Contact-dependent growth inhibition induces high levels of antibiotic-tolerant persister cells in clonal bacterial populations.

PubMed

Ghosh, Anirban; Baltekin, Özden; Wäneskog, Marcus; Elkhalifa, Dina; Hammarlöf, Disa L; Elf, Johan; Koskiniemi, Sanna

2018-05-02

Bacterial populations can use bet-hedging strategies to cope with rapidly changing environments. One example is non-growing cells in clonal bacterial populations that are able to persist antibiotic treatment. Previous studies suggest that persisters arise in bacterial populations either stochastically through variation in levels of global signalling molecules between individual cells, or in response to various stresses. Here, we show that toxins used in contact-dependent growth inhibition (CDI) create persisters upon direct contact with cells lacking sufficient levels of CdiI immunity protein, which would otherwise bind to and neutralize toxin activity. CDI-mediated persisters form through a feedforward cycle where the toxic activity of the CdiA toxin increases cellular (p)ppGpp levels, which results in Lon-mediated degradation of the immunity protein and more free toxin. Thus, CDI systems mediate a population density-dependent bet-hedging strategy, where the fraction of non-growing cells is increased only when there are many cells of the same genotype. This may be one of the mechanisms of how CDI systems increase the fitness of their hosts. © 2018 The Authors.

Plant growth-promoting bacterial endophytes.

PubMed

Santoyo, Gustavo; Moreno-Hagelsieb, Gabriel; Orozco-Mosqueda, Ma del Carmen; Glick, Bernard R

2016-02-01

Bacterial endophytes ubiquitously colonize the internal tissues of plants, being found in nearly every plant worldwide. Some endophytes are able to promote the growth of plants. For those strains the mechanisms of plant growth-promotion known to be employed by bacterial endophytes are similar to the mechanisms used by rhizospheric bacteria, e.g., the acquisition of resources needed for plant growth and modulation of plant growth and development. Similar to rhizospheric plant growth-promoting bacteria, endophytic plant growth-promoting bacteria can act to facilitate plant growth in agriculture, horticulture and silviculture as well as in strategies for environmental cleanup (i.e., phytoremediation). Genome comparisons between bacterial endophytes and the genomes of rhizospheric plant growth-promoting bacteria are starting to unveil potential genetic factors involved in an endophytic lifestyle, which should facilitate a better understanding of the functioning of bacterial endophytes. Copyright © 2015 Elsevier GmbH. All rights reserved.

Correlation between genome reduction and bacterial growth.

PubMed

Kurokawa, Masaomi; Seno, Shigeto; Matsuda, Hideo; Ying, Bei-Wen

2016-12-01

Genome reduction by removing dispensable genomic sequences in bacteria is commonly used in both fundamental and applied studies to determine the minimal genetic requirements for a living system or to develop highly efficient bioreactors. Nevertheless, whether and how the accumulative loss of dispensable genomic sequences disturbs bacterial growth remains unclear. To investigate the relationship between genome reduction and growth, a series of Escherichia coli strains carrying genomes reduced in a stepwise manner were used. Intensive growth analyses revealed that the accumulation of multiple genomic deletions caused decreases in the exponential growth rate and the saturated cell density in a deletion-length-dependent manner as well as gradual changes in the patterns of growth dynamics, regardless of the growth media. Accordingly, a perspective growth model linking genome evolution to genome engineering was proposed. This study provides the first demonstration of a quantitative connection between genomic sequence and bacterial growth, indicating that growth rate is potentially associated with dispensable genomic sequences. © The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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), andmore » 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.« less

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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Phenotypic signatures arising from unbalanced bacterial growth.

PubMed

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

2014-08-01

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.

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.

Coupling Bacterial Activity Measurements with Cell Sorting by Flow Cytometry.

PubMed

Servais; Courties; Lebaron; Troussellier

1999-08-01

> Abstract A new procedure to investigate the relationship between bacterial cell size and activity at the cellular level has been developed; it is based on the coupling of radioactive labeling of bacterial cells and cell sorting by flow cytometry after SYTO 13 staining. Before sorting, bacterial cells were incubated in the presence of tritiated leucine using a procedure similar to that used for measuring bacterial production by leucine incorporation and then stained with SYTO 13. Subpopulations of bacterial cells were sorted according to their average right-angle light scatter (RALS) and fluorescence. Average RALS was shown to be significantly related to the average biovolume. Experiments were performed on samples collected at different times in a Mediterranean seawater mesocosm enriched with nitrogen and phosphorus. At four sampling times, bacteria were sorted in two subpopulations (cells smaller and larger than 0.25 µm(3)). The results indicate that, at each sampling time, the growth rate of larger cells was higher than that of smaller cells. In order to confirm this tendency, cell sorting was performed on six subpopulations differing in average biovolume during the mesocosm follow-up. A clear increase of the bacterial growth rates was observed with increasing cell size for the conditions met in this enriched mesocosm.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p180.html

Can dead bacterial cells be defined and are genes expressed after cell death?

PubMed

Trevors, J T

2012-07-01

There is a paucity of knowledge on gene expression in dead bacterial cells. Why would this knowledge be useful? The cells are dead. However, the time duration of gene expression following cell death is often unknown, and possibly in the order of minutes. In addition, it is a challenge to determine if bacterial cells are dead, or viable but non-culturable (VBNC), and what is an agreed upon correct definition of dead bacteria. Cells in the bacterial population or community may die at different rates or times and this complicates both the viability and gene expression analysis. In this article, the definition of dead bacterial cells is discussed and its significance in continued gene expression in cells following death. The definition of living and dead has implications for possible, completely, synthetic bacterial cells that may be capable of growth and division. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

A size-structured model of bacterial growth and reproduction.

PubMed

Ellermeyer, S F; Pilyugin, S S

2012-01-01

We consider a size-structured bacterial population model in which the rate of cell growth is both size- and time-dependent and the average per capita reproduction rate is specified as a model parameter. It is shown that the model admits classical solutions. The population-level and distribution-level behaviours of these solutions are then determined in terms of the model parameters. The distribution-level behaviour is found to be different from that found in similar models of bacterial population dynamics. Rather than convergence to a stable size distribution, we find that size distributions repeat in cycles. This phenomenon is observed in similar models only under special assumptions on the functional form of the size-dependent growth rate factor. Our main results are illustrated with examples, and we also provide an introductory study of the bacterial growth in a chemostat within the framework of our model.

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...

Limitation of Bacterial Growth by Dissolved Organic Matter and Iron in the Southern Ocean†

PubMed Central

Church, Matthew J.; Hutchins, David A.; Ducklow, Hugh W.

2000-01-01

The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42°S and 55°S along 141°E. Bacterial abundance, mean cell volume, and [3H]thymidine and [3H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favorably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilization may be partly constrained by iron availability in the HNLC Southern Ocean. PMID:10653704

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.

Morphology, Growth, and Size Limit of Bacterial Cells

NASA Astrophysics Data System (ADS)

Jiang, Hongyuan; Sun, Sean X.

2010-07-01

Bacterial cells utilize a living peptidoglycan network (PG) to separate the cell interior from the surroundings. The shape of the cell is controlled by PG synthesis and cytoskeletal proteins that form bundles and filaments underneath the cell wall. The PG layer also resists turgor pressure and protects the cell from osmotic shock. We argue that mechanical influences alter the chemical equilibrium of the reversible PG assembly and determine the cell shape and cell size. Using a mechanochemical approach, we show that the cell shape can be regarded as a steady state of a growing network under the influence of turgor pressure and mechanical stress. Using simple elastic models, we predict the size of common spherical and rodlike bacteria. The influence of cytoskeletal bundles such as crescentin and MreB are discussed within the context of our model.

Periodic growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Yamazaki, Yoshihiro; Ikeda, Takemasa; Shimada, Hirotoshi; Hiramatsu, Fumiko; Kobayashi, Naoki; Wakita, Jun-ichi; Itoh, Hiroto; Kurosu, Sayuri; Nakatsuchi, Michio; Matsuyama, Tohey; Matsushita, Mitsugu

2005-06-01

The formation of concentric ring colonies by bacterial species Bacillus subtilis and Proteus mirabilis has been investigated experimentally, focusing our attention on the dependence of local cell density upon the bacterial motility. It has been confirmed that these concentric ring colonies reflect the periodic change of the bacterial motility between motile cell state and immotile cell state. We conclude that this periodic change is macroscopically determined neither by biological factors (i.e., biological clock) nor by chemical factors (chemotaxis as inhibitor). And our experimental results strongly suggest that the essential factor for the change of the bacterial motility during concentric ring formation is the local cell density.

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.

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.

Bacterial growth laws reflect the evolutionary importance of energy efficiency.

PubMed

Maitra, Arijit; Dill, Ken A

2015-01-13

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.

Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

NASA Astrophysics Data System (ADS)

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R.; Allen, Rosalind J.

2017-12-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance.

Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

PubMed Central

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R; Allen, Rosalind J

2017-01-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance. PMID:28714461

Bacterial Cell Mechanics.

PubMed

Auer, George K; Weibel, Douglas B

2017-07-25

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

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

PubMed Central

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

2011-01-01

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

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

2011-03-06

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.

Visual Estimation of Bacterial Growth Level in Microfluidic Culture Systems.

PubMed

Kim, Kyukwang; Kim, Seunggyu; Jeon, Jessie S

2018-02-03

Microfluidic devices are an emerging platform for a variety of experiments involving bacterial cell culture, and has advantages including cost and convenience. One inevitable step during bacterial cell culture is the measurement of cell concentration in the channel. The optical density measurement technique is generally used for bacterial growth estimation, but it is not applicable to microfluidic devices due to the small sample volumes in microfluidics. Alternately, cell counting or colony-forming unit methods may be applied, but these do not work in situ; nor do these methods show measurement results immediately. To this end, we present a new vision-based method to estimate the growth level of the bacteria in microfluidic channels. We use Fast Fourier transform (FFT) to detect the frequency level change of the microscopic image, focusing on the fact that the microscopic image becomes rough as the number of cells in the field of view increases, adding high frequencies to the spectrum of the image. Two types of microfluidic devices are used to culture bacteria in liquid and agar gel medium, and time-lapsed images are captured. The images obtained are analyzed using FFT, resulting in an increase in high-frequency noise proportional to the time passed. Furthermore, we apply the developed method in the microfluidic antibiotics susceptibility test by recognizing the regional concentration change of the bacteria that are cultured in the antibiotics gradient. Finally, a deep learning-based data regression is performed on the data obtained by the proposed vision-based method for robust reporting of data.

Phenotypic indications of FtsZ inhibition in hok/sok-induced bacterial growth changes and stress response.

PubMed

Chukwudi, Chinwe Uzoma; Good, Liam

2018-01-01

The hok/sok locus has been shown to enhance the growth of bacteria in adverse growth conditions such as high temperature, low starting-culture densities and antibiotic treatment. This is in addition to their well-established plasmid-stabilization effect via post-segregational killing of plasmid-free daughter cells. It delays the onset of growth by prolonging the lag phase of bacterial culture, and increases the rate of exponential growth when growth eventually begins. This enables the cells adapt to the prevailing growth conditions and enhance their survival in stressful conditions. These effects functionally complement defective SOS response mechanism, and appear analogous to the growth effects of FtsZ in the SOS pathway. In this study, the role of FtsZ in the hok/sok-induced changes in bacterial growth and cell division was investigated. Morphologic studies of early growth-phase cultures and cells growing under temperature stress showed elongated cells typical of FtsZ inhibition/deficiency. Both ftsZ silencing and over-expression produced comparable growth effects in control cells, and altered the growth changes observed otherwise in the hok/sok + cells. These changes were diminished in SOS-deficient strain containing mutant FtsZ. The involvement of FtsZ in the hok/sok-induced growth changes may be exploited as drug target in host bacteria, which often propagate antibiotic resistance elements. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

USDA-ARS?s Scientific Manuscript database

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...

Improving protein delivery of fibroblast growth factor-2 from bacterial inclusion bodies used as cell culture substrates.

PubMed

Seras-Franzoso, Joaquin; Peebo, Karl; García-Fruitós, Elena; Vázquez, Esther; Rinas, Ursula; Villaverde, Antonio

2014-03-01

Bacterial inclusion bodies (IBs) have recently been used to generate biocompatible cell culture interfaces, with diverse effects on cultured cells such as cell adhesion enhancement, stimulation of cell growth or induction of mesenchymal stem cell differentiation. Additionally, novel applications of IBs as sustained protein delivery systems with potential applications in regenerative medicine have been successfully explored. In this scenario, with IBs gaining significance in the biomedical field, the fine tuning of this functional biomaterial is crucial. In this work, the effect of temperature on fibroblast growth factor-2 (FGF-2) IB production and performance has been evaluated. FGF-2 was overexpressed in Escherichia coli at 25 and 37 °C, producing IBs with differences in size, particle structure and biological activity. Cell culture topographies made with FGF-2 IBs biofabricated at 25 °C showed higher levels of biological activity as well as a looser supramolecular structure, enabling a higher protein release from the particles. In addition, the controlled use of FGF-2 protein particles enabled the generation of functional topographies with multiple biological activities being effective on diverse cell types. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cell division and turgor mediate enhanced plant growth in Arabidopsis plants treated with the bacterial signalling molecule lumichrome.

PubMed

Pholo, Motlalepula; Coetzee, Beatrix; Maree, Hans J; Young, Philip R; Lloyd, James R; Kossmann, Jens; Hills, Paul N

2018-05-17

Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.

Measuring bacterial growth by refractive index tapered fiber optic biosensor.

PubMed

Zibaii, Mohammad Ismail; Kazemi, Alireza; Latifi, Hamid; Azar, Mahmoud Karimi; Hosseini, Seyed Masoud; Ghezelaiagh, Mohammad Hossein

2010-12-02

A single-mode tapered fiber optic biosensor was utilized for real-time monitoring of the Escherichia coli (E. coli K-12) growth in an aqueous medium. The applied fiber tapers were fabricated using heat-pulling method with waist diameter and length of 6-7μm and 3mm, respectively. The bacteria were immobilized on the tapered surface using Poly-l-Lysine. By providing the proper condition, bacterial population growth on the tapered surface increases the average surface density of the cells and consequently the refractive index (RI) of the tapered region would increase. The adsorption of the cells on the tapered fiber leads to changes in the optical characteristics of the taper. This affects the evanescent field leading to changes in optical throughput. The bacterial growth rate was monitored at room temperature by transmission of a 1558.17nm distributed feedback (DFB) laser through the tapered fiber. At the same condition, after determining the growth rate of E. coli by means of colony counting method, we compared the results with that obtained from the fiber sensor measurements. This novel sensing method, promises new application such as rapid analysis of the presence of bacteria. Copyright © 2010 Elsevier B.V. All rights reserved.

Gradient microfluidics enables rapid bacterial growth inhibition testing.

PubMed

Li, Bing; Qiu, Yong; Glidle, Andrew; McIlvenna, David; Luo, Qian; Cooper, Jon; Shi, Han-Chang; Yin, Huabing

2014-03-18

Bacterial growth inhibition tests have become a standard measure of the adverse effects of inhibitors for a wide range of applications, such as toxicity testing in the medical and environmental sciences. However, conventional well-plate formats for these tests are laborious and provide limited information (often being restricted to an end-point assay). In this study, we have developed a microfluidic system that enables fast quantification of the effect of an inhibitor on bacteria growth and survival, within a single experiment. This format offers a unique combination of advantages, including long-term continuous flow culture, generation of concentration gradients, and single cell morphology tracking. Using Escherichia coli and the inhibitor amoxicillin as one model system, we show excellent agreement between an on-chip single cell-based assay and conventional methods to obtain quantitative measures of antibiotic inhibition (for example, minimum inhibition concentration). Furthermore, we show that our methods can provide additional information, over and above that of the standard well-plate assay, including kinetic information on growth inhibition and measurements of bacterial morphological dynamics over a wide range of inhibitor concentrations. Finally, using a second model system, we show that this chip-based systems does not require the bacteria to be labeled and is well suited for the study of naturally occurring species. We illustrate this using Nitrosomonas europaea, an environmentally important bacteria, and show that the chip system can lead to a significant reduction in the period required for growth and inhibition measurements (<4 days, compared to weeks in a culture flask).

Accelerating bacterial growth detection and antimicrobial susceptibility assessment in integrated picoliter droplet platform.

PubMed

Kaushik, Aniruddha M; Hsieh, Kuangwen; Chen, Liben; Shin, Dong Jin; Liao, Joseph C; Wang, Tza-Huei

2017-11-15

There remains an urgent need for rapid diagnostic methods that can evaluate antibiotic resistance for pathogenic bacteria in order to deliver targeted antibiotic treatments. Toward this end, we present a rapid and integrated single-cell biosensing platform, termed dropFAST, for bacterial growth detection and antimicrobial susceptibility assessment. DropFAST utilizes a rapid resazurin-based fluorescent growth assay coupled with stochastic confinement of bacteria in 20 pL droplets to detect signal from growing bacteria after 1h incubation, equivalent to 2-3 bacterial replications. Full integration of droplet generation, incubation, and detection into a single, uninterrupted stream also renders this platform uniquely suitable for in-line bacterial phenotypic growth assessment. To illustrate the concept of rapid digital antimicrobial susceptibility assessment, we employ the dropFAST platform to evaluate the antibacterial effect of gentamicin on E. coli growth. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

Hasim, Sahar; Allison, David P; Mendez, Berlin; Farmer, Abigail T; Pelletier, Dale A; Retterer, Scott T; Campagna, Shawn R; Reynolds, Todd B; Doktycz, Mitchel J

2018-01-01

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

Marine Bacterial Polysaccharide EPS11 Inhibits Cancer Cell Growth via Blocking Cell Adhesion and Stimulating Anoikis

PubMed Central

Cao, Ruobing; Jin, Weihua; Shan, Yeqi; Wang, Ju; Liu, Ge; Kuang, Shan

2018-01-01

Tumor cells that acquire metastatic potential have developed resistance to anoikis, a cell death process, after detachment from their primary site to the second organ. In this study, we investigated the molecular mechanisms of a novel marine bacterial polysaccharide EPS11 which exerts its cytotoxic effects through affecting cancer cell adhesion and anoikis. Firstly, we found that EPS11 could significantly affect cell proliferation and block cell adhesion in A549 cells. We further demonstrated that the expression of several cell adhesion associated proteins is downregulated and the filiform structures of cancer cells are destroyed after EPS11 treatment. Interestingly, the destruction of filiform structures in A549 cells by EPS11 is in a dose-dependent manner, and the inhibitory tendency is very consistent with that observed in the cell adhesion assay, which confirms that filiform structures play important roles in modulating cell adhesion. Moreover, we showed that EPS11 induces apoptosis of A549 cells through stimulating βIII-tubulin associated anoikis: (i) EPS11 inhibits the expression of βIII-tubulin in both transcription and translation levels; and (ii) EPS11 treatment dramatically decreases the phosphorylation of protein kinase B (PKB or AKT), a critical downstream effector of βIII-tubulin. Importantly, EPS11 evidently inhibits the growth of A549-derived tumor xenografts in vivo. Thus, our results suggest that EPS11 may be a potential candidate for human non-small cell lung carcinoma treatment via blocking filiform structure mediated adhesion and stimulating βIII-tubulin associated anoikis. PMID:29518055

Coupled effects of chemotaxis and growth on traveling bacterial waves.

PubMed

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Bacterial growth and the decomposition of particulate organic carbon collected in sediment traps

NASA Astrophysics Data System (ADS)

Ducklow, Hugh W.; Hill, Suzanne M.; Gardner, Wilford D.

We have studied bacterial abundance and production in samples from sediment traps deployed for 1 and 100 days in several areas of the shelf and slope regions of the Middle Atlantic Bight, U.S.A. By making a series of assumptions about bacterial growth at the expense of POC in traps, we have estimated that the turnover time of organic particles collected in traps during long deployments is slow (mean 1500 ± 300 days), if only bacterial activity is considered. However the abundance and biomass of bacteria in traps is very high, ranging from 3 to 30 × 10 11 cells gC -1, i.e., 0.3 to 3% of the POC is bacterial carbon. Fifteen to 88% of the particles in traps were colonized by bacteria, but usually about half the particles had only 0 to 1 cell attached. Growth of bacteria was observed at all scales relevant to these trap deployments; over periods ranging from hours to weeks, at rates of 0.01 to 0.3 d -1. In spite of slow growth, bacteria appeared to be physiologically active in that [ 3H]adenine and [ 3H]thymidine were incorporated more rapidly into RNA and protein than into DNA. Total incorporation rates were high. We conclude that even relatively old (ca. 1 y) POC in sediment traps supports high levels of active bacterial biomass, but that POC decomposition is slow, so that bacteria may not be the principal agents of POC turnover following collection.

Intestinal Epithelial Cells Modulate Antigen-Presenting Cell Responses to Bacterial DNA

PubMed Central

Campeau, J. L.; Salim, S. Y.; Albert, E. J.; Hotte, N.

2012-01-01

Intestinal epithelial cells and antigen-presenting cells orchestrate mucosal innate immunity. This study investigated the role of bacterial DNA in modulating epithelial and bone marrow-derived antigen-presenting cells (BM-APCs) and subsequent T-lymphocyte responses. Murine MODE-K epithelial cells and BM-APCs were treated with DNA from either Bifidobacterium breve or Salmonella enterica serovar Dublin directly and under coculture conditions with CD4+ T cells. Apical stimulation of MODE-K cells with S. Dublin DNA enhanced secretion of cytokines from underlying BM-APCs and induced interleukin-17 (IL-17) and gamma interferon (IFN-γ) secretion from CD4+ T cells. Bacterial DNA isolated from either strain induced maturation and increased cytokine secretion from BM-APCs. Conditioned medium from S. Dublin-treated MODE-K cells elicited an increase in cytokine secretion similar to that seen for S. Dublin DNA. Treatment of conditioned medium from MODE-K cells with RNase and protease prevented the S. Dublin-induced increased cytokine secretion. Oral feeding of mice with B. breve DNA resulted in enhanced levels of colonic IL-10 and transforming growth factor β (TGFβ) compared with what was seen for mice treated with S. Dublin DNA. In contrast, feeding mice with S. Dublin DNA increased levels of colonic IL-17 and IL-12p70. T cells from S. Dublin DNA-treated mice secreted high levels of IL-12 and IFN-γ compared to controls and B. breve DNA-treated mice. These results demonstrate that intestinal epithelial cells are able to modulate subsequent antigen-presenting and T-cell responses to bacterial DNA with pathogenic but not commensal bacterial DNA inducing effector CD4+ T lymphocytes. PMID:22615241

A Computer Simulation of Bacterial Growth During Food-Processing

DTIC Science & Technology

1974-11-01

1 AD A TECHNICAL REPORT A COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD PROCESSING =r= by Edward W. Ross, Jr. Approved for public...COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD - PROCESSING Edward W. Ross, Jr. Army Natick Laboratories Natick, Massachusetts Novembe...CATALOG NUMBER 4. TITLE fand SubtKUJ "A Computer Sinulatlon of Bacterial Growth During Food - Processing " 5. TYPE OF REPORT A PERIOD COVERED 6

Bacterial Cell Production from Hexadecane at High Temperatures

PubMed Central

Sukatsch, Dieter A.; Johnson, Marvin J.

1972-01-01

On mineral medium with hexadecane as the sole carbon source, stable mixed bacterial enrichment cultures were obtained from soil inoculum at 25, 35, 45, 55, and 65 C. Cell yields (grams of dry cells per gram of hexadecane) were determined for each of the enrichment cultures grown at the temperature at which they were enriched, and also for the 55 and 65 C cultures grown at various temperatures. In all cases, cell yields decreased with increasing growth temperature. The highest yield obtained at 65 C was 0.26, and the lowest yield obtained at 25 or 35 C was 1.02. Slower growth was observed at higher temperatures. PMID:5021971

Seasonal Bacterial Production in a Dimictic Lake as Measured by Increases in Cell Numbers and Thymidine Incorporation

PubMed Central

Lovell, Charles R.; Konopka, Allan

1985-01-01

Rates of primary and bacterial production in Little Crooked Lake were calculated from the rates of incorporation of H14CO3− and [methyl-3H]thymidine, respectively. Growth rates of bacteria in diluted natural samples were determined for epilimnetic and metalimnetic bacterial populations during the summers of 1982 and 1983. Exponential growth was observed in these diluted samples, with increases in cell numbers of 30 to 250%. No lag was observed in bacterial growth in 14 of 16 experiments. Correlation of bacterial growth rates to corresponding rates of thymidine incorporation by natural samples produced a conversion factor of 2.2 × 1018 cells produced per mole of thymidine incorporated. The mass of the average bacterial cell in the lake was 1.40 × 10−14 ± 0.05 × 10−14 g of C cell−1. Doubling times of natural bacteria calculated from thymidine incorporation rates and in situ cell numbers ranged from 0.35 to 12.00 days (median, 1.50 days). Bacterial production amounted to 66.7 g of C m−2 from April through September, accounting for 29.4% of total (primary plus bacterial) production during this period. The vertical and seasonal distribution of bacterial production in Little Crooked Lake was strongly influenced by the distribution of primary production. From April through September 1983, the depth of maximum bacterial production rates in the water column was related to the depth of high rates of primary production. On a seasonal basis, primary production increased steadily from May through September, and bacterial production increased from May through August and then decreased in September. PMID:16346743

Flow and active mixing have a strong impact on bacterial growth dynamics in the proximal large intestine

NASA Astrophysics Data System (ADS)

Cremer, Jonas; Segota, Igor; Yang, Chih-Yu; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

2016-11-01

More than half of fecal dry weight is bacterial mass with bacterial densities reaching up to 1012 cells per gram. Mostly, these bacteria grow in the proximal large intestine where lateral flow along the intestine is strong: flow can in principal lead to a washout of bacteria from the proximal large intestine. Active mixing by contractions of the intestinal wall together with bacterial growth might counteract such a washout 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. 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. Based on this model, we discuss bacterial growth dynamics in the human large intestine using flow- and mixing-behavior having been observed for humans.

Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica.

PubMed

Grossmann, S; Dieckmann, G S

1994-08-01

Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 x 10 to 3 x 10 liter, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low concentrations of phytoplankton in the water column during freezing, incorporation of bacteria into newly formed ice via attachment to algal cells or aggregates was not recorded in this study. As soon as the ice had formed, the general metabolic activity of bacterial populations was strongly suppressed. Furthermore, the ratio of [H]leucine incorporation into proteins to [H]thymidine incorporation into DNA changed during ice growth. In thick pack ice, bacterial activity recovered and growth rates up to 0.6 day indicated actively dividing populations. However, biomass-specific utilization of organic compounds remained lower than in open water. Bacterial concentrations of up to 2.8 x 10 cells liter along with considerably enlarged cell volumes accumulated within thick pack ice, suggesting reduced mortality rates of bacteria within the small brine pores. In the course of ice development, bacterial carbon production increased from about 0.01 to 0.4 mug of C liter h. In thick ice, bacterial secondary production exceeded primary production of microalgae.

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

DOE PAGES

Hasim, Sahar; Allison, David P.; Mendez, Berlin; ...

2018-02-14

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasim, Sahar; Allison, David P.; Mendez, Berlin

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

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)

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.

Stable Regulation of Cell Cycle Events in Mycobacteria: Insights From Inherently Heterogeneous Bacterial Populations.

PubMed

Logsdon, Michelle M; Aldridge, Bree B

2018-01-01

Model bacteria, such as E. coli and B. subtilis , tightly regulate cell cycle progression to achieve consistent cell size distributions and replication dynamics. Many of the hallmark features of these model bacteria, including lateral cell wall elongation and symmetric growth and division, do not occur in mycobacteria. Instead, mycobacterial growth is characterized by asymmetric polar growth and division. This innate asymmetry creates unequal birth sizes and growth rates for daughter cells with each division, generating a phenotypically heterogeneous population. Although the asymmetric growth patterns of mycobacteria lead to a larger variation in birth size than typically seen in model bacterial populations, the cell size distribution is stable over time. Here, we review the cellular mechanisms of growth, division, and cell cycle progression in mycobacteria in the face of asymmetry and inherent heterogeneity. These processes coalesce to control cell size. Although Mycobacterium smegmatis and Mycobacterium bovis Bacillus Calmette-Guérin (BCG) utilize a novel model of cell size control, they are similar to previously studied bacteria in that initiation of DNA replication is a key checkpoint for cell division. We compare the regulation of DNA replication initiation and strategies used for cell size homeostasis in mycobacteria and model bacteria. Finally, we review the importance of cellular organization and chromosome segregation relating to the physiology of mycobacteria and consider how new frameworks could be applied across the wide spectrum of bacterial diversity.

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.

Bacterial safety of cell-based therapeutic preparations, focusing on haematopoietic progenitor cells.

PubMed

Störmer, M; Wood, E M; Schurig, U; Karo, O; Spreitzer, I; McDonald, C P; Montag, T

2014-05-01

Bacterial safety of cellular preparations, especially haematopoietic progenitor cells (HPCs), as well as advanced therapy medicinal products (ATMPs) derived from stem cells of various origins, present a challenge for physicians, manufacturers and regulators. The article describes the background and practical issues in this area and illustrates why sterility of these products cannot currently be guaranteed. Advantages and limitations of approaches both for classical sterility testing and for microbiological control using automated culture systems are discussed. The review considers novel approaches for growth-based rapid microbiological control with high sensitivity and faster availability of results, as well as new methods for rapid bacterial detection in cellular preparations enabling meaningful information about product contamination within one to two hours. Generally, however, these direct rapid methods are less sensitive and have greater sampling error compared with the growth-based methods. Opportunities for pyrogen testing of cell therapeutics are also discussed. There is an urgent need for development of novel principles and methods applicable to bacterial safety of cellular therapeutics. We also need a major shift in approach from the traditional view of sterility evaluation (identify anything and everything) to a new thinking about how to find what is clinically relevant within the time frame available for the special clinical circumstances in which these products are used. The review concludes with recommendations for optimization of microbiological control of cellular preparations, focusing on HPCs. © 2013 International Society of Blood Transfusion.

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

PubMed

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

2014-01-01

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

Effect of bacterial growth rate on bacteriophage population growth rate.

PubMed

Nabergoj, Dominik; Modic, Petra; Podgornik, Aleš

2018-04-01

It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well-studied phage T4 and Escherichia coli K-12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr -1 . It was found that the burst size increases linearly from 8 PFU·cell -1 to 89 PFU·cell -1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10 -9  ml·min -1 and 80 min to reach limiting values of 0.5 × 10 -9  ml·min -1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis-Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr -1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Antibacterial effect of silver nanoparticles and the modeling of bacterial growth kinetics using a modified Gompertz model.

PubMed

Chatterjee, Tanaya; Chatterjee, Barun K; Majumdar, Dipanwita; Chakrabarti, Pinak

2015-02-01

An alternative to conventional antibiotics is needed to fight against emerging multiple drug resistant pathogenic bacteria. In this endeavor, the effect of silver nanoparticle (Ag-NP) has been studied quantitatively on two common pathogenic bacteria Escherichia coli and Staphylococcus aureus, and the growth curves were modeled. The effect of Ag-NP on bacterial growth kinetics was studied by measuring the optical density, and was fitted by non-linear regression using the Logistic and modified Gompertz models. Scanning Electron Microscopy and fluorescence microscopy were used to study the morphological changes of the bacterial cells. Generation of reactive oxygen species for Ag-NP treated cells were measured by fluorescence emission spectra. The modified Gompertz model, incorporating cell death, fits the observed data better than the Logistic model. With increasing concentration of Ag-NP, the growth kinetics of both bacteria shows a decline in growth rate with simultaneous enhancement of death rate constants. The duration of the lag phase was found to increase with Ag-NP concentration. SEM showed morphological changes, while fluorescence microscopy using DAPI showed compaction of DNA for Ag-NP-treated bacterial cells. E. coli was found to be more susceptible to Ag-NP as compared to S. aureus. The modified Gompertz model, using a death term, was found to be useful in explaining the non-monotonic nature of the growth curve. The modified Gompertz model derived here is of general nature and can be used to study any microbial growth kinetics under the influence of antimicrobial agents. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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

PubMed

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

2017-01-01

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

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

PubMed Central

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

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications. PMID:29117218

Adaptive self-organization during growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Ben-Jacob, Eshel; Shmueli, Haim; Shochet, Ofer; Tenenbaum, Adam

1992-09-01

We present a study of interfacial pattern formation during diffusion-limited growth of Bacillus subtilis. It is demonstrated that bacterial colonies can develop patterns similar to morphologies observed during diffusion-limited growth in non-living (azoic) systems such as solidification and electro-chemical deposition. The various growth morphologies, that is the global structure of the colony, are observed as we vary the growth conditions. These include fractal growth, dense-branching growth, compact growth, dendritic growth and chiral growth. The results demonstrate the action of a singular interplay between the micro-level (individual bacterium) and macro-level (the colony) in selecting the observed morphologies as is understood for non-living systems. Furthermore, the observed morphologies can be organized within a morphology diagram indicating the existence of a morphology selection principle similar to the one proposed for azoic systems. We propose a phase-field-like model (the phase being the bacterial concentration and the field being the nutrient concentration) to describe the growth. The bacteria-bacteria interaction is manifested as a phase dependent diffusion constant. Growth of a bacterial colony presents an inherent additional level of complexity compared to azoic systems, since the building blocks themselves are living systems. Thus, our studies also focus on the transition between morphologies. We have observed extended morphology transitions due to phenotypic changes of the bacteria, as well as bursts of new morphologies resulting from genotypic changes. In addition, we have observed extended and heritable transitions (mainly between dense branching growth and chiral growth) as well as phenotypic transitions that turn genotypic over time. We discuss the implications of our results in the context of the evolving picture of genome cybernetics. Diffusion limited growth of bacterial colonies combined with new understanding of pattern formation in azoic

Colon-targeted delivery of live bacterial cell biotherapeutics including microencapsulated live bacterial cells

PubMed Central

Prakash, Satya; Malgorzata Urbanska, Aleksandra

2008-01-01

There has been an ample interest in delivery of therapeutic molecules using live cells. Oral delivery has been stipulated as best way to deliver live cells to humans for therapy. Colon, in particular, is a part of gastrointestinal (GI) tract that has been proposed to be an oral targeted site. The main objective of these oral therapy procedures is to deliver live cells not only to treat diseases like colorectal cancer, inflammatory bowel disease, and other GI tract diseases like intestinal obstruction and gastritis, but also to deliver therapeutic molecules for overall therapy in various diseases such as renal failure, coronary heart disease, hypertension, and others. This review provides a comprehensive summary of recent advancement in colon targeted live bacterial cell biotherapeutics. Current status of bacterial cell therapy, principles of artificial cells and its potentials in oral delivery of live bacterial cell biotherapeutics for clinical applications as well as biotherapeutic future perspectives are also discussed in our review. PMID:19707368

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

PubMed

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

2014-07-01

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. 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. 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. 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. 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.

Evaluating the 4-hour and 30-minute rules: effects of room temperature exposure on red blood cell quality and bacterial growth.

PubMed

Ramirez-Arcos, Sandra; Mastronardi, Cherie; Perkins, Heather; Kou, Yuntong; Turner, Tracey; Mastronardi, Emily; Hansen, Adele; Yi, Qi-Long; McLaughlin, Natasha; Kahwash, Eiad; Lin, Yulia; Acker, Jason

2013-04-01

A 30-minute rule was established to limit red blood cell (RBC) exposure to uncontrolled temperatures during storage and transportation. Also, RBC units issued for transfusion should not remain at room temperature (RT) for more than 4 hours (4-hour rule). This study was aimed at determining if single or multiple RT exposures affect RBC quality and/or promote bacterial growth. Growth and RT exposure experiments were performed in RBCs inoculated with Serratia liquefaciens and Serratia marcescens. RBCs were exposed once to RT for 5 hours (S. liquefaciens) or five times to RT for 30 minutes (S. marcescens) with periodic sampling for bacterial counts. Noncontaminated units were exposed to RT once (5 hr) or five times (30 min each) and sampled to measure in vitro quality variables. RBC core temperature was monitored using mock units with temperature loggers. Growth and RT exposure experiments were repeated three and at least six times, respectively. Statistical analysis was done using mixed-model analysis. RBC core temperature ranged from 7.3 to 11.6°C during 30-minute RT exposures and the time to reach 10°C varied from 22 to 55 minutes during 5-hour RT exposures. RBC quality was preserved after single or multiple RT exposures. Increased growth of S. liquefaciens was only observed after 2 hours of continuous RT exposure. S. marcescens concentration increased significantly in multiple-exposed units compared to the controls but did not reach clinically important levels. Single or multiple RT exposures did not affect RBC quality but slightly promoted bacterial growth in contaminated units. The clinical significance of these results remains unclear and needs further investigation. © 2012 American Association of Blood Banks.

Menaquinone analogs inhibit growth of bacterial pathogens.

PubMed

Schlievert, Patrick M; Merriman, Joseph A; Salgado-Pabón, Wilmara; Mueller, Elizabeth A; Spaulding, Adam R; Vu, Bao G; Chuang-Smith, Olivia N; Kohler, Petra L; Kirby, John R

2013-11-01

Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents.

Bacterial Cell Enlargement Requires Control of Cell Wall Stiffness Mediated by Peptidoglycan Hydrolases.

PubMed

Wheeler, Richard; Turner, Robert D; Bailey, Richard G; Salamaga, Bartłomiej; Mesnage, Stéphane; Mohamad, Sharifah A S; Hayhurst, Emma J; Horsburgh, Malcolm; Hobbs, Jamie K; Foster, Simon J

2015-07-28

Most bacterial cells are enclosed in a single macromolecule of the cell wall polymer, peptidoglycan, which is required for shape determination and maintenance of viability, while peptidoglycan biosynthesis is an important antibiotic target. It is hypothesized that cellular enlargement requires regional expansion of the cell wall through coordinated insertion and hydrolysis of peptidoglycan. Here, a group of (apparent glucosaminidase) peptidoglycan hydrolases are identified that are together required for cell enlargement and correct cellular morphology of Staphylococcus aureus, demonstrating the overall importance of this enzyme activity. These are Atl, SagA, ScaH, and SagB. The major advance here is the explanation of the observed morphological defects in terms of the mechanical and biochemical properties of peptidoglycan. It was shown that cells lacking groups of these hydrolases have increased surface stiffness and, in the absence of SagB, substantially increased glycan chain length. This indicates that, beyond their established roles (for example in cell separation), some hydrolases enable cellular enlargement by making peptidoglycan easier to stretch, providing the first direct evidence demonstrating that cellular enlargement occurs via modulation of the mechanical properties of peptidoglycan. Understanding bacterial growth and division is a fundamental problem, and knowledge in this area underlies the treatment of many infectious diseases. Almost all bacteria are surrounded by a macromolecule of peptidoglycan that encloses the cell and maintains shape, and bacterial cells must increase the size of this molecule in order to enlarge themselves. This requires not only the insertion of new peptidoglycan monomers, a process targeted by antibiotics, including penicillin, but also breakage of existing bonds, a potentially hazardous activity for the cell. Using Staphylococcus aureus, we have identified a set of enzymes that are critical for cellular enlargement. We

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Cassandra E.; Beri, Nina R.; Gardner, Jeffrey G.

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interactionmore » between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. Furthermore, we applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present.« less

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates

DOE PAGES

Nelson, Cassandra E.; Beri, Nina R.; Gardner, Jeffrey G.

2016-09-21

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interactionmore » between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. Furthermore, we applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present.« less

Effects of Fe nanoparticles on bacterial growth and biosurfactant production

NASA Astrophysics Data System (ADS)

Liu, Jia; Vipulanandan, Cumaraswamy; Cooper, Tim F.; Vipulanandan, Geethanjali

2013-01-01

Environmental conditions can have a major impact on bacterial growth and production of secondary products. In this study, the effect of different concentrations of Fe nanoparticles on the growth of Serratia sp. and on its production of a specific biosurfactant was investigated. The Fe nanoparticles were produced using the foam method, and the needle-shaped nanoparticles were about 30 nm in diameter. It was found that Fe nanoparticles can have either a positive or a negative impact on the bacterial growth and biosurfactant production, depending on their concentration. At 1 mg/L of Fe nanoparticle concentration the bacterial growth increased by 57 % and biosurfactant production increased by 63 %. When the Fe nanoparticle concentration was increased to 1 g/L, the bacterial growth decreased by 77 % and biosurfactant activity was undetectable. The biosurfactant itself was not directly affected by Fe nanoparticles over the range of concentrations studied, indicating that the observed changes in biosurfactant activity resulted indirectly from the effect of nanoparticles on the bacteria. These negative effects with nanoparticle exposures were temporary, demonstrated by the restoration of biosurfactant activity when the bacteria initially exposed to Fe nanoparticles were allowed to regrow in the absence of nanoparticles. Finally, the kinetics of bacterial growth and biosurfactant production were modeled. The model's predictions agreed with the experimental results.

Chemical interference with iron transport systems to suppress bacterial growth of Streptococcus pneumoniae.

PubMed

Yang, Xiao-Yan; Sun, Bin; 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.

Polyamine is a critical determinant of Pseudomonas chlororaphis O6 for GacS-dependent bacterial cell growth and biocontrol capacity.

PubMed

Park, Ju Yeon; Kang, Beom Ryong; Ryu, Choong-Min; Anderson, Anne J; Kim, Young Cheol

2018-05-01

The Gac/Rsm network regulates, at the transcriptional level, many beneficial traits in biocontrol-active pseudomonads. In this study, we used Phenotype MicroArrays, followed by specific growth studies and mutational analysis, to understand how catabolism is regulated by this sensor kinase system in the biocontrol isolate Pseudomonas chlororaphis O6. The growth of a gacS mutant was decreased significantly relative to that of the wild-type on ornithine and arginine, and on the precursor of these amino acids, N-acetyl-l-glutamic acid. The gacS mutant also showed reduced production of polyamines. Expression of the genes encoding arginine decarboxylase (speA) and ornithine decarboxylases (speC) was controlled at the transcriptional level by the GacS sensor of P. chlororaphis O6. Polyamine production was reduced in the speC mutant, and was eliminated in the speAspeC mutant. The addition of exogenous polyamines to the speAspeC mutant restored the in vitro growth inhibition of two fungal pathogens, as well as the secretion of three biological control-related factors: pyrrolnitrin, protease and siderophore. These results extend our knowledge of the regulation by the Gac/Rsm network in a biocontrol pseudomonad to include polyamine synthesis. Collectively, our studies demonstrate that bacterial polyamines act as important regulators of bacterial cell growth and biocontrol potential. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Spatial and temporal features of the growth of a bacterial species colonizing the zebrafish gut.

PubMed

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

2014-12-16

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. Our intestines are home to vast numbers of microbes that influence many aspects of health and disease. Though we now know a great deal about the constituents of the gut microbiota, we understand very little about their spatial structure and temporal dynamics in humans or in any animal: how microbial populations establish themselves, grow, fluctuate, and persist. To address this, we made use of a model organism, the zebrafish, and a new optical imaging technique, light sheet fluorescence microscopy

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates.

PubMed

Nelson, Cassandra E; Beri, Nina R; Gardner, Jeffrey G

2016-11-01

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interaction between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. We applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present. Copyright © 2016 Elsevier B.V. All rights reserved.

Growth of bacterial phytopathogens in animal manures.

PubMed

Sledz, Wojciech; Zoledowska, Sabina; Motyka, Agata; Kadziński, Leszek; Banecki, Bogdan

2017-01-01

Animal manures are routinely applied to agricultural lands to improve crop yield, but the possibility to spread bacterial phytopathogens through field fertilization has not been considered yet. We monitored 49 cattle, horse, swine, sheep or chicken manure samples collected in 14 Polish voivodeships for the most important plant pathogenic bacteria - Ralstonia solanacearum (Rsol), Xanthomonas campestris pv. campestris (Xcc), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pectobacterium atrosepticum (Pba), Erwinia amylovora (Eam), Clavibacter michiganensis subsp. sepedonicus (Cms) and Dickeya sp. (Dsp). All of the tested animal fertilizers were free of these pathogens. Subsequently, the growth dynamics of Pba, Pcc, Rsol, and Xcc in cattle, horse, swine, sheep and chicken manures sterilized either by autoclaving or filtration was evaluated. The investigated phytopathogens did not exhibit any growth in the poultry manure. However, the manure filtrates originating from other animals were suitable for microbial growth, which resulted in the optical density change of 0.03-0.22 reached within 26 h (48 h Rsol, 120 h Xcc), depending on bacterial species and the manure source. Pcc and Pba multiplied most efficiently in the cattle manure filtrate. These bacteria grew faster than Rsol and Xcc in all the tested manure samples, both the filtrates and the autoclaved semi-solid ones. Though the growth dynamics of investigated strains in different animal fertilizers was unequal, all of the tested bacterial plant pathogens were proven to use cattle, horse, swine and sheep manures as the sources of nutrients. These findings may contribute to further research on the alternative routes of spread of bacterial phytopathogens, especially because of the fact that the control of pectionolytic bacteria is only based on preventive methods.

Stochastic Individual-Based Modeling of Bacterial Growth and Division Using Flow Cytometry.

PubMed

García, Míriam R; Vázquez, José A; Teixeira, Isabel G; Alonso, Antonio A

2017-01-01

A realistic description of the variability in bacterial growth and division is critical to produce reliable predictions of safety risks along the food chain. Individual-based modeling of bacteria provides the theoretical framework to deal with this variability, but it requires information about the individual behavior of bacteria inside populations. In this work, we overcome this problem by estimating the individual behavior of bacteria from population statistics obtained with flow cytometry. For this objective, a stochastic individual-based modeling framework is defined based on standard assumptions during division and exponential growth. The unknown single-cell parameters required for running the individual-based modeling simulations, such as cell size growth rate, are estimated from the flow cytometry data. Instead of using directly the individual-based model, we make use of a modified Fokker-Plank equation. This only equation simulates the population statistics in function of the unknown single-cell parameters. We test the validity of the approach by modeling the growth and division of Pediococcus acidilactici within the exponential phase. Estimations reveal the statistics of cell growth and division using only data from flow cytometry at a given time. From the relationship between the mother and daughter volumes, we also predict that P. acidilactici divide into two successive parallel planes.

Glycerol Monolaurate Inhibits Lipase Production by Clinical Ocular Isolates Without Affecting Bacterial Cell Viability.

PubMed

Flanagan, Judith Louise; Khandekar, Neeta; Zhu, Hua; Watanabe, Keizo; Markoulli, Maria; Flanagan, John Terence; Papas, Eric

2016-02-01

We sought to determine the relative lipase production of a range of ocular bacterial isolates and to assess the efficacy of glycerol monolaurate (GML) in inhibiting this lipase production in high lipase-producing bacteria without affecting bacterial cell growth. Staphylococcus aureus,Staphylococcus epidermidis,Propionibacterium acnes, and Corynebacterium spp. were inoculated at a density of 10(6)/mL in varying concentrations of GML up to 25 μg/mL for 24 hours at 37 °C with constant shaking. Bacterial suspensions were centrifuged, bacterial cell density was determined, and production of bacterial lipase was quantified using a commercial lipase assay kit. Staphylococcus spp. produced high levels of lipase activity compared with P. acnes and Corynebacterium spp. GML inhibited lipase production by Staphylococcal spp. in a dose-dependent manner, with S. epidermidis lipase production consistently more sensitive to GML than S. aureus. Glycerol monolaurate showed significant (P < 0.05) lipase inhibition above concentrations of 15 μg/mL in S. aureus and was not cytotoxic up to 25 μg/mL. For S. epidermidis, GML showed significant (P < 0.05) lipase inhibition above 7.5 μg/mL. Lipase activity varied between species and between strains. Staphylococcal spp. produced higher lipase activity compared with P. acnes and Corynebacterium spp. Glycerol monolaurate inhibited lipase production by S. aureus and S. epidermidis at concentrations that did not adversely affect bacterial cell growth. GML can be used to inhibit ocular bacterial lipase production without proving detrimental to commensal bacteria viability.

A brief history of bacterial growth physiology.

PubMed

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.

Analytic derivation of bacterial growth laws from a simple model of intracellular chemical dynamics.

PubMed

Pandey, Parth Pratim; Jain, Sanjay

2016-09-01

Experiments have found that the growth rate and certain other macroscopic properties of bacterial cells in steady-state cultures depend upon the medium in a surprisingly simple manner; these dependencies are referred to as 'growth laws'. Here we construct a dynamical model of interacting intracellular populations to understand some of the growth laws. The model has only three population variables: an amino acid pool, a pool of enzymes that transport an external nutrient and produce the amino acids, and ribosomes that catalyze their own and the enzymes' production from the amino acids. We assume that the cell allocates its resources between the enzyme sector and the ribosomal sector to maximize its growth rate. We show that the empirical growth laws follow from this assumption and derive analytic expressions for the phenomenological parameters in terms of the more basic model parameters. Interestingly, the maximization of the growth rate of the cell as a whole implies that the cell allocates resources to the enzyme and ribosomal sectors in inverse proportion to their respective 'efficiencies'. The work introduces a mathematical scheme in which the cellular growth rate can be explicitly determined and shows that two large parameters, the number of amino acid residues per enzyme and per ribosome, are useful for making approximations.

Rapid Method of Determining Factors Limiting Bacterial Growth in Soil

PubMed Central

Aldén, L.; Demoling, F.; Bååth, E.

2001-01-01

A technique to determine which nutrients limit bacterial growth in soil was developed. The method was based on measuring the thymidine incorporation rate of bacteria after the addition of C, N, and P in different combinations to soil samples. First, the thymidine incorporation method was tested in two different soils: an agricultural soil and a forest humus soil. Carbon (as glucose) was found to be the limiting substance for bacterial growth in both of these soils. The effect of adding different amounts of nutrients was studied, and tests were performed to determine whether the additions affected the soil pH and subsequent bacterial activity. The incubation time required to detect bacterial growth after adding substrate to the soil was also evaluated. Second, the method was used in experiments in which three different size fractions of straw (1 to 2, 0.25 to 1, and <0.25 mm) were mixed into the agricultural soil in order to induce N limitation for bacterial growth. When the straw fraction was small enough (<0.25 mm), N became the limiting nutrient for bacterial growth after about 3 weeks. After the addition of the larger straw fractions (1 to 2 and 0.25 to 1 mm), the soil bacteria were C limited throughout the incubation period (10 weeks), although an increase in the thymidine incorporation rate after the addition of C and N together compared with adding them separately was seen in the sample containing the size fraction from 0.25 to 1 mm. Third, soils from high-pH, limestone-rich areas were examined. P limitation was observed in one of these soils, while tendencies toward P limitation were seen in some of the other soils. PMID:11282640

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.

Single-Cell Microfluidics to Study the Effects of Genome Deletion on Bacterial Growth Behavior.

PubMed

Yuan, Xiaofei; Couto, Jillian M; Glidle, Andrew; Song, Yanqing; Sloan, William; Yin, Huabing

2017-12-15

By directly monitoring single cell growth in a microfluidic platform, we interrogated genome-deletion effects in Escherichia coli strains. We compared the growth dynamics of a wild type strain with a clean genome strain, and their derived mutants at the single-cell level. A decreased average growth rate and extended average lag time were found for the clean genome strain, compared to those of the wild type strain. Direct correlation between the growth rate and lag time of individual cells showed that the clean genome population was more heterogeneous. Cell culturability (the ratio of growing cells to the sum of growing and nongrowing cells) of the clean genome population was also lower. Interestingly, after the random mutations induced by a glucose starvation treatment, for the clean genome population mutants that had survived the competition of chemostat culture, each parameter markedly improved (i.e., the average growth rate and cell culturability increased, and the lag time and heterogeneity decreased). However, this effect was not seen in the wild type strain; the wild type mutants cultured in a chemostat retained a high diversity of growth phenotypes. These results suggest that quasi-essential genes that were deleted in the clean genome might be required to retain a diversity of growth characteristics at the individual cell level under environmental stress. These observations highlight that single-cell microfluidics can reveal subtle individual cellular responses, enabling in-depth understanding of the population.

Modeling the cost and benefit of proteome regulation in a growing bacterial cell

NASA Astrophysics Data System (ADS)

Sharma, Pooja; Pratim Pandey, Parth; Jain, Sanjay

2018-07-01

Escherichia coli cells differentially regulate the production of metabolic and ribosomal proteins in order to stay close to an optimal growth rate in different environments, and exhibit the bacterial growth laws as a consequence. We present a simple mathematical model of a growing-dividing cell in which an internal dynamical mechanism regulates the allocation of proteomic resources between different protein sectors. The model allows an endogenous determination of the growth rate of the cell as a function of cellular and environmental parameters, and reproduces the bacterial growth laws. We use the model and its variants to study the balance between the cost and benefit of regulation. A cost is incurred because cellular resources are diverted to produce the regulatory apparatus. We show that there is a window of environments or a ‘niche’ in which the unregulated cell has a higher fitness than the regulated cell. Outside this niche there is a large space of constant and time varying environments in which regulation is an advantage. A knowledge of the ‘niche boundaries’ allows one to gain an intuitive understanding of the class of environments in which regulation is an advantage for the organism and which would therefore favour the evolution of regulation. The model allows us to determine the ‘niche boundaries’ as a function of cellular parameters such as the size of the burden of the regulatory apparatus. This class of models may be useful in elucidating various tradeoffs in cells and in making in-silico predictions relevant for synthetic biology.

Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems.

PubMed

Duedu, Kwabena O; French, Christopher E

2017-04-01

Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris. Colony counting enumerates live cells but the process is laborious and not suitable for large numbers of samples. Enumeration of live bacteria by flow cytometry is a more suitable rapid method with the use of dual staining with SYBR I Green nucleic acid gel stain and Propidium Iodide (SYBR-I/PI). Flow cytometry equipment and maintenance costs however are relatively high and this technique is unavailable in many laboratories that may require a rapid method for evaluating bacteria growth. We therefore sought to adapt and evaluate the SYBR-I/PI technique of enumerating live bacterial cells for a cheaper platform, a fluorimeter. The fluorimetry adapted SYBR-I/PI enumeration of bacteria in turbid growth media had direct correlations with OD600 (p>0.001). To enable comparison of fluorescence results across labs and instruments, a fluorescence intensity standard unit, the equivalent fluorescent DNA (EFD) was proposed, evaluated and found useful. The technique was further evaluated for its usefulness in enumerating bacteria in turbid media containing insoluble particles. Reproducible results were obtained which OD600 could not give. An alternative method based on the assessment of total protein using the Pierce Coomassie Plus (Bradford) Assay was also evaluated and compared. In all, the SYBR-I/PI method was found to be the quickest and most reliable. The protocol is potentially useful for high-throughput applications such as

Impact of electro-stimulation on denitrifying bacterial growth and analysis of bacterial growth kinetics using a modified Gompertz model in a bio-electrochemical denitrification reactor.

PubMed

Liu, Hengyuan; Chen, Nan; Feng, Chuanping; Tong, Shuang; Li, Rui

2017-05-01

This study aimed to investigate the effect of electro-stimulation on denitrifying bacterial growth in a bio-electrochemical reactor, and the growth were modeled using modified Gompertz model under different current densities at three C/Ns. It was found that the similar optimum current density of 250mA/m 2 was obtained at C/N=0.75, 1.00 and 1.25, correspondingly the maximum nitrate removal efficiencies were 98.0%, 99.2% and 99.9%. Moreover, ATP content and cell membrane permeability of denitrifying bacteria were significantly increased at optimum current density. Furthermore, modified Gompertz model fitted well with the microbial growth curves, and the highest maximum growth rates (µ max ) and shorter lag time were obtained at the optimum current density for all C/Ns. This study demonstrated that the modified Gompertz model could be used for describing microbial growth under different current densities and C/Ns in a bio-electrochemical denitrification reactor, and it provided an alternative for improving the performance of denitrification process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Targeting of a chlamydial protease impedes intracellular bacterial growth.

PubMed

Christian, Jan G; Heymann, Julia; Paschen, Stefan A; Vier, Juliane; Schauenburg, Linda; Rupp, Jan; Meyer, Thomas F; Häcker, Georg; Heuer, Dagmar

2011-09-01

Chlamydiae are obligate intracellular bacteria that propagate in a cytosolic vacuole. Recent work has shown that growth of Chlamydia induces the fragmentation of the Golgi apparatus (GA) into ministacks, which facilitates the acquisition of host lipids into the growing inclusion. GA fragmentation results from infection-associated cleavage of the integral GA protein, golgin-84. Golgin-84-cleavage, GA fragmentation and growth of Chlamydia trachomatis can be blocked by the peptide inhibitor WEHD-fmk. Here we identify the bacterial protease chlamydial protease-like activity factor (CPAF) as the factor mediating cleavage of golgin-84 and as the target of WEHD-fmk-inhibition. WEHD-fmk blocked cleavage of golgin-84 as well as cleavage of known CPAF targets during infection with C. trachomatis and C. pneumoniae. The same effect was seen when active CPAF was expressed in non-infected cells and in a cell-free system. Ectopic expression of active CPAF in non-infected cells was sufficient for GA fragmentation. GA fragmentation required the small GTPases Rab6 and Rab11 downstream of CPAF-activity. These results define CPAF as the first protein that is essential for replication of Chlamydia. We suggest that this role makes CPAF a potential anti-infective therapeutic target.

Changes in the bacterial community of soybean rhizospheres during growth in the field.

PubMed

Sugiyama, Akifumi; Ueda, Yoshikatsu; Zushi, Takahiro; Takase, Hisabumi; Yazaki, Kazufumi

2014-01-01

Highly diverse communities of bacteria inhabiting soybean rhizospheres play pivotal roles in plant growth and crop production; however, little is known about the changes that occur in these communities during growth. We used both culture-dependent physiological profiling and culture independent DNA-based approaches to characterize the bacterial communities of the soybean rhizosphere during growth in the field. The physiological properties of the bacterial communities were analyzed by a community-level substrate utilization assay with BioLog Eco plates, and the composition of the communities was assessed by gene pyrosequencing. Higher metabolic capabilities were found in rhizosphere soil than in bulk soil during all stages of the BioLog assay. Pyrosequencing analysis revealed that differences between the bacterial communities of rhizosphere and bulk soils at the phylum level; i.e., Proteobacteria were increased, while Acidobacteria and Firmicutes were decreased in rhizosphere soil during growth. Analysis of operational taxonomic units showed that the bacterial communities of the rhizosphere changed significantly during growth, with a higher abundance of potential plant growth promoting rhizobacteria, including Bacillus, Bradyrhizobium, and Rhizobium, in a stage-specific manner. These findings demonstrated that rhizosphere bacterial communities were changed during soybean growth in the field.

Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

PubMed

Monick, Martha M; 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

2013-06-01

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. 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/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). 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. 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.

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

Rod-like bacterial shape is maintained by feedback between cell curvature and cytoskeletal localization

PubMed Central

Ursell, Tristan S.; Nguyen, Jeffrey; Monds, Russell D.; Colavin, Alexandre; Billings, Gabriel; Ouzounov, Nikolay; Gitai, Zemer; Shaevitz, Joshua W.; Huang, Kerwyn Casey

2014-01-01

Cells typically maintain characteristic shapes, but the mechanisms of self-organization for robust morphological maintenance remain unclear in most systems. Precise regulation of rod-like shape in Escherichia coli cells requires the MreB actin-like cytoskeleton, but the mechanism by which MreB maintains rod-like shape is unknown. Here, we use time-lapse and 3D imaging coupled with computational analysis to map the growth, geometry, and cytoskeletal organization of single bacterial cells at subcellular resolution. Our results demonstrate that feedback between cell geometry and MreB localization maintains rod-like cell shape by targeting cell wall growth to regions of negative cell wall curvature. Pulse-chase labeling indicates that growth is heterogeneous and correlates spatially and temporally with MreB localization, whereas MreB inhibition results in more homogeneous growth, including growth in polar regions previously thought to be inert. Biophysical simulations establish that curvature feedback on the localization of cell wall growth is an effective mechanism for cell straightening and suggest that surface deformations caused by cell wall insertion could direct circumferential motion of MreB. Our work shows that MreB orchestrates persistent, heterogeneous growth at the subcellular scale, enabling robust, uniform growth at the cellular scale without requiring global organization. PMID:24550515

Diversity in ATP concentrations in a single bacterial cell population revealed by quantitative single-cell imaging

PubMed Central

Yaginuma, Hideyuki; Kawai, Shinnosuke; Tabata, Kazuhito V.; Tomiyama, Keisuke; Kakizuka, Akira; Komatsuzaki, Tamiki; Noji, Hiroyuki; Imamura, Hiromi

2014-01-01

Recent advances in quantitative single-cell analysis revealed large diversity in gene expression levels between individual cells, which could affect the physiology and/or fate of each cell. In contrast, for most metabolites, the concentrations were only measureable as ensemble averages of many cells. In living cells, adenosine triphosphate (ATP) is a critically important metabolite that powers many intracellular reactions. Quantitative measurement of the absolute ATP concentration in individual cells has not been achieved because of the lack of reliable methods. In this study, we developed a new genetically-encoded ratiometric fluorescent ATP indicator “QUEEN”, which is composed of a single circularly-permuted fluorescent protein and a bacterial ATP binding protein. Unlike previous FRET-based indicators, QUEEN was apparently insensitive to bacteria growth rate changes. Importantly, intracellular ATP concentrations of numbers of bacterial cells calculated from QUEEN fluorescence were almost equal to those from firefly luciferase assay. Thus, QUEEN is suitable for quantifying the absolute ATP concentration inside bacteria cells. Finally, we found that, even for a genetically-identical Escherichia coli cell population, absolute concentrations of intracellular ATP were significantly diverse between individual cells from the same culture, by imaging QUEEN signals from single cells. PMID:25283467

Effect of human milk fortifiers on bacterial growth in human milk.

PubMed

Santiago, Myla S; Codipilly, Champa N; Potak, Debra C; Schanler, Richard J

2005-10-01

As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC). TBCC did not differ between groups but declined from 0 to 72 hours, p<0.001. These data suggest that differences in iron content, or other nutrients in HMF, do not affect bacterial growth in human milk. Storage of fortified human milk at refrigerator temperature for 72 hours results in decreased bacterial growth. As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC).

Trafficking and processing of bacterial proteins by mammalian cells: Insights from chondroitinase ABC.

PubMed

Muir, Elizabeth; Raza, Mansoor; Ellis, Clare; Burnside, Emily; Love, Fiona; Heller, Simon; Elliot, Matthew; Daniell, Esther; Dasgupta, Debayan; Alves, Nuno; Day, Priscilla; Fawcett, James; Keynes, Roger

2017-01-01

There is very little reported in the literature about the relationship between modifications of bacterial proteins and their secretion by mammalian cells that synthesize them. We previously reported that the secretion of the bacterial enzyme Chondroitinase ABC by mammalian cells requires the strategic removal of at least three N-glycosylation sites. The aim of this study was to determine if it is possible to enhance the efficacy of the enzyme as a treatment for spinal cord injury by increasing the quantity of enzyme secreted or by altering its cellular location. To determine if the efficiency of enzyme secretion could be further increased, cells were transfected with constructs encoding the gene for chondroitinase ABC modified for expression by mammalian cells; these contained additional modifications of strategic N-glycosylation sites or alternative signal sequences to direct secretion of the enzyme from the cells. We show that while removal of certain specific N-glycosylation sites enhances enzyme secretion, N-glycosylation of at least two other sites, N-856 and N-773, is essential for both production and secretion of active enzyme. Furthermore, we find that the signal sequence directing secretion also influences the quantity of enzyme secreted, and that this varies widely amongst the cell types tested. Last, we find that replacing the 3'UTR on the cDNA encoding Chondroitinase ABC with that of β-actin is sufficient to target the enzyme to the neuronal growth cone when transfected into neurons. This also enhances neurite outgrowth on an inhibitory substrate. Some intracellular trafficking pathways are adversely affected by cryptic signals present in the bacterial gene sequence, whilst unexpectedly others are required for efficient secretion of the enzyme. Furthermore, targeting chondroitinase to the neuronal growth cone promotes its ability to increase neurite outgrowth on an inhibitory substrate. These findings are timely in view of the renewed prospects for

Fundamental principles in bacterial physiology—history, recent progress, and the future with focus on cell size control: a review

NASA Astrophysics Data System (ADS)

Jun, Suckjoon; Si, Fangwei; Pugatch, Rami; Scott, Matthew

2018-05-01

Bacterial physiology is a branch of biology that aims to understand overarching principles of cellular reproduction. Many important issues in bacterial physiology are inherently quantitative, and major contributors to the field have often brought together tools and ways of thinking from multiple disciplines. This article presents a comprehensive overview of major ideas and approaches developed since the early 20th century for anyone who is interested in the fundamental problems in bacterial physiology. This article is divided into two parts. In the first part (sections 1–3), we review the first ‘golden era’ of bacterial physiology from the 1940s to early 1970s and provide a complete list of major references from that period. In the second part (sections 4–7), we explain how the pioneering work from the first golden era has influenced various rediscoveries of general quantitative principles and significant further development in modern bacterial physiology. Specifically, section 4 presents the history and current progress of the ‘adder’ principle of cell size homeostasis. Section 5 discusses the implications of coarse-graining the cellular protein composition, and how the coarse-grained proteome ‘sectors’ re-balance under different growth conditions. Section 6 focuses on physiological invariants, and explains how they are the key to understanding the coordination between growth and the cell cycle underlying cell size control in steady-state growth. Section 7 overviews how the temporal organization of all the internal processes enables balanced growth. In the final section 8, we conclude by discussing the remaining challenges for the future in the field.

SuperSegger: robust image segmentation, analysis and lineage tracking of bacterial cells.

PubMed

Stylianidou, Stella; Brennan, Connor; Nissen, Silas B; Kuwada, Nathan J; Wiggins, Paul A

2016-11-01

Many quantitative cell biology questions require fast yet reliable automated image segmentation to identify and link cells from frame-to-frame, and characterize the cell morphology and fluorescence. We present SuperSegger, an automated MATLAB-based image processing package well-suited to quantitative analysis of high-throughput live-cell fluorescence microscopy of bacterial cells. SuperSegger incorporates machine-learning algorithms to optimize cellular boundaries and automated error resolution to reliably link cells from frame-to-frame. Unlike existing packages, it can reliably segment microcolonies with many cells, facilitating the analysis of cell-cycle dynamics in bacteria as well as cell-contact mediated phenomena. This package has a range of built-in capabilities for characterizing bacterial cells, including the identification of cell division events, mother, daughter and neighbouring cells, and computing statistics on cellular fluorescence, the location and intensity of fluorescent foci. SuperSegger provides a variety of postprocessing data visualization tools for single cell and population level analysis, such as histograms, kymographs, frame mosaics, movies and consensus images. Finally, we demonstrate the power of the package by analyzing lag phase growth with single cell resolution. © 2016 John Wiley & Sons Ltd.

Physics of Bacterial Morphogenesis

PubMed Central

Sun, Sean X.; Jiang, Hongyuan

2011-01-01

Summary: Bacterial cells utilize three-dimensional (3D) protein assemblies to perform important cellular functions such as growth, division, chemoreception, and motility. These assemblies are composed of mechanoproteins that can mechanically deform and exert force. Sometimes, small-nucleotide hydrolysis is coupled to mechanical deformations. In this review, we describe the general principle for an understanding of the coupling of mechanics with chemistry in mechanochemical systems. We apply this principle to understand bacterial cell shape and morphogenesis and how mechanical forces can influence peptidoglycan cell wall growth. We review a model that can potentially reconcile the growth dynamics of the cell wall with the role of cytoskeletal proteins such as MreB and crescentin. We also review the application of mechanochemical principles to understand the assembly and constriction of the FtsZ ring. A number of potential mechanisms are proposed, and important questions are discussed. PMID:22126993

No bacterial growth found in spiked intravenous fluids over an 8-hour period.

PubMed

Haas, Richard E; Beitz, Edwin; Reed, Amy; Burtnett, Howard; Lowe, Jason; Crist, Arthur E; Stierer, Kevin A; Birenberg, Allan M

2017-04-01

Protocol changes prompted by the Joint Commission mandating intravenous (IV) fluid bags to be used within 1 hour of spiking because of possible bacterial contamination have sparked clinical and economic concerns. This study investigated the degree of bacterial growth in which samples were obtained from spiked IV fluid bags at the time of spiking and 1, 2, 4, and 8 hours after spiking. No bacterial growth occurred in any of the 80 bags of Lactated Ringer's (LR) IV solutions sampled. This study demonstrated that LR IV bags do not support any bacterial growth for up to 8 hours after spiking. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Vision Marker-Based In Situ Examination of Bacterial Growth in Liquid Culture Media.

PubMed

Kim, Kyukwang; Choi, Duckyu; Lim, Hwijoon; Kim, Hyeongkeun; Jeon, Jessie S

2016-12-18

The detection of bacterial growth in liquid media is an essential process in determining antibiotic susceptibility or the level of bacterial presence for clinical or research purposes. We have developed a system, which enables simplified and automated detection using a camera and a striped pattern marker. The quantification of bacterial growth is possible as the bacterial growth in the culturing vessel blurs the marker image, which is placed on the back of the vessel, and the blurring results in a decrease in the high-frequency spectrum region of the marker image. The experiment results show that the FFT (fast Fourier transform)-based growth detection method is robust to the variations in the type of bacterial carrier and vessels ranging from the culture tubes to the microfluidic devices. Moreover, the automated incubator and image acquisition system are developed to be used as a comprehensive in situ detection system. We expect that this result can be applied in the automation of biological experiments, such as the Antibiotics Susceptibility Test or toxicity measurement. Furthermore, the simple framework of the proposed growth measurement method may be further utilized as an effective and convenient method for building point-of-care devices for developing countries.

Kinetics of Bacterial Growth on Chlorinated Aliphatic Compounds

PubMed Central

van den Wijngaard, Arjan J.; Wind, Richèle D.; Janssen, Dick B.

1993-01-01

With the pure bacterial cultures Ancylobacter aquaticus AD20 and AD25, Xanthobacter autotrophicus GJ10, and Pseudomonas sp. strain AD1, Monod kinetics was observed during growth in chemostat cultures on 1,2-dichloroethane (AD20, AD25, and GJ10), 2-chloroethanol (AD20 and GJ10), and 1,3-dichloro-2-propanol (AD1). Both the Michaelis-Menten constants (Km) of the first catabolic (dehalogenating) enzyme and the Monod half-saturation constants (Ks) followed the order 2-chloroethanol, 1,3-dichloro-2-propanol, epichlorohydrin, and 1,2-dichloroethane. The Ks values of strains GJ10, AD20, and AD25 for 1,2-dichloroethane were 260, 222, and 24 μM, respectively. The low Ks value of strain AD25 was correlated with a higher haloalkane dehalogenase content of this bacterium. The growth rates of strains AD20 and GJ10 in continuous cultures on 1,2-dichloroethane were higher than the rates predicted from the kinetics of the haloalkane dehalogenase and the concentration of the enzyme in the cells. The results indicate that the efficiency of chlorinated compound removal is indeed influenced by the kinetic properties and cellular content of the first catabolic enzyme. The cell envelope did not seem to act as a barrier for permeation of 1,2-dichloroethane. PMID:16348981

Bench-to-bedside review: Quorum sensing and the role of cell-to-cell communication during invasive bacterial infection

PubMed Central

Asad, Shadaba; Opal, Steven M

2008-01-01

Bacteria communicate extensively with each other and employ a communal approach to facilitate survival in hostile environments. A hierarchy of cell-to-cell signaling pathways regulates bacterial growth, metabolism, biofilm formation, virulence expression, and a myriad of other essential functions in bacterial populations. The notion that bacteria can signal each other and coordinate their assault patterns against susceptible hosts is now well established. These signaling networks represent a previously unrecognized survival strategy by which bacterial pathogens evade antimicrobial defenses and overwhelm the host. These quorum sensing communication signals can transgress species barriers and even kingdom barriers. Quorum sensing molecules can regulate human transcriptional programs to the advantage of the pathogen. Human stress hormones and cytokines can be detected by bacterial quorum sensing systems. By this mechanism, the pathogen can detect the physiologically stressed host, providing an opportunity to invade when the patient is most vulnerable. These rather sophisticated, microbial communication systems may prove to be a liability to pathogens as they make convenient targets for therapeutic intervention in our continuing struggle to control microbial pathogens. PMID:19040778

Fungal and bacterial growth in floor dust at elevated relative humidity levels.

PubMed

Dannemiller, K C; Weschler, C J; Peccia, J

2017-03-01

Under sustained, elevated building moisture conditions, bacterial and fungal growth occurs. The goal of this study was to characterize microbial growth in floor dust at variable equilibrium relative humidity (ERH) levels. Floor dust from one home was embedded in coupons cut from a worn medium-pile nylon carpet and incubated at 50%, 80%, 85%, 90%, 95%, and 100% ERH levels. Quantitative PCR and DNA sequencing of ribosomal DNA for bacteria and fungi were used to quantify growth and community shifts. Over a 1-wk period, fungal growth occurred above 80% ERH. Growth rates at 85% and 100% ERH were 1.1 × 10 4 and 1.5 × 10 5 spore equivalents d -1 mg dust -1 , respectively. Bacterial growth occurred only at 100% ERH after 1 wk (9.0 × 10 4 genomes d -1 mg dust -1 ). Growth resulted in significant changes in fungal (P<.00001) and bacterial community structure (P<.00001) at varying ERH levels. Comparisons between fungal taxa incubated at different ERH levels revealed more than 100 fungal and bacterial species that were attributable to elevated ERH. Resuspension modeling indicated that more than 50% of airborne microbes could originate from the resuspension of fungi grown at ERH levels of 85% and above. © 2016 The Authors. Indoor Air published by John Wiley & Sons Ltd.

Microbial dynamics during harmful dinoflagellate Ostreopsis cf. ovata growth: Bacterial succession and viral abundance pattern.

PubMed

Guidi, Flavio; Pezzolesi, Laura; Vanucci, Silvana

2018-02-27

Algal-bacterial interactions play a major role in shaping diversity of algal associated bacterial communities. Temporal variation in bacterial phylogenetic composition reflects changes of these complex interactions which occur during the algal growth cycle as well as throughout the lifetime of algal blooms. Viruses are also known to cause shifts in bacterial community diversity which could affect algal bloom phases. This study investigated on changes of bacterial and viral abundances, bacterial physiological status, and on bacterial successional pattern associated with the harmful benthic dinoflagellate Ostreopsis cf. ovata in batch cultures over the algal growth cycle. Bacterial community phylogenetic structure was assessed by 16S rRNA gene ION torrent sequencing. A comparison between bacterial community retrieved in cultures and that one co-occurring in situ during the development of the O. cf. ovata bloom from where the algal strain was isolated was also reported. Bacterial community growth was characterized by a biphasic pattern with the highest contributions (~60%) of highly active bacteria found at the two bacterial exponential growth steps. An alphaproteobacterial consortium composed by the Rhodobacteraceae Dinoroseobacter (22.2%-35.4%) and Roseovarius (5.7%-18.3%), together with Oceanicaulis (14.2-40.3%), was strongly associated with O. cf. ovata over the algal growth. The Rhodobacteraceae members encompassed phylotypes with an assessed mutualistic-pathogenic bimodal behavior. Fabibacter (0.7%-25.2%), Labrenzia (5.6%-24.3%), and Dietzia (0.04%-1.7%) were relevant at the stationary phase. Overall, the successional pattern and the metabolic and functional traits of the bacterial community retrieved in culture mirror those ones underpinning O. cf. ovata bloom dynamics in field. Viral abundances increased synoptically with bacterial abundances during the first bacterial exponential growth step while being stationary during the second step. Microbial trends

Evolution of Cell Size Homeostasis and Growth Rate Diversity during Initial Surface Colonization of Shewanella oneidensis.

PubMed

Lee, Calvin K; Kim, Alexander J; Santos, Giancarlo S; Lai, Peter Y; Lee, Stella Y; Qiao, David F; Anda, Jaime De; Young, Thomas D; Chen, Yujie; Rowe, Annette R; Nealson, Kenneth H; Weiss, Paul S; Wong, Gerard C L

2016-09-06

Cell size control and homeostasis are fundamental features of bacterial metabolism. Recent work suggests that cells add a constant size between birth and division ("adder" model). However, it is not known how cell size homeostasis is influenced by the existence of heterogeneous microenvironments, such as those during biofilm formation. Shewanella oneidensis MR-1 can use diverse energy sources on a range of surfaces via extracellular electron transport (EET), which can impact growth, metabolism, and size diversity. Here, we track bacterial surface communities at single-cell resolution to show that not only do bacterial motility appendages influence the transition from two- to three-dimensional biofilm growth and control postdivisional cell fates, they strongly impact cell size homeostasis. For every generation, we find that the average growth rate for cells that stay on the surface and continue to divide (nondetaching population) and that for cells that detach before their next division (detaching population) are roughly constant. However, the growth rate distribution is narrow for the nondetaching population, but broad for the detaching population in each generation. Interestingly, the appendage deletion mutants (ΔpilA, ΔmshA-D, Δflg) have significantly broader growth rate distributions than that of the wild type for both detaching and nondetaching populations, which suggests that Shewanella appendages are important for sensing and integrating environmental inputs that contribute to size homeostasis. Moreover, our results suggest multiplexing of appendages for sensing and motility functions contributes to cell size dysregulation. These results can potentially provide a framework for generating metabolic diversity in S. oneidensis populations to optimize EET in heterogeneous environments.

Tiny cells meet big questions: a closer look at bacterial cell biology.

PubMed

Goley, Erin D

2013-04-01

While studying actin assembly as a graduate student with Matt Welch at the University of California at Berkeley, my interest was piqued by reports of surprising observations in bacteria: the identification of numerous cytoskeletal proteins, actin homologues fulfilling spindle-like functions, and even the presence of membrane-bound organelles. Curiosity about these phenomena drew me to Lucy Shapiro's lab at Stanford University for my postdoctoral research. In the Shapiro lab, and now in my lab at Johns Hopkins, I have focused on investigating the mechanisms of bacterial cytokinesis. Spending time as both a eukaryotic cell biologist and a bacterial cell biologist has convinced me that bacterial cells present the same questions as eukaryotic cells: How are chromosomes organized and accurately segregated? How is force generated for cytokinesis? How is polarity established? How are signals transduced within and between cells? These problems are conceptually similar between eukaryotes and bacteria, although their solutions can differ significantly in specifics. In this Perspective, I provide a broad view of cell biological phenomena in bacteria, the technical challenges facing those of us who peer into bacterial cells, and areas of common ground as research in eukaryotic and bacterial cell biology moves forward.

Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

Dynamic succession of substrate-associated bacterial composition and function during Ganoderma lucidum growth

PubMed Central

Li, Qiang; Zou, Jie; Tan, Hao; Tan, Wei; Peng, Weihong

2018-01-01

Background Ganoderma lucidum, a valuable medicinal fungus, is widely distributed in China. It grows alongside with a complex microbial ecosystem in the substrate. As sequencing technology advances, it is possible to reveal the composition and functions of substrate-associated bacterial communities. Methods We analyzed the bacterial community dynamics in the substrate during the four typical growth stages of G. lucidum using next-generation sequencing. Results The physicochemical properties of the substrate (e.g. acidity, moisture, total nitrogen, total phosphorus and total potassium) changed between different growth stages. A total of 598,771 sequences from 12 samples were obtained and assigned to 22 bacterial phyla. Proteobacteria and Firmicutes were the dominant phyla. Bacterial community composition and diversity significantly differed between the elongation stage and the other three growth stages. LEfSe analysis revealed a large number of bacterial taxa (e.g. Bacteroidetes, Acidobacteria and Nitrospirae) with significantly higher abundance at the elongation stage. Functional pathway prediction uncovered significant abundance changes of a number of bacterial functional pathways between the elongation stage and other growth stages. At the elongation stage, the abundance of the environmental information processing pathway (mainly membrane transport) decreased, whereas that of the metabolism-related pathways increased. Discussion The changes in bacterial community composition, diversity and predicted functions were most likely related to the changes in the moisture and nutrient conditions in the substrate with the growth of G. lucidum, particularly at the elongation stage. Our findings shed light on the G. lucidum-bacteria-substrate relationships, which should facilitate the industrial cultivation of G. lucidum. PMID:29915697

Aptamer-functionalized capacitance sensors for real-time monitoring of bacterial growth and antibiotic susceptibility.

PubMed

Jo, Namgyeong; Kim, Bongjun; Lee, Sun-Mi; Oh, Jeseung; Park, In Ho; Jin Lim, Kook; Shin, Jeon-Soo; Yoo, Kyung-Hwa

2018-04-15

To prevent spread of infection and antibiotic resistance, fast and accurate diagnosis of bacterial infection and subsequent administration of antimicrobial agents are important. However, conventional methods for bacterial detection and antibiotic susceptibility testing (AST) require more than two days, leading to delays that have contributed to an increase in antibiotic-resistant bacteria. Here, we report an aptamer-functionalized capacitance sensor array that can monitor bacterial growth and antibiotic susceptibility in real-time. While E. coli and S. aureus were cultured, the capacitance increased over time, and apparent bacterial growth curves were observed even when 10 CFU/mL bacteria was inoculated. Furthermore, because of the selectivity of aptamers, bacteria could be identified within 1h using the capacitance sensor array functionalized with aptamers. In addition to bacterial growth, antibiotic susceptibility could be monitored in real-time. When bacteria were treated with antibiotics above the minimum inhibitory concentration (MIC), the capacitance decreased because the bacterial growth was inhibited. These results demonstrate that the aptamer-functionalized capacitance sensor array might be applied for rapid ASTs. Copyright © 2017 Elsevier B.V. All rights reserved.

Isolation of cell-free bacterial inclusion bodies.

PubMed

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

2010-09-17

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

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

PubMed

Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular mechanisms of cell-cell spread of intracellular bacterial pathogens.

PubMed

Ireton, Keith

2013-07-17

Several bacterial pathogens, including Listeria monocytogenes, Shigella flexneri and Rickettsia spp., have evolved mechanisms to actively spread within human tissues. Spreading is initiated by the pathogen-induced recruitment of host filamentous (F)-actin. F-actin forms a tail behind the microbe, propelling it through the cytoplasm. The motile pathogen then encounters the host plasma membrane, forming a bacterium-containing protrusion that is engulfed by an adjacent cell. Over the past two decades, much progress has been made in elucidating mechanisms of F-actin tail formation. Listeria and Shigella produce tails of branched actin filaments by subverting the host Arp2/3 complex. By contrast, Rickettsia forms tails with linear actin filaments through a bacterial mimic of eukaryotic formins. Compared with F-actin tail formation, mechanisms controlling bacterial protrusions are less well understood. However, recent findings have highlighted the importance of pathogen manipulation of host cell-cell junctions in spread. Listeria produces a soluble protein that enhances bacterial protrusions by perturbing tight junctions. Shigella protrusions are engulfed through a clathrin-mediated pathway at 'tricellular junctions'--specialized membrane regions at the intersection of three epithelial cells. This review summarizes key past findings in pathogen spread, and focuses on recent developments in actin-based motility and the formation and internalization of bacterial protrusions.

Cellulose-ethylenediaminetetraacetic acid conjugates protect mammalian cells from bacterial cells.

PubMed

Luo, Jie; Lv, Wei; Deng, Ying; Sun, Yuyu

2013-04-08

Cellulose-ethylenediaminetetraacetic acid (EDTA) conjugates were synthesized by the esterification of cellulose with ethylenediaminetetraacetic dianhydride (EDTAD). The new materials provided potent antimicrobial activities against Staphylococcus aureus (S. aureus, Gram-positive bacteria) and Pseudomonas aeruginosa (P. aeruginosa, Gram-negative bacteria), and inhibited the formation of bacterial biofilms. The biocompatibility of the new cellulose-EDTA conjugates was evaluated with mouse skin fibroblasts for up to 14 days. SEM observation and DNA content analysis suggested that the new materials sustained the viability of fibroblast cells. Moreover, in mouse skin fibroblast-bacteria co-culture systems, the new cellulose-EDTA conjugates prevented bacterial biofilm formation and protected the mammalian cells from the bacterial cells for at least one day.

The effect of antibacterial acting extracorporeal shockwaves on bacterial cell integrity.

PubMed

Horn, Carsten; Mengele, Karin; Gerdesmeyer, Ludger; Gradinger, Reiner; Gollwitzer, Hans

2009-12-01

Antibacterial effects of extracorporeal shockwaves (ESWs) have been demonstrated in vitro against bacteria under static and dynamic growth conditions. This study assessed the effects of ESWs on the cell wall integrity of bacteria. Standardized suspensions of Staphylococcus aureus were exposed to various shockwave impulses (2000-12,000) of different energy flux densities (EFD, 0.38-0.96 mJ/mm(2)). Bacterial suspensions of equal concentration that had been permeabilized (to >99%) with isopropanol were used as positive controls. The bacteria of all groups were stained with Sytox Green nucleic acid stain. The fluorescence of the shockwave-treated, permeabilized, and untreated suspensions was measured and compared for bacterial survival, quantified by colony-forming units after plating. Although ESWs showed a significant energy-dependent antibacterial effect that reduced CFUs in the treated suspensions by between 56% and 99%, only maximum energies (4000 impulses at 0.96 mJ/mm(2) and 12,000 impulses at 0.59 mJ/mm(2)) were followed by a significant increase in fluorescence compared with the untreated control (p<0.05). However, the fluorescence of these treated groups was still far less than that of the alcohol-permeabilized positive control groups (p<0.05). Lower energies and impulse rates did not show increased intracellular uptake of the fluorescent dye (p>0.05). This is the first study to assess bacterial cell wall permeability after ESW treatment. It was found that the permeabilization of bacterial cells after ESW treatment was far less than expected due to the corresponding antibacterial effect. Other mechanisms, such as intracellular effects, might be involved in bacterial killing after ESWs and still must be elucidated.

Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

PubMed

An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

2015-02-01

Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

PMAnalyzer: a new web interface for bacterial growth curve analysis.

PubMed

Cuevas, Daniel A; Edwards, Robert A

2017-06-15

Bacterial growth curves are essential representations for characterizing bacteria metabolism within a variety of media compositions. Using high-throughput, spectrophotometers capable of processing tens of 96-well plates, quantitative phenotypic information can be easily integrated into the current data structures that describe a bacterial organism. The PMAnalyzer pipeline performs a growth curve analysis to parameterize the unique features occurring within microtiter wells containing specific growth media sources. We have expanded the pipeline capabilities and provide a user-friendly, online implementation of this automated pipeline. PMAnalyzer version 2.0 provides fast automatic growth curve parameter analysis, growth identification and high resolution figures of sample-replicate growth curves and several statistical analyses. PMAnalyzer v2.0 can be found at https://edwards.sdsu.edu/pmanalyzer/ . Source code for the pipeline can be found on GitHub at https://github.com/dacuevas/PMAnalyzer . Source code for the online implementation can be found on GitHub at https://github.com/dacuevas/PMAnalyzerWeb . dcuevas08@gmail.com. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press.

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.

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.

Bacterial spread from cell to cell: beyond actin-based motility.

PubMed

Kuehl, Carole J; Dragoi, Ana-Maria; Talman, Arthur; Agaisse, Hervé

2015-09-01

Several intracellular pathogens display the ability to propagate within host tissues by displaying actin-based motility in the cytosol of infected cells. As motile bacteria reach cell-cell contacts they form plasma membrane protrusions that project into adjacent cells and resolve into vacuoles from which the pathogen escapes, thereby achieving spread from cell to cell. Seminal studies have defined the bacterial and cellular factors that support actin-based motility. By contrast, the mechanisms supporting the formation of protrusions and their resolution into vacuoles have remained elusive. Here, we review recent advances in the field showing that Listeria monocytogenes and Shigella flexneri have evolved pathogen-specific mechanisms of bacterial spread from cell to cell. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cell-to-cell variation and specialization in sugar metabolism in clonal bacterial populations

PubMed Central

Schreiber, Frank; Dal Co, Alma; Kiviet, Daniel J.; Littmann, Sten

2017-01-01

While we have good understanding of bacterial metabolism at the population level, we know little about the metabolic behavior of individual cells: do single cells in clonal populations sometimes specialize on different metabolic pathways? Such metabolic specialization could be driven by stochastic gene expression and could provide individual cells with growth benefits of specialization. We measured the degree of phenotypic specialization in two parallel metabolic pathways, the assimilation of glucose and arabinose. We grew Escherichia coli in chemostats, and used isotope-labeled sugars in combination with nanometer-scale secondary ion mass spectrometry and mathematical modeling to quantify sugar assimilation at the single-cell level. We found large variation in metabolic activities between single cells, both in absolute assimilation and in the degree to which individual cells specialize in the assimilation of different sugars. Analysis of transcriptional reporters indicated that this variation was at least partially based on cell-to-cell variation in gene expression. Metabolic differences between cells in clonal populations could potentially reduce metabolic incompatibilities between different pathways, and increase the rate at which parallel reactions can be performed. PMID:29253903

Label-free isolation and deposition of single bacterial cells from heterogeneous samples for clonal culturing

NASA Astrophysics Data System (ADS)

Riba, J.; Gleichmann, T.; Zimmermann, S.; Zengerle, R.; Koltay, P.

2016-09-01

The isolation and analysis of single prokaryotic cells down to 1 μm and less in size poses a special challenge and requires micro-engineered devices to handle volumes in the picoliter to nanoliter range. Here, an advanced Single-Cell Printer (SCP) was applied for automated and label-free isolation and deposition of bacterial cells encapsulated in 35 pl droplets by inkjet-like printing. To achieve this, dispenser chips to generate micro droplets have been fabricated with nozzles 20 μm in size. Further, the magnification of the optical system used for cell detection was increased. Redesign of the optical path allows for collision-free addressing of any flat substrate since no compartment protrudes below the nozzle of the dispenser chip anymore. The improved system allows for deterministic isolation of individual bacterial cells. A single-cell printing efficiency of 93% was obtained as shown by printing fluorescent labeled E. coli. A 96-well plate filled with growth medium is inoculated with single bacteria cells on average within about 8 min. Finally, individual bacterial cells from a heterogeneous sample of E. coli and E. faecalis were isolated for clonal culturing directly on agar plates in user-defined array geometry.

Sequence-Specific Affinity Chromatography of Bacterial Small Regulatory RNA-Binding Proteins from Bacterial Cells.

PubMed

Gans, Jonathan; Osborne, Jonathan; Cheng, Juliet; Djapgne, Louise; Oglesby-Sherrouse, Amanda G

2018-01-01

Bacterial small RNA molecules (sRNAs) are increasingly recognized as central regulators of bacterial stress responses and pathogenesis. In many cases, RNA-binding proteins are critical for the stability and function of sRNAs. Previous studies have adopted strategies to genetically tag an sRNA of interest, allowing isolation of RNA-protein complexes from cells. Here we present a sequence-specific affinity purification protocol that requires no prior genetic manipulation of bacterial cells, allowing isolation of RNA-binding proteins bound to native RNA molecules.

Elevated guanosine 5'-diphosphate 3'-diphosphate level inhibits bacterial growth and interferes with FtsZ assembly.

PubMed

Yamaguchi, Takayoshi; Iida, Ken-Ichiro; Shiota, Susumu; Nakayama, Hiroaki; Yoshida, Shin-Ichi

2015-12-01

FtsZ, a protein essential for prokaryotic cell division, forms a ring structure known as the Z-ring at the division site. FtsZ has a GTP binding site and is assembled into linear structures in a GTP-dependent manner in vitro. We assessed whether guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a global regulator of gene expression in starved bacteria, affects cell division in Salmonella Paratyphi A. Elevation of intracellular ppGpp levels by using the relA expression vector induced repression of bacterial growth and incorrect FtsZ assembly. We found that FtsZ forms helical structures in the presence of ppGpp by using the GTP binding site; however, ppGpp levels required to form helical structures were at least 20-fold higher than the required GTP levels in vitro. Furthermore, once formed, helical structures did not change to the straight form even after GTP addition. Our data indicate that elevation of the ppGpp level leads to inhibition of bacterial growth and interferes with FtsZ assembly. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences

PubMed Central

Purohit, Vishnudutt; Bode, J. Christian; Bode, Christiane; Brenner, David A.; Choudhry, Mashkoor A.; Hamilton, Frank; Kang, Y. James; Keshavarzian, Ali; Rao, Radhakrishna; Sartor, R. Balfour; Swanson, Christine; Turner, Jerrold R.

2008-01-01

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram negative bacteria in the intestine which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, L-glutamine, oats supplementation, or zinc thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram negative bacteria and

Graphene-Iodine Nanocomposites: Highly Potent Bacterial Inhibitors that are Bio-compatible with Human Cells

PubMed Central

Some, Surajit; Sohn, Ji Soo; Kim, Junmoo; Lee, Su-Hyun; Lee, Su Chan; Lee, Jungpyo; Shackery, Iman; Kim, Sang Kyum; Kim, So Hyun; Choi, Nakwon; Cho, Il-Joo; Jung, Hyo-Il; Kang, Shinill; Jun, Seong Chan

2016-01-01

Graphene-composites, capable of inhibiting bacterial growth which is also bio-compatible with human cells have been highly sought after. Here we report for the first time the preparation of new graphene-iodine nano-composites via electrostatic interactions between positively charged graphene derivatives and triiodide anions. The resulting composites were characterized by X-ray photoemission spectroscopy, UV-spectroscopy, Raman spectroscopy and Scanning electron microscopy. The antibacterial potential of these graphene-iodine composites against Klebsiella pneumonia, Pseudomonas aeruginosa, Proteus mirobilis, Staphylococcus aureus, and E. coli was investigated. In addition, the cytotoxicity of the nanocomposite with human cells [human white blood cells (WBC), HeLa, MDA-MB-231, Fibroblast (primary human keratinocyte) and Keratinocyte (immortalized fibroblast)], was assessed. DGO (Double-oxidizes graphene oxide) was prepared by the additional oxidation of GO (graphene oxide). This generates more oxygen containing functional groups that can readily trap more H+, thus generating a positively charged surface area under highly acidic conditions. This step allowed bonding with a greater number of anionic triiodides and generated the most potent antibacterial agent among graphene-iodine and as-made povidone-iodine (PVP-I) composites also exhibited nontoxic to human cells culture. Thus, these nano-composites can be used to inhibit the growth of various bacterial species. Importantly, they are also very low-cytotoxic to human cells culture. PMID:26843066

Surface nanoporosity has a greater influence on osteogenic and bacterial cell adhesion than crystallinity and wettability

NASA Astrophysics Data System (ADS)

Rodriguez-Contreras, Alejandra; Guadarrama Bello, Dainelys; Nanci, Antonio

2018-07-01

There has been much emphasis on the influence of crystallinity and wettability for modulating cell activity, particularly for bone biomaterials. In this context, we have generated titanium oxide layers with similar mesoporous topography and surface roughness but with amorphous or crystalline oxide layers and differential wettability. We then investigated their influence on the behavior of MC3T3 osteoblastic and bacterial cells. There was no difference in cell adhesion, spreading and growth on amorphous and crystalline surfaces. The number of focal adhesions was similar, however, cells on the amorphous surface exhibited a higher frequency of mature adhesions. The crystallinity of the surface layers also had no bearing on bacterial adhesion. While it cannot be excluded that surface crystallinity, roughness and wettability contribute to some degree to determining cell behavior, our data suggest that physical characteristics of surfaces represent the major determinant.

Bacterial growth on stream insects: potential for use in bioassessment

Treesearch

A. Dennis Lemly

1998-01-01

Growth of filamentous bacteria (Sphaerotilus sp., Leptothrix sp.) on aquatic insects was evaluated for its usefulness as a bioindicator of detrimental nutrient levels in streams. Field measurements of insect abundance, nutrient concentrations, and incidence/ degree of bacterial growth on insects upstream and downstream of livestock pastures were made in 2 Virginia, USA...

Electrical response of culture media during bacterial growth on a paper-based device

NASA Astrophysics Data System (ADS)

Srimongkon, Tithimanan; Buerkle, Marius; Nakamura, Akira; Enomae, Toshiharu; Ushijima, Hirobumi; Fukuda, Nobuko

2017-05-01

In this work, we evaluated the feasibility of a paper-based bacterial detection system. The paper served as a substrate for the measurement electrodes and the culture medium. Using a printing technique, we patterned gold electrodes onto the paper substrate and applied Luria broth (LB) agar gel as a culture medium on top of the electrodes. As the first step towards the development of a bacterial detection system, we determined changes in the surface potential during bacterial growth and monitored these changes over 24 h. This allowed us to correlate changes in the surface potential with the different growth phases of the bacteria.

Functional properties of peanut fractions on the growth of probiotics and foodborne bacterial pathogens.

PubMed

Peng, Mengfei; Bitsko, Elizabeth; Biswas, Debabrata

2015-03-01

Various compounds found in peanut (Arachis hypogaea) have been shown to provide multiple benefits to human health and may influence the growth of a broad range of gut bacteria. In this study, we investigated the effects of peanut white kernel and peanut skin on 3 strains of Lactobacillus and 3 major foodborne enteric bacterial pathogens. Significant (P < 0.05) growth stimulation of Lactobacillus casei and Lactobacillus rhamnosus was observed in the presence of 0.5% peanut flour (PF) made from peanut white kernel, whereas 0.5% peanut skin extract (PSE) exerted the inhibitory effect on the growth of these beneficial microbes. We also found that within 72 h, PF inhibited growth of enterohemorrhagic Escherichia coli O157:H7 (EHEC), while PSE significantly (P < 0.05) inhibited Listeria monocytogenes but promoted the growth of both EHEC and Salmonella Typhimurium. The cell adhesion and invasion abilities of 3 pathogens to the host cells were also significantly (P < 0.05) reduced by 0.5% PF and 0.5% PSE. These results suggest that peanut white kernel might assist in improving human gut flora as well as reducing EHEC, whereas the beneficial effects of peanut skins require further research and investigation. © 2015 Institute of Food Technologists®

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.

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

Evaluation of environmental bacterial communities as a factor affecting the growth of duckweed Lemna minor.

PubMed

Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

2017-01-01

Duckweed (family Lemnaceae ) has recently been recognized as an ideal biomass feedstock for biofuel production due to its rapid growth and high starch content, which inspired interest in improving their productivity. Since microbes that co-exist with plants are known to have significant effects on their growth according to the previous studies for terrestrial plants, this study has attempted to understand the plant-microbial interactions of a duckweed, Lemna minor , focusing on the growth promotion/inhibition effects so as to assess the possibility of accelerated duckweed production by modifying co-existing bacterial community. Co-cultivation of aseptic L. minor and bacterial communities collected from various aquatic environments resulted in changes in duckweed growth ranging from -24 to +14% compared to aseptic control. A number of bacterial strains were isolated from both growth-promoting and growth-inhibitory communities, and examined for their co-existing effects on duckweed growth. Irrespective of the source, each strain showed promotive, inhibitory, or neutral effects when individually co-cultured with L. minor . To further analyze the interactions among these bacterial strains in a community, binary combinations of promotive and inhibitory strains were co-cultured with aseptic L. minor , resulting in that combinations of promotive-promotive or inhibitory-inhibitory strains generally showed effects similar to those of individual strains. However, combinations of promotive-inhibitory strains tended to show inhibitory effects while only Aquitalea magnusonii H3 exerted its plant growth-promoting effect in all combinations tested. Significant change in biomass production was observed when duckweed was co-cultivated with environmental bacterial communities. Promotive, neutral, and inhibitory bacteria in the community would synergistically determine the effects. The results indicate the possibility of improving duckweed biomass production via regulation of co

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

High density growth of T7 expression strains with auto-induction option

DOEpatents

Studier, F. William

2010-07-20

A bacterial growth medium for promoting auto-induction of transcription of cloned DNA in cultures of bacterial cells grown batchwise is disclosed. The transcription is under the control of a lac repressor. Also disclosed is a bacterial growth medium for improving the production of a selenomethionine-containing protein or polypeptide in a bacterial cell, the protein or polypeptide being produced by recombinant DNA techniques from a lac or T7lac promoter, the bacterial cell encoding a vitamin B12-dependent homocysteine methylase. Finally, disclosed is a bacterial growth medium for suppressing auto-induction of expression in cultures of bacterial cells grown batchwise, said transcription being under the control of lac repressor.

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

PubMed

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

2012-07-01

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 this 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. A caprine model of a contaminated complex musculoskeletal wound was used. Complex musculoskeletal wounds were created and inoculated with bioluminescent Pseudomonas aeruginosa. Goats were divided into three experimental groups: ground control, simulated AE, and simulated AE with supplemental oxygen. Simulated AE was induced in a hypobaric chamber pressurized to 8,800 feet for 7 hours. Bacterial luminescence was measured using a photon counting camera at three time points: preflight (20 hours postsurgery), postflight (7 hours from preflight and 27 hours postsurgery), and necropsy (24 hours from preflight and 44 hours postsurgery). There was a significant increase in bacterial growth in the AE group compared with 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. 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.

The impact of date palm fruits and their component polyphenols, on gut microbial ecology, bacterial metabolites and colon cancer cell proliferation.

PubMed

Eid, Noura; Enani, Sumia; Walton, Gemma; Corona, Giulia; Costabile, Adele; Gibson, Glenn; Rowland, Ian; Spencer, Jeremy P E

2014-01-01

The fruit of the date palm (Phoenix dactylifera L.) is a rich source of dietary fibre and polyphenols. We have investigated gut bacterial changes induced by the whole date fruit extract (digested date extract; DDE) and its polyphenol-rich extract (date polyphenol extract; DPE) using faecal, pH-controlled, mixed batch cultures mimicking the distal part of the human large intestine, and utilising an array of microbial group-specific 16S rRNA oligonucleotide probes. Fluorescence microscopic enumeration indicated that there was a significant increase in the growth of bifidobacteria in response to both treatments, whilst whole dates also increased bacteroides at 24 h and the total bacterial counts at later fermentation time points when compared with DPE alone. Bacterial metabolism of whole date fruit led to the production of SCFA, with acetate significantly increasing following bacterial incubation with DDE. In addition, the production of flavonoid aglycones (myricetin, luteolin, quercetin and apigenin) and the anthocyanidin petunidin in less than 1 h was also observed. Lastly, the potential of DDE, DPE and metabolites to inhibit Caco-2 cell growth was investigated, indicating that both were capable of potentially acting as antiproliferative agents in vitro, following a 48 h exposure. This potential to inhibit growth was reduced following fermentation. Together these data suggest that consumption of date fruits may enhance colon health by increasing beneficial bacterial growth and inhibiting the proliferation of colon cancer cells. This is an early suggestion that date intake by humans may aid in the maintenance of bowel health and even the reduction of colorectal cancer development.

Induction of gram-negative bacterial growth by neurochemical containing banana (Musa x paradisiaca) extracts.

PubMed

Lyte, M

1997-09-15

Bananas contain large quantities of neurochemicals. Extracts from the peel and pulp of bananas in increasing stages of ripening were prepared and evaluated for their ability to modulate the growth of non-pathogenic and pathogenic bacteria. Extracts from the peel, and to a much lesser degree the pulp, increased the growth of Gram-negative bacterial strains Escherichia coli O157:H7, Shigella flexneri, Enterobacter cloacae and Salmonella typhimurium, as well as two non-pathogenic E. coli strains, in direct relation to the content of norepinephrine and dopamine, but not serotonin. The growth of Gram-positive bacteria was not altered by any of the extracts. Supplementation of vehicle and pulp cultures with norepinephrine or dopamine yielded growth equivalent to peel cultures. Total organic analysis of extracts further demonstrated that the differential effects of peel and pulp on bacterial growth was not nutritionally based, but due to norepinephrine and dopamine. These results suggest that neurochemicals contained within foodstuffs may influence the growth of pathogenic and indigenous bacteria through direct neurochemical-bacterial interactions.

Biofilm growth program and architecture revealed by single-cell live imaging

NASA Astrophysics Data System (ADS)

Yan, Jing; Sabass, Benedikt; Stone, Howard; Wingreen, Ned; Bassler, Bonnie

Biofilms are surface-associated bacterial communities. Little is known about biofilm structure at the level of individual cells. We image living, growing Vibrio cholerae biofilms from founder cells to ten thousand cells at single-cell resolution, and discover the forces underpinning the architectural evolution of the biofilm. Mutagenesis, matrix labeling, and simulations demonstrate that surface-adhesion-mediated compression causes V. cholerae biofilms to transition from a two-dimensional branched morphology to a dense, ordered three-dimensional cluster. We discover that directional proliferation of rod-shaped bacteria plays a dominant role in shaping the biofilm architecture, and this growth pattern is controlled by a single gene. Competition analyses reveal the advantages of the dense growth mode in providing the biofilm with superior mechanical properties. We will further present continuum theory to model the three-dimensional growth of biofilms at the solid-liquid interface as well as solid-air interface.

A dynamic regression analysis tool for quantitative assessment of bacterial growth written in Python.

PubMed

Hoeflinger, Jennifer L; Hoeflinger, Daniel E; Miller, Michael J

2017-01-01

Herein, an open-source method to generate quantitative bacterial growth data from high-throughput microplate assays is described. The bacterial lag time, maximum specific growth rate, doubling time and delta OD are reported. Our method was validated by carbohydrate utilization of lactobacilli, and visual inspection revealed 94% of regressions were deemed excellent. Copyright © 2016 Elsevier B.V. All rights reserved.

Bacterial Growth as a Practical Indicator of Extensive Biodegradability of Organic Compounds

PubMed Central

Prochazka, G. J.; Payne, W. J.

1965-01-01

The proportionality of growth, as indicated by turbidity of cultures of Pseudomonas C12B, to the initial concentration of sodium dodecyl sulfate, dodecanol, or a mixture of C10-C20 secondary alcohol sulfates, each provided as sole carbon source in basal mineral salts medium, was demonstrated. Subsequently, the direct correlation of culture turbidity as a growth indicator and degradation of sodium dodecyl sulfate and the C10-C20 compounds was established. Degradation of these detergents was measured by the rise in surface tension and the decrease in methylene blue values, respectively. Turbidimetry was found to be a poor indicator of degradation of dodecanol in the early hours of culture, however, and did not correlate over a significant range with degradation of substrate. Viable cell counts did parallel dodecanol degradation as measured by gas-liquid chromatography. The use of bacterial growth as a reliable, quantitative, and easily measured parameter indicating biodegradability was suggested for those organic compounds which can be shown to serve as a carbon source for a bacterium. PMID:5867651

The effect of temperature and bacterial growth phase on protein extraction by means of electroporation.

PubMed

Haberl-Meglič, Saša; Levičnik, Eva; Luengo, Elisa; Raso, Javier; Miklavčič, Damijan

2016-12-01

Different chemical and physical methods are used for extraction of proteins from bacteria, which are used in variety of fields. But on a large scale, many methods have severe drawbacks. Recently, extraction by means of electroporation showed a great potential to quickly obtain proteins from bacteria. Since many parameters are affecting the yield of extracted proteins, our aim was to investigate the effect of temperature and bacterial growth phase on the yield of extracted proteins. At the same time bacterial viability was tested. Our results showed that the temperature has a great effect on protein extraction, the best temperature post treatment being 4°C. No effect on bacterial viability was observed for all temperatures tested. Also bacterial growth phase did not affect the yield of extracted proteins or bacterial viability. Nevertheless, further experiments may need to be performed to confirm this observation, since only one incubation temperature (4°C) and one incubation time before and after electroporation (0.5 and 1h) were tested for bacterial growth phase. Based on our results we conclude that temperature is a key element for bacterial membrane to stay in a permeabilized state, so more proteins flow out of bacteria into surrounding media. Copyright © 2016 Elsevier B.V. All rights reserved.

Consequences of packaging on bacterial growth. Meat is an ecological niche.

PubMed

Labadie, J

1999-07-01

Meat is a good support for bacterial growth and particularly for bacteria which are specific of meat and meat products. Little is known about the physiological and biochemical factors which could explain why some bacterial species are only isolated from meat. This review tentatively points out, from an ecological point of view, some of these factors in Gram negative and Gram positive micro-organisms influencing storage life.

Using Bacterial Growth on Insects to Assess Nutrient Impacts in Streams

Treesearch

A. Dennis Lemly

2000-01-01

A combination field and laboratory study was conducted to evaluate the ability of a recently developed bioindicator to detect detrimental nutrient conditions in streams. The method utilizes bacterial growth on aquatic insects to determine nutrient impacts. Field investigations indicated that elevated concentrations of nitrate and phosphate were associated with growth...

Incidence and Predictors of Bacterial infection in Febrile Children with Sickle Cell Disease.

PubMed

Morrissey, Benita J; Bycroft, Thomas P; Almossawi, Ofran; Wilkey, Olufunke B; Daniels, Justin G

2015-01-01

Children with sickle cell disease are at increased risk of developing bacteremia and other serious bacterial infections. Fever is a common symptom in sickle cell disease and can also occur with sickle cell crises and viral infections. We aimed to evaluate the incidence and predictors of bacteremia and bacterial infection in children with sickle cell disease presenting with fever to a district hospital and sickle cell center in London. A retrospective analysis was performed on all attendances of children (aged under 16 years) with sickle cell disease presenting with a fever of 38.5 °C or higher over a 1-year period. Confirmed bacterial infection was defined as bacteremia, bacterial meningitis, urinary tract infection (UTI), pneumonia, osteomyelitis or other bacterial infection with positive identification of organism. Children were defined as having a suspected bacterial infection if a bacterial infection was suspected clinically, but no organism was identified. Over a 1-year period there were 88 episodes analyzed in 59 children. Bacteremia occurred in 3.4% of episodes and confirmed bacterial infection in 7.0%. Suspected bacterial infection occurred in 33.0%. One death occurred from Salmonella typhirium septicemia. C-reactive protein (CRP) level and white blood cell (WBC) count were both significantly associated with bacterial infection (p = 0.004 and 0.02, respectively.) In conclusion, bacterial infections continue to be a significant problem in children with sickle cell disease. C-reactive protein was significantly associated with bacterial infections, and could be included in clinical risk criteria for febrile children with sickle cell disease.

Poisons, ruffles and rockets: bacterial pathogens and the host cell cytoskeleton.

PubMed

Steele-Mortimer, O; Knodler, L A; Finlay, B B

2000-02-01

The cytoskeleton of eukaryotic cells is affected by a number of bacterial and viral pathogens. In this review we consider three recurring themes of cytoskeletal involvement in bacterial pathogenesis: 1) the effect of bacterial toxins on actin-regulating small GTP-binding proteins; 2) the invasion of non-phagocytic cells by the bacterial induction of ruffles at the plasma membrane; 3) the formation of actin tails and pedestals by intracellular and extracellular bacteria, respectively. Considerable progress has been made recently in the characterization of these processes. It is becoming clear that bacterial pathogens have developed a variety of sophisticated mechanisms for utilizing the complex cytoskeletal system of host cells. These bacterially-induced processes are now providing unique insights into the regulation of fundamental eukaryotic mechanisms.

Proteomic analysis of the bacterial cell cycle

PubMed Central

Grünenfelder, Björn; Rummel, Gabriele; Vohradsky, Jiri; Röder, Daniel; Langen, Hanno; Jenal, Urs

2001-01-01

A global approach was used to analyze protein synthesis and stability during the cell cycle of the bacterium Caulobacter crescentus. Approximately one-fourth (979) of the estimated C. crescentus gene products were detected by two-dimensional gel electrophoresis, 144 of which showed differential cell cycle expression patterns. Eighty-one of these proteins were identified by mass spectrometry and were assigned to a wide variety of functional groups. Pattern analysis revealed that coexpression groups were functionally clustered. A total of 48 proteins were rapidly degraded in the course of one cell cycle. More than half of these unstable proteins were also found to be synthesized in a cell cycle-dependent manner, establishing a strong correlation between rapid protein turnover and the periodicity of the bacterial cell cycle. This is, to our knowledge, the first evidence for a global role of proteolysis in bacterial cell cycle control. PMID:11287652

Biosensors for Whole-Cell Bacterial Detection

PubMed Central

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

2014-01-01

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

Chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of animal bacterial pathogens.

PubMed

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

2014-05-01

To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. 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. 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. Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains.

Symbiotic Cell Differentiation and Cooperative Growth in Multicellular Aggregates

PubMed Central

Yamagishi, Jumpei F; Saito, Nen; Kaneko, Kunihiko

2016-01-01

As cells grow and divide under a given environment, they become crowded and resources are limited, as seen in bacterial biofilms and multicellular aggregates. These cells often show strong interactions through exchanging chemicals, as evident in quorum sensing, to achieve mutualism and division of labor. Here, to achieve stable division of labor, three characteristics are required. First, isogenous cells differentiate into several types. Second, this aggregate of distinct cell types shows better growth than that of isolated cells without interaction and differentiation, by achieving division of labor. Third, this cell aggregate is robust with respect to the number distribution of differentiated cell types. Indeed, theoretical studies have thus far considered how such cooperation is achieved when the ability of cell differentiation is presumed. Here, we address how cells acquire the ability of cell differentiation and division of labor simultaneously, which is also connected with the robustness of a cell society. For this purpose, we developed a dynamical-systems model of cells consisting of chemical components with intracellular catalytic reaction dynamics. The reactions convert external nutrients into internal components for cellular growth, and the divided cells interact through chemical diffusion. We found that cells sharing an identical catalytic network spontaneously differentiate via induction from cell-cell interactions, and then achieve division of labor, enabling a higher growth rate than that in the unicellular case. This symbiotic differentiation emerged for a class of reaction networks under the condition of nutrient limitation and strong cell-cell interactions. Then, robustness in the cell type distribution was achieved, while instability of collective growth could emerge even among the cooperative cells when the internal reserves of products were dominant. The present mechanism is simple and general as a natural consequence of interacting cells with

Impact assessment of silver nanoparticles on plant growth and soil bacterial diversity.

PubMed

Pallavi; Mehta, C M; Srivastava, Rashmi; Arora, Sandeep; Sharma, A K

2016-12-01

The present study was carried out to investigate the impact of silver nanoparticles (AgNPs) on the growth of three different crop species, wheat (Triticum aestivum, var. UP2338), cowpea (Vigna sinensis, var. Pusa Komal), and Brassica (Brassica juncea, var. Pusa Jai Kisan), along with their impact on the rhizospheric bacterial diversity. Three different concentrations (0, 50 and 75 ppm) of AgNPs were applied through foliar spray. After harvesting, shoot and root parameters were compared, and it was observed that wheat was relatively unaffected by all AgNP treatments. The optimum growth promotion and increased root nodulation were observed at 50 ppm treatment in cowpea, while improved shoot parameters were recorded at 75 ppm in Brassica. To observe the impact of AgNPs on soil bacterial community, sampling was carried out from the rhizosphere of these crops at 20 and 40 days after the spraying of AgNPS. The bacterial diversity of these samples was analyzed by both cultural and molecular techniques (denaturing gradient gel electrophoresis). It is clearly evident from the results that application of AgNPs changes the soil bacterial diversity and this is further influenced by the plant species grown in that soil. Also, the functional bacterial diversity differed with different concentrations of AgNPs.

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.

Self-Organization in High-Density Bacterial Colonies: Efficient Crowd Control

PubMed Central

Campbell, Kyle; Melke, Pontus; Williams, Joshua W; Jedynak, Bruno; Stevens, Ann M; Groisman, Alex; Levchenko, Andre

2007-01-01

Colonies of bacterial cells can display complex collective dynamics, frequently culminating in the formation of biofilms and other ordered super-structures. Recent studies suggest that to cope with local environmental challenges, bacterial cells can actively seek out small chambers or cavities and assemble there, engaging in quorum sensing behavior. By using a novel microfluidic device, we showed that within chambers of distinct shapes and sizes allowing continuous cell escape, bacterial colonies can gradually self-organize. The directions of orientation of cells, their growth, and collective motion are mutually correlated and dictated by the chamber walls and locations of chamber exits. The ultimate highly organized steady state is conducive to a more-organized escape of cells from the chambers and increased access of nutrients into and evacuation of waste out of the colonies. Using a computational model, we suggest that the lengths of the cells might be optimized to maximize self-organization while minimizing the potential for stampede-like exit blockage. The self-organization described here may be crucial for the early stage of the organization of high-density bacterial colonies populating small, physically confined growth niches. It suggests that this phenomenon can play a critical role in bacterial biofilm initiation and development of other complex multicellular bacterial super-structures, including those implicated in infectious diseases. PMID:18044986

Antimicrobial peptides secreted by equine mesenchymal stromal cells inhibit the growth of bacteria commonly found in skin wounds.

PubMed

Harman, Rebecca M; Yang, Steven; He, Megan K; Van de Walle, Gerlinde R

2017-07-04

The prevalence of chronic skin wounds in humans is high, and treatment is often complicated by the presence of pathogenic bacteria. Therefore, safe and innovative treatments to reduce the bacterial load in cutaneous wounds are needed. Mesenchymal stromal cells (MSC) are known to provide paracrine signals that act on resident skin cells to promote wound healing, but their potential antibacterial activities are not well described. The present study was designed to examine the antibacterial properties of MSC from horses, as this animal model offers a readily translatable model for MSC therapies in humans. Specifically, we aimed to (i) evaluate the in vitro effects of equine MSC on the growth of representative gram-negative and gram-positive bacterial species commonly found in skin wounds and (ii) define the mechanisms by which MSC inhibit bacterial growth. MSC were isolated from the peripheral blood of healthy horses. Gram-negative E. coli and gram-positive S. aureus were cultured in the presence of MSC and MSC conditioned medium (CM), containing all factors secreted by MSC. Bacterial growth was measured by plating bacteria and counting viable colonies or by reading the absorbance of bacterial cultures. Bacterial membrane damage was detected by incorporation of N-phenyl-1-naphthylamine (NPN). Antimicrobial peptide (AMP) gene and protein expression by equine MSC were determined by RT-PCR and Western blot analysis, respectively. Blocking of AMP activity of MSC CM was achieved using AMP-specific antibodies. We found that equine MSC and MSC CM inhibit the growth of E. coli and S. aureus, and that MSC CM depolarizes the cell membranes of these bacteria. In addition, we found that equine MSC CM contains AMPs, and blocking these AMPs with antibodies reduces the effects of MSC CM on bacteria. Our results demonstrate that equine MSC inhibit bacterial growth and secrete factors that compromise the membrane integrity of bacteria commonly found in skin wounds. We also identified

Estimation of lactic acid bacterial cell number by DNA quantification.

PubMed

Ishii, Masaki; Matsumoto, Yasuhiko; Sekimizu, Kazuhisa

2018-01-01

Lactic acid bacteria are provided by fermented foods, beverages, medicines, and supplements. Because the beneficial effects of medicines and supplements containing functional lactic acid bacteria are related to the bacterial cell number, it is important to establish a simple method for estimating the total number of lactic acid bacterial cells in the products for quality control. Almost all of the lactic acid bacteria in the products are dead, however, making it difficult to estimate the total number of lactic acid bacterial cells in the products using a standard colony-counting method. Here we estimated the total lactic acid bacterial cell number in samples containing dead bacteria by quantifying the DNA. The number of viable Enterococcus faecalis 0831-07 cells decreased to less than 1 × 10 -8 by 15 min of heat treatment at 80°C. The amount of extracted DNA from heat-treated cells was 78% that of non-heated cells. The number of viable Lactobacillus paraplantarum 11-1 cells decreased to 1 × 10 -4 after 4 days culture. The amount of extracted DNA of the long-cultured cells, however, was maintained at 97%. These results suggest that cell number of lactic acid bacteria killed by heat-treatment or long-term culture can be estimated by DNA quantification.

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

Effects of Grape Xylem Sap and Cell-Wall Constituents on In Vitro Growth, Biofilm Formation and Cellular Aggregation of Xylella fastidiosa

USDA-ARS?s Scientific Manuscript database

Purified cell-wall constituents or grape xylem sap added to media affected in vitro growth, biofilm formation, cell aggregation and gene expression of Xylella fastidiosa. Media containing xylem sap from Pierce’s disease (PD)-susceptible plants provided better support for bacterial growth and biofil...

How to Build a Bacterial Cell: MreB as the Foreman of E. coli Construction.

PubMed

Shi, Handuo; Bratton, Benjamin P; Gitai, Zemer; Huang, Kerwyn Casey

2018-03-08

Cell shape matters across the kingdoms of life, and cells have the remarkable capacity to define and maintain specific shapes and sizes. But how are the shapes of micron-sized cells determined from the coordinated activities of nanometer-sized proteins? Here, we review general principles that have surfaced through the study of rod-shaped bacterial growth. Imaging approaches have revealed that polymers of the actin homolog MreB play a central role. MreB both senses and changes cell shape, thereby generating a self-organizing feedback system for shape maintenance. At the molecular level, structural and computational studies indicate that MreB filaments exhibit tunable mechanical properties that explain their preference for certain geometries and orientations along the cylindrical cell body. We illustrate the regulatory landscape of rod-shape formation and the connectivity between cell shape, cell growth, and other aspects of cell physiology. These discoveries provide a framework for future investigations into the architecture and construction of microbes. Copyright © 2018 Elsevier Inc. All rights reserved.

Burkholderia Type VI Secretion Systems Have Distinct Roles in Eukaryotic and Bacterial Cell Interactions

PubMed Central

Schwarz, Sandra; West, T. Eoin; Boyer, Frédéric; Chiang, Wen-Chi; Carl, Mike A.; Hood, Rachel D.; Rohmer, Laurence; Tolker-Nielsen, Tim; Skerrett, Shawn J.; Mougous, Joseph D.

2010-01-01

Bacteria that live in the environment have evolved pathways specialized to defend against eukaryotic organisms or other bacteria. In this manuscript, we systematically examined the role of the five type VI secretion systems (T6SSs) of Burkholderia thailandensis (B. thai) in eukaryotic and bacterial cell interactions. Consistent with phylogenetic analyses comparing the distribution of the B. thai T6SSs with well-characterized bacterial and eukaryotic cell-targeting T6SSs, we found that T6SS-5 plays a critical role in the virulence of the organism in a murine melioidosis model, while a strain lacking the other four T6SSs remained as virulent as the wild-type. The function of T6SS-5 appeared to be specialized to the host and not related to an in vivo growth defect, as ΔT6SS-5 was fully virulent in mice lacking MyD88. Next we probed the role of the five systems in interbacterial interactions. From a group of 31 diverse bacteria, we identified several organisms that competed less effectively against wild-type B. thai than a strain lacking T6SS-1 function. Inactivation of T6SS-1 renders B. thai greatly more susceptible to cell contact-induced stasis by Pseudomonas putida, Pseudomonas fluorescens and Serratia proteamaculans—leaving it 100- to 1000-fold less fit than the wild-type in competition experiments with these organisms. Flow cell biofilm assays showed that T6S-dependent interbacterial interactions are likely relevant in the environment. B. thai cells lacking T6SS-1 were rapidly displaced in mixed biofilms with P. putida, whereas wild-type cells persisted and overran the competitor. Our data show that T6SSs within a single organism can have distinct functions in eukaryotic versus bacterial cell interactions. These systems are likely to be a decisive factor in the survival of bacterial cells of one species in intimate association with those of another, such as in polymicrobial communities present both in the environment and in many infections. PMID:20865170

Effect of dissolved oxygen on two bacterial pathogens examined using ATR-FTIR spectroscopy, microelectrophoresis, and potentiometric titration.

PubMed

Castro, Felipe D; Sedman, Jacqueline; Ismail, Ashraf A; Asadishad, Bahareh; Tufenkji, Nathalie

2010-06-01

The effects of dissolved oxygen tension during bacterial growth and acclimation on the cell surface properties and biochemical composition of the bacterial pathogens Escherichia coli O157:H7 and Yersinia enterocolitica are characterized. Three experimental techniques are used in an effort to understand the influence of bacterial growth and acclimation conditions on cell surface charge and the composition of the bacterial cell: (i) electrophoretic mobility measurements; (ii) potentiometric titration; and (iii) ATR-FTIR spectroscopy. Potentiometric titration data analyzed using chemical speciation software are related to measured electrophoretic mobilities at the pH of interest. Titration of bacterial cells is used to identify the major proton-active functional groups and the overall concentration of these cell surface ligands at the cell membrane. Analysis of titration data shows notable differences between strains and conditions, confirming the appropriateness of this tool for an overall charge characterization. ATR-FTIR spectroscopy of whole cells is used to further characterize the bacterial biochemical composition and macromolecular structures that might be involved in the development of the net surficial charge of the organisms examined. The evaluation of the integrated intensities of HPO(2)(-) and carbohydrate absorption bands in the IR spectra reveals clear differences between growth protocols. Taken together, the three techniques seem to indicate that the dissolved oxygen tension during cell growth or acclimation can noticeably influence the expression of cell surface molecules and the measurable cell surface charge, though in a strain-dependent fashion.

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.

Identification of individual biofilm-forming bacterial cells using Raman tweezers

NASA Astrophysics Data System (ADS)

Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmir; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, Veronika; Růžička, Filip

2015-05-01

A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral "Raman fingerprints" obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

Identification of individual biofilm-forming bacterial cells using Raman tweezers.

PubMed

Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmir; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, Veronika; Růžička, Filip

2015-05-01

A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral “Raman fingerprints” obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

Effect of disinfectant residual on the interaction between bacterial growth and assimilable organic carbon in a drinking water distribution system.

PubMed

Li, Weiying; Zhang, Junpeng; Wang, Feng; Qian, Lin; Zhou, Yanyan; Qi, Wanqi; Chen, Jiping

2018-07-01

Public health is threatened by deteriorated water quality due to bacterial regrowth and uncontrolled growth-related problems in drinking water distribution systems (DWDSs). To investigate the scope of this problem, a two-year field study was conducted in south China. The amount of assimilable organic carbon (AOC), total cell concentrations (TCC), and intact cell concentrations (ICC) of water samples were determined by flow cytometry. The results indicated that ICC was significantly correlated to AOC concentration when the chlorine concentration was less than 0.15 mg/L, and ICC was lower at chlorine concentrations greater than 0.15 mg/L, suggesting that free chlorine level had effect on AOC and ICC. To further analyze the effect of disinfectant on AOC and bacterial growth, we designed an orthogonal experiment with different dosages of two commonly used disinfectants, chlorine and chloramine. The results demonstrated that high concentrations of free chlorine (＞0.15 mg/L) and chloramine (＞0.4 mg/L) were associated with relatively low proportions of intact cells and cultivable bacteria. Compared with chlorine, chloramine tended to cause lower AOC level and intact cells, likely because the chlorinated disinfection byproducts (DBPs) were more easily absorbed by bacteria than the chloraminated DBPs. Based on the statistical analysis of 240 water samples, ICC was limited when AOC concentration was less than 135 μg/L, while temperature and the number of small-size particles showed positive effects on ICC (P＜0.05). We conclude that the use of chloramine and controlling particle numbers should be suitable strategies to limit bacterial regrowth. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of assimilable organic carbon and free chlorine on bacterial growth in drinking water.

PubMed

Liu, Xiaolu; Wang, Jingqi; 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 × 10(5) cells.mL(-1) to 2.6 × 10(4) cells.mL(-1) at an initial free chlorine dose of 0.6 mg.L(-1) to 4.8 × 10(4) 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.

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

Antibacterial and anticancer PDMS surface for mammalian cell growth using the Chinese herb extract paeonol(4-methoxy-2-hydroxyacetophenone)

NASA Astrophysics Data System (ADS)

Jiao, Jiajia; Sun, Lili; Guo, Zaiyu; Hou, Sen; Holyst, Robert; Lu, Yun; Feng, Xizeng

2016-12-01

Polydimethylsiloxane (PDMS) is widely used as a cell culture platform to produce micro- and nano-technology based microdevices. However, the native PDMS surface is not suitable for cell adhesion and is always subject to bacterial pollution and cancer cell invasion. Coating the PDMS surface with antibacterial or anticancer materials often causes considerable harm to the non-cancer mammalian cells on it. We have developed a method to fabricate a biocompatible PDMS surface which not only promotes non-cancer mammalian cell growth but also has antibacterial and anticancer activities, by coating the PDMS surface with a Chinese herb extract, paeonol. Coating changes the wettability and the elemental composition of the PDMS surface. Molecular dynamic simulation indicates that the absorption of paeonol onto the PDMS surface is an energy favourable process. The paeonol-coated PDMS surface exhibits good antibacterial activity against both Gram-positive and Gram-negative bacteria. Moreover considerable antibacterial activity is maintained after the coated surface is rinsed or incubated in water. The coated PDMS surface inhibits bacterial growth on the contact surface and promotes non-cancer mammalian cell growth with low cell toxicity; meanwhile the growth of cancer cells is significantly inhibited. Our study will potentially guide PDMS surface modification approaches to produce biomedical devices.

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.

Circular Dichroism studies on the interactions of antimicrobial peptides with bacterial cells

NASA Astrophysics Data System (ADS)

Avitabile, Concetta; D'Andrea, Luca Domenico; Romanelli, Alessandra

2014-03-01

Studying how antimicrobial peptides interact with bacterial cells is pivotal to understand their mechanism of action. In this paper we explored the use of Circular Dichroism to detect the secondary structure of two antimicrobial peptides, magainin 2 and cecropin A, with E. coli bacterial cells. The results of our studies allow us to gain two important information in the context of antimicrobial peptides- bacterial cells interactions: peptides fold mainly due to interaction with LPS, which is the main component of the Gram negative bacteria outer membrane and the time required for the folding on the bacterial cells depends on the peptide analyzed.

Spatial organization of transcription machinery and its segregation from the replisome in fast-growing bacterial cells

PubMed Central

Cagliero, Cedric; Zhou, Yan Ning; Jin, Ding Jun

2014-01-01

In a fast-growing Escherichia coli cell, most RNA polymerase (RNAP) is allocated to rRNA synthesis forming transcription foci at clusters of rrn operons or bacterial nucleolus, and each of the several nascent nucleoids contains multiple pairs of replication forks. The composition of transcription foci has not been determined. In addition, how the transcription machinery is three-dimensionally organized to promote cell growth in concord with replication machinery in the nucleoid remains essentially unknown. Here, we determine the spatial and functional landscapes of transcription and replication machineries in fast-growing E. coli cells using super-resolution-structured illumination microscopy. Co-images of RNAP and DNA reveal spatial compartmentation and duplication of the transcription foci at the surface of the bacterial chromosome, encompassing multiple nascent nucleoids. Transcription foci cluster with NusA and NusB, which are the rrn anti-termination system and are associated with nascent rRNAs. However, transcription foci tend to separate from SeqA and SSB foci, which track DNA replication forks and/or the replisomes, demonstrating that transcription machinery and replisome are mostly located in different chromosomal territories to maintain harmony between the two major cellular functions in fast-growing cells. Our study suggests that bacterial chromosomes are spatially and functionally organized, analogous to eukaryotes. PMID:25416798

Development of a restricted state space stochastic differential equation model for bacterial growth in rich media.

PubMed

Møller, Jan Kloppenborg; Bergmann, Kirsten Riber; Christiansen, Lasse Engbo; Madsen, Henrik

2012-07-21

In the present study, bacterial growth in a rich media is analysed in a Stochastic Differential Equation (SDE) framework. It is demonstrated that the SDE formulation and smoothened state estimates provide a systematic framework for data driven model improvements, using random walk hidden states. Bacterial growth is limited by the available substrate and the inclusion of diffusion must obey this natural restriction. By inclusion of a modified logistic diffusion term it is possible to introduce a diffusion term flexible enough to capture both the growth phase and the stationary phase, while concentration is restricted to the natural state space (substrate and bacteria non-negative). The case considered is the growth of Salmonella and Enterococcus in a rich media. It is found that a hidden state is necessary to capture the lag phase of growth, and that a flexible logistic diffusion term is needed to capture the random behaviour of the growth model. Further, it is concluded that the Monod effect is not needed to capture the dynamics of bacterial growth in the data presented. Copyright © 2012 Elsevier Ltd. All rights reserved.

Antibacterial Compounds of Canadian Honeys Target Bacterial Cell Wall Inducing Phenotype Changes, Growth Inhibition and Cell Lysis That Resemble Action of β-Lactam Antibiotics

PubMed Central

Brudzynski, Katrina; Sjaarda, Calvin

2014-01-01

Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicillin, the cell wall-active β-lactam of known mechanism of action. Firstly, we demonstrated the purity of tested honeys from potential β-lactam contaminations using quantitative LC-ESI-MS. Exposure of log-phase E. coli to honey or ampicillin resulted in time- and concentration-dependent changes in bacterial cell shape with the appearance of filamentous phenotypes at sub-inhibitory concentrations and spheroplasts at the MBC. Cell wall destruction by both agents, clearly visible on microscopic micrographs, was accompanied by increased permeability of the lipopolysaccharide outer membrane as indicated by fluorescence-activated cell sorting (FACS). More than 90% E. coli exposed to honey or ampicillin became permeable to propidium iodide. Consistently with the FACS results, both honey-treated and ampicillin-treated E. coli cells released lipopolysaccharide endotoxins at comparable levels, which were significantly higher than controls (p<0.0001). E. coli cells transformed with the ampicillin-resistance gene (β–lactamase) remained sensitive to honey, displayed the same level of cytotoxicity, cell shape changes and endotoxin release as ampicillin-sensitive cells. As expected, β–lactamase protected the host cell from antibacterial action of ampicillin. Thus, both honey and ampicillin induced similar structural changes to the cell wall and LPS and that this ability underlies antibacterial activities of both agents. Since the cell wall is critical for cell growth and survival, honey

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

2015-09-28

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.

Synthetic inhibitors of bacterial cell division targeting the GTP-binding site of FtsZ.

PubMed

Ruiz-Avila, Laura B; Huecas, Sonia; Artola, Marta; Vergoñós, Albert; Ramírez-Aportela, Erney; Cercenado, Emilia; Barasoain, Isabel; Vázquez-Villa, Henar; Martín-Fontecha, Mar; Chacón, Pablo; López-Rodríguez, María L; Andreu, José M

2013-09-20

Cell division protein FtsZ is the organizer of the cytokinetic Z-ring in most bacteria and a target for new antibiotics. FtsZ assembles with GTP into filaments that hydrolyze the nucleotide at the association interface between monomers and then disassemble. We have replaced FtsZ's GTP with non-nucleotide synthetic inhibitors of bacterial division. We searched for these small molecules among compounds from the literature, from virtual screening (VS), and from our in-house synthetic library (UCM), employing a fluorescence anisotropy primary assay. From these screens we have identified the polyhydroxy aromatic compound UCM05 and its simplified analogue UCM44 that specifically bind to Bacillus subtilis FtsZ monomers with micromolar affinities and perturb normal assembly, as examined with light scattering, polymer sedimentation, and negative stain electron microscopy. On the other hand, these ligands induce the cooperative assembly of nucleotide-devoid archaeal FtsZ into distinct well-ordered polymers, different from GTP-induced filaments. These FtsZ inhibitors impair localization of FtsZ into the Z-ring and inhibit bacterial cell division. The chlorinated analogue UCM53 inhibits the growth of clinical isolates of antibiotic-resistant Staphylococcus aureus and Enterococcus faecalis. We suggest that these interfacial inhibitors recapitulate binding and some assembly-inducing effects of GTP but impair the correct structural dynamics of FtsZ filaments and thus inhibit bacterial division, possibly by binding to a small fraction of the FtsZ molecules in a bacterial cell, which opens a new approach to FtsZ-based antibacterial drug discovery.

Host-Polarized Cell Growth in Animal Symbionts.

PubMed

Pende, Nika; Wang, Jinglan; Weber, Philipp M; Verheul, Jolanda; Kuru, Erkin; Rittmann, Simon K-M R; Leisch, Nikolaus; VanNieuwenhze, Michael S; Brun, Yves V; den Blaauwen, Tanneke; Bulgheresi, Silvia

2018-04-02

To determine the fundamentals of cell growth, we must extend cell biological studies to non-model organisms. Here, we investigated the growth modes of the only two rods known to widen instead of elongating, Candidatus Thiosymbion oneisti and Thiosymbion hypermnestrae. These bacteria are attached by one pole to the surface of their respective nematode hosts. By incubating live Ca. T. oneisti and T. hypermnestrae with a peptidoglycan metabolic probe, we observed that the insertion of new cell wall starts at the poles and proceeds inward, concomitantly with FtsZ-based membrane constriction. Remarkably, in Ca. T. hypermnestrae, the proximal, animal-attached pole grows before the distal, free pole, indicating that the peptidoglycan synthesis machinery is host oriented. Immunostaining of the symbionts with an antibody against the actin homolog MreB revealed that it was arranged medially-that is, parallel to the cell long axis-throughout the symbiont life cycle. Given that depolymerization of MreB abolished newly synthesized peptidoglycan insertion and impaired divisome assembly, we conclude that MreB function is required for symbiont widening and division. In conclusion, our data invoke a reassessment of the localization and function of the bacterial actin homolog. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Ammonia produced by bacterial colonies promotes growth of ampicillin-sensitive Serratia sp. by means of antibiotic inactivation.

PubMed

Cepl, Jaroslav; Blahůšková, Anna; Cvrčková, Fatima; Markoš, Anton

2014-05-01

Volatiles produced by bacterial cultures are known to induce regulatory and metabolic alterations in nearby con-specific or heterospecific bacteria, resulting in phenotypic changes including acquisition of antibiotic resistance. We observed unhindered growth of ampicillin-sensitive Serratia rubidaea and S. marcescens on ampicillin-containing media, when exposed to volatiles produced by dense bacterial growth. However, this phenomenon appeared to result from pH increase in the medium caused by bacterial volatiles rather than alterations in the properties of the bacterial cultures, as alkalization of ampicillin-containing culture media to pH 8.5 by ammonia or Tris exhibited the same effects, while pretreatment of bacterial cultures under the same conditions prior to antibiotic exposure did not increase ampicillin resistance. Ampicillin was readily inactivated at pH 8.5, suggesting that observed bacterial growth results from metabolic alteration of the medium, rather than an active change in the target bacterial population (i.e. induction of resistance or tolerance). However, even such seemingly simple mechanism may provide a biologically meaningful basis for protection against antibiotics in microbial communities growing on semi-solid media. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Exploring bacterial infections: theoretical and experimental studies of the bacterial population dynamics and antibiotic treatment

NASA Astrophysics Data System (ADS)

Shao, Xinxian

Bacterial infections are very common in human society. Thus extensive research has been conducted to reveal the molecular mechanisms of the pathogenesis and to evaluate the antibiotics' efficacy against bacteria. Little is known, however, about the population dynamics of bacterial populations and their interactions with the host's immune system. In this dissertation, a stochatic model is developed featuring stochastic phenotypic switching of bacterial individuals to explain the single-variant bottleneck discovered in multi strain bacterial infections. I explored early events in a bacterial infection establishment using classical experiments of Moxon and Murphy on neonatal rats. I showed that the minimal model and its simple variants do not work. I proposed modifications to the model that could explain the data quantitatively. The bacterial infections are also commonly established in physical structures, as biofilms or 3-d colonies. In contrast, most research on antibiotic treatment of bacterial infections has been conducted in well-mixed liquid cultures. I explored the efficacy of antibiotics to treat such bacterial colonies, a broadly applicable method is designed and evaluated where discrete bacterial colonies on 2-d surfaces were exposed to antibiotics. I discuss possible explanations and hypotheses for the experimental results. To verify these hypotheses, we investigated the dynamics of bacterial population as 3-d colonies. We showed that a minimal mathematical model of bacterial colony growth in 3-d was able to account for the experimentally observed presence of a diffusion-limited regime. The model further revealed highly loose packing of the cells in 3-d colonies and smaller cell sizes in colonies than plancktonic cells in corresponding liquid culture. Further experimental tests of the model predictions have revealed that the ratio of the cell size in liquid culture to that in colony cultures was consistent with the model prediction, that the dead cells

The papain inhibitor (SPI) of Streptomyces mobaraensis inhibits bacterial cysteine proteases and is an antagonist of bacterial growth.

PubMed

Zindel, Stephan; Kaman, Wendy E; Fröls, Sabrina; Pfeifer, Felicitas; Peters, Anna; Hays, John P; Fuchsbauer, Hans-Lothar

2013-07-01

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.

Bacterial diversity, community structure and potential growth rates along an estuarine salinity gradient

PubMed Central

Campbell, Barbara J; Kirchman, David L

2013-01-01

Very little is known about growth rates of individual bacterial taxa and how they respond to environmental flux. Here, we characterized bacterial community diversity, structure and the relative abundance of 16S rRNA and 16S rRNA genes (rDNA) using pyrosequencing along the salinity gradient in the Delaware Bay. Indices of diversity, evenness, structure and growth rates of the surface bacterial community significantly varied along the transect, reflecting active mixing between the freshwater and marine ends of the estuary. There was no positive correlation between relative abundances of 16S rRNA and rDNA for the entire bacterial community, suggesting that abundance of bacteria does not necessarily reflect potential growth rate or activity. However, for almost half of the individual taxa, 16S rRNA positively correlated with rDNA, suggesting that activity did follow abundance in these cases. The positive relationship between 16S rRNA and rDNA was less in the whole water community than for free-living taxa, indicating that the two communities differed in activity. The 16S rRNA:rDNA ratios of some typically marine taxa reflected differences in light, nutrient concentrations and other environmental factors along the estuarine gradient. The ratios of individual freshwater taxa declined as salinity increased, whereas the 16S rRNA:rDNA ratios of only some typical marine bacteria increased as salinity increased. These data suggest that physical and other bottom-up factors differentially affect growth rates, but not necessarily abundance of individual taxa in this highly variable environment. PMID:22895159

Bacterial flagella grow through an injection-diffusion mechanism

PubMed Central

Renault, Thibaud T; Abraham, Anthony O; Bergmiller, Tobias; Paradis, Guillaume; Rainville, Simon; Charpentier, Emmanuelle; Guet, Călin C; Tu, Yuhai; Namba, Keiichi; Keener, James P; Minamino, Tohru; Erhardt, Marc

2017-01-01

The bacterial flagellum is a self-assembling nanomachine. The external flagellar filament, several times longer than a bacterial cell body, is made of a few tens of thousands subunits of a single protein: flagellin. A fundamental problem concerns the molecular mechanism of how the flagellum grows outside the cell, where no discernible energy source is available. Here, we monitored the dynamic assembly of individual flagella using in situ labelling and real-time immunostaining of elongating flagellar filaments. We report that the rate of flagellum growth, initially ∼1,700 amino acids per second, decreases with length and that the previously proposed chain mechanism does not contribute to the filament elongation dynamics. Inhibition of the proton motive force-dependent export apparatus revealed a major contribution of substrate injection in driving filament elongation. The combination of experimental and mathematical evidence demonstrates that a simple, injection-diffusion mechanism controls bacterial flagella growth outside the cell. DOI: http://dx.doi.org/10.7554/eLife.23136.001 PMID:28262091

Bacterial flagella grow through an injection-diffusion mechanism.

PubMed

Renault, Thibaud T; Abraham, Anthony O; Bergmiller, Tobias; Paradis, Guillaume; Rainville, Simon; Charpentier, Emmanuelle; Guet, Călin C; Tu, Yuhai; Namba, Keiichi; Keener, James P; Minamino, Tohru; Erhardt, Marc

2017-03-06

The bacterial flagellum is a self-assembling nanomachine. The external flagellar filament, several times longer than a bacterial cell body, is made of a few tens of thousands subunits of a single protein: flagellin. A fundamental problem concerns the molecular mechanism of how the flagellum grows outside the cell, where no discernible energy source is available. Here, we monitored the dynamic assembly of individual flagella using in situ labelling and real-time immunostaining of elongating flagellar filaments. We report that the rate of flagellum growth, initially ∼1,700 amino acids per second, decreases with length and that the previously proposed chain mechanism does not contribute to the filament elongation dynamics. Inhibition of the proton motive force-dependent export apparatus revealed a major contribution of substrate injection in driving filament elongation. The combination of experimental and mathematical evidence demonstrates that a simple, injection-diffusion mechanism controls bacterial flagella growth outside the cell.

Hydration dynamics promote bacterial coexistence on rough surfaces

PubMed Central

Wang, Gang; Or, Dani

2013-01-01

Identification of mechanisms that promote and maintain the immense microbial diversity found in soil is a central challenge for contemporary microbial ecology. Quantitative tools for systematic integration of complex biophysical and trophic processes at spatial scales, relevant for individual cell interactions, are essential for making progress. We report a modeling study of competing bacterial populations cohabiting soil surfaces subjected to highly dynamic hydration conditions. The model explicitly tracks growth, motion and life histories of individual bacterial cells on surfaces spanning dynamic aqueous networks that shape heterogeneous nutrient fields. The range of hydration conditions that confer physical advantages for rapidly growing species and support competitive exclusion is surprisingly narrow. The rapid fragmentation of soil aqueous phase under most natural conditions suppresses bacterial growth and cell dispersion, thereby balancing conditions experienced by competing populations with diverse physiological traits. In addition, hydration fluctuations intensify localized interactions that promote coexistence through disproportional effects within densely populated regions during dry periods. Consequently, bacterial population dynamics is affected well beyond responses predicted from equivalent and uniform hydration conditions. New insights on hydration dynamics could be considered in future designs of soil bioremediation activities, affect longevity of dry food products, and advance basic understanding of bacterial diversity dynamics and its role in global biogeochemical cycles. PMID:23051694

Biolistic transformation of tobacco and maize suspension cells using bacterial cells as microprojectiles.

PubMed

Rasmussen, J L; Kikkert, J R; Roy, M K; Sanford, J C

1994-01-01

We have used both Escherichia coli cells and Agrobacterium tumefaciens cells as microprojectiles to deliver DNA into suspension-cultured tobacco (Nicotiana tabacum L. line NT1) cells using a helium powered biolistic device. In addition, E. coli cells were used as microprojectiles for the transformation of suspension-cultured maize (Zea mays cv. Black Mexican Sweet) cells. Pretreating the bacterial cells with phenol at a concentration of 1.0%, and combining the bacterial cells with tungsten particles increased the rates of transformation. In N. tabacum, we obtained hundreds of transient transformants per bombardment, but were unable to recover any stable transformants. In Z. mays we obtained thousands of transient transformants and an average of six stable transformants per bombardment. This difference is discussed.

Role of the gut microbiota in host appetite control: bacterial growth to animal feeding behaviour.

PubMed

Fetissov, Sergueï O

2017-01-01

The life of all animals is dominated by alternating feelings of hunger and satiety - the main involuntary motivations for feeding-related behaviour. Gut bacteria depend fully on their host for providing the nutrients necessary for their growth. The intrinsic ability of bacteria to regulate their growth and to maintain their population within the gut suggests that gut bacteria can interfere with molecular pathways controlling energy balance in the host. The current model of appetite control is based mainly on gut-brain signalling and the animal's own needs to maintain energy homeostasis; an alternative model might also involve bacteria-host communications. Several bacterial components and metabolites have been shown to stimulate intestinal satiety pathways; at the same time, their production depends on bacterial growth cycles. This short-term bacterial growth-linked modulation of intestinal satiety can be coupled with long-term regulation of appetite, controlled by the neuropeptidergic circuitry in the hypothalamus. Indeed, several bacterial products are detected in the systemic circulation, which might act directly on hypothalamic neurons. This Review analyses the data relevant to possible involvement of the gut bacteria in the regulation of host appetite and proposes an integrative homeostatic model of appetite control that includes energy needs of both the host and its gut bacteria.

Atropine and glycopyrrolate do not support bacterial growth-safety and economic considerations.

PubMed

Ittzes, Balazs; Weiling, Zsolt; Batai, Istvan Zoard; Kerenyi, Monika; Batai, Istvan

2016-12-01

Evaluation of bacterial growth in atropine and glycopyrrolate. Laboratory investigation. Standard microbiological methods were used to evaluate the impact of atropine and glycopyrrolate on the growth of Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Bacterial count was checked at 0, 1, 2, 3, 4, 6, and 24 hours. Atropine or glycopyrrolate did not support the growth of the above bacteria at any examined time at room temperature. Glycopyrrolate killed all of the examined strains (P < .05), whereas in atropine, only the clinical isolates of Staphylococcus and Acinetobacter were killed (P < .05). Drawing up atropine or glycopyrrolate at the beginning of the operating list and use within 24 hours if needed are a safe practice and do not pose infection hazard. We can also reduce hospital costs if we do not throw away these unused syringes following each case. Copyright © 2016 Elsevier Inc. All rights reserved.

Selection of peptidoglycan-specific aptamers for bacterial cells identification.

PubMed

Ferreira, Iêda Mendes; de Souza Lacerda, Camila Maria; de Faria, Lígia Santana; Corrêa, Cristiane Rodrigues; de Andrade, Antero Silva Ribeiro

2014-12-01

Peptidoglycan is a highly complex and essential macromolecule of bacterial outer cell wall; it is a heteropolymer made up of linear glycan strands cross-linked by peptides. Peptidoglycan has a particular composition which makes it a possible target for specific bacterial recognition. Aptamers are single-stranded DNA or RNA oligonucleotides that bind to target molecules with high affinity and specificity. Aptamers can be labeled with different radioisotopes and possess several properties that make them suitable for molecular imaging. The purpose of this study was to obtain aptamers for use as radiopharmaceutical in bacterial infection diagnosis. Two aptamers (Antibac1 and Antibac2) against peptidoglycan were selected through the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology. The dissociation constant (Kd) for Antibac1 was 0.415 + 0.047 μM and for Antibac2 was 1.261 + 0.280 μM. These aptamers labeled with (32)P showed high affinity for Staphylococcus aureus cells. The binding to S. aureus and Escherichia coli in vitro were significantly higher than for Candida albicans and human fibroblasts, demonstrating their specificity for bacterial cells. These results point Antibac1 and Antibac2 as promising tools for bacterial infections identification.

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly

PubMed Central

van Teeffelen, Sven; Wang, Siyuan; Furchtgott, Leon; Huang, Kerwyn Casey; Wingreen, Ned S.; Shaevitz, Joshua W.; Gitai, Zemer

2011-01-01

Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis. PMID:21903929

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly.

PubMed

van Teeffelen, Sven; Wang, Siyuan; Furchtgott, Leon; Huang, Kerwyn Casey; Wingreen, Ned S; Shaevitz, Joshua W; Gitai, Zemer

2011-09-20

Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis.

Enterococcus faecium LKE12 Cell-Free Extract Accelerates Host Plant Growth via Gibberellin and Indole-3-Acetic Acid Secretion.

PubMed

Lee, Ko-Eun; Radhakrishnan, Ramalingam; Kang, Sang-Mo; You, Young-Hyun; Joo, Gil-Jae; Lee, In-Jung; Ko, Jae-Hwan; Kim, Jin-Ho

2015-09-01

The use of microbial extracts containing plant hormones is a promising technique to improve crop growth. Little is known about the effect of bacterial cell-free extracts on plant growth promotion. This study, based on phytohormonal analyses, aimed at exploring the potential mechanisms by which Enterococcus faecium LKE12 enhances plant growth in oriental melon. A bacterial strain, LKE12, was isolated from soil, and further identified as E. faecium by 16S rDNA sequencing and phylogenetic analysis. The plant growth-promoting ability of an LKE12 bacterial culture was tested in a gibberellin (GA)-deficient rice dwarf mutant (waito-C) and a normal GA biosynthesis rice cultivar (Hwayongbyeo). E. faecium LKE12 significantly improved the length and biomass of rice shoots in both normal and dwarf cultivars through the secretion of an array of gibberellins (GA1, GA3, GA7, GA8, GA9, GA12, GA19, GA20, GA24, and GA53), as well as indole-3-acetic acid (IAA). To the best of our knowledge, this is the first study indicating that E. faecium can produce GAs. Increases in shoot and root lengths, plant fresh weight, and chlorophyll content promoted by E. faecium LKE12 and its cell-free extract inoculated in oriental melon plants revealed a favorable interaction of E. faecium LKE12 with plants. Higher plant growth rates and nutrient contents of magnesium, calcium, sodium, iron, manganese, silicon, zinc, and nitrogen were found in cell-free extract-treated plants than in control plants. The results of the current study suggest that E. faecium LKE12 promotes plant growth by producing GAs and IAA; interestingly, the exogenous application of its cell-free culture extract can be a potential strategy to accelerate plant growth.

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

Changing the 30-min Rule in Canada: The Effect of Room Temperature on Bacterial Growth in Red Blood Cells.

PubMed

Ramirez-Arcos, Sandra; Kou, Yuntong; Ducas, Éric; Thibault, Louis

2016-11-01

To maintain product quality and safety, the '30-min rule' requires the discard of red blood cells (RBCs) that are exposed to uncontrolled temperatures for more than 30 min. Recent studies suggest this rule may safely be extended to a 60-min rule. A pool-and-split design study (N = 4) was run in parallel at Canadian Blood Services (SAGM RBCs) and Héma-Québec (AS-3 RBCs). RBCs were spiked with ∼1 colony-forming unit/ml of mesophilic and psychrophilic bacteria. Control units remained in storage at 1-6 °C for 42 days. Test 30 (T30) and T60 units were exposed to room temperature (RT) six times during storage, each time for 30 and 60 min, respectively. Bacterial proliferation was monitored. Mesophilic bacteria do not proliferate in RBCs. The growth of psychrophilic bacteria is not significantly different in RBCs exposed for 30 or 60 min to RT (p < 0.05). The study findings were the final evidence to support extension from a 30-min rule to a 60-min rule in Canada.

Toxicity of a polymer-graphene oxide composite against bacterial planktonic cells, biofilms, and mammalian cells

NASA Astrophysics Data System (ADS)

Mejías Carpio, Isis E.; Santos, Catherine M.; Wei, Xin; Rodrigues, Debora F.

2012-07-01

-N-carbazole (PVK)-graphene oxide (GO) nanocomposite (PVK-GO), which contains only 3 wt% of GO well-dispersed in a 97 wt% PVK matrix, presents excellent antibacterial properties without significant cytotoxicity to mammalian cells. The high polymer content in this nanocomposite makes future large-scale material manufacturing possible in a high-yield process of adiabatic bulk polymerization. In this study, the toxicity of PVK-GO was assessed with planktonic microbial cells, biofilms, and NIH 3T3 fibroblast cells. The antibacterial effects were evaluated against two Gram-negative bacteria: Escherichia coli and Cupriavidus metallidurans; and two Gram-positive bacteria: Bacillus subtilis and Rhodococcus opacus. The results show that the PVK-GO nanocomposite presents higher antimicrobial effects than the pristine GO. The effectiveness of the PVK-GO in solution was demonstrated as the nanocomposite ``encapsulated'' the bacterial cells, which led to reduced microbial metabolic activity and cell death. The fact that the PVK-GO did not present significant cytotoxicity to fibroblast cells offers a great opportunity for potential applications in important biomedical and industrial fields. Electronic supplementary information (ESI) available: Bacterial OD600 absorbance growth curves, representative LIVE/DEAD images and percent of inactive cells after treatment with the most toxic concentrations of nanomaterials, bacterial OD540 nm biofilm absorbance, percent toxicity on the ITO-modified surfaces, additional TEM/SEM images of the nanomaterials and B. subtilis, NIH 3T3 fibroblast cells percent toxicity. See DOI: 10.1039/c2nr30774j

Measuring bacterial cells size with AFM

PubMed Central

Osiro, Denise; Filho, Rubens Bernardes; Assis, Odilio Benedito Garrido; Jorge, Lúcio André de Castro; Colnago, Luiz Alberto

2012-01-01

Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described. PMID:24031837

High density growth of T7 expression strains with auto-induction option

DOEpatents

Studier, F William [Stony Brook, NY

2009-07-14

Disclosed is a method for promoting auto-induction of transcription of cloned DNA in cultures of bacterial cells grown batchwise, the transcription being under the control of a promoter whose activity can be induced by an exogenous inducer whose ability to induce said promoter is dependent on the metabolic state of said bacterial cells. Initially, a culture media is provided which includes: i) an inducer that causes induction of transcription from said promoter in said bacterial cells; and ii) a metabolite that prevents induction by said inducer, the concentration of said metabolite being adjusted so as to substantially preclude induction by said inducer in the early stages of growth of the bacterial culture, but such that said metabolite is depleted to a level that allows induction by said inducer at a later stage of growth. The culture medium is inoculated with a bacterial inoculum, the inoculum comprising bacterial cells containing cloned DNA, the transcription of which is induced by said inducer. The culture is then incubated under conditions appropriate for growth of the bacterial cells.

Vaginal lactobacilli inhibiting growth of Gardnerella vaginalis, Mobiluncus and other bacterial species cultured from vaginal content of women with bacterial vaginosis.

PubMed

Skarin, A; Sylwan, J

1986-12-01

On a solid agar medium the growth-inhibitory effect of 9 Lactobacillus strains cultured from vaginal content was tested on bacteria cultured from vaginal content of women with bacterial vaginosis: Mobiluncus, Gardnerella vaginalis, Bacteroides and anaerobic cocci. Inhibition zones were observed in the growth of all of the strains isolated from women with bacterial vaginosis around all lactobacilli. The inhibitory effect of the lactobacilli was further tested on various anaerobic and facultatively anaerobic species, both type strains and fresh extragenitally cultured strains. Four Bacteroides fragilis strains as well as 2 out of 4 Staphylococcus aureus strains were clearly inhibited by the lactobacilli. The inhibition zones were generally wider at pH 5.5 than at 6.0. For all inhibited strains, (the S. aureus excepted) a low pH on the agar around the lactobacilli correlated to wider growth-inhibition zones.

Effect of primycin on growth-arrested cultures and cell integrity of Staphylococcus aureus.

PubMed

Feiszt, Péter; Schneider, György; Emődy, Levente

2017-06-01

Bactericidal effect against non-dividing bacteria is a very advantageous, but rare characteristic among antimicrobial agents, mostly possessed by those affecting the cell membrane. These kinds of agents can kill bacterial cells without lysis. We assessed these characteristics on primycin, a topical anti-staphylococcal agent highly effective against prevalent multiresistant strains, as it also acts on the cell membrane. In time-kill studies, primycin preserved its bactericidal activity against growth-arrested Staphylococcus aureus cultures. The bactericidal action was slower against growth-arrested cultures compared to the exponentially growing ones to different extents depending on the manner of arrest. The bactericidal effect was less influenced by stringent response and by protein synthesis inhibition, proving that it does not depend on metabolic activity. In contrast, uncoupling of the membrane potential predominantly slowed, and low temperature almost stopped killing of bacteria. In consideration of published data, these facts suggest that the antibacterial action of primycin involves disrupting of the membrane potential, and is predominantly influenced by the membrane fluidity. Optical density measurements and transmission electron microscopy verified that primycin kills bacterial cells without lysis. These results reveal favorable characteristics of primycin and point to, and broaden the knowledge on its membrane-targeted effect.

Growth of bacteria in 3-d colonies

PubMed Central

Mugler, Andrew; Kim, Justin

2017-01-01

The dynamics of growth of bacterial populations has been extensively studied for planktonic cells in well-agitated liquid culture, in which all cells have equal access to nutrients. In the real world, bacteria are more likely to live in physically structured habitats as colonies, within which individual cells vary in their access to nutrients. The dynamics of bacterial growth in such conditions is poorly understood, and, unlike that for liquid culture, there is not a standard broadly used mathematical model for bacterial populations growing in colonies in three dimensions (3-d). By extending the classic Monod model of resource-limited population growth to allow for spatial heterogeneity in the bacterial access to nutrients, we develop a 3-d model of colonies, in which bacteria consume diffusing nutrients in their vicinity. By following the changes in density of E. coli in liquid and embedded in glucose-limited soft agar, we evaluate the fit of this model to experimental data. The model accounts for the experimentally observed presence of a sub-exponential, diffusion-limited growth regime in colonies, which is absent in liquid cultures. The model predicts and our experiments confirm that, as a consequence of inter-colony competition for the diffusing nutrients and of cell death, there is a non-monotonic relationship between total number of colonies within the habitat and the total number of individual cells in all of these colonies. This combined theoretical-experimental study reveals that, within 3-d colonies, E. coli cells are loosely packed, and colonies produce about 2.5 times as many cells as the liquid culture from the same amount of nutrients. We verify that this is because cells in liquid culture are larger than in colonies. Our model provides a baseline description of bacterial growth in 3-d, deviations from which can be used to identify phenotypic heterogeneities and inter-cellular interactions that further contribute to the structure of bacterial

Effect of flow and peristaltic mixing on bacterial growth in a gut-like channel

PubMed Central

Cremer, Jonas; Segota, Igor; Yang, Chih-yu; Arnoldini, Markus; Sauls, John T.; Zhang, Zhongge; Gutierrez, Edgar; Groisman, Alex; Hwa, Terence

2016-01-01

The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the “minigut.” This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction–diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon. PMID:27681630

BACTERIAL GROWTH AND MULTIPLICATION AS DISCLOSED BY MICRO MOTION PICTURES

PubMed Central

Wyckoff, Ralph W. G.

1934-01-01

Using a micro motion picture technique for making records, studies covering several thousand hours of observation have been made of the growth of a number of bacteria. On the basis of these experiments a discussion is offered of bacterial division and its influence on gross colony appearance, of different kinds of pleomorphism that have been observed, and of the nature of the internal structure that is seen in some bacteria. Several of the microorganisms chosen for examination are ones that have been thought to give evidence of life cycle phenomena. The present pictures, however, contain no evidence of a bacterial cycle in the commonly accepted meaning of the term. PMID:19870252

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.

Structure of a bacterial cell surface decaheme electron conduit

USDA-ARS?s Scientific Manuscript database

Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits...

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.

Bacterial cell identification in differential interference contrast microscopy images.

PubMed

Obara, Boguslaw; Roberts, Mark A J; Armitage, Judith P; Grau, Vicente

2013-04-23

Microscopy image segmentation lays the foundation for shape analysis, motion tracking, and classification of biological objects. Despite its importance, automated segmentation remains challenging for several widely used non-fluorescence, interference-based microscopy imaging modalities. For example in differential interference contrast microscopy which plays an important role in modern bacterial cell biology. Therefore, new revolutions in the field require the development of tools, technologies and work-flows to extract and exploit information from interference-based imaging data so as to achieve new fundamental biological insights and understanding. We have developed and evaluated a high-throughput image analysis and processing approach to detect and characterize bacterial cells and chemotaxis proteins. Its performance was evaluated using differential interference contrast and fluorescence microscopy images of Rhodobacter sphaeroides. Results demonstrate that the proposed approach provides a fast and robust method for detection and analysis of spatial relationship between bacterial cells and their chemotaxis proteins.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

NASA Astrophysics Data System (ADS)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-06-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Metabolic Regulation of a Bacterial Cell System with Emphasis on Escherichia coli Metabolism

PubMed Central

Shimizu, Kazuyuki

2013-01-01

It is quite important to understand the overall metabolic regulation mechanism of bacterial cells such as Escherichia coli from both science (such as biochemistry) and engineering (such as metabolic engineering) points of view. Here, an attempt was made to clarify the overall metabolic regulation mechanism by focusing on the roles of global regulators which detect the culture or growth condition and manipulate a set of metabolic pathways by modulating the related gene expressions. For this, it was considered how the cell responds to a variety of culture environments such as carbon (catabolite regulation), nitrogen, and phosphate limitations, as well as the effects of oxygen level, pH (acid shock), temperature (heat shock), and nutrient starvation. PMID:25937963

An In vitro Model for Bacterial Growth on Human Stratum Corneum.

PubMed

van der Krieken, Danique A; Ederveen, Thomas H A; van Hijum, Sacha A F T; Jansen, Patrick A M; Melchers, Willem J G; Scheepers, Paul T J; Schalkwijk, Joost; Zeeuwen, Patrick L J M

2016-11-02

The diversity and dynamics of the skin microbiome in health and disease have been studied recently, but adequate model systems to study skin microbiotas in vitro are largely lacking. We developed an in vitro system that mimics human stratum corneum, using human callus as substrate and nutrient source for bacterial growth. The growth of several commensal and pathogenic bacterial strains was measured for up to one week by counting colony-forming units or by quantitative PCR with strain-specific primers. Human skin pathogens were found to survive amidst a minimal microbiome consisting of 2 major skin commensals: Staphylococcus epidermidis and Propionibacterium acnes. In addition, complete microbiomes, taken from the backs of healthy volunteers, were inoculated and maintained using this system. This model may enable the modulation of skin microbiomes in vitro and allow testing of pathogens, biological agents and antibiotics in a medium-throughput format.

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

Dissecting Bacterial Cell Wall Entry and Signaling in Eukaryotic Cells: an Actin-Dependent Pathway Parallels Platelet-Activating Factor Receptor-Mediated Endocytosis.

PubMed

Loh, Lip Nam; Gao, Geli; Tuomanen, Elaine I

2017-01-03

The Gram-positive bacterial cell wall (CW) peptidoglycan-teichoic acid complex is released into the host environment during bacterial metabolism or death. It is a highly inflammatory Toll-like receptor 2 (TLR2) ligand, and previous in vivo studies have demonstrated its ability to recapitulate pathological features of pneumonia and meningitis. We report that an actin-dependent pathway is involved in the internalization of the CW by epithelial and endothelial cells, in addition to the previously described platelet-activating factor receptor (PAFr)-dependent uptake pathway. Unlike the PAFr-dependent pathway, which is mediated by clathrin and dynamin and does not lead to signaling, the alternative pathway is sensitive to 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and engenders Rac1, Cdc42, and phosphatidylinositol 3-kinase (PI3K) signaling. Upon internalization by this macropinocytosis-like pathway, CW is trafficked to lysosomes. Intracellular CW trafficking is more complex than previously recognized and suggests multiple points of interaction with and without innate immune signaling. Streptococcus pneumoniae is a major human pathogen infecting the respiratory tract and brain. It is an established model organism for understanding how infection injures the host. During infection or bacterial growth, bacteria shed their cell wall (CW) into the host environment and trigger inflammation. A previous study has shown that CW enters and crosses cell barriers by interacting with a receptor on the surfaces of host cells, termed platelet-activating factor receptor (PAFr). In the present study, by using cells that are depleted of PAFr, we identified a second pathway with features of macropinocytosis, which is a receptor-independent fluid uptake mechanism by cells. Each pathway contributes approximately the same amount of cell wall trafficking, but the PAFr pathway is silent, while the new pathway appears to contribute to the host inflammatory response to CW insult. Copyright © 2017

Bacterial Community Associated with Healthy and Diseased Pacific White Shrimp (Litopenaeus vannamei) Larvae and Rearing Water across Different Growth Stages.

PubMed

Zheng, Yanfen; Yu, Min; Liu, Jiwen; Qiao, Yanlu; Wang, Long; Li, Zhitao; Zhang, Xiao-Hua; Yu, Mingchao

2017-01-01

Bacterial communities are called another "organ" for aquatic animals and their important influence on the health of host has drawn increasing attention. Thus, it is important to study the relationships between aquatic animals and bacterial communities. Here, bacterial communities associated with Litopenaeus vannamei larvae at different healthy statuses (diseased and healthy) and growth stages (i.e., zoea, mysis, and early postlarvae periods) were examined using 454-pyrosequencing of the 16S rRNA gene. Bacterial communities with significant difference were observed between healthy and diseased rearing water, and several bacterial groups, such as genera Nautella and Kordiimonas could also distinguish healthy and diseased shrimp. Rhodobacteraceae was widely distributed in rearing water at all growth stages but there were several stage-specific groups, indicating that bacterial members in rearing water assembled into distinct communities throughout the larval development. However, Gammaproteobacteria , mainly family Enterobacteriaceae , was the most abundant group (accounting for more than 85%) in shrimp larvae at all growth stages. This study compared bacterial communities associated with healthy and diseased L . vannamei larvae and rearing water, and identified several health- and growth stage-specific bacterial groups, which might be provided as indicators for monitoring the healthy status of shrimp larvae in hatchery.

Bacterial Community Associated with Healthy and Diseased Pacific White Shrimp (Litopenaeus vannamei) Larvae and Rearing Water across Different Growth Stages

PubMed Central

Zheng, Yanfen; Yu, Min; Liu, Jiwen; Qiao, Yanlu; Wang, Long; Li, Zhitao; Zhang, Xiao-Hua; Yu, Mingchao

2017-01-01

Bacterial communities are called another “organ” for aquatic animals and their important influence on the health of host has drawn increasing attention. Thus, it is important to study the relationships between aquatic animals and bacterial communities. Here, bacterial communities associated with Litopenaeus vannamei larvae at different healthy statuses (diseased and healthy) and growth stages (i.e., zoea, mysis, and early postlarvae periods) were examined using 454-pyrosequencing of the 16S rRNA gene. Bacterial communities with significant difference were observed between healthy and diseased rearing water, and several bacterial groups, such as genera Nautella and Kordiimonas could also distinguish healthy and diseased shrimp. Rhodobacteraceae was widely distributed in rearing water at all growth stages but there were several stage-specific groups, indicating that bacterial members in rearing water assembled into distinct communities throughout the larval development. However, Gammaproteobacteria, mainly family Enterobacteriaceae, was the most abundant group (accounting for more than 85%) in shrimp larvae at all growth stages. This study compared bacterial communities associated with healthy and diseased L. vannamei larvae and rearing water, and identified several health- and growth stage-specific bacterial groups, which might be provided as indicators for monitoring the healthy status of shrimp larvae in hatchery. PMID:28769916

Heterologous Expression of Secreted Bacterial BPP and HAP Phytases in Plants Stimulates Arabidopsis thaliana Growth on Phytate.

PubMed

Valeeva, Lia R; Nyamsuren, Chuluuntsetseg; Sharipova, Margarita R; Shakirov, Eugene V

2018-01-01

Phytases are specialized phosphatases capable of releasing inorganic phosphate from myo -inositol hexakisphosphate (phytate), which is highly abundant in many soils. As inorganic phosphorus reserves decrease over time in many agricultural soils, genetic manipulation of plants to enable secretion of potent phytases into the rhizosphere has been proposed as a promising approach to improve plant phosphorus nutrition. Several families of biotechnologically important phytases have been discovered and characterized, but little data are available on which phytase families can offer the most benefits toward improving plant phosphorus intake. We have developed transgenic Arabidopsis thaliana plants expressing bacterial phytases PaPhyC (HAP family of phytases) and 168phyA (BPP family) under the control of root-specific inducible promoter Pht1;2 . The effects of each phytase expression on growth, morphology and inorganic phosphorus accumulation in plants grown on phytate hydroponically or in perlite as the only source of phosphorus were investigated. The most enzymatic activity for both phytases was detected in cell wall-bound fractions of roots, indicating that these enzymes were efficiently secreted. Expression of both bacterial phytases in roots improved plant growth on phytate and resulted in larger rosette leaf area and diameter, higher phosphorus content and increased shoot dry weight, implying that these plants were indeed capable of utilizing phytate as the source of phosphorus for growth and development. When grown on phytate the HAP-type phytase outperformed its BPP-type counterpart for plant biomass production, though this effect was only observed in hydroponic conditions and not in perlite. Furthermore, we found no evidence of adverse side effects of microbial phytase expression in A. thaliana on plant physiology and seed germination. Our data highlight important functional differences between these members of bacterial phytase families and indicate that future

Heterologous Expression of Secreted Bacterial BPP and HAP Phytases in Plants Stimulates Arabidopsis thaliana Growth on Phytate

PubMed Central

Valeeva, Lia R.; Nyamsuren, Chuluuntsetseg; Sharipova, Margarita R.; Shakirov, Eugene V.

2018-01-01

Phytases are specialized phosphatases capable of releasing inorganic phosphate from myo-inositol hexakisphosphate (phytate), which is highly abundant in many soils. As inorganic phosphorus reserves decrease over time in many agricultural soils, genetic manipulation of plants to enable secretion of potent phytases into the rhizosphere has been proposed as a promising approach to improve plant phosphorus nutrition. Several families of biotechnologically important phytases have been discovered and characterized, but little data are available on which phytase families can offer the most benefits toward improving plant phosphorus intake. We have developed transgenic Arabidopsis thaliana plants expressing bacterial phytases PaPhyC (HAP family of phytases) and 168phyA (BPP family) under the control of root-specific inducible promoter Pht1;2. The effects of each phytase expression on growth, morphology and inorganic phosphorus accumulation in plants grown on phytate hydroponically or in perlite as the only source of phosphorus were investigated. The most enzymatic activity for both phytases was detected in cell wall-bound fractions of roots, indicating that these enzymes were efficiently secreted. Expression of both bacterial phytases in roots improved plant growth on phytate and resulted in larger rosette leaf area and diameter, higher phosphorus content and increased shoot dry weight, implying that these plants were indeed capable of utilizing phytate as the source of phosphorus for growth and development. When grown on phytate the HAP-type phytase outperformed its BPP-type counterpart for plant biomass production, though this effect was only observed in hydroponic conditions and not in perlite. Furthermore, we found no evidence of adverse side effects of microbial phytase expression in A. thaliana on plant physiology and seed germination. Our data highlight important functional differences between these members of bacterial phytase families and indicate that future crop

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.

Harnessing cell-to-cell variations to probe bacterial structure and biophysics

NASA Astrophysics Data System (ADS)

Cass, Julie A.

Advances in microscopy and biotechnology have given us novel insights into cellular biology and physics. While bacteria were long considered to be relatively unstructured, the development of fluorescence microscopy techniques, and spatially and temporally resolved high-throughput quantitative studies, have uncovered that the bacterial cell is highly organized, and its structure rigorously maintained. In this thesis I will describe our gateTool software, designed to harness cell-to-cell variations to probe bacterial structure, and discuss two exciting aspects of structure that we have employed gateTool to investigate: (i) chromosome organization and the cellular mechanisms for controlling DNA dynamics, and (ii) the study of cell wall synthesis, and how the genes in the synthesis pathway impact cellular shape. In the first project, we develop a spatial and temporal mapping of cell-cycle-dependent chromosomal organization, and use this quantitative map to discover that chromosomal loci segregate from midcell with universal dynamics. In the second project, I describe preliminary time- lapse and snapshot imaging analysis suggesting phentoypical coherence across peptidoglycan synthesis pathways.

Note: An automated image analysis method for high-throughput classification of surface-bound bacterial cell motions.

PubMed

Shen, Simon; Syal, Karan; Tao, Nongjian; Wang, Shaopeng

2015-12-01

We present a Single-Cell Motion Characterization System (SiCMoCS) to automatically extract bacterial cell morphological features from microscope images and use those features to automatically classify cell motion for rod shaped motile bacterial cells. In some imaging based studies, bacteria cells need to be attached to the surface for time-lapse observation of cellular processes such as cell membrane-protein interactions and membrane elasticity. These studies often generate large volumes of images. Extracting accurate bacterial cell morphology features from these images is critical for quantitative assessment. Using SiCMoCS, we demonstrated simultaneous and automated motion tracking and classification of hundreds of individual cells in an image sequence of several hundred frames. This is a significant improvement from traditional manual and semi-automated approaches to segmenting bacterial cells based on empirical thresholds, and a first attempt to automatically classify bacterial motion types for motile rod shaped bacterial cells, which enables rapid and quantitative analysis of various types of bacterial motion.

Role of Sulfhydryl Sites on Bacterial Cell Walls in the Biosorption, Mobility and Bioavailability of Mercury and Uranium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myneni, Satish C.; Mishra, Bhoopesh; Fein, Jeremy

2009-04-01

The goal of this exploratory study is to provide a quantitative and mechanistic understanding of the impact of bacterial sulfhydryl groups on the bacterial uptake, speciation, methylation and bioavailability of Hg and redox changes of uranium. The relative concentration and reactivity of different functional groups present on bacterial surfaces will be determined, enabling quantitative predictions of the role of biosorption of Hg under the physicochemical conditions found at contaminated DOE sites.The hypotheses we propose to test in this investigation are as follows- 1) Sulfhydryl groups on bacterial cell surfaces modify Hg speciation and solubility, and play an important role, specificallymore » in the sub-micromolar concentration ranges of metals in the natural and contaminated systems. 2) Sulfhydryl binding of Hg on bacterial surfaces significantly influences Hg transport into the cell and the methylation rates by the bacteria. 3) Sulfhydryls on cell membranes can interact with hexavalent uranium and convert to insoluble tetravalent species. 4) Bacterial sulfhydryl surface groups are inducible by the presence of metals during cell growth. Our studies focused on the first hypothesis, and we examined the nature of sulfhydryl sites on three representative bacterial species: Bacillus subtilis, a common gram-positive aerobic soil species; Shewanella oneidensis, a facultative gram-negative surface water species; and Geobacter sulfurreducens, an anaerobic iron-reducing gram-negative species that is capable of Hg methylation; and at a range of Hg concentration (and Hg:bacterial concentration ratio) in which these sites become important. A summary of our findings is as follows- Hg adsorbs more extensively to bacteria than other metals. Hg adsorption also varies strongly with pH and chloride concentration, with maximum adsorption occurring under circumneutral pH conditions for both Cl-bearing and Cl-free systems. Under these conditions, all bacterial species tested

Inflating bacterial cells by increased protein synthesis

PubMed Central

Basan, Markus; Zhu, Manlu; Dai, Xiongfeng; Warren, Mya; Sévin, Daniel; Wang, Yi-Ping; Hwa, Terence

2015-01-01

Understanding how the homeostasis of cellular size and composition is accomplished by different organisms is an outstanding challenge in biology. For exponentially growing Escherichia coli cells, it is long known that the size of cells exhibits a strong positive relation with their growth rates in different nutrient conditions. Here, we characterized cell sizes in a set of orthogonal growth limitations. We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied. In particular, synthesizing large amounts of “useless” proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7- to 8-fold compared to cells growing at similar rates under nutrient limitation. Strikingly, this increase in cell size was accompanied by a 3- to 4-fold increase in cellular DNA content at slow growth, reaching up to an amount equivalent to ∼8 chromosomes per cell. Despite drastic changes in cell mass and macromolecular composition, cellular dry mass density remained constant. Our findings reveal an important role of protein synthesis in cell division control. PMID:26519362

Surveillance study of bacterial contamination of the parent's cell phone in the NICU and the effectiveness of an anti-microbial gel in reducing transmission to the hands.

PubMed

Beckstrom, A C; Cleman, P E; Cassis-Ghavami, F L; Kamitsuka, M D

2013-12-01

To determine the bacterial contamination rate of the parent's cell phone and the effectiveness of anti-microbial gel in reducing transmission of bacteria from cell phone to hands. Cross-sectional study of cultures from the cell phone and hands before and after applying anti-microbial gel (n=50). All cell phones demonstrated bacterial contamination. Ninety percent had the same bacteria on the cell phone and their cleaned hands. Twenty two percent had no growth on their hands after applying anti-microbial gel after they had the same bacteria on the cell phone and hands. Ninety-two percent of parents were aware that cell phones carried bacteria, but only 38% cleaned their cell phones at least weekly. Bacterial contamination of cell phones may serve as vectors for nosocomial infection in the neonatal intensive care unit. Bacteria transmitted from cell phone to hands may not be eliminated using anti-microbial gel. Development of hand hygiene and cell phone cleaning guidelines are needed regarding bedside cell phone use.

Viability of 3h grown bacterial micro-colonies after direct Raman identification.

PubMed

Mathey, R; Dupoy, M; Espagnon, I; Leroux, D; Mallard, F; Novelli-Rousseau, A

2015-02-01

Clinical diagnostics in routine microbiology still mostly relies on bacterial growth, a time-consuming process that prevents test results to be used directly as key decision-making elements for therapeutic decisions. There is some evidence that Raman micro-spectroscopy provides clinically relevant information from a limited amount of bacterial cells, thus holding the promise of reduced growth times and accelerated result delivery. Indeed, bacterial identification at the species level directly from micro-colonies at an early time of growth (6h) directly on their growth medium has been demonstrated. However, such analysis is suspected to be partly destructive and could prevent the further growth of the colony needed for other tests, e.g. antibiotic susceptibility testing (AST). In the present study, we evaluated the effect of the powerful laser excitation used for Raman identification on micro-colonies probed after very short growth times. We show here, using envelope integrity markers (Syto 9 and Propidium Iodide) directly on ultra-small micro-colonies of a few tens of Escherichia coli and Staphylococcus epidermidis cells (3h growth time), that only the cells that are directly impacted by the laser lose their membrane integrity. Growth kinetics experiments show that the non-probed surrounding cells are sometimes also affected but that the micro-colonies keep their ability to grow, resulting in normal aspect and size of colonies after 15h of growth. Thus, Raman spectroscopy could be used for very early (<3h) identification of grown micro-organisms without impairing further antibiotics susceptibility characterization steps. Copyright © 2014 Elsevier B.V. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldfarb, K.C.; Karaoz, U.; Hanson, C.A.

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-labeledmore » 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

GROWTH AND METABOLISM OF INDIVIDUAL BACTERIAL CELLS UTILIZING NANOSIMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

NEALSON, H. K.

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 ofmore » 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

Different binarization processes validated against manual counts of fluorescent bacterial cells.

PubMed

Tamminga, Gerrit G; Paulitsch-Fuchs, Astrid H; Jansen, Gijsbert J; Euverink, Gert-Jan W

2016-09-01

State of the art software methods (such as fixed value approaches or statistical approaches) to create a binary image of fluorescent bacterial cells are not as accurate and precise as they should be for counting bacteria and measuring their area. To overcome these bottlenecks, we introduce biological significance to obtain a binary image from a greyscale microscopic image. Using our biological significance approach we are able to automatically count about the same number of cells as an individual researcher would do by manual/visual counting. Using the fixed value or statistical approach to obtain a binary image leads to about 20% less cells in automatic counting. In our procedure we included the area measurements of the bacterial cells to determine the right parameters for background subtraction and threshold values. In an iterative process the threshold and background subtraction values were incremented until the number of particles smaller than a typical bacterial cell is less than the number of bacterial cells with a certain area. This research also shows that every image has a specific threshold with respect to the optical system, magnification and staining procedure as well as the exposure time. The biological significance approach shows that automatic counting can be performed with the same accuracy, precision and reproducibility as manual counting. The same approach can be used to count bacterial cells using different optical systems (Leica, Olympus and Navitar), magnification factors (200× and 400×), staining procedures (DNA (Propidium Iodide) and RNA (FISH)) and substrates (polycarbonate filter or glass). Copyright © 2016 Elsevier B.V. All rights reserved.

Stimulation of the follicular bulge LGR5+ and LGR6+ stem cells with the gut-derived human alpha defensin 5 results in decreased bacterial presence, enhanced wound healing, and hair growth from tissues devoid of adnexal structures.

PubMed

Lough, Denver; Dai, Hui; Yang, Mei; Reichensperger, Joel; Cox, Lisa; Harrison, Carrie; Neumeister, Michael W

2013-11-01

Discovery of leucine-rich repeat-containing G-protein-coupled receptors 5 and 6 (LGR5 and LGR6) as markers of adult epithelial stem cells of the skin and intestine permits researchers to draw on the intrinsic cellular fundamentals of wound healing and proliferation dynamics of epithelial surfaces. In this study, the authors use the intestine-derived human alpha defensin 5 to stimulate epithelial proliferation, bacterial reduction, and hair production in burn wound beds to provide the field with initial insight on augmenting wound healing in tissues devoid of adnexal stem cells. Murine third-degree burn wound beds were treated with (1) intestine-derived human alpha defensin 5, (2) skin-derived human beta defensin 1, and (3) sulfadiazine to determine their roles in wound healing, bacterial reduction, and hair growth. The human alpha defensin 5 peptide significantly enhanced wound healing and reduced basal bacterial load compared with human beta defensin 1 and sulfadiazine. Human alpha defensin 5 was the only therapy to induce LGR stem cell migration into the wound bed. In addition, gene heat mapping showed significant mRNA up-regulation of key wound healing and Wnt pathway transcripts such as Wnt1 and Wisp1. Ex vivo studies showed enhanced cell migration in human alpha defensin 5-treated wounds compared with controls. Application of human alpha defensin 5 increases LGR stem cell migration into wound beds, leading to enhanced healing, bacterial reduction, and hair production through the augmentation of key Wnt and wound healing transcripts. These findings can be used to derive gut protein-based therapeutics in wound healing.

Effects of storage temperature on bacterial growth rates and community structure in fresh retail sushi.

PubMed

Hoel, S; Jakobsen, A N; Vadstein, O

2017-09-01

This study was conducted to assess the effects of different storage temperatures (4-20°C), on bacterial concentrations, growth rates and community structure in fresh retail sushi, a popular retail product with a claimed shelf life of 2-3 days. The maximum specific growth rate based on aerobic plate count (APC) at 4°C was 0·06 h -1 and displayed a sixfold increase (0·37 h -1 ) at 20°C. Refrigeration resulted in no growth of hydrogen sulphide (H 2 S)-producing bacteria, but this group had the strongest temperature response. The bacterial community structure was determined by PCR/DGGE (denaturing gradient gel electrophoresis). Multivariate analysis based on Bray-Curtis similarities demonstrated that temperature alone was not the major determinant for the bacterial community structure. The total concentration of aerobic bacteria was the variable that most successfully explained the differences between the communities. The dominating organisms, detected by sequencing of DNA bands excised from the DGGE gel, were Brochothrix thermosphacta and genera of lactic acid bacteria (LAB). The relationship between growth rates and storage temperatures clearly demonstrates that these products are sensitive to deviations from optimal storage temperature, possibly resulting in loss of quality during shelf life. Regardless of the storage temperature, the bacterial communities converged towards a similar structure and density, but the storage temperature determined how fast the community reached its carrying capacity. Little information is available on the microbial composition of ready-to-eat food that are prepared with raw fish, subjected to contamination during handling, and susceptible to microbial growth during cold storage. Moreover, the data are a good first possibility to simulate growth of APC, H 2 S-producing bacteria and LAB under different temperature scenarios that might occur during production, distribution or storage. © 2017 The Society for Applied Microbiology.

Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells.

PubMed

Peternel, Spela; Komel, Radovan

2010-09-10

In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry.To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process.To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared.During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation.During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity.High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells.

Actin polymerization drives septation of Listeria monocytogenes namA hydrolase mutants, demonstrating host correction of a bacterial defect.

PubMed

Alonzo, Francis; McMullen, P David; Freitag, Nancy E

2011-04-01

The Gram-positive bacterial cell wall presents a structural barrier that requires modification for protein secretion and large-molecule transport as well as for bacterial growth and cell division. The Gram-positive bacterium Listeria monocytogenes adjusts cell wall architecture to promote its survival in diverse environments that include soil and the cytosol of mammalian cells. Here we provide evidence for the enzymatic flexibility of the murein hydrolase NamA and demonstrate that bacterial septation defects associated with a loss of NamA are functionally complemented by physical forces associated with actin polymerization within the host cell cytosol. L. monocytogenes ΔnamA mutants formed long bacterial chains during exponential growth in broth culture; however, normal septation could be restored if mutant cells were cocultured with wild-type L. monocytogenes bacteria or by the addition of exogenous NamA. Surprisingly, ΔnamA mutants were not significantly attenuated for virulence in mice despite the pronounced exponential growth septation defect. The physical force of L. monocytogenes-mediated actin polymerization within the cytosol was sufficient to sever ΔnamA mutant intracellular chains and thereby enable the process of bacterial cell-to-cell spread so critical for L. monocytogenes virulence. The inhibition of actin polymerization by cytochalasin D resulted in extended intracellular bacterial chains for which septation was restored following drug removal. Thus, despite the requirement for NamA for the normal septation of exponentially growing L. monocytogenes cells, the hydrolase is essentially dispensable once L. monocytogenes gains access to the host cell cytosol. This phenomenon represents a notable example of eukaryotic host cell complementation of a bacterial defect.

Production of peptone from boso fish (Oxyeleotris marmorata) for bacterial growth medium

NASA Astrophysics Data System (ADS)

Priatni, S.; Kosasih, W.; Budiwati, T. A.; Ratnaningrum, D.

2017-03-01

Underutilized Oxyeleotris marmorata fish is abundant and widespread in Indonesia. The study aimed to use O. marmorata fish for peptone production using papain from dried latex of papaya fruit. The peptone was applied as nitrogen sources for bacterial growth. The resulted peptone was optimized at 50-65°C for 5-8 hr, using 0.1% of papain at pH 6.0. Characterization of peptone was based on the soluble protein content, N-amino content, % degree hydrolysis (DH), SDS PAGE profile and growth of bacteria Escherichia coli and Staphylococcus aureus. The results indicated that the optimum condition for hydrolysis was at 50°C for 7 hr (p < 0.05). Fish peptone soluble protein content was of 8.6 mg/mL, α-amino was 0.59%, and AN/TN 5.47%. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS PAGE) profile of peptone showed a major band with molecular weight between 17-28 kDa. Fish peptone effectiveness for E. coli and S. aureus growth was similar with commercial bacterial peptone.

DBIO Best Thesis Award: Mechanics, Dynamics, and Organization of the Bacterial Cytoskeleton and Cell Wall

NASA Astrophysics Data System (ADS)

Wang, Siyuan

2012-02-01

Bacteria come in a variety of shapes. While the peptidoglycan (PG) cell wall serves as an exoskeleton that defines the static cell shape, the internal bacterial cytoskeleton mediates cell shape by recruiting PG synthesis machinery and thus defining the pattern of cell-wall synthesis. While much is known about the chemistry and biology of the cytoskeleton and cell wall, much of their biophysics, including essential aspects of the functionality, dynamics, and organization, remain unknown. This dissertation aims to elucidate the detailed biophysical mechanisms of cytoskeleton guided wall synthesis. First, I find that the bacterial cytoskeleton MreB contributes nearly as much to the rigidity of an Escherichia coli cell as the cell wall. This conclusion implies that the cytoskeletal polymer MreB applies meaningful force to the cell wall, an idea favored by theoretical modeling of wall growth, and suggests an evolutionary origin of cytoskeleton-governed cell rigidity. Second, I observe that MreB rotates around the long axis of E. coli, and the motion depends on wall synthesis. This is the first discovery of a cell-wall assembly driven molecular motor in bacteria. Third, I prove that both cell-wall synthesis and the PG network have chiral ordering, which is established by the spatial pattern of MreB. This work links the molecular structure of the cytoskeleton and of the cell wall with organismal-scale behavior. Finally, I develop a mathematical model of cytoskeleton-cell membrane interactions, which explains the preferential orientation of different cytoskeleton components in bacteria.

On the intrinsic constraint of bacterial growth rate: M. tuberculosis's view of the protein translation capacity.

PubMed

Zhu, Manlu; Dai, Xiongfeng

2018-01-15

In nature, the maximal growth rates vary widely among different bacteria species. Fast-growing bacteria species such as Escherichia coli can have a shortest generation time of 20 min. Slow-growing bacteria species are perhaps best known for Mycobacterium tuberculosis, a human pathogen with a generation time being no less than 16 h. Despite of the significant progress made on understanding the pathogenesis of M. tuberculosis, we know little on the origin of its intriguingly slow growth. From a global view, the intrinsic constraint of the maximal growth rate of bacteria remains to be a fundamental question in microbiology. In this review, we analyze and discuss this issue from the angle of protein translation capacity, which is the major demand for cell growth. Based on quantitative analysis, we propose four parameters: rRNA chain elongation rate, abundance of RNA polymerase engaged in rRNA synthesis, polypeptide chain elongation rate, and active ribosome fraction, which potentially limit the maximal growth rate of bacteria. We further discuss the relation of these parameters with the growth rate for M. tuberculosis as well as other bacterial species. We highlight future comprehensive investigation of these parameters for different bacteria species to understand how bacteria set their own specific growth rates.

Silver-decorated orthorhombic nanotubes of lithium vanadium oxide: an impeder of bacterial growth and biofilm.

PubMed

Diggikar, Rahul S; Patil, Rajendra H; Kale, Sheetal B; Thombre, Dipalee K; Gade, Wasudeo N; Kulkarni, Milind V; Kale, Bharat B

2013-09-01

Reoccurrence of infectious diseases and ability of pathogens to resist antibacterial action has raised enormous challenges which may possibly be confronted by nanotechnology routes. In the present study, uniformly embedded silver nanoparticles in orthorhombic nanotubes of lithium vanadium oxide (LiV2O5/Ag) were explored as an impeder of bacterial growth and biofilm. The LiV2O5/Ag nanocomposites have impeded growth of Gram-positive Bacillus subtilis NCIM 2063 and Gram-negative Escherichia coli NCIM 2931 at 60 to 120 μg/mL. It also impeded the biofilm in Pseudomonas aeruginosa NCIM 2948 at 12.5 to 25 μg/mL. Impedance in the growth and biofilm occurs primarily by direct action of the nanocomposites on the cell surfaces of test organisms as revealed by surface perturbation in scanning electron microscopy. As the metabolic growth and biofilm formation phenomena of pathogens play a central role in progression of pathogenesis, LiV2O5/Ag nanocomposite-based approach is likely to curb the menace of reoccurrence of infectious diseases. Thus, LiV2O5/Ag nanocomposites can be viewed as a promising candidate in biofabrication of biomedical materials.

Facile method to stain the bacterial cell surface for super-resolution fluorescence microscopy†

PubMed Central

Gunsolus, Ian L.; Hu, Dehong; Mihai, Cosmin; Lohse, Samuel E.; Lee, Chang-soo; Torelli, Marco D.; Hamers, Robert J.; Murhpy, Catherine J.; Orr, Galya

2015-01-01

A method to fluorescently stain the surfaces of both Gram-negative and Gram-positive bacterial cells compatible with super-resolution fluorescence microscopy is presented. This method utilizes a commercially-available fluorescent probe to label primary amines at the surface of the cell. We demonstrate eficient staining of two bacterial strains, the Gram-negative Shewanella oneidensis MR-1 and the Gram-positive Bacillus subtilis 168. Using structured illumination microscopy and stochastic optical reconstruction microscopy, which require high quantum yield or specialized dyes, we show that this staining method may be used to resolve the bacterial cell surface with sub-diffraction-limited resolution. We further use this method to identify localization patterns of nanomaterials, specifically cadmium selenide quantum dots, following interaction with bacterial cells. PMID:24816810

Facile method to stain the bacterial cell surface for super-resolution fluorescence microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunsolus, Ian L.; Hu, Dehong; Mihai, Cosmin

A method to fluorescently stain the surfaces of both Gram-negative and Gram-positive bacterial cells compatible with super-resolution fluorescence microscopy is presented. This method utilizes a commercially-available fluorescent probe to label primary amines at the surface of the cell. We demonstrate efficient staining of two bacterial strains, the Gram-negative Shewanella oneidensis MR-1 and the Gram-positive Bacillus subtilis 168. Using structured illumination microscopy and stochastic optical reconstruction microscopy, which require high quantum yield or specialized dyes, we show that this staining method may be used to resolve the bacterial cell surface with sub-diffraction-limited resolution. We further use this method to identify localizationmore » patterns of nanomaterials, specifically cadmium selenide quantum dots, following interaction with bacterial cells.« less

Myeloid-Derived Suppressor Cells in Bacterial Infections

PubMed Central

Ost, Michael; Singh, Anurag; Peschel, Andreas; Mehling, Roman; Rieber, Nikolaus; Hartl, Dominik

2016-01-01

Myeloid-derived suppressor cells (MDSCs) comprise monocytic and granulocytic innate immune cells with the capability of suppressing T- and NK-cell responses. While the role of MDSCs has been studied in depth in malignant diseases, the understanding of their regulation and function in infectious disease conditions has just begun to evolve. Here we summarize and discuss the current view how MDSCs participate in bacterial infections and how this knowledge could be exploited for potential future therapeutics. PMID:27066459

Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells

PubMed Central

2010-01-01

Background In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry. To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process. To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. Results In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared. During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation. During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity. High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. Conclusions The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells. PMID:20831775

Electroporation of Functional Bacterial Effectors into Mammalian Cells

DOE PAGES

Sontag, Ryan L.; Mihai, Cosmin; Orr, Galya; ...

2015-01-19

Electroporation was used to insert purified bacterial virulence effector proteins directly into living eukaryotic cells. Protein localization was monitored by confocal immunofluorescence microscopy. This method allows for studies on trafficking, function, and protein-protein interactions using active exogenous proteins, avoiding the need for heterologous expression in eukaryotic cells.

Do bacterial cell numbers follow a theoretical Poisson distribution? Comparison of experimentally obtained numbers of single cells with random number generation via computer simulation.

PubMed

Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso; Koseki, Shigenobu

2016-12-01

We investigated a bacterial sample preparation procedure for single-cell studies. In the present study, we examined whether single bacterial cells obtained via 10-fold dilution followed a theoretical Poisson distribution. Four serotypes of Salmonella enterica, three serotypes of enterohaemorrhagic Escherichia coli and one serotype of Listeria monocytogenes were used as sample bacteria. An inoculum of each serotype was prepared via a 10-fold dilution series to obtain bacterial cell counts with mean values of one or two. To determine whether the experimentally obtained bacterial cell counts follow a theoretical Poisson distribution, a likelihood ratio test between the experimentally obtained cell counts and Poisson distribution which parameter estimated by maximum likelihood estimation (MLE) was conducted. The bacterial cell counts of each serotype sufficiently followed a Poisson distribution. Furthermore, to examine the validity of the parameters of Poisson distribution from experimentally obtained bacterial cell counts, we compared these with the parameters of a Poisson distribution that were estimated using random number generation via computer simulation. The Poisson distribution parameters experimentally obtained from bacterial cell counts were within the range of the parameters estimated using a computer simulation. These results demonstrate that the bacterial cell counts of each serotype obtained via 10-fold dilution followed a Poisson distribution. The fact that the frequency of bacterial cell counts follows a Poisson distribution at low number would be applied to some single-cell studies with a few bacterial cells. In particular, the procedure presented in this study enables us to develop an inactivation model at the single-cell level that can estimate the variability of survival bacterial numbers during the bacterial death process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Arginine Metabolism in Bacterial Pathogenesis and Cancer Therapy

PubMed Central

Xiong, Lifeng; Teng, Jade L. L.; Botelho, Michael G.; Lo, Regina C.; Lau, Susanna K. P.; Woo, Patrick C. Y.

2016-01-01

Antibacterial resistance to infectious diseases is a significant global concern for health care organizations; along with aging populations and increasing cancer rates, it represents a great burden for government healthcare systems. Therefore, the development of therapies against bacterial infection and cancer is an important strategy for healthcare research. Pathogenic bacteria and cancer have developed a broad range of sophisticated strategies to survive or propagate inside a host and cause infection or spread disease. Bacteria can employ their own metabolism pathways to obtain nutrients from the host cells in order to survive. Similarly, cancer cells can dysregulate normal human cell metabolic pathways so that they can grow and spread. One common feature of the adaption and disruption of metabolic pathways observed in bacterial and cancer cell growth is amino acid pathways; these have recently been targeted as a novel approach to manage bacterial infections and cancer therapy. In particular, arginine metabolism has been illustrated to be important not only for bacterial pathogenesis but also for cancer therapy. Therefore, greater insights into arginine metabolism of pathogenic bacteria and cancer cells would provide possible targets for controlling of bacterial infection and cancer treatment. This review will summarize the recent progress on the relationship of arginine metabolism with bacterial pathogenesis and cancer therapy, with a particular focus on arginase and arginine deiminase pathways of arginine catabolism. PMID:26978353

Monitoring growth and movement of Ralstonia solanacearum cells harboring plasmid pRSS12 derived from bacteriophage phiRSS1.

PubMed

Fujie, Makoto; Takamoto, Hirofumi; Kawasaki, Takeru; Fujiwara, Akiko; Yamada, Takashi

2010-02-01

We monitored growth and movement of Ralstonia solanacearum harboring the plasmid pRSS12 in tomato seedlings. The plasmid contains a gene for green fluorescent protein (GFP) and is stably maintained in R. solanacearum cells without selection pressure. Bacteria harboring the plasmid can be tracked in planta by visualizing GFP fluorescence. Stems of seedlings were infected with R. solanacearum cells transformed with pRSS12, and bacterial growth and movement, particularly around the vascular bundles, were monitored for more than 7 days. Our results showed that vascular bundles are independent of each other within the stem, and that it takes a long time for R. solanacearum cells to migrate from one vascular bundle to another. For real-time monitoring of bacteria in planta, tomato seedlings were grown on agar medium and bacterial suspension was applied to the root apex. The bacterial invasion process was monitored by fluorescent microscopy. Bacteria invaded taproots within 6 h, and movement of the bacteria was observed until 144 h after inoculation. In susceptible tomato cultivars, strong GFP fluorescence was observed in hypocotyls and lateral roots as well as the taproot. In resistant cultivars, however, GFP fluorescence was rarely observed on lateral roots. Our results show that this monitoring system can be used to assess bacterial pathogenicity efficiently. Copyright (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Helicobacter pylori-induced IL-33 modulates mast cell responses, benefits bacterial growth, and contributes to gastritis.

PubMed

Lv, Yi-Pin; Teng, Yong-Sheng; Mao, Fang-Yuan; Peng, Liu-Sheng; Zhang, Jin-Yu; Cheng, Ping; Liu, Yu-Gang; Kong, Hui; Wang, Ting-Ting; Wu, Xiao-Long; Hao, Chuan-Jie; Chen, Weisan; Yang, Shi-Ming; Zhao, Yong-Liang; Han, Bin; Ma, Qiang; Zou, Quan-Ming; Zhuang, Yuan

2018-04-25

Interleukin (IL)-induced inflammatory responses are critical for the pathogenesis of Helicobacter pylori (H. pylori)-induced gastritis. IL-33 represents a recently discovered proinflammatory cytokine involved in inflammatory diseases, but its relevance to H. pylori-induced gastritis is unknown. Here, we found that gastric IL-33 mRNA and protein expression were elevated in gastric mucosa of both patients and mice infected with H. pylori, which is positively correlated with bacterial load and the degree of gastritis. IL-33 production was promoted via extracellular regulated protein kinases (ERK) signaling pathway activation by gastric epithelial cells in a cagA-dependent manner during H. pylori infection, and resulted in increased inflammation and bacteria burden within the gastric mucosa. Gastric epithelial cell-derived IL-33 promoted TNF-α production from mast cells in vitro, and IL-33 increased TNF-α production in vivo. Increased TNF-α inhibited gastric epithelial cell proliferation, conducing to the progress of H. pylori-associated gastritis and bacteria colonization. This study defined a patent regulatory networks involving H. pylori, gastric epithelial cell, IL-33, mast cell, and TNF-α, which jointly play a pathological effect within the gastric circumstances. It may be a valuable strategy to restrain this IL-33-dependent pathway in the treatment of H. pylori-associated gastritis.

Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds.

PubMed

Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Al-Hosni, Khadija; Kang, Sang-Mo; Seo, Chang-Woo; Lee, In-Jung

2017-06-01

Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml -1 to 38.80 ± 1.35 μg ml -1 . We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.

Bacterial population in intestines of the black tiger shrimp (Penaeus monodon) under different growth stages.

PubMed

Rungrassamee, Wanilada; Klanchui, Amornpan; Chaiyapechara, Sage; Maibunkaew, Sawarot; Tangphatsornruang, Sithichoke; Jiravanichpaisal, Pikul; Karoonuthaisiri, Nitsara

2013-01-01

Intestinal bacterial communities in aquaculture have been drawn to attention due to potential benefit to their hosts. To identify core intestinal bacteria in the black tiger shrimp (Penaeus monodon), bacterial populations of disease-free shrimp were characterized from intestines of four developmental stages (15-day-old post larvae (PL15), 1- (J1), 2- (J2), and 3-month-old (J3) juveniles) using pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis (DGGE) approaches. A total of 25,121 pyrosequencing reads (reading length = 442±24 bases) were obtained, which were categorized by barcode for PL15 (7,045 sequences), J1 (3,055 sequences), J2 (13,130 sequences) and J3 (1,890 sequences). Bacteria in the phyla Bacteroides, Firmicutes and Proteobacteria were found in intestines at all four growth stages. There were 88, 14, 27, and 20 bacterial genera associated with the intestinal tract of PL15, J1, J2 and J3, respectively. Pyrosequencing analysis revealed that Proteobacteria (class Gammaproteobacteria) was a dominant bacteria group with a relative abundance of 89% for PL15 and 99% for J1, J2 and J3. Real-time PCR assay also confirmed that Gammaproteobacteria had the highest relative abundance in intestines from all growth stages. Intestinal bacterial communities from the three juvenile stages were more similar to each other than that of the PL shrimp based on PCA analyses of pyrosequencing results and their DGGE profiles. This study provides descriptive bacterial communities associated to the black tiger shrimp intestines during these growth development stages in rearing facilities.

Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis

PubMed Central

Liu, Xiaokun; Grabherr, Heini M; Willmann, Roland; Kolb, Dagmar; Brunner, Frédéric; Bertsche, Ute; Kühner, Daniel; Franz-Wachtel, Mirita; Amin, Bushra; Felix, Georg; Ongena, Marc; Nürnberger, Thorsten; Gust, Andrea A

2014-01-01

Peptidoglycans (PGNs) are immunogenic bacterial surface patterns that trigger immune activation in metazoans and plants. It is generally unknown how complex bacterial structures such as PGNs are perceived by plant pattern recognition receptors (PRRs) and whether host hydrolytic activities facilitate decomposition of bacterial matrices and generation of soluble PRR ligands. Here we show that Arabidopsis thaliana, upon bacterial infection or exposure to microbial patterns, produces a metazoan lysozyme-like hydrolase (lysozyme 1, LYS1). LYS1 activity releases soluble PGN fragments from insoluble bacterial cell walls and cleavage products are able to trigger responses typically associated with plant immunity. Importantly, LYS1 mutant genotypes exhibit super-susceptibility to bacterial infections similar to that observed on PGN receptor mutants. We propose that plants employ hydrolytic activities for the decomposition of complex bacterial structures, and that soluble pattern generation might aid PRR-mediated immune activation in cell layers adjacent to infection sites. DOI: http://dx.doi.org/10.7554/eLife.01990.001 PMID:24957336

Platelet-rich plasma affects bacterial growth in vitro.

PubMed

Mariani, Erminia; Filardo, Giuseppe; Canella, Valentina; Berlingeri, Andrea; Bielli, Alessandra; Cattini, Luca; Landini, Maria Paola; Kon, Elizaveta; Marcacci, Maurilio; Facchini, Andrea

2014-09-01

Platelet-rich plasma (PRP), a blood derivative rich in platelets, is a relatively new technique used in tissue regeneration and engineering. The increased quantity of platelets makes this formulation of considerable value for their role in tissue healing and microbicidal activity. This activity was investigated against five of the most important strains involved in nosocomial infections (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Streptococcus faecalis) to understand the prophylactic role of pure (P)-PRP. Microbicidal proteins released from activated P-PRP platelets were also determined. The microbicidal activity of P-PRP and platelet-poor plasma (PPP) was evaluated on different concentrations of the five bacterial strains incubated for 1, 2, 4 and 18 h and plated on agar for 18-24 h. P-PRP and PPP-released microbicidal proteins were evaluated by means of multiplex bead-based immunoassays. P-PRP and PPP inhibited bacterial growth for up to 2 h of incubation. The effect of P-PRP was significantly higher than that of PPP, mainly at the low seeding concentrations and/or shorter incubation times, depending on the bacterial strain. Chemokine (C-C motif) ligand-3, chemokine (C-C motif) ligand-5 and chemokine (C-X-C motif) ligand-1 were the molecules mostly related to Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus faecalis inhibition. Escherichia coli and Klebsiella pneumoniae were less influenced. The present results show that P-PRP might supply an early protection against bacterial contaminations during surgical interventions because the inhibitory activity is already evident from the first hour of treatment, which suggests that physiological molecules supplied in loco might be important in the time frame needed for the activation of the innate immune response. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Dynamic light scattering: A fast and reliable method to analyze bacterial growth during the lag phase.

PubMed

Vargas, Susana; Millán-Chiu, Blanca E; Arvizu-Medrano, Sofía M; Loske, Achim M; Rodríguez, Rogelio

2017-06-01

A comparison between plate counting (PC) and dynamic light scattering (DLS) is reported. PC is the standard technique to determine bacterial population as a function of time; however, this method has drawbacks, such as the cumbersome preparation and handling of samples, as well as the long time required to obtain results. Alternative methods based on optical density are faster, but do not distinguish viable from non-viable cells. These inconveniences are overcome by using DLS. Two different bacteria strains were considered: Escherichia coli and Staphylococcus aureus. DLS was performed at two different illuminating conditions: continuous and intermittent. By the increment of particle size as a function of time, it was possible to observe cell division and the formation of aggregates containing very few bacteria. The scattered intensity profiles showed the lag phase and the transition to the exponential phase of growth, providing a quantity proportional to viable bacteria concentration. The results revealed a clear and linear correlation in both lag and exponential phase, between the Log 10 (colony-forming units/mL) from PC and the Log 10 of the scattered intensity I s from DLS. These correlations provide a good support to use DLS as an alternative technique to determine bacterial population. Copyright © 2017 Elsevier B.V. All rights reserved.

Heteroresistance at the single-cell level: adapting to antibiotic stress through a population-based strategy and growth-controlled interphenotypic coordination.

PubMed

Wang, Xiaorong; Kang, Yu; Luo, Chunxiong; Zhao, Tong; Liu, Lin; Jiang, Xiangdan; Fu, Rongrong; An, Shuchang; Chen, Jichao; Jiang, Ning; Ren, Lufeng; Wang, Qi; Baillie, J Kenneth; Gao, Zhancheng; Yu, Jun

2014-02-11

Heteroresistance refers to phenotypic heterogeneity of microbial clonal populations under antibiotic stress, and it has been thought to be an allocation of a subset of "resistant" cells for surviving in higher concentrations of antibiotic. The assumption fits the so-called bet-hedging strategy, where a bacterial population "hedges" its "bet" on different phenotypes to be selected by unpredicted environment stresses. To test this hypothesis, we constructed a heteroresistance model by introducing a blaCTX-M-14 gene (coding for a cephalosporin hydrolase) into a sensitive Escherichia coli strain. We confirmed heteroresistance in this clone and that a subset of the cells expressed more hydrolase and formed more colonies in the presence of ceftriaxone (exhibited stronger "resistance"). However, subsequent single-cell-level investigation by using a microfluidic device showed that a subset of cells with a distinguishable phenotype of slowed growth and intensified hydrolase expression emerged, and they were not positively selected but increased their proportion in the population with ascending antibiotic concentrations. Therefore, heteroresistance--the gradually decreased colony-forming capability in the presence of antibiotic--was a result of a decreased growth rate rather than of selection for resistant cells. Using a mock strain without the resistance gene, we further demonstrated the existence of two nested growth-centric feedback loops that control the expression of the hydrolase and maximize population growth in various antibiotic concentrations. In conclusion, phenotypic heterogeneity is a population-based strategy beneficial for bacterial survival and propagation through task allocation and interphenotypic collaboration, and the growth rate provides a critical control for the expression of stress-related genes and an essential mechanism in responding to environmental stresses. Heteroresistance is essentially phenotypic heterogeneity, where a population

Formulation of bacterial consortium as whole cell biocatalyst for degradation of oil compounds

NASA Astrophysics Data System (ADS)

Yetti, Elvi; A'la, Amalia; Luthfiyah, Nailul; Wijaya, Hans; Thontowi, Ahmad; Yopi

2017-11-01

In this research, weaim to investigateformulation of bacterial consortium as whole cell biocatalyst for degradation of oil compounds. We constructed microbial consortium from 4 (four) selected marine oil bacteria to become 15 (twelve) combination culture. Those bacteria were from collection of Laboratory of Biocatalyst and Fermentation, Research Center for Biotechnology, Indonesian Institutes of Sciences and designated as Labrenzia sp. MBTDCMFRIMab26, Labrenzia aggregata strasin HQB397, Novosphingobium pentaromativorans strain PQ-3 16S, and Novosphingobium pentaromativorans strain US6-1. The mixture or bacteria consortia, denoted as F1, F2, …F15 consisted of 1, 2, 3 and 4 bacterial strains, respectively. The strains were selected based on the criteria that they were able to display good growth in crude oil containing media. Five bacterialformulationsshowed good potentialas candidates for microbial consortium. We will optimize these consortium with carrier matrix choosed from biomass materials and also carry out oil content analysis.

Directed evolution of cell size in Escherichia coli.

PubMed

Yoshida, Mari; Tsuru, Saburo; Hirata, Naoko; Seno, Shigeto; Matsuda, Hideo; Ying, Bei-Wen; Yomo, Tetsuya

2014-12-17

In bacteria, cell size affects chromosome replication, the assembly of division machinery, cell wall synthesis, membrane synthesis and ultimately growth rate. In addition, cell size can also be a target for Darwinian evolution for protection from predators. This strong coupling of cell size and growth, however, could lead to the introduction of growth defects after size evolution. An important question remains: can bacterial cell size change and/or evolve without imposing a growth burden? The directed evolution of particular cell sizes, without a growth burden, was tested with a laboratory Escherichia coli strain. Cells of defined size ranges were collected by a cell sorter and were subsequently cultured. This selection-propagation cycle was repeated, and significant changes in cell size were detected within 400 generations. In addition, the width of the size distribution was altered. The changes in cell size were unaccompanied by a growth burden. Whole genome sequencing revealed that only a few mutations in genes related to membrane synthesis conferred the size evolution. In conclusion, bacterial cell size could evolve, through a few mutations, without growth reduction. The size evolution without growth reduction suggests a rapid evolutionary change to diverse cell sizes in bacterial survival strategies.

Bacterial effectors target the plant cell nucleus to subvert host transcription.

PubMed

Canonne, Joanne; Rivas, Susana

2012-02-01

In order to promote virulence, Gram-negative bacteria have evolved the ability to inject so-called type III effector proteins into host cells. The plant cell nucleus appears to be a subcellular compartment repeatedly targeted by bacterial effectors. In agreement with this observation, mounting evidence suggests that manipulation of host transcription is a major strategy developed by bacteria to counteract plant defense responses. It has been suggested that bacterial effectors may adopt at least three alternative, although not mutually exclusive, strategies to subvert host transcription. T3Es may (1) act as transcription factors that directly activate transcription in host cells, (2) affect histone packing and chromatin configuration, and/or (3) target host transcription factor activity. Here, we provide an overview on how all these strategies may lead to host transcriptional re-programming and, as a result, to improved bacterial multiplication inside plant cells.

The essential features and modes of bacterial polar growth.

PubMed

Cameron, Todd A; Zupan, John R; Zambryski, Patricia C

2015-06-01

Polar growth represents a surprising departure from the canonical dispersed cell growth model. However, we know relatively little of the underlying mechanisms governing polar growth or the requisite suite of factors that direct polar growth. Underscoring how classic doctrine can be turned on its head, the peptidoglycan layer of polar-growing bacteria features unusual crosslinks and in some species the quintessential cell division proteins FtsA and FtsZ are recruited to the growing poles. Remarkably, numerous medically important pathogens utilize polar growth, accentuating the need for intensive research in this area. Here we review models of polar growth in bacteria based on recent research in the Actinomycetales and Rhizobiales, with emphasis on Mycobacterium and Agrobacterium species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Bhoopesh; Shoenfelt, Elizabeth; Yu, Qiang

We have examined the speciation of Hg(II) complexed with intact cell suspensions (1013 cells L- 1) of Bacillus subtilis, a common gram-positive soil bacterium, Shewanella oneidensis MR-1, a facultative gram-negative aquatic organism, and Geobacter sulfurreducens, a gram-negative anaerobic bacterium capable of Hg-methylation at Hg(II) loadings spanning four orders of magnitude (120 nM to 350 μM) at pH 5.5 (± 0.2). The coordination environments of Hg on bacterial cells were analyzed using synchrotron based X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Hg LIII edge. The abundance of thiols on intact cells wasmore » determined by a fluorescence-spectroscopy based method using a soluble bromobimane, monobromo(trimethylammonio)bimane (qBBr) to block thiol sites, and potentiometric titrations of biomass with and without qBBr treatment. The chemical forms of S on intact bacterial cells were determined using S k-edge XANES spectroscopy.« less

Microspectrometric insights on the uptake of antibiotics at the single bacterial cell level

PubMed Central

Cinquin, Bertrand; Maigre, Laure; Pinet, Elizabeth; Chevalier, Jacqueline; Stavenger, Robert A.; Mills, Scott; Réfrégiers, Matthieu; Pagès, Jean-Marie

2015-01-01

Bacterial multidrug resistance is a significant health issue. A key challenge, particularly in Gram-negative antibacterial research, is to better understand membrane permeation of antibiotics in clinically relevant bacterial pathogens. Passing through the membrane barrier to reach the required concentration inside the bacterium is a pivotal step for most antibacterials. Spectrometric methodology has been developed to detect drugs inside bacteria and recent studies have focused on bacterial cell imaging. Ultimately, we seek to use this method to identify pharmacophoric groups which improve penetration, and therefore accumulation, of small-molecule antibiotics inside bacteria. We developed a method to quantify the time scale of antibiotic accumulation in living bacterial cells. Tunable ultraviolet excitation provided by DISCO beamline (synchrotron Soleil) combined with microscopy allows spectroscopic analysis of the antibiotic signal in individual bacterial cells. Robust controls and measurement of the crosstalk between fluorescence channels can provide real time quantification of drug. This technique represents a new method to assay drug translocation inside the cell and therefore incorporate rational drug design to impact antibiotic uptake. PMID:26656111

Bacterial Population in Intestines of the Black Tiger Shrimp (Penaeus monodon) under Different Growth Stages

PubMed Central

Rungrassamee, Wanilada; Klanchui, Amornpan; Chaiyapechara, Sage; Maibunkaew, Sawarot; Tangphatsornruang, Sithichoke; Jiravanichpaisal, Pikul; Karoonuthaisiri, Nitsara

2013-01-01

Intestinal bacterial communities in aquaculture have been drawn to attention due to potential benefit to their hosts. To identify core intestinal bacteria in the black tiger shrimp (Penaeus monodon), bacterial populations of disease-free shrimp were characterized from intestines of four developmental stages (15-day-old post larvae (PL15), 1- (J1), 2- (J2), and 3-month-old (J3) juveniles) using pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis (DGGE) approaches. A total of 25,121 pyrosequencing reads (reading length = 442±24 bases) were obtained, which were categorized by barcode for PL15 (7,045 sequences), J1 (3,055 sequences), J2 (13,130 sequences) and J3 (1,890 sequences). Bacteria in the phyla Bacteroides, Firmicutes and Proteobacteria were found in intestines at all four growth stages. There were 88, 14, 27, and 20 bacterial genera associated with the intestinal tract of PL15, J1, J2 and J3, respectively. Pyrosequencing analysis revealed that Proteobacteria (class Gammaproteobacteria) was a dominant bacteria group with a relative abundance of 89% for PL15 and 99% for J1, J2 and J3. Real-time PCR assay also confirmed that Gammaproteobacteria had the highest relative abundance in intestines from all growth stages. Intestinal bacterial communities from the three juvenile stages were more similar to each other than that of the PL shrimp based on PCA analyses of pyrosequencing results and their DGGE profiles. This study provides descriptive bacterial communities associated to the black tiger shrimp intestines during these growth development stages in rearing facilities. PMID:23577162

Bacterial growth, flow, and mixing shape human gut microbiota density and composition.

PubMed

Arnoldini, Markus; Cremer, Jonas; Hwa, Terence

2018-03-13

The human gut microbiota is highly dynamic, and host physiology and diet exert major influences on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework. This can generate predictions of how changes in different host factors influence microbiota composition. For instance, hydrodynamic forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition. This can be mechanistically explained by their effect on colonic pH which directly affects microbiota competition for food. In this addendum, we describe the underlying analysis in more detail. In particular, we discuss the mixing dynamics of luminal content by wall contractions and its implications for bacterial growth and density, as well as the broader implications of our insights for the field of gut microbiota research.

Genetic reprogramming of host cells by bacterial pathogens.

PubMed

Tran Van Nhieu, Guy; Arbibe, Laurence

2009-10-29

During the course of infection, pathogens often induce changes in gene expression in host cells and these changes can be long lasting and global or transient and of limited amplitude. Defining how, when, and why bacterial pathogens reprogram host cells represents an exciting challenge that opens up the opportunity to grasp the essence of pathogenesis and its molecular details.

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.

Oral iron acutely elevates bacterial growth in human serum.

PubMed

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

2015-11-23

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.

Macrophages inhibit human osteosarcoma cell growth after activation with the bacterial cell wall derivative liposomal muramyl tripeptide in combination with interferon-γ.

PubMed

Pahl, Jens H W; Kwappenberg, Kitty M C; Varypataki, Eleni M; Santos, Susy J; Kuijjer, Marieke L; Mohamed, Susan; Wijnen, Juul T; van Tol, Maarten J D; Cleton-Jansen, Anne-Marie; Egeler, R Maarten; Jiskoot, Wim; Lankester, Arjan C; Schilham, Marco W

2014-03-10

In osteosarcoma, the presence of tumor-infiltrating macrophages positively correlates with patient survival in contrast to the negative effect of tumor-associated macrophages in patients with other tumors. Liposome-encapsulated muramyl tripeptide (L-MTP-PE) has been introduced in the treatment of osteosarcoma patients, which may enhance the potential anti-tumor activity of macrophages. Direct anti-tumor activity of human macrophages against human osteosarcoma cells has not been described so far. Hence, we assessed osteosarcoma cell growth after co-culture with human macrophages. Monocyte-derived M1-like and M2-like macrophages were polarized with LPS + IFN-γ, L-MTP-PE +/- IFN-γ or IL-10 and incubated with osteosarcoma cells. Two days later, viable tumor cell numbers were analyzed. Antibody-dependent effects were investigated using the therapeutic anti-EGFR antibody cetuximab. M1-like macrophages inhibited osteosarcoma cell growth when activated with LPS + IFN-γ. Likewise, stimulation of M1-like macrophages with liposomal muramyl tripeptide (L-MTP-PE) inhibited tumor growth, but only when combined with IFN-γ. Addition of the tumor-reactive anti-EGFR antibody cetuximab did not further improve the anti-tumor activity of activated M1-like macrophages. The inhibition was mediated by supernatants of activated M1-like macrophages, containing TNF-α and IL-1β. However, specific blockage of these cytokines, nitric oxide or reactive oxygen species did not inhibit the anti-tumor effect, suggesting the involvement of other soluble factors released upon macrophage activation. While LPS + IFN-γ-activated M2-like macrophages had low anti-tumor activity, IL-10-polarized M2-like macrophages were able to reduce osteosarcoma cell growth in the presence of the anti-EGFR cetuximab involving antibody-dependent tumor cell phagocytosis. This study demonstrates that human macrophages can be induced to exert direct anti-tumor activity against osteosarcoma cells. Our

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.

Relationship between Milk Microbiota, Bacterial Load, Macronutrients, and Human Cells during Lactation.

PubMed

Boix-Amorós, Alba; Collado, Maria C; Mira, Alex

2016-01-01

Human breast milk is considered the optimal nutrition for infants, providing essential nutrients and a broad range of bioactive compounds, as well as its own microbiota. However, the interaction among those components and the biological role of milk microorganisms is still uncovered. Thus, our aim was to identify the relationships between milk microbiota composition, bacterial load, macronutrients, and human cells during lactation. Bacterial load was estimated in milk samples from a total of 21 healthy mothers through lactation time by bacteria-specific qPCR targeted to the single-copy gene fusA. Milk microbiome composition and diversity was estimated by 16S-pyrosequencing and the structure of these bacteria in the fluid was studied by flow cytometry, qPCR, and microscopy. Fat, protein, lactose, and dry extract of milk as well as the number of somatic cells were also analyzed. We observed that milk bacterial communities were generally complex, and showed individual-specific profiles. Milk microbiota was dominated by Staphylococcus, Pseudomonas, Streptococcus, and Acinetobacter. Staphylococcus aureus was not detected in any of these samples from healthy mothers. There was high variability in composition and number of bacteria per milliliter among mothers and in some cases even within mothers at different time points. The median bacterial load was 10(6) bacterial cells/ml through time, higher than those numbers reported by 16S gene PCR and culture methods. Furthermore, milk bacteria were present in a free-living, "planktonic" state, but also in equal proportion associated to human immune cells. There was no correlation between bacterial load and the amount of immune cells in milk, strengthening the idea that milk bacteria are not sensed as an infection by the immune system.

Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR

PubMed Central

Romaniuk, Joseph A. H.; Cegelski, Lynette

2015-01-01

The ability to characterize bacterial cell-wall composition and structure is crucial to understanding the function of the bacterial cell wall, determining drug modes of action and developing new-generation therapeutics. Solid-state NMR has emerged as a powerful tool to quantify chemical composition and to map cell-wall architecture in bacteria and plants, even in the context of unperturbed intact whole cells. In this review, we discuss solid-state NMR approaches to define peptidoglycan composition and to characterize the modes of action of old and new antibiotics, focusing on examples in Staphylococcus aureus. We provide perspectives regarding the selected NMR strategies as we describe the exciting and still-developing cell-wall and whole-cell NMR toolkit. We also discuss specific discoveries regarding the modes of action of vancomycin analogues, including oritavancin, and briefly address the reconsideration of the killing action of β-lactam antibiotics. In such chemical genetics approaches, there is still much to be learned from perturbations enacted by cell-wall assembly inhibitors, and solid-state NMR approaches are poised to address questions of cell-wall composition and assembly in S. aureus and other organisms. PMID:26370936

Effects of inoculation with organic-phosphorus-mineralizing bacteria on soybean (Glycine max) growth and indigenous bacterial community diversity.

PubMed

Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Li, Yang; Duan, Man-Li

2017-05-01

Three different organic-phosphorus-mineralizing bacteria (OPMB) strains were inoculated to soil planted with soybean (Glycine max), and their effects on soybean growth and indigenous bacterial community diversity were investigated. Inoculation with Pseudomonas fluorescens Z4-1 and Brevibacillus agri L7-1 increased organic phosphorus degradation by 22% and 30%, respectively, compared with the control at the mature stage. Strains P. fluorescens Z4-1 and B. agri L7-1 significantly improved the soil alkaline phosphatase activity, average well color development, and the soybean root activity. Terminal restriction fragment length polymorphism analysis demonstrated that P. fluorescens Z4-1 and B. agri L7-1 could persist in the soil at relative abundances of 2.0%-6.4% throughout soybean growth. Thus, P. fluorescens Z4-1 and B. agri L7-1 could potentially be used in organic-phosphorus-mineralizing biofertilizers. OPMB inoculation altered the genetic structure of the soil bacterial communities but had no apparent influence on the carbon source utilization profiles of the soil bacterial communities. Principal components analysis showed that the changes in the carbon source utilization profiles of bacterial community depended mainly on the plant growth stages rather than inoculation with OPMB. The results help to understand the evolution of the soil bacterial community after OPMB inoculation.

Novel approach for the use of dairy industry wastes for bacterial growth media production.

PubMed

Kasmi, Mariam; Elleuch, Lobna; Dahmeni, Ameni; Hamdi, Moktar; Trabelsi, Ismail; Snoussi, Mejdi

2018-04-15

This work proposes a novel approach for the reuse and the recovery of dairy wastes valuable components. Thermal coagulation was performed for dairy effluents and the main responsible fraction for the organic matter content (protein and fat) was separated. Dairy curds were prepared for the formulation of bacterial growth media. Protein, sugar, fat and fatty acids contents have been assessed. Samples treated at 100 °C exhibited marked improvement in terms of protein (25-50%) recovery compared to those treated at 80 °C. Fatty acid analysis revealed the presence of unsaturated fatty acids (mainly oleic acid) that are essential to promote Lactobacillus growth. Previously isolated and identified bacterial strains from dairy wastes (Lactobacillus paracasei, Lactobacillus plantarum, Lactococcus lactis and Lactobacillus brevis) were investigated for their ability to grow on the formulated media. All the tested lactic acid bacteria exhibited greater bacterial growth on the formulated media supplemented with glucose only or with both glucose and yeast extract compared to the control media. By reference to the commercial growth medium, the productivity ratio of the supplemented bactofugate (B) and decreaming (D) formulated media exceeded 0.6 for L. paracasei culture. Whereas, the productivity ratio of the supplemented B medium was greater than 1 compared to the control medium for all the tested strains. As for the supplemented D medium, its productivity ratio was greater than 1 compared to the control medium for both L. paracasei and L. plantarum strains. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biofabrication of morphology improved cadmium sulfide nanoparticles using Shewanella oneidensis bacterial cells and ionic liquid: For toxicity against brain cancer cell lines.

PubMed

Wang, Li; Chen, Siyuan; Ding, Yiming; Zhu, Qiang; Zhang, Nijia; Yu, Shuqing

2018-01-01

The present work determines the anticancer activity of bio-mediated synthesized cadmium sulfide nanoparticles using the ionic liquid and bacterial cells (Shewanella oneidensis). Bacterial cells have been exposed to be important resources that hold huge potential as ecofriendly, cost-effective, evading toxic of dangerous chemicals and the alternative of conventional physiochemical synthesis. The Shewanella oneidensis is an important kind of metal reducing bacterium, known as its special anaerobic respiratory and sulfate reducing capacity. The crystalline nature, phase purity and surface morphology of biosynthesized cadmium sulfide nanoparticles were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Energy dispersive spectroscopy and Transmission electron microscopy. The use of imidazolium based ionic liquids as soft templating agent for controlling self-assembly and crystal growth direction of metal sulfide nanoparticles has also advanced as an important method. The microscopic techniques showed that the nanoparticles are designed on the nano form and have an excellent spherical morphology, due to the self-assembled mechanism of ionic liquid assistance. The antitumor efficiency of the cadmium sulfide nanoparticles was investigated against brain cancer cell lines using rat glioma cell lines. The effectively improved nano-crystalline and morphological structure of CdS nanoparticles in the presence of IL exhibit excellent cytotoxicity and dispersion ability on the cell shape is completely spread out showing a nice toxic environment against cancer cells. The cytotoxicity effect of cadmium sulfide nanoparticles was discussed with a diagrammatic representation. Copyright © 2017. Published by Elsevier B.V.

Disinfection byproduct formation from chlorination of pure bacterial cells and pipeline biofilms.

PubMed

Wang, Jun-Jian; Liu, Xin; Ng, Tsz Wai; Xiao, Jie-Wen; Chow, Alex T; Wong, Po Keung

2013-05-15

Disinfection byproduct (DBP) formation is commonly attributed to the reaction between natural organic matters and disinfectants, yet few have considered the contribution from disinfecting bacterial materials - the essential process of water disinfection. Here, we explored the DBP formation from chlorination and chloramination of Escherichia coli and found that most selected DBPs were detectable, including trihalomethanes, haloacetonitriles, chloral hydrate, chloropicrin, and 1,1,1-trichloro-2-propanone. A positive correlation (P = 0.08-0.09) between DBP formation and the log reduction of E. coli implied that breaking down of bacterial cells released precursors for DBP formation. As Pseudomonas aeruginosa is a dominant bacterial species in pipeline biofilms, the DBP formation potentials (DBPFPs) from its planktonic cells and biofilms were characterized. Planktonic cells formed 7-11 times greater trihalomethanes per carbon of those from biofilms but significantly lower (P < 0.05) chloral hydrate, highlighting the bacterial phenotype's impact on the bacteria-derived DBPFP. Pipe material appeared to affect the DBPFP of bacteria, with 4-28% lower bromine incorporation factor for biofilms on polyvinyl chloride compared to that on galvanized zinc. This study revealed both the in situ disinfection of bacterial planktonic cells in source water and ex situ reaction between biofilms and residual chlorine in pipeline networks as hitherto unknown DBP sources in drinking water. Copyright © 2013 Elsevier Ltd. All rights reserved.

The bio-physics of condensation of divalent cations into the bacterial wall has implications for growth of Gram-positive bacteria.

PubMed

Rauch, Cyril; Cherkaoui, Mohammed; Egan, Sharon; Leigh, James

2017-02-01

The anionic-polyelectrolyte nature of the wall of Gram-positive bacteria has long been suspected to be involved in homeostasis of essential cations and bacterial growth. A better understanding of the coupling between the biophysics and the biology of the wall is essential to understand some key features at play in ion-homeostasis in this living system. We consider the wall as a polyelectrolyte gel and balance the long-range electrostatic repulsion within this structure against the penalty entropy required to condense cations around wall polyelectrolytes. The resulting equations define how cations interact physically with the wall and the characteristic time required for a cation to leave the wall and enter into the bacterium to enable its usage for bacterial metabolism and growth. The model was challenged against experimental data regarding growth of Gram-positive bacteria in the presence of varying concentration of divalent ions. The model explains qualitatively and quantitatively how divalent cations interact with the wall as well as how the biophysical properties of the wall impact on bacterial growth (in particular the initiation of bacterial growth). The interplay between polymer biophysics and the biology of Gram positive bacteria is defined for the first time as a new set of variables that contribute to the kinetics of bacterial growth. Providing an understanding of how bacteria capture essential metal cations in way that does not follow usual binding laws has implications when considering the control of such organisms and their ability to survive and grow in extreme environments. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Relationship between Milk Microbiota, Bacterial Load, Macronutrients, and Human Cells during Lactation

PubMed Central

Boix-Amorós, Alba; Collado, Maria C.; Mira, Alex

2016-01-01

Human breast milk is considered the optimal nutrition for infants, providing essential nutrients and a broad range of bioactive compounds, as well as its own microbiota. However, the interaction among those components and the biological role of milk microorganisms is still uncovered. Thus, our aim was to identify the relationships between milk microbiota composition, bacterial load, macronutrients, and human cells during lactation. Bacterial load was estimated in milk samples from a total of 21 healthy mothers through lactation time by bacteria-specific qPCR targeted to the single-copy gene fusA. Milk microbiome composition and diversity was estimated by 16S-pyrosequencing and the structure of these bacteria in the fluid was studied by flow cytometry, qPCR, and microscopy. Fat, protein, lactose, and dry extract of milk as well as the number of somatic cells were also analyzed. We observed that milk bacterial communities were generally complex, and showed individual-specific profiles. Milk microbiota was dominated by Staphylococcus, Pseudomonas, Streptococcus, and Acinetobacter. Staphylococcus aureus was not detected in any of these samples from healthy mothers. There was high variability in composition and number of bacteria per milliliter among mothers and in some cases even within mothers at different time points. The median bacterial load was 106 bacterial cells/ml through time, higher than those numbers reported by 16S gene PCR and culture methods. Furthermore, milk bacteria were present in a free-living, “planktonic” state, but also in equal proportion associated to human immune cells. There was no correlation between bacterial load and the amount of immune cells in milk, strengthening the idea that milk bacteria are not sensed as an infection by the immune system. PMID:27148183

Sonication reduces the attachment of Salmonella Typhimurium ATCC 14028 cells to bacterial cellulose-based plant cell wall models and cut plant material.

PubMed

Tan, Michelle S F; Rahman, Sadequr; Dykes, Gary A

2017-04-01

This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm 2 ) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Vibrio cholerae biofilm growth program and architecture revealed by single-cell live imaging

PubMed Central

Yan, Jing; Sharo, Andrew G.; Stone, Howard A.; Wingreen, Ned S.; Bassler, Bonnie L.

2016-01-01

Biofilms are surface-associated bacterial communities that are crucial in nature and during infection. Despite extensive work to identify biofilm components and to discover how they are regulated, little is known about biofilm structure at the level of individual cells. Here, we use state-of-the-art microscopy techniques to enable live single-cell resolution imaging of a Vibrio cholerae biofilm as it develops from one single founder cell to a mature biofilm of 10,000 cells, and to discover the forces underpinning the architectural evolution. Mutagenesis, matrix labeling, and simulations demonstrate that surface adhesion-mediated compression causes V. cholerae biofilms to transition from a 2D branched morphology to a dense, ordered 3D cluster. We discover that directional proliferation of rod-shaped bacteria plays a dominant role in shaping the biofilm architecture in V. cholerae biofilms, and this growth pattern is controlled by a single gene, rbmA. Competition analyses reveal that the dense growth mode has the advantage of providing the biofilm with superior mechanical properties. Our single-cell technology can broadly link genes to biofilm fine structure and provides a route to assessing cell-to-cell heterogeneity in response to external stimuli. PMID:27555592

Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells

NASA Astrophysics Data System (ADS)

Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

2016-04-01

Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20-40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells.

Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells

PubMed Central

Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

2016-01-01

Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells. PMID:27125749

A new predictive dynamic model describing the effect of the ambient temperature and the convective heat transfer coefficient on bacterial growth.

PubMed

Ben Yaghlene, H; Leguerinel, I; Hamdi, M; Mafart, P

2009-07-31

In this study, predictive microbiology and food engineering were combined in order to develop a new analytical model predicting the bacterial growth under dynamic temperature conditions. The proposed model associates a simplified primary bacterial growth model without lag, the secondary Ratkowsky "square root" model and a simplified two-parameter heat transfer model regarding an infinite slab. The model takes into consideration the product thickness, its thermal properties, the ambient air temperature, the convective heat transfer coefficient and the growth parameters of the micro organism of concern. For the validation of the overall model, five different combinations of ambient air temperature (ranging from 8 degrees C to 12 degrees C), product thickness (ranging from 1 cm to 6 cm) and convective heat transfer coefficient (ranging from 8 W/(m(2) K) to 60 W/(m(2) K)) were tested during a cooling procedure. Moreover, three different ambient air temperature scenarios assuming alternated cooling and heating stages, drawn from real refrigerated food processes, were tested. General agreement between predicted and observed bacterial growth was obtained and less than 5% of the experimental data fell outside the 95% confidence bands estimated by the bootstrap percentile method, at all the tested conditions. Accordingly, the overall model was successfully validated for isothermal and dynamic refrigeration cycles allowing for temperature dynamic changes at the centre and at the surface of the product. The major impact of the convective heat transfer coefficient and the product thickness on bacterial growth during the product cooling was demonstrated. For instance, the time needed for the same level of bacterial growth to be reached at the product's half thickness was estimated to be 5 and 16.5 h at low and high convection level, respectively. Moreover, simulation results demonstrated that the predicted bacterial growth at the air ambient temperature cannot be assumed to be

Multiple regulatory systems coordinate DNA replication with cell growth in Bacillus subtilis.

PubMed

Murray, Heath; Koh, Alan

2014-10-01

In many bacteria the rate of DNA replication is linked with cellular physiology to ensure that genome duplication is coordinated with growth. Nutrient-mediated growth rate control of DNA replication initiation has been appreciated for decades, however the mechanism(s) that connects these cell cycle activities has eluded understanding. In order to help address this fundamental question we have investigated regulation of DNA replication in the model organism Bacillus subtilis. Contrary to the prevailing view we find that changes in DnaA protein level are not sufficient to account for nutrient-mediated growth rate control of DNA replication initiation, although this regulation does require both DnaA and the endogenous replication origin. We go on to report connections between DNA replication and several essential cellular activities required for rapid bacterial growth, including respiration, central carbon metabolism, fatty acid synthesis, phospholipid synthesis, and protein synthesis. Unexpectedly, the results indicate that multiple regulatory systems are involved in coordinating DNA replication with cell physiology, with some of the regulatory systems targeting oriC while others act in a oriC-independent manner. We propose that distinct regulatory systems are utilized to control DNA replication in response to diverse physiological and chemical changes.

Dynamic metabolic exchange governs a marine algal-bacterial interaction.

PubMed

Segev, Einat; Wyche, Thomas P; Kim, Ki Hyun; Petersen, Jörn; Ellebrandt, Claire; Vlamakis, Hera; Barteneva, Natasha; Paulson, Joseph N; Chai, Liraz; Clardy, Jon; Kolter, Roberto

2016-11-18

Emiliania huxleyi is a model coccolithophore micro-alga that generates vast blooms in the ocean. Bacteria are not considered among the major factors influencing coccolithophore physiology. Here we show through a laboratory model system that the bacterium Phaeobacter inhibens , a well-studied member of the Roseobacter group, intimately interacts with E. huxleyi. While attached to the algal cell, bacteria initially promote algal growth but ultimately kill their algal host. Both algal growth enhancement and algal death are driven by the bacterially-produced phytohormone indole-3-acetic acid. Bacterial production of indole-3-acetic acid and attachment to algae are significantly increased by tryptophan, which is exuded from the algal cell. Algal death triggered by bacteria involves activation of pathways unique to oxidative stress response and programmed cell death. Our observations suggest that bacteria greatly influence the physiology and metabolism of E. huxleyi. Coccolithophore-bacteria interactions should be further studied in the environment to determine whether they impact micro-algal population dynamics on a global scale.

The disruptive effect of lysozyme on the bacterial cell wall explored by an in-silico structural outlook.

PubMed

Primo, Emiliano D; Otero, Lisandro H; Ruiz, Francisco; Klinke, Sebastián; Giordano, Walter

2018-01-01

The bacterial cell wall, a structural unit of peptidoglycan polymer comprised of glycan strands consisting of a repeating disaccharide motif [N-acetylglucosamine (NAG) and N-acetylmuramylpentapeptide (NAM pentapeptide)], encases bacteria and provides structural integrity and protection. Lysozymes are enzymes that break down the bacterial cell wall and disrupt the bacterial life cycle by cleaving the linkage between the NAG and NAM carbohydrates. Lab exercises focused on the effects of lysozyme on the bacterial cell wall are frequently incorporated in biochemistry classes designed for undergraduate students in diverse fields as biology, microbiology, chemistry, agronomy, medicine, and veterinary medicine. Such exercises typically do not include structural data. We describe here a sequence of computer tasks designed to illustrate and reinforce both physiological and structural concepts involved in lysozyme effects on the bacterial cell-wall structure. This lab class usually lasts 3.5 hours. First, the instructor presents introductory concepts of the bacterial cell wall and the effect of lysozyme on its structure. Then, students are taught to use computer modeling to visualize the three-dimensional structure of a lysozyme in complex with bacterial cell-wall fragments. Finally, the lysozyme inhibitory effect on a bacterial culture is optionally proposed as a simple microbiological assay. The computer lab exercises described here give students a realistic understanding of the disruptive effect of lysozymes on the bacterial cell wall, a crucial component in bacterial survival. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(1):83-90, 2018. © 2017 The International Union of Biochemistry and Molecular Biology.

Mechanisms of bacterial morphogenesis: evolutionary cell biology approaches provide new insights.

PubMed

Jiang, Chao; Caccamo, Paul D; Brun, Yves V

2015-04-01

How Darwin's "endless forms most beautiful" have evolved remains one of the most exciting questions in biology. The significant variety of bacterial shapes is most likely due to the specific advantages they confer with respect to the diverse environments they occupy. While our understanding of the mechanisms generating relatively simple shapes has improved tremendously in the last few years, the molecular mechanisms underlying the generation of complex shapes and the evolution of shape diversity are largely unknown. The emerging field of bacterial evolutionary cell biology provides a novel strategy to answer this question in a comparative phylogenetic framework. This relatively novel approach provides hypotheses and insights into cell biological mechanisms, such as morphogenesis, and their evolution that would have been difficult to obtain by studying only model organisms. We discuss the necessary steps, challenges, and impact of integrating "evolutionary thinking" into bacterial cell biology in the genomic era. © 2015 WILEY Periodicals, Inc.

Biophysical model of bacterial cell interactions with nanopatterned cicada wing surfaces.

PubMed

Pogodin, Sergey; Hasan, Jafar; Baulin, Vladimir A; Webb, Hayden K; Truong, Vi Khanh; Phong Nguyen, The Hong; Boshkovikj, Veselin; Fluke, Christopher J; Watson, Gregory S; Watson, Jolanta A; Crawford, Russell J; Ivanova, Elena P

2013-02-19

The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on their physical surface structure. The wings provide a model for the development of novel functional surfaces that possess an increased resistance to bacterial contamination and infection. We propose a biophysical model of the interactions between bacterial cells and cicada wing surface structures, and show that mechanical properties, in particular cell rigidity, are key factors in determining bacterial resistance/sensitivity to the bactericidal nature of the wing surface. We confirmed this experimentally by decreasing the rigidity of surface-resistant strains through microwave irradiation of the cells, which renders them susceptible to the wing effects. Our findings demonstrate the potential benefits of incorporating cicada wing nanopatterns into the design of antibacterial nanomaterials. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The actin homologue MreB organizes the bacterial cell membrane

PubMed Central

Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W.

2014-01-01

The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes. PMID:24603761

The actin homologue MreB organizes the bacterial cell membrane.

PubMed

Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W

2014-03-07

The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes.

Process to Selectively Distinguish Viable from Non-Viable Bacterial Cells

NASA Technical Reports Server (NTRS)

LaDuc, Myron T.; Bernardini, Jame N.; Stam, Christina N.

2010-01-01

The combination of ethidium monoazide (EMA) and post-fragmentation, randomly primed DNA amplification technologies will enhance the analytical capability to discern viable from non-viable bacterial cells in spacecraft-related samples. Intercalating agents have been widely used since the inception of molecular biology to stain and visualize nucleic acids. Only recently, intercalating agents such as EMA have been exploited to selectively distinguish viable from dead bacterial cells. Intercalating dyes can only penetrate the membranes of dead cells. Once through the membrane and actually inside the cell, they intercalate DNA and, upon photolysis with visible light, produce stable DNA monoadducts. Once the DNA is crosslinked, it becomes insoluble and unable to be fragmented for post-fragmentation, randomly primed DNA library formation. Viable organisms DNA remains unaffected by the intercalating agents, allowing for amplification via post-fragmentation, randomly primed technologies. This results in the ability to carry out downstream nucleic acid-based analyses on viable microbes to the exclusion of all non-viable cells.

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

PubMed Central

Busalmen, J. P.; de Sánchez, S. R.; Schiffrin, D. J.

1998-01-01

Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf) of 1.38 and a thickness (df) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated. PMID:9758786

Morphodynamics of growing bacterial colony

NASA Astrophysics Data System (ADS)

Ghosh, Pushpita; Perlekar, Prasad; Rana, Navdeep

Self-organization into multicellular communities is a natural trend of most of the bacteria. Mutual interactions and competition among the bacterial cells in such multicellular organization play essential role in governing the spatiotemporal dynamics. We here present the spatiotemporal dynamics of growing bacterial colony using theory and a particle-based or individual-based simulation model of nonmotile cells growing utilizing a diffusing nutrient/food on a semi-solid surface by their growth and division forces and by pushing each-other through sliding motility. We show how the resource competition over a fixed amount of food, the diffusion coefficient of the nutrient and the random genetic noise govern the morphodynamics of a single species and a well-mixed two-species bacterial colonies. Our results show that for a very low initial food concentrations, colony develops fingering pattern at the front, while for intermediate values of initial food sources, the colony undergoes transitions to branched structures at the periphery and for very high values of food colony develops smoother fronts.

Host-Directed Antimicrobial Drugs with Broad-Spectrum Efficacy against Intracellular Bacterial Pathogens

PubMed Central

Czyż, Daniel M.; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P.; Martinez, Juan J.; Steck, Theodore L.; Crosson, Sean; Gabay, Joëlle E.

2014-01-01

ABSTRACT We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. PMID:25073644

[Influence of human gastrointestinal tract bacterial pathogens on host cell apoptosis].

PubMed

Wronowska, Weronika; Godlewska, Renata; Jagusztyn-Krynicka, Elzbieta Katarzyna

2005-01-01

Several pathogenic bacteria are able to trigger apoptosis in the host cell, but the mechanisms by which it occurs differ, and the resulting pathology can take different courses. Induction and/or blockage of programmed cell death upon infection is a result of complex interaction of bacterial proteins with cellular proteins involved in signal transduction and apoptosis. In this review we focus on pro/anti-apoptotic activities exhibited by two enteric pathogens Salmonella enterica, Yersinia spp. and gastric pathogen Helicobacter pylori. We present current knowledge on how interaction between mammalian and bacterial cell relates to the molecular pathways of apoptosis, and what is the role of apoptosis in pathogenesis.

The impact of metabolic state on Cd adsorption onto bacterial cells

USGS Publications Warehouse

Johnson, K.J.; Ams, D.A.; Wedel, A.N.; Szymanowski, J.E.S.; Weber, D.L.; Schneegurt, M.A.; Fein, J.B.

2007-01-01

This study examines the effect of bacterial metabolism on the adsorption of Cd onto Gram-positive and Gram-negative bacterial cells. Metabolically active Gram-positive cells adsorbed significantly less Cd than non-metabolizing cells. Gram-negative cells, however, showed no systematic difference in Cd adsorption between metabolizing and non-metabolizing cells. The effect of metabolism on Cd adsorption to Gram-positive cells was likely due to an influx of protons in and around the cell wall from the metabolic proton motive force, promoting competition between Cd and protons for adsorption sites on the cell wall. The relative lack of a metabolic effect on Cd adsorption onto Gram-negative compared to Gram-positive cells suggests that Cd binding in Gram-negative cells is focused in a region of the cell wall that is not reached, or is unaffected by this proton flux. Thermodynamic modeling was used to estimate that proton pumping causes the pH in the cell wall of metabolizing Gram-positive bacteria to decrease from the bulk solution value of 7.0 to approximately 5.7. ?? 2007 The Authors.

The Leucine Incorporation Method Estimates Bacterial Growth Equally Well in Both Oxic and Anoxic Lake Waters

PubMed Central

Bastviken, David; Tranvik, Lars

2001-01-01

Bacterial biomass production is often estimated from incorporation of radioactively labeled leucine into protein, in both oxic and anoxic waters and sediments. However, the validity of the method in anoxic environments has so far not been tested. We compared the leucine incorporation of bacterial assemblages growing in oxic and anoxic waters from three lakes differing in nutrient and humic contents. The method was modified to avoid O2 contamination by performing the incubation in syringes. Isotope saturation levels in oxic and anoxic waters were determined, and leucine incorporation rates were compared to microscopically observed bacterial growth. Finally, we evaluated the effects of O2 contamination during incubation with leucine, as well as the potential effects of a headspace in the incubation vessel. Isotope saturation occurred at a leucine concentration of above about 50 nM in both oxic and anoxic waters from all three lakes. Leucine incorporation rates were linearly correlated to observed growth, and there was no significant difference between oxic and anoxic conditions. O2 contamination of anoxic water during 1-h incubations with leucine had no detectable impact on the incorporation rate, while a headspace in the incubation vessel caused leucine incorporation to increase in both anoxic and O2-contaminated samples. The results indicate that the leucine incorporation method relates equally to bacterial growth rates under oxic and anoxic conditions and that incubation should be performed without a headspace. PMID:11425702

Hydrogels with Modulated Ionic Load for Mammalian Cell Harvesting with Reduced Bacterial Adhesion.

PubMed

Gallardo, Alberto; Martínez-Campos, Enrique; García, Carolina; Cortajarena, Aitziber L; Rodríguez-Hernández, Juan

2017-05-08

In this manuscript, we describe the fabrication of hydrogel supports for mammalian cell handling that can simultaneously prevent materials from microbial contamination and therefore allow storage in aqueous media. For that purpose, hydrogels based on the antifouling polymer polyvinylpyrrolidone (PVP) were functionalized with different ionic groups (anionic, cationic, or two types of zwitterions). In order to prevent bacterial adhesion in the long-term, we took advantage of the synergistic effect of inherently antifouling PVP and additional antifouling moieties incorporated within the hydrogel structure. We evaluated, in a separated series of experiments, both the capability of the materials to act as supports for the growth of mammalian cell monolayers for transplantation (using C-166-GFP endothelial cell line), as well their antifouling properties against Staphylococcus aureus, were studied. All of the hydrogels are structurally pseudodouble networks with high swelling (around 90%) and similar mechanical properties (in the low range for hydrogel materials with Young modulus below 1250 kPa). With some differences, all the charged hydrogels were capable of hosting mouse endothelial cell line C166-GFP to confluence, as well as a monolayer detachment and transplantation through simple mechanical agitation. On the contrary, the uncharged hydrogel was not capable to detach a full monolayer for transplantation. Bacterial adhesion and proliferation was highly sensitive to the functionality (type of charge and density). In particular, we evidenced that monomers bearing zwitterionic sulfobetaine groups, those negatively charged as well as "electro neutral" hydrogels fabricated from stoichiometric amounts of positive and negative units, exhibit excellent antifouling properties both at initial adhesion times and during longer periods up to 72 h.

Chemically synthesized silver nanoparticles as cell lysis agent for bacterial genomic DNA isolation

NASA Astrophysics Data System (ADS)

Goswami, Gunajit; Boruah, Himangshu; Gautom, Trishnamoni; Jyoti Hazarika, Dibya; Barooah, Madhumita; Boro, Robin Chandra

2017-12-01

Silver nanoparticles (AgNPs) have seen a recent spurt of use in varied fields of science. In this paper, we showed a novel application of AgNP as a promising microbial cell-lysis agent for genomic DNA isolation. We utilized chemically synthesized AgNPs for lysing bacterial cells to isolate their genomic DNA. The AgNPs efficiently lysed bacterial cells to yield good quality DNA that could be subsequently used for several molecular biology works.

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.

PGE2 suppresses intestinal T cell function in thermal injury: a cause of enhanced bacterial translocation.

PubMed

Choudhry, M A; Fazal, N; Namak, S Y; Haque, F; Ravindranath, T; Sayeed, M M

2001-09-01

Increased gut bacterial translocation in burn and trauma patients has been demonstrated in a number of previous studies, however, the mechanism for such an increased gut bacterial translocation in injured patients remains poorly understood. Utilizing a rat model of burn injury, in the present study we examined the role of intestinal immune defense by analyzing the T cell functions. We investigated if intestinal T cells dysfunction contributes to bacterial translocation after burn injury. Also our study determined if burn-mediated alterations in intestinal T cell functions are related to enhanced release of PGE2. Finally, we examined whether or not burn-related alterations in intestinal T cell function are due to inappropriate activation of signaling molecule P59fyn, which is required for T cell activation and proliferation. The results presented here showed an increase in gut bacterial accumulation in mesenteric lymph nodes after thermal injury. This was accompanied by a decrease in the intestinal T cell proliferative responses. Furthermore, the treatments of burn-injured animals with PGE2 synthesis blocker (indomethacin or NS398) prevented both the decrease in intestinal T cell proliferation and enhanced bacterial translocation. Finally, our data suggested that the inhibition of intestinal T cell proliferation could result via PGE2-mediated down-regulation of the T cell activation-signaling molecule P59fyn. These findings support a role of T cell-mediated immune defense against bacterial translocation in burn injury.

Model comparison for Escherichia coli growth in pouched food.

PubMed

Fujikawa, Hiroshi; Yano, Kazuyoshi; Morozumi, Satoshi

2006-06-01

We recently studied the growth characteristics of Escherichia coli cells in pouched mashed potatoes (Fujikawa et al., J. Food Hyg. Soc. Japan, 47, 95-98 (2006)). Using those experimental data, in the present study, we compared a logistic model newly developed by us with the modified Gompertz and the Baranyi models, which are used as growth models worldwide. Bacterial growth curves at constant temperatures in the range of 12 to 34 degrees C were successfully described with the new logistic model, as well as with the other models. The Baranyi gave the least error in cell number and our model gave the least error in the rate constant and the lag period. For dynamic temperature, our model successfully predicted the bacterial growth, whereas the Baranyi model considerably overestimated it. Also, there was a discrepancy between the growth curves described with the differential equations of the Baranyi model and those obtained with DMfit, a software program for Baranyi model fitting. These results indicate that the new logistic model can be used to predict bacterial growth in pouched food.

Conventional CD4+ T cells present bacterial antigens to induce cytotoxic and memory CD8+ T cell responses.

PubMed

Cruz-Adalia, Aránzazu; Ramirez-Santiago, Guillermo; Osuna-Pérez, Jesús; Torres-Torresano, Mónica; Zorita, Virgina; Martínez-Riaño, Ana; Boccasavia, Viola; Borroto, Aldo; Martínez Del Hoyo, Gloria; González-Granado, José María; Alarcón, Balbino; Sánchez-Madrid, Francisco; Veiga, Esteban

2017-11-17

Bacterial phagocytosis and antigen cross-presentation to activate CD8 + T cells are principal functions of professional antigen presenting cells. However, conventional CD4 + T cells also capture and kill bacteria from infected dendritic cells in a process termed transphagocytosis (also known as transinfection). Here, we show that transphagocytic T cells present bacterial antigens to naive CD8 + T cells, which proliferate and become cytotoxic in response. CD4 + T-cell-mediated antigen presentation also occurs in vivo in the course of infection, and induces the generation of central memory CD8 + T cells with low PD-1 expression. Moreover, transphagocytic CD4 + T cells induce protective anti-tumour immune responses by priming CD8 + T cells, highlighting the potential of CD4 + T cells as a tool for cancer immunotherapy.

Characterizing endophytic competence and plant growth promotion of bacterial endophytes inhabiting the seed endosphere of Rice.

PubMed

Walitang, Denver I; Kim, Kiyoon; Madhaiyan, Munusamy; Kim, Young Kee; Kang, Yeongyeong; Sa, Tongmin

2017-10-26

Rice (Oryza sativa L. ssp. indica) seeds as plant microbiome present both an opportunity and a challenge to colonizing bacterial community living in close association with plants. Nevertheless, the roles and activities of bacterial endophytes remain largely unexplored and insights into plant-microbe interaction are compounded by its complexity. In this study, putative functions or physiological properties associated with bacterial endophytic nature were assessed. Also, endophytic roles in plant growth and germination that may allow them to be selectively chosen by plants were also studied. The cultivable seed endophytes were dominated by Proteobacteria particularly class Gammaproteobacteria. Highly identical type strains were isolated from the seed endosphere regardless of the rice host's physiological tolerance to salinity. Among the type strains, Flavobacterium sp., Microbacterium sp. and Xanthomonas sp. were isolated from the salt-sensitive and salt-tolerant cultivars. PCA-Biplot ordination also showed that specific type strains isolated from different rice cultivars have distinguishing similar characteristics. Flavobacterium sp. strains are phosphate solubilizers and indole-3-acetic acid producers with high tolerance to salinity and osmotic stress. Pseudomonas strains are characterized as high siderophore producers while Microbacterium sp. and Xanthomonas sp. strains have very high pectinase and cellulase activity. Among the physiological traits of the seed endophytes, bacterial pectinase and cellulase activity are positively correlated as well as salt and osmotic tolerance. Overall characterization shows that majority of the isolates could survive in 4-8% salt concentration as well as in 0.6 M and 1.2 M sucrose solution. The activities of catalase, pectinase and cellulase were also observed in almost all of the isolates indicating the importance of these characteristics for survival and colonization into the seed endosphere. Seed bacterial endophytes also

A simple expression for quantifying bacterial chemotaxis using capillary assay data: application to the analysis of enhanced chemotactic responses from growth-limited cultures.

PubMed

Ford, R M; Lauffenburger, D A

1992-05-01

An individual cell-based mathematical model of Rivero et al. provides a framework for determining values of the chemotactic sensitivity coefficient chi 0, an intrinsic cell population parameter that characterizes the chemotactic response of bacterial populations. This coefficient can theoretically relate the swimming behavior of individual cells to the resulting migration of a bacterial population. When this model is applied to the commonly used capillary assay, an approximate solution can be obtained for a particular range of chemotactic strengths yielding a very simple analytical expression for estimating the value of chi 0, [formula: see text] from measurements of cell accumulation in the capillary, N, when attractant uptake is negligible. A0 and A infinity are the dimensionless attractant concentrations initially present at the mouth of the capillary and far into the capillary, respectively, which are scaled by Kd, the effective dissociation constant for receptor-attractant binding. D is the attractant diffusivity, and mu is the cell random motility coefficient. NRM is the cell accumulation in the capillary in the absence of an attractant gradient, from which mu can be determined independently as mu = (pi/4t)(NRM/pi r2bc)2, with r the capillary tube radius and bc the bacterial density initially in the chamber. When attractant uptake is significant, a slightly more involved procedure requiring a simple numerical integration becomes necessary. As an example, we apply this approach to quantitatively characterize, in terms of the chemotactic sensitivity coefficient chi 0, data from Terracciano indicating enhanced chemotactic responses of Escherichia coli to galactose when cultured under growth-limiting galactose levels in a chemostat.

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

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.

Osmotic Pressure, Bacterial Cell Walls, and Penicillin: A Demonstration.

ERIC Educational Resources Information Center

Lennox, John E.

1984-01-01

An easily constructed apparatus that models the effect of penicillin on the structure of bacterial cells is described. Background information and procedures for using the apparatus during a classroom demonstration are included. (JN)

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth.

PubMed

Jarisz, Tasha A; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K

2018-06-14

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

NASA Astrophysics Data System (ADS)

Jarisz, Tasha A.; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K.

2018-06-01

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Identical bacterial populations colonize premature infant gut, skin, and oral microbiomes and exhibit different in situ growth rates

PubMed Central

Olm, Matthew R.; Brown, Christopher T.; Brooks, Brandon; Firek, Brian; Baker, Robyn; Burstein, David; Soenjoyo, Karina; Thomas, Brian C.; Morowitz, Michael; Banfield, Jillian F.

2017-01-01

The initial microbiome impacts the health and future development of premature infants. Methodological limitations have led to gaps in our understanding of the habitat range and subpopulation complexity of founding strains, as well as how different body sites support microbial growth. Here, we used metagenomics to reconstruct genomes of strains that colonized the skin, mouth, and gut of two hospitalized premature infants during the first month of life. Seven bacterial populations, considered to be identical given whole-genome average nucleotide identity of >99.9%, colonized multiple body sites, yet none were shared between infants. Gut-associated Citrobacter koseri genomes harbored 47 polymorphic sites that we used to define 10 subpopulations, one of which appeared in the gut after 1 wk but did not spread to other body sites. Differential genome coverage was used to measure bacterial population replication rates in situ. In all cases where the same bacterial population was detected in multiple body sites, replication rates were faster in mouth and skin compared to the gut. The ability of identical strains to colonize multiple body sites underscores the habit flexibility of initial colonists, whereas differences in microbial replication rates between body sites suggest differences in host control and/or resource availability. Population genomic analyses revealed microdiversity within bacterial populations, implying initial inoculation by multiple individual cells with distinct genotypes. Overall, however, the overlap of strains across body sites implies that the premature infant microbiome can exhibit very low microbial diversity. PMID:28073918

Development and Validation of a Whole-Cell Inhibition Assay for Bacterial Methionine Aminopeptidase by Surface-Enhanced Laser Desorption Ionization-Time of Flight Mass Spectrometry

PubMed Central

Greis, Kenneth D.; Zhou, Songtao; Siehnel, Richard; Klanke, Chuck; Curnow, Alan; Howard, Jeremy; Layh-Schmitt, Gerlinde

2005-01-01

Bacterial methionine aminopeptidase (MAP) is a protease that removes methionine from the N termini of newly synthesized bacterial proteins after the peptide deformylase enzyme cleaves the formyl group from the initiator formylmethionine. MAP is an essential bacterial gene product and thus represents a potential target for therapeutic intervention. A fundamental challenge in the antibacterial drug discovery field is demonstrating conclusively that compounds with in vitro enzyme inhibition activity produce the desired antibacterial effect by interfering with the same target in whole bacterial cells. One way to address the activity of inhibitor compounds is by profiling cellular biomarkers in whole bacterial cells using compounds that are known inhibitors of a particular target. However, in the case of MAP, no specific inhibitors were available for such studies. Instead, a genetically attenuated MAP strain was generated in which MAP expression was placed under the control of an inducible arabinose promoter. Thus, MAP inhibition in whole cells could be mimicked by growth in the absence of arabinose. This genetically attenuated strain was used as a benchmark for MAP inhibition by profiling whole-cell lysates for unprocessed proteins using surface-enhanced laser desorption ionization-time of flight mass spectrometry (MS). Eight proteins between 4 and 14 kDa were confirmed as being unprocessed and containing the initiator methionine by adding back purified MAP to the preparations prior to MS analysis. Upon establishing these unprocessed proteins as biomarkers for MAP inhibition, the assay was used to screen small-molecule chemical inhibitors of purified MAP for whole-cell activity. Fifteen compound classes yielded three classes of compound with whole-cell activity for further optimization by chemical expansion. This report presents the development, validation, and implementation of a whole-cell inhibition assay for MAP. PMID:16048957

Development and validation of a whole-cell inhibition assay for bacterial methionine aminopeptidase by surface-enhanced laser desorption ionization-time of flight mass spectrometry.

PubMed

Greis, Kenneth D; Zhou, Songtao; Siehnel, Richard; Klanke, Chuck; Curnow, Alan; Howard, Jeremy; Layh-Schmitt, Gerlinde

2005-08-01

Bacterial methionine aminopeptidase (MAP) is a protease that removes methionine from the N termini of newly synthesized bacterial proteins after the peptide deformylase enzyme cleaves the formyl group from the initiator formylmethionine. MAP is an essential bacterial gene product and thus represents a potential target for therapeutic intervention. A fundamental challenge in the antibacterial drug discovery field is demonstrating conclusively that compounds with in vitro enzyme inhibition activity produce the desired antibacterial effect by interfering with the same target in whole bacterial cells. One way to address the activity of inhibitor compounds is by profiling cellular biomarkers in whole bacterial cells using compounds that are known inhibitors of a particular target. However, in the case of MAP, no specific inhibitors were available for such studies. Instead, a genetically attenuated MAP strain was generated in which MAP expression was placed under the control of an inducible arabinose promoter. Thus, MAP inhibition in whole cells could be mimicked by growth in the absence of arabinose. This genetically attenuated strain was used as a benchmark for MAP inhibition by profiling whole-cell lysates for unprocessed proteins using surface-enhanced laser desorption ionization-time of flight mass spectrometry (MS). Eight proteins between 4 and 14 kDa were confirmed as being unprocessed and containing the initiator methionine by adding back purified MAP to the preparations prior to MS analysis. Upon establishing these unprocessed proteins as biomarkers for MAP inhibition, the assay was used to screen small-molecule chemical inhibitors of purified MAP for whole-cell activity. Fifteen compound classes yielded three classes of compound with whole-cell activity for further optimization by chemical expansion. This report presents the development, validation, and implementation of a whole-cell inhibition assay for MAP.

Modeling Surface Growth of Escherichia coli on Agar Plates

PubMed Central

Fujikawa, Hiroshi; Morozumi, Satoshi

2005-01-01

Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves. PMID:16332768

Density-dependent regulation of growth of BSC-1 cells in cell culture: growth inhibitors formed by the cells.

PubMed Central

Holley, R W; Armour, R; Baldwin, J H

1978-01-01

Inhibitors formed by a monkey epithelial cell line, BSC-1, play an important role in limiting growth at high cell densities. At least three inhibitors are formed: lactic acid, ammonia, and an unidentified inhibitor that may be an unstable protein. The unidentified inhibitor is destroyed by shaking the conditioned medium, by bubbling gas through the medium, or by heating or storing the medium in the absence of cells. The concentrations of lactic acid and ammonia that accumulate in conditioned medium inhibit growth when added to fresh medium. These results, together with earlier studies, indicate that density-dependent regulation of growth of BSC-1 cells results from the combined effects of (a) inhibitors formed by the cells, (b) decreased availability of receptor sites for serum growth factors as the cells become crowded, and (c) limiting concentrations of low molecular weight nutrients in the medium. In contrast, density-dependent regulation of growth in 3T3 mouse embryo fibroblasts results almost entirely from inactivation of serum factors. PMID:273914

In vitro bacterial cytotoxicity of CNTs: reactive oxygen species mediate cell damage edges over direct physical puncturing.

PubMed

Rajavel, Krishnamoorthy; Gomathi, Rajkumar; Manian, Sellamuthu; Rajendra Kumar, Ramasamy Thangavelu

2014-01-21

Understanding the bacterial cytotoxicity of CNTs is important for a wide variety of applications in the biomedical, environmental, and health sectors. A majority of the earlier reports attributed the bactericidal cytotoxicity of CNTs to bacterial cell membrane damage by direct physical puncturing. Our results reveal that bacterial cell death via bacterial cell membrane damage is induced by reactive oxygen species (ROS) produced from CNTs and is not due to direct physical puncturing by CNTs. To understand the actual mechanism of bacterial killing, we elucidated the bacterial cytotoxicity of SWCNTs and MWCNTs against Gram-negative human pathogenic bacterial species Escherichia coli, Shigella sonnei, Klebsiella pneumoniae, and Pseudomonas aeruginosa and its amelioration upon functionalizing the CNTs with antioxidant tannic acid (TA). Interestingly, the bacterial cells treated with CNTs exhibited severe cell damage under laboratory (ambient) and sunlight irradiation conditions. However, CNTs showed no cytotoxicity to the bacterial cells when incubated in the dark. The quantitative assessments carried out by us made it explicit that CNTs are effective generators of ROS such as (1)O2, O2(•-), and (•)OH in an aqueous medium under both ambient and sunlight-irradiated conditions. Both naked and TA-functionalized CNTs showed negligible ROS production in the dark. Furthermore, strong correlations were obtained between ROS produced by CNTs and the bacterial cell mortality (with the correlation coefficient varying between 0.7618 and 0.9891) for all four tested pathogens. The absence of bactericidal cytotoxicity in both naked and functionalized CNTs in the dark reveals that the presence of ROS is the major factor responsible for the bactericidal action compared to direct physical puncturing. This understanding of the bactericidal activity of the irradiated CNTs, mediated through the generation of ROS, could be interesting for novel applications such as regulated ROS delivery

Water reservoir maintained by cell growth fuels the spreading of a bacterial swarm.

PubMed

Wu, Yilin; Berg, Howard C

2012-03-13

Flagellated bacteria can swim across moist surfaces within a thin layer of fluid, a means for surface colonization known as swarming. This fluid spreads with the swarm, but how it does so is unclear. We used micron-sized air bubbles to study the motion of this fluid within swarms of Escherichia coli. The bubbles moved diffusively, with drift. Bubbles starting at the swarm edge drifted inward for the first 5 s and then moved outward. Bubbles starting 30 μm from the swarm edge moved inward for the first 20 s, wandered around in place for the next 40 s, and then moved outward. Bubbles starting at 200 or 300 μm from the edge moved outward or wandered around in place, respectively. So the general trend was inward near the outer edge of the swarm and outward farther inside, with flows converging on a region about 100 μm from the swarm edge. We measured cellular metabolic activities with cells expressing a short-lived GFP and cell densities with cells labeled with a membrane fluorescent dye. The fluorescence plots were similar, with peaks about 80 μm from the swarm edge and slopes that mimicked the particle drift rates. These plots suggest that net fluid flow is driven by cell growth. Fluid depth is largest in the multilayered region between approximately 30 and 200 μm from the swarm edge, where fluid agitation is more vigorous. This water reservoir travels with the swarm, fueling its spreading. Intercellular communication is not required; cells need only grow.

Autologous tumor cells engineered to express bacterial antigens.

PubMed

Ramiya, Vijayakumar K; Jerald, Maya M; Lawman, Patricia D; Lawman, Michael J P

2014-01-01

Cancer immunotherapies are emerging as promising treatment modalities in the management of the disease. As a result, cancer vaccines are considered to be immensely crucial in preventing recurrence, a well-known nemesis in cancer patients because they have the potential to activate memory antitumor immunity. Due to poor antigenicity and self-tolerance, most tumor antigens require interventional vaccine therapies to provide an adequate "danger" signal to the immune system in order to activate a robust, clinically meaningful antitumor immunity. It has been postulated that this requirement may be achieved by providing bacterial and/or viral immunogens to prime this type of immune response. Briefly, we provide here a method of transfecting whole tumor cells with plasmid DNA encoding an immunogenic bacterial protein such as Emm55, which was derived from Streptococcus pyogenes (S. pyogenes). Subsequent inactivation of the transfected cells by irradiation (100 Gray) prevents replication. This type of whole-cell vaccine, e.g., ImmuneFx™, has demonstrated activity in a murine neuroblastoma model, in canine lymphoma patients with naturally occurring disease, and in many cancer types in companion animals. The protocols described in this chapter provide the necessary materials and methodologies to manufacture such a vaccine.

Bacterial community dynamics during polysaccharide degradation at contrasting sites in the Southern and Atlantic Oceans.

PubMed

Wietz, Matthias; Wemheuer, Bernd; Simon, Heike; Giebel, Helge-Ansgar; Seibt, Maren A; Daniel, Rolf; Brinkhoff, Thorsten; Simon, Meinhard

2015-10-01

The bacterial degradation of polysaccharides is central to marine carbon cycling, but little is known about the bacterial taxa that degrade specific marine polysaccharides. Here, bacterial growth and community dynamics were studied during the degradation of the polysaccharides chitin, alginate and agarose in microcosm experiments at four contrasting locations in the Southern and Atlantic Oceans. At the Southern polar front, chitin-supplemented microcosms were characterized by higher fractions of actively growing cells and a community shift from Alphaproteobacteria to Gammaproteobacteria and Bacteroidetes. At the Antarctic ice shelf, chitin degradation was associated with growth of Bacteroidetes, with 24% higher cell numbers compared with the control. At the Patagonian continental shelf, alginate and agarose degradation covaried with growth of different Alteromonadaceae populations, each with specific temporal growth patterns. At the Mauritanian upwelling, only the alginate hydrolysis product guluronate was consumed, coincident with increasing abundances of Alteromonadaceae and possibly cross-feeding SAR11. 16S rRNA gene amplicon libraries indicated that growth of the Bacteroidetes-affiliated genus Reichenbachiella was stimulated by chitin at all cold and temperate water stations, suggesting comparable ecological roles over wide geographical scales. Overall, the predominance of location-specific patterns showed that bacterial communities from contrasting oceanic biomes have members with different potentials to hydrolyse polysaccharides. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Rumen Bacterial Degradation of Forage Cell Walls Investigated by Electron Microscopy

PubMed Central

Akin, Danny E.; Amos, Henry E.

1975-01-01

The association of rumen bacteria with specific leaf tissues of the forage grass Kentucky-31 tall fescue (Festuca arundinacea Schreb.) during in vitro degradation was investigated by transmission and scanning electron microscopy. Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis. Rumen bacteria appeared to degrade the mesophyll, in some cases, and phloem without prior attachment to the plant cell walls. The degradation of bundle sheath and epidermal cell walls appeared to be preceded by attachment of bacteria to the plant cell wall. Ultrastructural features apparently involved in the adhesion of large cocci to plant cells were observed by transmission and scanning electron microscopy. The physical association between plant and rumen bacterial cells during degradation apparently varies with tissue types. Bacterial attachment, by extracellular features in some microorganisms, is required prior to degradation of the more resistant tissues. Images PMID:16350017

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. Copyright © 2015 Elsevier GmbH. All rights reserved.

Bacterial growth tolerance to concentrations of chlorate and perchlorate salts relevant to Mars

NASA Astrophysics Data System (ADS)

Al Soudi, Amer F.; Farhat, Omar; Chen, Fei; Clark, Benton C.; Schneegurt, Mark A.

2017-07-01

The Phoenix lander at Mars polar cap found appreciable levels of (per)chlorate salts, a mixture of perchlorate and chlorate salts of Ca, Fe, Mg and Na at levels of ~0.6% in regolith. These salts are highly hygroscopic and can form saturated brines through deliquescence, likely producing aqueous solutions with very low freezing points on Mars. To support planetary protection efforts, we have measured bacterial growth tolerance to (per)chlorate salts. Existing bacterial isolates from the Great Salt Plains of Oklahoma (NaCl-rich) and Hot Lake in Washington (MgSO4-rich) were tested in high concentrations of Mg, K and Na salts of chlorate and perchlorate. Strong growth was observed with nearly all of these salinotolerant isolates at 1% (~0.1 M) (per)chlorate salts, similar to concentrations observed in bulk soils on Mars. Growth in perchlorate salts was observed at concentrations of at least 10% (~1.0 M). Greater tolerance was observed for chlorate salts, where growth was observed to 2.75 M (>25%). Tolerance to K salts was greatest, followed by Mg salts and then Na salts. Tolerances varied among isolates, even among those within the same phylogenetic clade. Tolerant bacteria included genera that also are found in spacecraft assembly facilities. Substantial microbial tolerance to (per)chlorate salts is a concern for planetary protection since tolerant microbes contaminating spacecraft would have a greater chance for survival and proliferation, despite the harsh chemical conditions found near the surface of Mars.

Periodic Colony Formation by Bacterial Species Bacillus subtilis

NASA Astrophysics Data System (ADS)

Wakita, Jun-ichi; Shimada, Hirotoshi; Itoh, Hiroto; Matsuyama, Tohey; Matsushita, Mitsugu

2001-03-01

We have investigated the periodic colony growth of bacterial species Bacillus subtilis. A colony grows cyclically with the interface repeating an advance (migration phase) and a rest (consolidation phase) alternately on a surface of semi-solid agar plate under appropriate environmental conditions, resulting in a concentric ring-like colony. It was found from macroscopic observations that the characteristic quantities for the periodic growth such as the migration time, the consolidation time and the terrace spacing do not depend so much on nutrient concentration Cn, but do on agar concentration Ca. The consolidation time was a weakly increasing function of Ca, while the migration time and the terrace spacing were, respectively, weakly and strongly decreasing function of Ca. Overall, the cycle (migration-plus-consolidation) time seems to be constant, and does not depend so much on both Cn and Ca. Microscopically, bacterial cells inside the growing front of a colony keep increasing their population during both migration and consolidation phases. It was also confirmed that their secreting surfactant called surfactin does not affect their periodic growth qualitatively, i.e., mutant cells which cannot secrete surfactin produce a concentric ring-like colony. All these results suggest that the diffusion of the nutrient and the surfactin are irrelevant to their periodic growth.

Response of Escherichia coli growth rate to osmotic shock.

PubMed

Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

2014-05-27

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan.

Response of Escherichia coli growth rate to osmotic shock

PubMed Central

Rojas, Enrique; Theriot, Julie A.; Huang, Kerwyn Casey

2014-01-01

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless “stored” growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

Differentiation of epithelial cells to M cells in response to bacterial colonization on the follicle-associated epithelium of Peyer's patch in rat small intestine.

PubMed

Chin, Keigi; Onishi, Sachiko; Yuji, Midori; Inamoto, Tetsurou; Qi, Wang-Mei; Warita, Katsuhiko; Yokoyama, Toshifumi; Hoshi, Nobuhiko; Kitagawa, Hiroshi

2006-10-01

To clarify the relationship between M cells and intestinal microflora, histoplanimetrical investigation into the bacterial colonization and the differentiation to M cells was carried out in rat Peyer's patch under physiological conditions. The follicle-associated epithelium (FAE), except for the narrow area of apical region, was closely covered with both neighboring intestinal villi and a thick mucous layer, the latter of which also filled the intervillous spaces as well as the space between the FAE and the neighboring intestinal villi. Indigenous bacteria adhered almost constantly to the narrow areas of apical regions of both intestinal villi and the FAE. Bacterial colonies were occasionally located on the basal to middle region of FAE, where M cells also appeared, forming large pockets. When bacterial colonies were located on the basal to middle region of FAE, bacteria with the same morphological characteristics also proliferated in the intervillous spaces neighboring the Peyer's patch. In cases with no bacterial colonies on the basal to middle region of FAE, however, M cells were rare in the FAE. Histoplanimetrical analysis showed the similar distribution pattern of bacterial colonies on the FAE and M cells in the FAE. M cells ultrastructurally engulfed indigenous bacteria, which were then transported to the pockets. These results suggest that indigenous bacterial colonization on the FAE stimulates the differentiation of M cells in the FAE under physiological conditions. The uptake of bacteria by M cells might contribute the regulation of the development of indigenous bacterial colonies in the small intestine.

New Application of Hyperspectral Imaging for Bacterial Cell Classification

USDA-ARS?s Scientific Manuscript database

Hyperspectral microscopy has shown potential as a method for rapid detection of foodborne pathogenic bacteria with spectral characteristics from bacterial cells. Hyperspectral microscope images (HMIs) are collected from broiler chicken isolates of Salmonella serotypes Enteritidis, Typhimurium, Infa...

Multiple Regulatory Systems Coordinate DNA Replication with Cell Growth in Bacillus subtilis

PubMed Central

Murray, Heath; Koh, Alan

2014-01-01

In many bacteria the rate of DNA replication is linked with cellular physiology to ensure that genome duplication is coordinated with growth. Nutrient-mediated growth rate control of DNA replication initiation has been appreciated for decades, however the mechanism(s) that connects these cell cycle activities has eluded understanding. In order to help address this fundamental question we have investigated regulation of DNA replication in the model organism Bacillus subtilis. Contrary to the prevailing view we find that changes in DnaA protein level are not sufficient to account for nutrient-mediated growth rate control of DNA replication initiation, although this regulation does require both DnaA and the endogenous replication origin. We go on to report connections between DNA replication and several essential cellular activities required for rapid bacterial growth, including respiration, central carbon metabolism, fatty acid synthesis, phospholipid synthesis, and protein synthesis. Unexpectedly, the results indicate that multiple regulatory systems are involved in coordinating DNA replication with cell physiology, with some of the regulatory systems targeting oriC while others act in a oriC-independent manner. We propose that distinct regulatory systems are utilized to control DNA replication in response to diverse physiological and chemical changes. PMID:25340815

Bacterial growth kinetics in ACD-A apheresis platelets: comparison of plasma and PAS III storage.

PubMed

Dumont, Larry J; Wood, Tammara A; Housman, Molly; Herschel, Louise; Brantigan, Barbara; Heber, Cheryl; Houghton, Jaime

2011-05-01

Our objective was to determine the growth kinetics of bacteria in leukoreduced apheresis platelets (LR-AP) in a platelet (PLT) additive solution (PAS; InterSol, Fenwal, Inc.) compared to LR-AP stored in plasma. Hyperconcentrated, double-dose LR-AP were collected from healthy donors with a separator (AMICUS, Fenwal, Inc.). LR-AP were evenly divided, InterSol was added to half (65% InterSol:35% plasma [PAS]), and PLTs in autologous plasma were used for a paired control (PL). Bacteria were inoculated into each LR-AP PAS/PL pair (0.5-1.6 colony-forming units [CFUs]/mL), and bacterial growth was followed for up to 7 days. Time to the end of the lag phase, doubling times, maximum concentration (conc-max), and time to maximum concentration (time-max) were estimated. Streptococcus viridans did not grow to detectable levels in either PAS or PL units. The other bacteria had no significant overall difference in the conc-max (p = 0.47) or time-max (p = 0.7) between PL and PAS LR-AP; PL had a 0.14 hours faster doubling rate (p = 0.023); and PAS had a 4.7 hours shorter lag time (p = 0.016). We observed that five index organisms will grow in LR-AP stored in a 35%:65% ratio of plasma to InterSol where initial bacterial concentrations are 0.5 to 1.6 CFUs/mL. The more rapid initiation of log-phase growth for bacteria within a PAS storage environment resulted in a bacterial concentration up to 4 logs higher in the PAS units compared to the plasma units at 24 hours, but with no difference in the conc-max. This may present an early bacterial detection advantage for PAS-stored PLTs. © 2010 American Association of Blood Banks.

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

Cell shape can mediate the spatial organization of the bacterial cytoskeleton

NASA Astrophysics Data System (ADS)

Wang, Siyuan; Wingreen, Ned

2013-03-01

The bacterial cytoskeleton guides the synthesis of cell wall and thus regulates cell shape. Since spatial patterning of the bacterial cytoskeleton is critical to the proper control of cell shape, it is important to ask how the cytoskeleton spatially self-organizes in the first place. In this work, we develop a quantitative model to account for the various spatial patterns adopted by bacterial cytoskeletal proteins, especially the orientation and length of cytoskeletal filaments such as FtsZ and MreB in rod-shaped cells. We show that the combined mechanical energy of membrane bending, membrane pinning, and filament bending of a membrane-attached cytoskeletal filament can be sufficient to prescribe orientation, e.g. circumferential for FtsZ or helical for MreB, with the accuracy of orientation increasing with the length of the cytoskeletal filament. Moreover, the mechanical energy can compete with the chemical energy of cytoskeletal polymerization to regulate filament length. Notably, we predict a conformational transition with increasing polymer length from smoothly curved to end-bent polymers. Finally, the mechanical energy also results in a mutual attraction among polymers on the same membrane, which could facilitate tight polymer spacing or bundling. The predictions of the model can be verified through genetic, microscopic, and microfluidic approaches.

Bacterial growth and substrate degradation by BTX-oxidizing culture in response to salt stress.

PubMed

Lee, Chi-Yuan; Lin, Ching-Hsing

2006-01-01

Interactions between microbial growth and substrate degradation are important in determining the performance of trickle-bed bioreactors (TBB), especially when salt is added to reduce biomass formation in order to alleviate media clogging. This study was aimed at quantifying salinity effects on bacterial growth and substrate degradation, and at acquiring kinetic information in order to improve the design and operation of TBB. Experiment works began by cultivating a mixed culture in a chemostat reactor receiving artificial influent containing a mixture of benzene, toluene, and xylene (BTX), followed by using the enrichment culture to degrade the individual BTX substrates under a particular salinity, which ranged 0-50 g l(-1) in batch mode. Then, the measured concentrations of biomass and residual substrate versus time were analyzed with the microbial kinetics; moreover, the obtained microbial kinetic constants under various salinities were modeled using noncompetitive inhibition kinetics. For the three substrates the observed bacterial yields appeared to be decreased from 0.51-0.74 to 0.20-0.22 mg mg(-1) and the maximum specific rate of substrate utilization, q, declined from 0.25-0.42 to 0.07-0.11 h(-1), as the salinity increased from 0 to 50 NaCl g l(-1). The NaCl acted as noncompetitive inhibitor, where the modeling inhibitions of the coefficients, K ( T(S)), were 22.7-29.7 g l(-1) for substrate degradation and K ( T(mu)), 13.0-19.0 g l(-1), for biomass formation. The calculated ratios for the bacterial maintenance rate, m (S), to q, further indicated that the percentage energy spent on maintenance increased from 19-24 to 86-91% as salinity level increased from 0 to 50 g l(-1). These results revealed that the bacterial growth was more inhibited than substrate degradation by the BTX oxidizers under the tested salinity levels. The findings from this study demonstrate the potential of applying NaCl salt to control excessive biomass formation in biotrickling filters.

The Population Biology of Bacterial Plasmids: A PRIORI Conditions for the Existence of Conjugationally Transmitted Factors

PubMed Central

Stewart, Frank M.; Levin, Bruce R.

1977-01-01

A mathematical model for the population dynamics of conjugationally transmitted plasmids in bacterial populations is presented and its properties analyzed. Consideration is given to nonbacteriocinogenic factors that are incapable of incorporation into the chromosome of their host cells, and to bacterial populations maintained in either continuous (chemostat) or discrete (serial transfer) culture. The conditions for the establishment and maintenance of these infectious extrachromosomal elements and equilibrium frequencies of cells carrying them are presented for different values of the biological parameters: population growth functions, conjugational transfer and segregation rate constants. With these parameters in a biologically realistic range, the theory predicts a broad set of physical conditions, resource concentrations and dilution rates, where conjugationally transmitted plasmids can become established and where cells carrying them will maintain high frequencies in bacterial populations. This can occur even when plasmid-bearing cells are much less fit (i.e., have substantially lower growth rates) than cells free of these factors. The implications of these results and the reality and limitations of the model are discussed and the values of its parameters in natural populations speculated upon. PMID:17248761

The role of magnetic iron oxide nanoparticles in the bacterially induced calcium carbonate precipitation.

PubMed

Seifan, Mostafa; Ebrahiminezhad, Alireza; Ghasemi, Younes; Samani, Ali Khajeh; Berenjian, Aydin

2018-04-01

Recently, magnetic iron oxide nanoparticles (IONs) have been used to control and modify the characteristics of concrete and mortar. Concrete is one of the most used materials in the world; however, it is susceptible to cracking. Over recent years, a sustainable biotechnological approach has emerged as an alternative approach to conventional techniques to heal the concrete cracks by the incorporation of bacterial cells and nutrients into the concrete matrix. Once cracking occurs, CaCO 3 is induced and the crack is healed. Considering the positive effects of IONs on the concrete properties, the effect of these nanoparticles on bacterial growth and CaCO 3 biosynthesis needs to be evaluated for their possible application in bio self-healing concrete. In the present work, IONs were successfully synthesized and characterized using various techniques. The presence of IONs showed a significant effect on both bacterial growth and CaCO 3 precipitation. The highest bacterial growth was observed in the presence of 150 μg/mL IONs. The highest concentration of induced CaCO 3 (34.54 g/L) was achieved when the bacterial cells were immobilized with 300 μg/mL of IONs. This study provides new data and supports the possibility of using IONs as a new tool in designing the next generation of bio self-healing concrete.

Water reservoir maintained by cell growth fuels the spreading of a bacterial swarm

PubMed Central

Wu, Yilin; Berg, Howard C.

2012-01-01

Flagellated bacteria can swim across moist surfaces within a thin layer of fluid, a means for surface colonization known as swarming. This fluid spreads with the swarm, but how it does so is unclear. We used micron-sized air bubbles to study the motion of this fluid within swarms of Escherichia coli. The bubbles moved diffusively, with drift. Bubbles starting at the swarm edge drifted inward for the first 5 s and then moved outward. Bubbles starting 30 μm from the swarm edge moved inward for the first 20 s, wandered around in place for the next 40 s, and then moved outward. Bubbles starting at 200 or 300 μm from the edge moved outward or wandered around in place, respectively. So the general trend was inward near the outer edge of the swarm and outward farther inside, with flows converging on a region about 100 μm from the swarm edge. We measured cellular metabolic activities with cells expressing a short-lived GFP and cell densities with cells labeled with a membrane fluorescent dye. The fluorescence plots were similar, with peaks about 80 μm from the swarm edge and slopes that mimicked the particle drift rates. These plots suggest that net fluid flow is driven by cell growth. Fluid depth is largest in the multilayered region between approximately 30 and 200 μm from the swarm edge, where fluid agitation is more vigorous. This water reservoir travels with the swarm, fueling its spreading. Intercellular communication is not required; cells need only grow. PMID:22371567

Dynamic metabolic exchange governs a marine algal-bacterial interaction

PubMed Central

Segev, Einat; Wyche, Thomas P; Kim, Ki Hyun; Petersen, Jörn; Ellebrandt, Claire; Vlamakis, Hera; Barteneva, Natasha; Paulson, Joseph N; Chai, Liraz; Clardy, Jon; Kolter, Roberto

2016-01-01

Emiliania huxleyi is a model coccolithophore micro-alga that generates vast blooms in the ocean. Bacteria are not considered among the major factors influencing coccolithophore physiology. Here we show through a laboratory model system that the bacterium Phaeobacter inhibens, a well-studied member of the Roseobacter group, intimately interacts with E. huxleyi. While attached to the algal cell, bacteria initially promote algal growth but ultimately kill their algal host. Both algal growth enhancement and algal death are driven by the bacterially-produced phytohormone indole-3-acetic acid. Bacterial production of indole-3-acetic acid and attachment to algae are significantly increased by tryptophan, which is exuded from the algal cell. Algal death triggered by bacteria involves activation of pathways unique to oxidative stress response and programmed cell death. Our observations suggest that bacteria greatly influence the physiology and metabolism of E. huxleyi. Coccolithophore-bacteria interactions should be further studied in the environment to determine whether they impact micro-algal population dynamics on a global scale. DOI: http://dx.doi.org/10.7554/eLife.17473.001 PMID:27855786

The linkage between nutrient supply, intracellular enzyme abundances and bacterial growth: New evidences from the central carbon metabolism of Corynebacterium glutamicum.

PubMed

Noack, Stephan; Voges, Raphael; Gätgens, Jochem; Wiechert, Wolfgang

2017-09-20

Corynebacterium glutamicum serves as important production host for small molecular compounds that are derived from precursor molecules of the central carbon metabolism. It is therefore a well-studied model organism of industrial biotechnology. However, a deeper understanding of the regulatory principles underlying the synthesis of central metabolic enzymes under different environmental conditions as well as its impact on cell growth is still missing. We studied enzyme abundances in C. glutamicum in response to growth on: (i) one limiting carbon source by sampling chemostat and fed-batch cultivations and (ii) changing carbon sources provided in excess by sampling batch cultivations. The targeted quantification of 20 central metabolic enzymes by isotope dilution mass spectrometry revealed that cells maintain stable enzyme concentrations when grown on d-glucose as single carbon and energy source and, most importantly, independent of its availability. By contrast, switching from d-glucose to d-fructose, d-mannose, d-arabitol, acetate, l-lactate or l-glutamate results in highly specific enzyme regulation patterns that can partly be explained by the activity of known transcriptional regulators. Based on these experimental results we propose a simple framework for modeling cell population growth as a nested function of nutrient supply and intracellular enzyme abundances. In summary, our study extends the basis for the formulation of predictive mechanistic models of bacterial growth, applicable in industrial bioprocess development. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater

USGS Publications Warehouse

Becker, M.W.; Collins, S.A.; Metge, D.W.; Harvey, R.W.; Shapiro, A.M.

2004-01-01

The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates. ?? 2003 Elsevier B.V. All rights reserved.

Polarized Cell Division of Chlamydia trachomatis

PubMed Central

Abdelrahman, Yasser; Ouellette, Scot P.; Belland, Robert J.; Cox, John V.

2016-01-01

Bacterial cell division predominantly occurs by a highly conserved process, termed binary fission, that requires the bacterial homologue of tubulin, FtsZ. Other mechanisms of bacterial cell division that are independent of FtsZ are rare. Although the obligate intracellular human pathogen Chlamydia trachomatis, the leading bacterial cause of sexually transmitted infections and trachoma, lacks FtsZ, it has been assumed to divide by binary fission. We show here that Chlamydia divides by a polarized cell division process similar to the budding process of a subset of the Planctomycetes that also lack FtsZ. Prior to cell division, the major outer-membrane protein of Chlamydia is restricted to one pole of the cell, and the nascent daughter cell emerges from this pole by an asymmetric expansion of the membrane. Components of the chlamydial cell division machinery accumulate at the site of polar growth prior to the initiation of asymmetric membrane expansion and inhibitors that disrupt the polarity of C. trachomatis prevent cell division. The polarized cell division of C. trachomatis is the result of the unipolar growth and FtsZ-independent fission of this coccoid organism. This mechanism of cell division has not been documented in other human bacterial pathogens suggesting the potential for developing Chlamydia-specific therapeutic treatments. PMID:27505160

Bacterial cell-wall recycling

PubMed Central

Johnson, Jarrod W.; Fisher, Jed F.; Mobashery, Shahriar

2012-01-01

Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many—and quite possibly all—bacteria, the peptidoglycan fragments are recovered and recycled. While cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall–targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall recycling inhibitors. PMID:23163477

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

PubMed

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

Stimulation and inhibition of bacterial growth by caffeine dependent on chloramphenicol and a phenolic uncoupler--a ternary toxicity study using microfluid segment technique.

PubMed

Cao, Jialan; Kürsten, Dana; Schneider, Steffen; Köhler, J Michael

2012-10-01

A droplet-based microfluidic technique for the fast generation of three dimensional concentration spaces within nanoliter segments was introduced. The technique was applied for the evaluation of the effect of two selected antibiotic substances on the toxicity and activation of bacterial growth by caffeine. Therefore a three-dimensional concentration space was completely addressed by generating large sequences with about 1150 well separated microdroplets containing 216 different combinations of concentrations. To evaluate the toxicity of the ternary mixtures a time-resolved miniaturized optical double endpoint detection unit using a microflow-through fluorimeter and a two channel microflow-through photometer was used for the simultaneous analysis of changes on the endogenous cellular fluorescence signal and on the cell density of E. coli cultivated inside 500 nL microfluid segments. Both endpoints supplied similar results for the dose related cellular response. Strong non-linear combination effects, concentration dependent stimulation and the formation of activity summits on bolographic maps were determined. The results reflect a complex response of growing bacterial cultures in dependence on the combined effectors. A strong caffeine induced enhancement of bacterial growth was found at sublethal chloramphenicol and sublethal 2,4-dinitrophenol concentrations. The reliability of the method was proved by a high redundancy of fluidic experiments. The results indicate the importance of multi-parameter investigations for toxicological studies and prove the potential of the microsegmented flow technique for such requirements.

Impact of antiseptics on Chlamydia trachomatis growth.

PubMed

Párducz, L; Eszik, I; Wagner, G; Burián, K; Endrész, V; Virok, D P

2016-10-01

Bacterial vaginosis is a frequent dysbiosis, where the normal lactobacillus-dominated flora is replaced by an anaerob/aerob polymicrobial flora. Bacterial vaginosis increases the risk of acquiring sexually transmitted infections (STI) including the most frequent Chlamydia trachomatis infections. Intravaginal antiseptics are part of the bacterial vaginosis treatment, and ideally they should also inhibit the bacterial vaginosis-related STI. Therefore, we tested the antichlamydial activity of four antiseptics: iodine aqueous solution, povidone-iodine, chlorhexidine and borax. First, we measured the impact of antiseptics on the viability of the HeLa cervical epithelial cells, and calculated the maximum nontoxic concentrations. Next, we infected the cells with C. trachomatis preincubated for 1 h with the particular antiseptic. The chlamydial growth was measured by direct quantitative PCR (qPCR) of the infected cells. The minimal inhibitory concentrations (MIC) of chlorhexidine and povidone-iodine were 3·91 and 97 μg ml(-1) respectively; however, the MIC of chlorhexidine was close to its maximum nontoxic concentration. The iodine aqueous solution and the borax showed no antichlamydial activity. Our in vitro studies showed that chlorhexidine and particularly povidone-iodine are potentially able to limit the bacterial vaginosis-related C. trachomatis infection. We measured the antichlamydial effects of various antiseptics. These antiseptics are being used for the treatment of bacterial vaginosis, but their effect on the bacterial vaginosis-related sexually transmitted infections, particularly the most frequent Chlamydia trachomatis (C. trachomatis) infections has not been investigated. We showed that povidone-iodine (Betadine) inhibited the chlamydial growth in concentrations that was not toxic to the epithelial cells. We concluded that due to its additional antichlamydial effect, povidone-iodine could be a preferable antiseptic in bacterial vaginosis treatment. �

An Ancient Bacterial Signaling Pathway Regulates Chloroplast Function to Influence Growth and Development in Arabidopsis.

PubMed

Sugliani, Matteo; Abdelkefi, Hela; Ke, Hang; Bouveret, Emmanuelle; Robaglia, Christophe; Caffarri, Stefano; Field, Ben

2016-03-01

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. © 2016 American Society of Plant Biologists. All rights reserved.

Changes in urine composition after trauma facilitate bacterial growth

PubMed Central

2012-01-01

Background Critically ill patients including trauma patients are at high risk of urinary tract infection (UTI). The composition of urine in trauma patients may be modified due to inflammation, systemic stress, rhabdomyolysis, life support treatment and/or urinary catheter insertion. Methods Prospective, single-centre, observational study conducted in patients with severe trauma and without a history of UTIs or recent antibiotic treatment. The 24-hour urine samples were collected on the first and the fifth days and the growth of Escherichia coli in urine from patients and healthy volunteers was compared. Biochemical and hormonal modifications in urine that could potentially influence bacterial growth were explored. Results Growth of E. coli in urine from trauma patients was significantly higher on days 1 and 5 than in urine of healthy volunteers. Several significant modifications of urine composition could explain these findings. On days 1 and 5, trauma patients had an increase in glycosuria, in urine iron concentration, and in the concentrations of several amino acids compared to healthy volunteers. On day 1, the urinary osmotic pressure was significantly lower than for healthy volunteers. Conclusion We showed that urine of trauma patients facilitated growth of E. coli when compared to urine from healthy volunteers. This effect was present in the first 24 hours and until at least the fifth day after trauma. This phenomenon may be involved in the pathophysiology of UTIs in trauma patients. Further studies are required to define the exact causes of such modifications. PMID:23194649

[Effects of bamboo charcoal on the growth of Trifolium repens and soil bacterial community structure].

PubMed

Li, Song-Hao; He, Dong-Hua; Shen, Qiu-Lan; Xu, Qiu-Fang

2014-08-01

The effects of addition rates (0, 3% and 9%) and particle sizes (0.05, 0.05-1.0 and 1.0-2.0 mm) of bamboo charcoal on the growth of Trifolium repens and soil microbial community structure were investigated. The results showed that bamboo charcoal addition greatly promoted the early growth of T. repens, with the 9% charcoal addition rate being slightly better than the 3% charcoal addition rate. The effects of different particle sizes of bamboo charcoal on the growth of T. repens were not different significantly. Growth promotion declined with time during 120 days after sowing, and disappeared completely after 5 months. DGGE analysis of the bacterial 16S rDNA V3 fragment indicated that bamboo charcoal altered the soil bacterial community structure. The amount and Shannon diversity index of bacteria in the bamboo charcoal addition treatments increased compared with CK. The quantitative analysis showed that the amount of bacteria in the treatment with bamboo charcoal of fine particle (D < 0.05 mm) at the 9% addition rate was significantly higher than in the other treatments. The fine bamboo charcoal had a great effect on soil bacteria amount compared with the charcoal of other sizes at the same addition rate.

Evaluation of the sensitivity of bacterial and yeast cells to cold atmospheric plasma jet treatments.

PubMed

Sharkey, Michael A; Chebbi, Ahmed; McDonnell, Kevin A; Staunton, Claire; Dowling, Denis P

2015-06-07

The focus of this research was first to determine the influence of the atmospheric plasma drive frequency on the generation of atomic oxygen species and its correlation with the reduction of bacterial load after treatment in vitro. The treatments were carried out using a helium-plasma jet source called PlasmaStream™. The susceptibility of multiple microbial cell lines was investigated in order to compare the response of gram-positive and gram-negative bacteria, as well as a yeast cell line to the atmospheric plasma treatment. It was observed for the source evaluated that at a frequency of 160 kHz, increased levels of oxygen-laden active species (i.e., OH, NO) were generated. At this frequency, the maximum level of bacterial inactivation in vitro was also achieved. Ex vivo studies (using freshly excised porcine skin as a human analog) were also carried out to verify the antibacterial effect of the plasma jet treatment at this optimal operational frequency and to investigate the effect of treatment duration on the reduction of bacterial load. The plasma jet treatment was found to yield a 4 log reduction in bacterial load after 6 min of treatment, with no observable adverse effects on the treatment surface. The gram-negative bacterial cell lines were found to be far more susceptible to the atmospheric plasma treatments than the gram-positive bacteria. Flow cytometric analysis of plasma treated bacterial cells (Escherichia coli) was conducted in order to attain a fundamental understanding of the mode of action of the treatment on bacteria at a cellular level. This study showed that after treatment with the plasma jet, E. coli cells progressed through the following steps of cell death; the inactivation of transport systems, followed by depolarization of the cytoplasmic membrane, and finally permeabilization of the cell wall.

Ultrastructure of Bacterial Cells Infected with Bacteriophage PM2, a Lipid-containing Bacterial Virus

PubMed Central

Cota-Robles, Eugene; Espejo, Romilio Torres; Haywood, Patricia Williams

1968-01-01

The cytological pattern of infection of a host pseudomonad with PM2, a lipid-containing bacterial virus, was investigated by electron microscopy. Normal and infected cells frequently contain a myelin figure, which is found in the nucleoid region or at the periphery of the cell. The most striking finding in this investigation was that completed virions are found in the cell adjacent to or in association with the cytoplasmic membrane. This localization is precise; virions are not found elsewhere in infected cells. The completed virions occasionally appear to be attached to the cytoplasmic membrane. The virus contains a darkly staining core surrounded by a tripartite envelope of a thickness of approximately 70 A, which is identical to the thickness of the cytoplasmic membrane. Lysing cells appear to undergo extensive damage of the cytoplasmic membrane prior to rupture of the L layer of the cell wall. Images PMID:5742028

Impact of capsaicin, an active component of chili pepper, on pathogenic chlamydial growth (Chlamydia trachomatis and Chlamydia pneumoniae) in immortal human epithelial HeLa cells.

PubMed

Yamakawa, Kazuya; Matsuo, Junji; Okubo, Torahiko; Nakamura, Shinji; Yamaguchi, Hiroyuki

2018-02-01

Chlamydia trachomatis is the leading cause of sexually transmitted infections worldwide. Capsaicin, a component of chili pepper, which can stimulate actin remodeling via capsaicin receptor TRPV1 (transient receptor potential vanilloid 1) and anti-inflammatory effects via PPARγ (peroxisome proliferator-activated receptor-γ) and LXRα (liver X receptor α), is a potential candidate to control chlamydial growth in host cells. We examined whether capsaicin could inhibit C. trachomatis growth in immortal human epithelial HeLa cells. Inclusion forming unit and quantitative PCR assays showed that capsaicin significantly inhibited bacterial growth in cells in a dose-dependent manner, even in the presence of cycloheximide, a eukaryotic protein synthesis inhibitor. Confocal microscopic and transmission electron microscopic observations revealed an obvious decrease in bacterial numbers to inclusions bodies formed in the cells. Although capsaicin can stimulate the apoptosis of cells, no increase in cleaved PARP (poly (ADP-ribose) polymerase), an apoptotic indicator, was observed at a working concentration. All of the drugs tested (capsazepine, a TRPV1 antagonist; 5CPPSS-50, an LXRα inhibitor; and T0070907, a PPARγ inhibitor) had no effect on chlamydial inhibition in the presence of capsaicin. In addition, we also confirmed that capsaicin inhibited Chlamydia pneumoniae growth, indicating a phenomena not specific to C. trachomatis. Thus, we conclude that capsaicin can block chlamydial growth without the requirement of host cell protein synthesis, but by another, yet to be defined, mechanism. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

A Model to Explain Plant Growth Promotion Traits: A Multivariate Analysis of 2,211 Bacterial Isolates