose improved production of the various compounds. Biological treatment improved the quality of the expressed water to the extent that in an industrial process it could be returned to the environment.

  8. Improved detection of bacterial growth in continuous ambulatory peritoneal dialysis effluent by use of BacT/Alert FAN bottles.

    PubMed Central

    Alfa, M J; Degagne, P; Olson, N; Harding, G K

    1997-01-01

    Culture-negative peritonitis is a major complication for patients on continuous ambulatory peritoneal dialysis (CAPD) and precludes organism-specific therapy. The aim of the present study was to compare inoculation of 10 ml of CAPD effluent into BacT/Alert blood culture bottles (FAN [fastidious antimicrobic neutralizing], BacTAlert aerobic [BTA], and BacT/Alert anaerobic [BTAn] bottles) to our conventional method of using 50 ml of concentrated CAPD effluent to inoculate peptone broth bottles (BD bottles) and MacConkey agar and blood agar medium (BA-MAC). The FAN, BTA, and BTAn bottles were monitored automatically in the BacT/Alert blood culture instrument. A total of 207 CAPD effluents were studied, and in 97 bacteria were detected by at least one method. Compared to BTA bottles (79 of 97; 81.4%), BTAn bottles (78 of 97; 80.4%), and BD bottles (88 of 97; 90.7%), the single best broth medium for detecting bacterial growth in CAPD effluents was the FAN bottle (90 of 97 effluents; 92.8%). A total of 125 bacterial species were detected by any method, and the majority (91.8%) of CAPD effluents were infected with a single species. A combination of FAN and BTAn bottles detected 111 of 125 (88.8%) of all organisms, whereas a combination of BD bottles and BA-MAC detected 107 of 125 (85.6%) of all organisms. One or more organisms that would have been completely missed by the conventional method with BD bottles and BA-MAC were detected in 18 CAPD effluents. Of these 18 CAPD effluents, 6 showed no growth by the conventional method with BD bottles and BA-MAC. On the basis of our data, the most sensitive and least labor intensive method was direct inoculation of 10 ml of CAPD effluent into a FAN bottle and a BTAn bottle, which could be automatically monitored by the BacT/Alert blood culture instrument. On the basis of case definitions for peritonitis, the sensitivities and specificities of the methods with FAN and BTAn bottles and with BD bottles and BA-MAC were 81.1 and 98

  9. Divergent selection for shape of growth curve in Japanese quail. 6. Hatching time, hatchability and embryo mortality.

    PubMed

    Hyánková, L; Starosta, F

    2012-01-01

    1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12 ± 1°C and 55% relative humidity) and incubation conditions (37.5 ± 0.2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28 d of age, respectively, and constant body weight at 49 d of age. 2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406 h after egg setting, respectively). 3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1 d storage: 96.0 vs. 82.5%; 5 d storage: 88.7 vs. 72.7%, respectively). 4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation. 5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation. PMID:23281752

  10. CdTe-TiO2 nanocomposite: an impeder of bacterial growth and biofilm

    NASA Astrophysics Data System (ADS)

    Gholap, Haribhau; Patil, Rajendra; Yadav, Prasad; Banpurkar, Arun; Ogale, Satishchandra; Gade, Wasudeo

    2013-05-01

    The resurgence of infectious diseases and associated issues related to antibiotic resistance has raised enormous challenges which may possibly be confronted primarily by nanotechnology routes. One key need of critical significance in this context is the development of an agent capable of inhibiting quorum sensing mediated biofilm formation in pathogenic organisms. In this work we examine the possible use of a nanocomposite, CdTe-TiO2, as an impeder of growth and biofilm. In the presence of CdTe-TiO2, scanning electron microscopy (SEM) analysis shows exposed cells without the surrounding matrix. Confocal laser scanning microscopy shows spatially distributed fluorescence, a typical indication of an impeded biofilm, as opposed to the control which shows matrix-covered cells and continuous fluorescence, typical of biofilm formation. Quantitatively, the inhibition of biofilm was ˜57%. CdTe-TiO2 also exhibits good antibacterial properties against Gram positive and Gram negative organisms by virtue of the generation of reactive oxygen species inside the cells, reflected by a ruptured appearance in the SEM analysis.

  11. Selenium nanoparticles incorporated into titania nanotubes inhibit bacterial growth and macrophage proliferation.

    PubMed

    Liu, Wenwen; Golshan, Negar H; Deng, Xuliang; Hickey, Daniel J; Zeimer, Katherine; Li, Hongyi; Webster, Thomas J

    2016-08-25

    Since implants often fail due to infection and uncontrolled inflammatory responses, we designed an in vitro study to investigate the antibacterial and anti-inflammatory properties of titanium dioxide nanotubes (TNTs) incorporated with selenium nanoparticles (SeNPs). Selenium incorporation was achieved by the reaction of sodium selenite (Na2SeO3) with glutathione (GSH) under a vacuum in the presence of TNTs. Two types of bacteria and macrophages were cultured on the samples to determine their respective antibacterial and anti-inflammatory properties. The results showed that the TNT samples incorporating SeNPs (TNT-Se) inhibited the growth of Escherichia coli and Staphylococcus aureus compared to unmodified TNTs, albeit the SeNP concentration still needs to be optimized for maximal effect. At their maximum effect, the TNT-Se samples reduced the density of E. coli by 94.6% and of S. aureus by 89.6% compared to titanium controls. To investigate the underlying mechanism of this effect, the expression of six E. coli genes were tracked using qRT-PCR. Results indicated that SeNPs weakened E. coli membranes (ompA and ompF were down-regulated), decreased the function of adhesion-mediating proteins (csgA and csgG were progressively down-regulated with increasing SeNP content), and induced the production of damaging reactive oxygen species (ahpF was up-regulated). Moreover, TNT-Se samples inhibited the proliferation of macrophages, indicating that they can be used to control the inflammatory response and even prevent chronic inflammation, a condition that often leads to implant failure. In conclusion, we demonstrated that SeNP-TNTs display antibacterial and anti-inflammatory properties that are promising for improving the performance of titanium-based implants for numerous orthopedic and dental applications. PMID:27533297

  12. 3D rotating wall vessel and 2D cell culture of four veterinary virus pathogens: A comparison of virus yields, portions of infectious particles and virus growth curves.

    PubMed

    Malenovská, Hana

    2016-02-01

    Only very few comparative studies have been performed that evaluate general trends of virus growth under 3D in comparison with 2D cell culture conditions. The aim of this study was to investigate differences when four animal viruses are cultured in 2D and 3D. Suid herpesvirus 1 (SuHV-1), Vesicular stomatitis virus (VSIV), Bovine adenovirus (BAdV) and Bovine parainfluenza 3 virus (BPIV-3) were cultivated in 3D rotating wall vessels (RWVs) and conventional 2D cultures. The production of virus particles, the portion of infectious particles, and the infectious growth curves were compared. For all viruses, the production of virus particles (related to cell density), including the non-infectious ones, was lower in 3D than in 2D culture. The production of only infectious particles was significantly lower in BAdV and BPIV-3 in 3D cultures in relation to cell density. The two cultivation approaches resulted in significantly different virus particle-to-TCID50 ratios in three of the four viruses: lower in SuHV-1 and BPIV-3 and higher in BAdV in 3D culture. The infectious virus growth rates were not significantly different in all viruses. Although 3D RWV culture resulted in lower production of virus particles compared to 2D systems, the portion of infectious particles was higher for some viruses. PMID:26562056

  13. Biodegradation of soil-applied pesticides by selected strains of plant growth-promoting rhizobacteria (PGPR) and their effects on bacterial growth.

    PubMed

    Myresiotis, Charalampos K; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

    2012-04-01

    A laboratory study was conducted to investigate the influence of four PGPR strains on the degradation of five soil applied pesticides and their effects on bacterial growth. Interactions of Bacillus subtilis GB03, Bacillus subtilis FZB24, Bacillus amyloliquefaciens IN937a and Bacillus pumilus SE34 with two concentrations of acibenzolar-S-methyl, metribuzin, napropamide, propamocarb hydrochloride and thiamethoxam in liquid culture and soil microcosm were studied. The degradation of acibenzolar-S-methyl by all PGPR tested in low and high concentration, was 5.4 and 5.7 times, respectively, faster than that in non-inoculated liquid culture medium. At the end of the 72-h liquid cultured experiments, 8-18, 9-11, 15-36 and 11-22% of metribuzin, napropamide, propamocarb hydrochloride and thiamethoxam, respectively, had disappeared from PGPR inoculated medium. Under the soil microcosm experimental conditions, the half-lives of acibenzolar-S-methyl incubated in the presence of PGPR strains spiked at 1.0 and 10.0 mg kg(-1) were 10.3-16.4 and 9.2-15.9 days, respectively, markedly lower compared with >34.2 days in the control. From the rest pesticides studied degradation of propamocarb hydrochloride and thiamethoxam was enhanced in the presence of B. amyloliquefaciens IN937a and B. pumilus SE34. Acibenzolar-S-methyl, propamocarb hydrochloride and thiamethoxam significantly increased the PGPR growth. However, the stimulatory effect was related to the level of pesticide spiked. PMID:21870159

  14. Viral protein suppresses oxidative burst and salicylic acid-dependent autophagy and facilitates bacterial growth on virus-infected plants.

    PubMed

    Zvereva, Anna S; Golyaev, Victor; Turco, Silvia; Gubaeva, Ekaterina G; Rajeswaran, Rajendran; Schepetilnikov, Mikhail V; Srour, Ola; Ryabova, Lyubov A; Boller, Thomas; Pooggin, Mikhail M

    2016-08-01

    Virus interactions with plant silencing and innate immunity pathways can potentially alter the susceptibility of virus-infected plants to secondary infections with nonviral pathogens. We found that Arabidopsis plants infected with Cauliflower mosaic virus (CaMV) or transgenic for CaMV silencing suppressor P6 exhibit increased susceptibility to Pseudomonas syringae pv. tomato (Pst) and allow robust growth of the Pst mutant hrcC-, which cannot deploy effectors to suppress innate immunity. The impaired antibacterial defense correlated with the suppressed oxidative burst, reduced accumulation of the defense hormone salicylic acid (SA) and diminished SA-dependent autophagy. The viral protein domain required for suppression of these plant defense responses is dispensable for silencing suppression but essential for binding and activation of the plant target-of-rapamycin (TOR) kinase which, in its active state, blocks cellular autophagy and promotes CaMV translation. Our findings imply that CaMV P6 is a versatile viral effector suppressing both silencing and innate immunity. P6-mediated suppression of oxidative burst and SA-dependent autophagy may predispose CaMV-infected plants to bacterial infection. PMID:27120694

  15. Mycobacterium leprae-induced Insulin-like Growth Factor I attenuates antimicrobial mechanisms, promoting bacterial survival in macrophages

    PubMed Central

    Batista-Silva, L. R.; Rodrigues, Luciana Silva; Vivarini, Aislan de Carvalho; Costa, Fabrício da Mota Ramalho; Mattos, Katherine Antunes de; Costa, Maria Renata Sales Nogueira; Rosa, Patricia Sammarco; Toledo-Pinto, T. G.; Dias, André Alves; Moura, Danielle Fonseca; Sarno, Euzenir Nunes; Lopes, Ulisses Gazos; Pessolani, Maria Cristina Vidal

    2016-01-01

    Mycobacterium leprae (ML), the etiologic agent of leprosy, can subvert macrophage antimicrobial activity by mechanisms that remain only partially understood. In the present study, the participation of hormone insulin-like growth factor I (IGF-I) in this phenomenum was investigated. Macrophages from the dermal lesions of the disseminated multibacillary lepromatous form (LL) of leprosy expressed higher levels of IGF-I than those from the self-limited paucibacillary tuberculoid form (BT). Higher levels of IGF-I secretion by ML-infected macrophages were confirmed in ex vivo and in vitro studies. Of note, the dampening of IGF-I signaling reverted the capacity of ML-infected human and murine macrophages to produce antimicrobial molecules and promoted bacterial killing. Moreover, IGF-I was shown to inhibit the JAK/STAT1-dependent signaling pathways triggered by both mycobacteria and IFN-γ most probably through its capacity to induce the suppressor of cytokine signaling-3 (SOCS3). Finally, these in vitro findings were corroborated by in vivo observations in which higher SOCS3 expression and lower phosphorylation of STAT1 levels were found in LL versus BT dermal lesions. Altogether, our data strongly suggest that IGF-I contributes to the maintenance of a functional program in infected macrophages that suits ML persistence in the host, reinforcing a key role for IGF-I in leprosy pathogenesis. PMID:27282338

  16. Mycobacterium leprae-induced Insulin-like Growth Factor I attenuates antimicrobial mechanisms, promoting bacterial survival in macrophages.

    PubMed

    Batista-Silva, L R; Rodrigues, Luciana Silva; Vivarini, Aislan de Carvalho; Costa, Fabrício da Mota Ramalho; Mattos, Katherine Antunes de; Costa, Maria Renata Sales Nogueira; Rosa, Patricia Sammarco; Toledo-Pinto, T G; Dias, André Alves; Moura, Danielle Fonseca; Sarno, Euzenir Nunes; Lopes, Ulisses Gazos; Pessolani, Maria Cristina Vidal

    2016-01-01

    Mycobacterium leprae (ML), the etiologic agent of leprosy, can subvert macrophage antimicrobial activity by mechanisms that remain only partially understood. In the present study, the participation of hormone insulin-like growth factor I (IGF-I) in this phenomenum was investigated. Macrophages from the dermal lesions of the disseminated multibacillary lepromatous form (LL) of leprosy expressed higher levels of IGF-I than those from the self-limited paucibacillary tuberculoid form (BT). Higher levels of IGF-I secretion by ML-infected macrophages were confirmed in ex vivo and in vitro studies. Of note, the dampening of IGF-I signaling reverted the capacity of ML-infected human and murine macrophages to produce antimicrobial molecules and promoted bacterial killing. Moreover, IGF-I was shown to inhibit the JAK/STAT1-dependent signaling pathways triggered by both mycobacteria and IFN-γ most probably through its capacity to induce the suppressor of cytokine signaling-3 (SOCS3). Finally, these in vitro findings were corroborated by in vivo observations in which higher SOCS3 expression and lower phosphorylation of STAT1 levels were found in LL versus BT dermal lesions. Altogether, our data strongly suggest that IGF-I contributes to the maintenance of a functional program in infected macrophages that suits ML persistence in the host, reinforcing a key role for IGF-I in leprosy pathogenesis. PMID:27282338

  17. Anxiety sensitivity-physical concerns as a moderator of the emotional consequences of emotion suppression during biological challenge: an experimental test using individual growth curve analysis.

    PubMed

    Feldner, Matthew T; Zvolensky, Michael J; Stickle, Timothy R; Bonn-Miller, Marcel O; Leen-Feldner, Ellen W

    2006-02-01

    Anxiety-related responding to, and recovery from, a 5-min 10% carbon dioxide-enriched air presentation among 80 participants with no history of psychopathology was examined. Half of participants were instructed to suppress challenge-induced emotional responses, whereas their matched counterparts were instructed to observe such responses. Responding from immediately post-challenge through a 10-min recovery period was analyzed as a function of Anxiety Sensitivity-Physical Concerns and experimental condition using individual growth curve modeling. Anxiety Sensitivity-Physical Concerns moderated the effect of suppression only on emotion valence during recovery. In terms of main effects, suppression resulted in increased heart rate during recovery and Anxiety Sensitivity-Physical Concerns was positively associated with post-challenge self-reported anxiety. Results are discussed in terms of the potential role of inhibition-oriented affect regulation processes in the etiology of panic disorder. PMID:16389064

  18. Overcoming the anaerobic hurdle in phenotypic microarrays: Generation andvisualization of growth curve data for Desulfovibrio vulgaris Hildenborough

    SciTech Connect

    Borglin, Sharon E; Joyner, Dominique; Jacobsen, Janet; Mukhopadhyay, Aindrila; Hazen, Terry C.

    2008-10-04

    Growing anaerobic microorganisms in phenotypic microarrays (PM) and 96-well microtiter plates is an emerging technology that allows high throughput survey of the growth and physiology and/or phenotype of cultivable microorganisms. For non-model bacteria, a method for phenotypic analysis is invaluable, not only to serve as a starting point for further evaluation, but also to provide a broad understanding of the physiology of an uncharacterized wild-type organism or the physiology/phenotype of a newly created mutant of that organism. Given recent advances in genetic characterization and targeted mutations to elucidate genetic networks and metabolic pathways, high-throughput methods for determining phenotypic differences are essential. Here we outline challenges presented in studying the physiology and phenotype of a sulfate reducing anaerobic delta proteobacterium, Desulfovibrio vulgaris Hildenborough. Modifications of the commercially available OmniLog(TM) system (Hayward, CA) for experimental setup, and configuration, as well as considerations in PM data analysis are presented. Also highlighted here is data viewing software that enables users to view and compare multiple PM data sets. The PM method promises to be a valuable strategy in our systems biology approach to D. vulgaris studies and is readily applicable to other anaerobic and aerobic bacteria.

  19. Long-term effect of early protein malnutrition on growth curve, hematological parameters and macrophage function of rats.

    PubMed

    Prestes-Carneiro, Luiz Euribel; Laraya, Rodrigo Domingues; Silva, Paula Roberta Colacino; Moliterno, Ricardo Alberto; Felipe, Ionice; Mathias, Paulo Cezar

    2006-12-01

    To evaluate the long-term effect of mild-early maternal protein malnutrition on weight gain, hematological parameters and macrophage function in rats at adult age, we compared rats whose dams were fed diets containing either 9.5% (low protein-LPD) or 23% protein (normal-NPD) for the first 12 d of lactation. At 80 d of age, the functions of spreading, phagocytosis and killing Candida albicans were determined in resident peritoneal macrophages, whereas leukocytes and red blood cells were counted in peripheral blood. The number of resident peritoneal macrophages from LPD was the same as from NPD, but the ability of spreading and phagocytosing opsonised yeast was impaired. Besides, they were not able to block the germ tube formation or kill C. albicans to the same extent as in the control group. The low protein diet produced a significant reduction in the pups' growth and in hematological parameters although no difference was found in leukocyte counts. Taken together the data suggest that protein malnutrition during early lactation induces permanent alterations in macrophage function, body composition and hematological status, which are not restored completely even after a normal protein diet is supplied. PMID:17330504

  20. Initiation and growth of multiple-site damage in the riveted lap joint of a curved stiffened fuselage panel: An experimental and analytical study

    NASA Astrophysics Data System (ADS)

    Ahmed, Abubaker Ali

    As part of the structural integrity research of the National Aging Aircraft Research Program, a comprehensive study on multiple-site damage (MSD) initiation and growth in a pristine lap-joint fuselage panel has been conducted. The curved stiffened fuselage panel was tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center. A strain survey test was conducted to verify proper load application. The panel was then subjected to a fatigue test with constant-amplitude cyclic loading. The applied loading spectrum included underload marker cycles so that crack growth history could be reconstructed from post-test fractographic examinations. Crack formation and growth were monitored via nondestructive and high-magnification visual inspections. Strain gage measurements recorded during the strain survey tests indicated that the inner surface of the skin along the upper rivet row of the lap joint experienced high tensile stresses due to local bending. During the fatigue loading, cracks were detected by eddy-current inspections at multiple rivet holes along the upper rivet row. Through-thickness cracks were detected visually after about 80% of the fatigue life. Once MSD cracks from two adjacent rivet holes linked up, there was a quick deterioration in the structural integrity of the lap joint. The linkup resulted in a 2.87" (72.9-mm) lead fatigue crack that rapidly propagated across 12 rivet holes and crossed over into the next skin bay, at which stage the fatigue test was terminated. A post-fatigue residual strength test was then conducted by loading the panel quasi-statically up to final failure. The panel failed catastrophically when the crack extended instantaneously across three additional bays. Post-test fractographic examinations of the fracture surfaces in the lap joint of the fuselage panel were conducted to characterize subsurface crack initiation and

  1. The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

    PubMed

    Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

    2009-01-01

    In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact. PMID:19121038

  2. Effects of Bacillus amyloliquefaciens FZB42 on lettuce growth and health under pathogen pressure and its impact on the rhizosphere bacterial community.

    PubMed

    Chowdhury, Soumitra Paul; Dietel, Kristin; Rändler, Manuela; Schmid, Michael; Junge, Helmut; Borriss, Rainer; Hartmann, Anton; Grosch, Rita

    2013-01-01

    The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments. Results of both experiments demonstrated that FZB42 is able to effectively colonize the rhizosphere (7.45 to 6.61 Log 10 CFU g(-1) root dry mass) within the growth period of lettuce in the field. The disease severity (DS) of bottom rot on lettuce was significantly reduced from severe symptoms with DS category 5 to slight symptom expression with DS category 3 on average through treatment of young plants with FZB42 before and after planting. The 16S rRNA gene based fingerprinting method terminal restriction fragment length polymorphism (T-RFLP) showed that the treatment with FZB42 did not have a major impact on the indigenous rhizosphere bacterial community. However, the bacterial community showed a clear temporal shift. The results also indicated that the pathogen R. solani AG1-IB affects the rhizosphere microbial community after inoculation. Thus, we revealed that the inoculant FZB42 could establish itself successfully in the rhizosphere without showing any durable effect on the rhizosphere bacterial community. PMID:23935892

  3. Characterization of bacterial communities associated with Brassica napus L. growing on a Zn-contaminated soil and their effects on root growth.

    PubMed

    Montalbán, Blanca; Croes, Sarah; Weyens, Nele; Lobo, M Carmen; Pérez-Sanz, Araceli; Vangronsveld, Jaco

    2016-10-01

    The interaction between plant growth-promoting bacteria (PGPB) and plants can enhance biomass production and metal tolerance of the host plants. This work aimed at isolating and characterizing the cultivable bacterial community associated with Brassica napus growing on a Zn-contaminated site, for selecting cultivable PGPB that might enhance biomass production and metal tolerance of energy crops. The effects of some of these bacterial strains on root growth of B. napus exposed to increasing Zn and Cd concentrations were assessed. A total of 426 morphologically different bacterial strains were isolated from the soil, the rhizosphere, and the roots and stems of B. napus. The diversity of the isolated bacterial populations was similar in rhizosphere and roots, but lower in soil and stem compartments. Burkoholderia, Alcaligenes, Agrococcus, Polaromonas, Stenotrophomonas, Serratia, Microbacterium, and Caulobacter were found as root endophytes exclusively. The inoculation of seeds with Pseudomonas sp. strains 228 and 256, and Serratia sp. strain 246 facilitated the root development of B. napus at 1,000 µM Zn. Arthrobacter sp. strain 222, Serratia sp. strain 246, and Pseudomonas sp. 228 and 262 increased the root length at 300 µM Cd. PMID:27159736

  4. Effects of Bacillus amyloliquefaciens FZB42 on Lettuce Growth and Health under Pathogen Pressure and Its Impact on the Rhizosphere Bacterial Community

    PubMed Central

    Rändler, Manuela; Schmid, Michael; Junge, Helmut; Borriss, Rainer; Hartmann, Anton; Grosch, Rita

    2013-01-01

    The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments. Results of both experiments demonstrated that FZB42 is able to effectively colonize the rhizosphere (7.45 to 6.61 Log 10 CFU g−1 root dry mass) within the growth period of lettuce in the field. The disease severity (DS) of bottom rot on lettuce was significantly reduced from severe symptoms with DS category 5 to slight symptom expression with DS category 3 on average through treatment of young plants with FZB42 before and after planting. The 16S rRNA gene based fingerprinting method terminal restriction fragment length polymorphism (T-RFLP) showed that the treatment with FZB42 did not have a major impact on the indigenous rhizosphere bacterial community. However, the bacterial community showed a clear temporal shift. The results also indicated that the pathogen R. solani AG1-IB affects the rhizosphere microbial community after inoculation. Thus, we revealed that the inoculant FZB42 could establish itself successfully in the rhizosphere without showing any durable effect on the rhizosphere bacterial community. PMID:23935892

  5. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... recommendations as specified under 40 CFR part 792, subpart J the following specific information should be... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.”...

  6. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... recommendations as specified under 40 CFR part 792, subpart J the following specific information should be... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.”...

  7. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... recommendations as specified under 40 CFR part 792, subpart J the following specific information should be... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.”...

  8. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... recommendations as specified under 40 CFR part 792, subpart J the following specific information should be... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.”...

  9. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... recommendations as specified under 40 CFR part 792, subpart J the following specific information should be... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.”...

  10. RELATIONS BETWEEN BACTERIAL NITROGEN METABOLISM AND GROWTH EFFICIENCY IN AN ESTUARINE AND AN OPEN-WATER ECOSYSTEM

    EPA Science Inventory

    Bacterial uptake or release of dissolved nitrogen compounds (amino nitrogen, urea, ammonium and nitrate) were examined in 0.8 |m filtered water from an estuary (Santa Rosa Sound [SRS], northwestern Florida) and an open-water location in the Gulf of Mexico [GM]. The bacterial nutr...

  11. Test-retest, retest, and retest: Growth curve models of repeat testing with Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT).

    PubMed

    Maerlender, Arthur C; Masterson, Caitlin J; James, Tiffany D; Beckwith, Jonathan; Brolinson, Per Gunner; Crisco, Joe; Duma, Stefan; Flashman, Laura A; Greenwald, Rick; Rowson, Steven; Wilcox, Beth; McAllister, Tom W

    2016-10-01

    Computerized neuropsychological testing has become an important tool in the identification and management of sports-related concussions; however, the psychometric effect of repeat testing has not been studied extensively beyond test-retest statistics. The current study analyzed data from Division I collegiate athletes who completed Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) baseline assessments at four sequential time points that varied over the course of their athletic careers. Administrations were part of a larger National Institutes of Health (NIH) study. Growth curve modeling showed that the two memory composite scores increased significantly with successive administrations: Change in Verbal Memory was best represented with a quadratic model, while a linear model best fit Visual Memory. Visual Motor Speed and Reaction Time composites showed no significant linear or quadratic growth. The results demonstrate the effect of repeated test administrations for memory composite scores, while speed composites were not significantly impacted by repeat testing. Acceptable test-retest reliability was demonstrated for all four composites as well. PMID:27266563

  12. Efficiency of N2 Gas Flushing Compared to the Lactoperoxidase System at Controlling Bacterial Growth in Bovine Raw Milk Stored at Mild Temperatures

    PubMed Central

    Munsch-Alatossava, Patricia; Quintyn, Romanie; De Man, Ingrid; Alatossava, Tapani; Gauchi, Jean-Pierrre

    2016-01-01

    To prevent excessive bacterial growth in raw milk, the FAO recommends two options: either cold storage or activation of the lactoperoxidase system (LPs/HT) in milk with the addition of two chemical preservatives, hydrogen peroxide (H) and thiocyanate (T). N2 gas flushing of raw milk has shown great potential to control bacterial growth in a temperature range of 6–12°C without promoting undesired side effects. Here, the effect of N2 gas (N) was tested as a single treatment and in combination with the lactoperoxidase system (NHT) on seven raw milk samples stored at 15 or 25°C. For the ratio defined as bacterial counts from a certain treatment/counts on the corresponding control, a classical Analyse of Variance (ANOVA) was performed, followed by mean comparison with the Ryan-Einot-Gabriel-Welsch multiple range test (REGWQ). Altogether, the growth inhibition was slightly but significantly higher at 25°C than at 15°C. Except for one sample, all ratios were lower for HT than for N alone; however, these differences were not judged to be significant for five samples by the REGWQ test; in the remaining two samples, N was more effective than HT in one case and less effective in the other case. This study shows that N2 gas flushing, which inhibited bacterial growth in raw milk at 15 and 25°C for 24 and 12 h, respectively, could constitute an alternative to LPs where no cold storage facilities exist, especially as a replacement for adulterating substances. PMID:27313575

  13. The effects of indoor and outdoor dust exposure on the growth, sensitivity to oxidative-stress, and biofilm production of three opportunistic bacterial pathogens.

    PubMed

    Suraju, Mohammed O; Lalinde-Barnes, Sloan; Sanamvenkata, Sachindra; Esmaeili, Mahsa; Shishodia, Shishir; Rosenzweig, Jason A

    2015-12-15

    Within the last decade, many studies have highlighted the radical changes in the components of indoor and outdoor dust. For example, agents like automobile emitted platinum group elements and different kinds of organic phthalates and esters have been reported to be accumulating in the biosphere. Humans consistently face dermal, respiratory, and dietary exposures to these particles while indoors and outdoors. In fact, dust particulate matter has been associated with close to 500,000 deaths per year in Europe and about 200,000 deaths per year in the United States. To date, there has been limited examination of the physiological impact of indoor and outdoor dust exposure on normal flora microbes. In this study, the effect of indoor- and outdoor-dust exposure on three opportunistic bacterial species (Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa) was assessed. Specifically, bacterial growth, oxidative stress resistance, and biofilm production were measured following indoor- and outdoor-dust exposures. Studies were conducted in nutritionally-rich and -poor environments typically encountered by bacteria. Surprisingly, indoor-dust (200μg/mL), enhanced the growth of all three bacterial species in nutrient-poor conditions, but slowed growth in nutrient-rich conditions. In nutrient-rich medium, 100μg/mL exposure of either indoor- or outdoor-dust resulted in significantly reduced oxidative stress resistance in E. coli. Most interestingly, dust (indoor and outdoor), either in nutrient-rich or -poor conditions, significantly increased biofilm production in all three bacterial species. These data suggest that indoor and outdoor dust, can modify opportunistic bacteria through altering growth, sensitivity to oxidative stress, and their virulence potential through enhanced biofilm formation. PMID:26363607

  14. Common components of industrial metal-working fluids as sources of carbon for bacterial growth. [Acinetobacter; Pseudomonas

    SciTech Connect

    Foxall-vanAken, S.; Brown, J.A. Jr.; Young, W.; Salmeen, I.; McClure, T.; Napier, S. Jr.; Olsen, R.H.

    1986-06-01

    Water-based metal-working fluids in large-scale industrial operations consist of many components, but in the most commonly used formulations only three classes of components are present in high enough concentrations that they could, in principle, provide enough carbon to support the high bacterial densities (10/sup 9/ CFU/ml) often observed in contaminated factory fluids. These components are petroleum oil (1 to 5%), petroleum sulfonates (0.1 to 0.5%), and fatty acids (less than 0.1%, mainly linoleic and oleic acids supplied as tall oils). Pure strains of predominating bacteria were isolated from contaminated reservoirs of two metal-working systems and randomly selected 12 strains which were tested in liquid culture for growth with each of the metal-working fluid components as the sole source of carbon. Of the 12 strains, 7 reached high density (10/sup 9/ CFU/ml from an initial inoculum of less than 2 x 10/sup 3/) in 24 h, and 1 strain did the same in 48 h with 0.05% oleic or linoleic acid as the carbon source. These same strains also grew on 1% naphthenic petroleum oil but required up to 72 h to reach densities near 10/sup 8/ CFU/ml. One strain grew slightly and the others not at all on the petroleum sulfonates. The four remaining strains did not grow on any of the components, even though they were among the predominating bacteria in the contaminated system. Of the seven strains that grew best on the fatty acids and on the naphthenic petroleum oil, five were tentatively identified as Acinetobacter species and two were identified as Pseudomonas species. Four of the bacteria that did not grow were tentatively identified as species of Pseudomonas, and one could not be identified.

  15. Optimized polymeric film-based nitric oxide delivery inhibits bacterial growth in a mouse burn wound model.

    PubMed

    Brisbois, Elizabeth J; Bayliss, Jill; Wu, Jianfeng; Major, Terry C; Xi, Chuanwu; Wang, Stewart C; Bartlett, Robert H; Handa, Hitesh; Meyerhoff, Mark E

    2014-10-01

    Nitric oxide (NO) has many biological roles (e.g. antimicrobial agent, promoter of angiogenesis, prevention of platelet activation) that make NO releasing materials desirable for a variety of biomedical applications. Localized NO release can be achieved from biomedical grade polymers doped with diazeniumdiolated dibutylhexanediamine (DBHD/N2O2) and poly(lactic-co-glycolic acid) (PLGA). In this study, the optimization of this chemistry to create film/patches that can be used to decrease microbial infection at wound sites is examined. Two polyurethanes with different water uptakes (Tecoflex SG-80A (6.2±0.7wt.%) and Tecophilic SP-60D-20 (22.5±1.1wt.%)) were doped with 25wt.% DBHD/N2O2 and 10wt.% of PLGA with various hydrolysis rates. Films prepared with the polymer that has the higher water uptake (SP-60D-20) were found to have higher NO release and for a longer duration than the polyurethane with the lower water uptake (SG-80A). The more hydrophilic polymer enhances the hydrolysis rate of the PLGA additive, thereby providing a more acidic environment that increases the rate of NO release from the NO donor. The optimal NO releasing and control SG-80A patches were then applied to scald burn wounds that were infected with Acinetobacter baumannii. The NO released from these patches applied to the wounds is shown to significantly reduce the A. baumannii infection after 24h (∼4 log reduction). The NO release patches are also able to reduce the level of transforming growth factor-β in comparison to controls, which can enhance re-epithelialization, decrease scarring and reduce migration of bacteria. The combined DBHD/N2O2 and PLGA-doped polymer patches, which could be replaced periodically throughout the wound healing process, demonstrate the potential to reduce risk of bacterial infection and promote the overall wound healing process. PMID:24980058

  16. Inhibition of bacterial growth and intramniotic infection in a guinea pig model of chorioamnionitis using PAMAM dendrimers.

    PubMed

    Wang, Bing; Navath, Raghavendra S; Menjoge, Anupa R; Balakrishnan, Bindu; Bellair, Robert; Dai, Hui; Romero, Roberto; Kannan, Sujatha; Kannan, Rangaramanujam M

    2010-08-16

    Dendrimers have emerged as topical microbicides to treat vaginal infections. This study explores the in vitro, in vivo antimicrobial activity of PAMAM dendrimers, and the associated mechanism. Interestingly, topical cervical application of 500 microg of generation-4 neutral dendrimer (G(4)-PAMAM-OH) showed potential to treat the Escherichia coli induced ascending uterine infection in guinea pig model of chorioamnionitis. Amniotic fluid collected from different gestational sacs of infected guinea pigs posttreatment showed absence of E. coli growth in the cultures plated with it. The cytokine level [tumor necrosis factor (TNFalpha) and interleukin (IL-6 and IL-1beta)] in placenta of the G(4)-PAMAM-OH treated animals were comparable to those in healthy animals while these were notably high in infected animals. Since, antibacterial activity of amine-terminated PAMAM dendrimers is known, the activity of hydroxyl and carboxylic acid terminated PAMAM dendrimers was compared with it. Though the G(4)-PAMAM-NH(2) shows superior antibacterial activity, it was found to be cytotoxic to human cervical epithelial cell line above 10 microg/mL, while the G(4)-PAMAM-OH was non-cytotoxic up to 1mg/mL concentration. Cell integrity, outer (OM) and inner (IM) membrane permeabilization assays showed that G(4)-PAMAM-OH dendrimer efficiently changed the OM permeability, while G(4)-PAMAM-NH(2) and G(3.5)-PAMAM-COOH damaged both OM and IM causing the bacterial lysis. The possible antibacterial mechanism are G(4)-PAMAM-NH(2) acts as polycation binding to the polyanionic lipopolysaccharide in E. coli, the G(4)-PAMAM-OH forms hydrogen bonds with the hydrophilic O-antigens in E. coli membrane and the G(3.5)-PAMAM-COOH acts as a polyanion, chelating the divalent ions in outer cell membrane of E. coli. This is the first study which shows that G(4)-PAMAM-OH dendrimer acts as an antibacterial agent. PMID:20580797

  17. Growth of Tl 2Ba 2CaCu 2O 8 superconducting thin films on curved substrates for metamaterials applications

    NASA Astrophysics Data System (ADS)

    Speller, S. C.; Dinner, R. B.; Grovenor, C. R. M.

    2008-08-01

    Recent developments in the field of magnetic metamaterials have shown that coupled resonator structures can manipulate magnetic fields on a scale shorter than the wavelength of the electromagnetic radiation [E. Shamonina, V.A. Kalinin, K.H. Ringhofer, L. Solymar, J. Appl. Phys. 92 (10) (2002) 6252]. Major improvements in the sensitivity of such devices could be achieved by fabricating the resonating elements from high temperature superconducting (HTS) films on appropriate dielectric substrates. In order to produce a stack of superconducting/dielectric resonator structures, the ideal method involves patterning them into an HTS film grown on the curved surface of a dielectric cylinder. We report here our initial attempts at the growth of Tl 2Ba 2CaCu 2O 8 (Tl-2212) thin films on the surface of LaAlO 3 and MgO single-crystal cylinders. We have found that Tl-2212 thin films grow epitaxially on LaAlO 3 cylinders with Tl-2212 [0 0 1] aligned with the closest LaAlO 3 pseudocubic <1 0 0> direction, resulting in abrupt changes in Tl-2212 plate orientation at four positions around the cylinder. In contrast, Tl-2212 films grow smoothly on MgO cylinders, with Tl-2212 [0 0 1] aligned roughly parallel to the surface normal at all positions around the cylinder. This smooth growth on MgO leads to higher critical current values than epitaxial growth, making HTS on MgO a promising candidate for metamaterial device applications.

  18. Novel components of leaf bacterial communities of field-grown tomato plants and their potential for plant growth promotion and biocontrol of tomato diseases.

    PubMed

    Romero, Fernando M; Marina, María; Pieckenstain, Fernando L

    2016-04-01

    This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth. PMID:26654914

  19. Bradford Curves.

    ERIC Educational Resources Information Center

    Rousseau, Ronald

    1994-01-01

    Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)

  20. Different bacterial communities in heat and gamma irradiation treated replant disease soils revealed by 16S rRNA gene analysis - contribution to improved aboveground apple plant growth?

    PubMed

    Yim, Bunlong; Winkelmann, Traud; Ding, Guo-Chun; Smalla, Kornelia

    2015-01-01

    Replant disease (RD) severely affects apple production in propagation tree nurseries and in fruit orchards worldwide. This study aimed to investigate the effects of soil disinfection treatments on plant growth and health in a biotest in two different RD soil types under greenhouse conditions and to link the plant growth status with the bacterial community composition at the time of plant sampling. In the biotest performed we observed that the aboveground growth of apple rootstock M26 plants after 8 weeks was improved in the two RD soils either treated at 50°C or with gamma irradiation compared to the untreated RD soils. Total community DNA was extracted from soil loosely adhering to the roots and quantitative real-time PCR revealed no pronounced differences in 16S rRNA gene copy numbers. 16S rRNA gene-based bacterial community analysis by denaturing gradient gel electrophoresis (DGGE) and 454-pyrosequencing revealed significant differences in the bacterial community composition even after 8 weeks of plant growth. In both soils, the treatments affected different phyla but only the relative abundance of Acidobacteria was reduced by both treatments. The genera Streptomyces, Bacillus, Paenibacillus, and Sphingomonas had a higher relative abundance in both heat treated soils, whereas the relative abundance of Mucilaginibacter, Devosia, and Rhodanobacter was increased in the gamma-irradiated soils and only the genus Phenylobacterium was increased in both treatments. The increased abundance of genera with potentially beneficial bacteria, i.e., potential degraders of phenolic compounds might have contributed to the improved plant growth in both treatments. PMID:26635733