Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

McDonald, H M; Brocklehurst, P; Gordon, A

2007-01-24

). Clindamycin did not reduce the risk of PTB before 37 weeks (Peto OR 0.80, 95% CI 0.60 to 1.05; six trials, 2406 women). Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. This review provides little evidence that screening and treating all pregnant women with asymptomatic bacterial vaginosis will prevent PTB and its consequences. However, there is some suggestion that treatment before 20 weeks' gestation may reduce the risk of PTB. This needs to be further verified by future trials.

Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

McDonald, H; Brocklehurst, P; Parsons, J

2005-01-25

0.75, two trials of 114 women). Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. However, this review provides little evidence that screening and treating all pregnant women with asymptomatic bacterial vaginosis will prevent preterm birth and its consequences. For women with a previous preterm birth, there is some suggestion that treatment of bacterial vaginosis may reduce the risk of preterm prelabour rupture of membranes and low birthweight.

In situ probing the interior of single bacterial cells at nanometer scale

NASA Astrophysics Data System (ADS)

Liu, Boyin; Hemayet Uddin, Md; Ng, Tuck Wah; Paterson, David L.; Velkov, Tony; Li, Jian; Fu, Jing

2014-10-01

We report a novel approach to probe the interior of single bacterial cells at nanometre resolution by combining focused ion beam (FIB) and atomic force microscopy (AFM). After removing layers of pre-defined thickness in the order of 100 nm on the target bacterial cells with FIB milling, AFM of different modes can be employed to probe the cellular interior under both ambient and aqueous environments. Our initial investigations focused on the surface topology induced by FIB milling and the hydration effects on AFM measurements, followed by assessment of the sample protocols. With fine-tuning of the process parameters, in situ AFM probing beneath the bacterial cell wall was achieved for the first time. We further demonstrate the proposed method by performing a spatial mapping of intracellular elasticity and chemistry of the multi-drug resistant strain Klebsiella pneumoniae cells prior to and after it was exposed to the ‘last-line’ antibiotic polymyxin B. Our results revealed increased stiffness occurring in both surface and interior regions of the treated cells, suggesting loss of integrity of the outer membrane from polymyxin treatments. In addition, the hydrophobicity measurement using a functionalized AFM tip was able to highlight the evident hydrophobic portion of the cell such as the regions containing cell membrane. We expect that the proposed FIB-AFM platform will help in gaining deeper insights of bacteria-drug interactions to develop potential strategies for combating multi-drug resistance.

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.

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.

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.

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.

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.

Antibiotics for treating bacterial vaginosis in pregnancy

PubMed Central

McDonald, Helen Margaret; Brocklehurst, Peter; Gordon, Adrienne

2014-01-01

women). In women with abnormal vaginal flora (intermediate flora or bacterial vaginosis) treatment may reduce the risk of PTB before 37 weeks (Peto OR 0.51, 95% CI 0.32 to 0.81; two trials, 894 women). Clindamycin did not reduce the risk of PTB before 37 weeks (Peto OR 0.80, 95% CI 0.60 to 1.05; six trials, 2406 women). Authors’ conclusions Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. This review provides little evidence that screening and treating all pregnant women with asymptomatic bacterial vaginosis will prevent PTB and its consequences. However, there is some suggestion that treatment before 20 weeks’ gestation may reduce the risk of PTB. This needs to be further verified by future trials. [Note: The eleven citations in the awaiting assessment section of the review may alter the conclusions of the review once assessed.] PMID:17253447

Oral metronidazole vs. Metrogel Vaginal for treating bacterial vaginosis. Cost-effectiveness evaluation.

PubMed

Ransom, S B; McComish, J F; Greenberg, R; Tolford, D A

1999-04-01

To compare the cost-effectiveness of metronidazole versus Metrogel Vaginal in the treatment of bacterial vaginosis. Sixty consecutive patients with a clinical diagnosis of bacterial vaginosis were randomly assigned prospectively into either the metronidazole, 500 mg (twice daily for seven days by mouth) or Metrogel Vaginal (one applicator twice daily for five days) treatment group. The study patients were aged 18-30 years, without other medical problems. The patients proceeded with outpatient therapy and returned 7-10 days after the completion of treatment for reevaluation. During the study, patients refrained from sexual relations, avoided alcohol and drugs, and avoided all medication. The physician evaluated the patients for bacterial vaginosis through standard wet preparation, whiff test and pH testing prior to and after treatment. The patients were randomized by a nurse and were blinded for study purposes to the evaluating physician. Successful treatment outcomes for bacterial vaginosis occurred in 27 and 28 patients for Metrogel Vaginal and metronidazole, respectively, out of the original 30 patients in each study group. All patients introduced into the study completed the study without difficulty. No significant complications were found in either treatment group. Three patients treated with metronidazole experienced nausea during the treatment interval. The entire cost of treatment was $19.71 and $1.51 for Metrogel Vaginal and metronidazole, respectively. The most cost-effective treatment for bacterial vaginosis was generic metronidazole. While the use of the more expensive Metrogel Vaginal may be reasonable for patients experiencing side effects of oral metronidazole, most patients should be treated with the less expensive generic metronidazole.

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

Using Natural Products to Treat Resistant and Persistent Bacterial Infections

NASA Astrophysics Data System (ADS)

Deering, Robert W.

Antimicrobial resistance is a growing threat to human health both worldwide and in the United States. Most concerning is the emergence of multi-drug resistant (MDR) bacterial pathogens, especially the 'ESKAPE' pathogens for which treatment options are dwindling. To complicate the problem, approvals of antibiotic drugs are extremely low and many research and development efforts in the pharmaceutical industry have ceased, leaving little certainty that critical new antibiotics are nearing the clinic. New antibiotics are needed to continue treating these evolving infections. In addition to antibiotics, approaches that aim to inhibit or prevent antimicrobial resistance could be useful. Also, studies that improve our understanding of bacterial pathophysiology could lead to new therapies for infectious disease. Natural products, especially those from the microbial world, have been invaluable as resources for new antibacterial compounds and as insights into bacterial physiology. The goal of this dissertation is to find new ways to treat resistant bacterial infections and learn more about the pathophysiology of these bacteria. Investigations of natural products to find molecules able to be used as new antibiotics or to modulate resistance and other parts of bacterial physiology are crucial aspects of the included studies. The first included study, which is reported in chapter two, details a chemical investigation of a marine Pseudoalteromonas sp. Purification efforts of the microbial metabolites were guided by testing against a resistance nodulation of cell division model of efflux pumps expressed in E. coli. These pumps play an important role in the resistance of MDR Gram negative pathogens such as Pseudomonas aeruginosa and Enterobacteriaceae. Through this process, 3,4-dibromopyrrole-2,5-dione was identified as a potent inhibitor of the RND efflux pumps and showed synergistic effects against the E. coli strain with common antibiotics including fluoroquinolones, beta

Adsorption and mineralization of REE-lanthanum onto bacterial cell surface.

PubMed

Cheng, Yangjian; Zhang, Li; Bian, Xiaojing; Zuo, Hongyang; Dong, Hailiang

2017-07-11

A large number of rare earth element mining and application resulted in a series of problems of soil and water pollution. Environmental remediation of these REE-contaminated sites has become a top priority. This paper explores the use of Bacillus licheniformis to adsorb lanthanum and subsequent mineralization process in contaminated water. The maximum adsorption capacity of lanthanum on bacteria was 113.98 mg/g (dry weight) biomass. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated that adsorbed lanthanum on bacterial cell surface occurred in an amorphous form at the initial stage. Scanning electron microscopy with X-ray energy-dispersive spectroscopy (SEM/EDS) results indicated that lanthanum adsorption was correlated with phosphate. The amorphous material was converted into scorpion-like monazite (LaPO 4 nanoparticles) in a month. The above results provide a method of using bacterial surface as adsorption and nucleation sites to treat REE-contaminated water.

Growth mechanics of bacterial cell wall and morphology of bacteria

NASA Astrophysics Data System (ADS)

Jiang, Hongyuan; Sun, Sean

2010-03-01

The peptidoglycan cell wall of bacteria is responsible for maintaining the cell shape and integrity. During the bacterial life cycle, the growth of the cell wall is affected by mechanical stress and osmotic pressure internal to the cell. We develop a theory to describe cell shape changes under the influence of mechanical forces. We find that the theory predicts a steady state size and shape for bacterial cells ranging from cocci to spirillum. Moreover, the theory suggest a mechanism by which bacterial cytoskeletal proteins such as MreB and crescentin can maintain the shape of the cell. The theory can also explain the several recent experiments on growing bacteria in micro-environments.

Characterization of the COD removal, electricity generation, and bacterial communities in microbial fuel cells treating molasses wastewater.

PubMed

Lee, Yun-Yeong; Kim, Tae G; Cho, Kyung-Suk

2016-11-09

The chemical oxygen demand (COD) removal, electricity generation, and microbial communities were compared in 3 types of microbial fuel cells (MFCs) treating molasses wastewater. Single-chamber MFCs without and with a proton exchange membrane (PEM), and double-chamber MFC were constructed. A total of 10,000 mg L(-1) COD of molasses wastewater was continuously fed. The COD removal, electricity generation, and microbial communities in the two types of single-chamber MFCs were similar, indicating that the PEM did not enhance the reactor performance. The COD removal in the single-chamber MFCs (89-90%) was higher than that in the double-chamber MFC (50%). However, electricity generation in the double-chamber MFC was higher than that in the single-chamber MFCs. The current density (80 mA m(-2)) and power density (17 mW m(-2)) in the double-chamber MFC were 1.4- and 2.2-times higher than those in the single-chamber MFCs, respectively. The bacterial community structures in single- and double-chamber MFCs were also distinguishable. The amount of Proteobacteria in the double-chamber MFC was 2-3 times higher than those in the single-chamber MFCs. For the archaeal community, Methanothrix (96.4%) was remarkably dominant in the single-chamber MFCs, but Methanobacterium (35.1%), Methanosarcina (28.3%), and Methanothrix (16.2%) were abundant in the double-chamber MFC.

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

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.

Establishment and Early Succession of Bacterial Communities in Monochloramine-treated Drinking Water Biofilms

EPA Science Inventory

The use of monochloramine as drinking water disinfectant is increasing because it forms lower levels of traditional disinfection by-products compared to free-chlorine. However, little is known about the bacterial succession within biofilms in monochloramine-treated systems. The d...

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.

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

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.

Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

Brocklehurst, Peter; Gordon, Adrienne; Heatley, Emer; Milan, Stephen J

2013-01-31

(RR 1.66; 95% CI 1.02 to 2.68; four trials, 2323 women, fixed-effect, I² = 0%).In this updated review, treatment before 20 weeks' gestation did not reduce the risk of PTB less than 37 weeks (average RR 0.85; 95% CI 0.62 to 1.17; five trials, 4088 women; random-effects, T² = 0.06, I² = 49%).In women with a previous PTB, treatment did not affect the risk of subsequent PTB (average RR 0.78; 95% CI 0.42 to 1.48; three trials, 421 women; random-effects, T² = 0.19, I² = 72%).In women with abnormal vaginal flora (intermediate flora or bacterial vaginosis), treatment may reduce the risk of PTB before 37 weeks (RR 0.53; 95% CI 0.34 to 0.84; two trials, 894 women).One small trial of 156 women compared metronidazole and clindamycin, both oral and vaginal, with no significant differences seen for any of the pre-specified primary outcomes. Statistically significant differences were seen for the outcomes of prolongation of gestational age (days) (mean difference (MD) 1.00; 95% CI 0.26 to 1.74) and birthweight (grams) (MD 75.18; 95% CI 25.37 to 124.99) however these represent relatively small differences in the clinical setting.Oral antibiotics versus vaginal antibiotics did not reduce the risk of PTB (RR 1.09; 95% CI 0.78 to 1.52; two trials, 264 women). Oral antibiotics had some advantage over vaginal antibiotics (whether metronidazole or clindamycin) with respect to admission to neonatal unit (RR 0.63; 95% CI 0.42 to 0.92, one trial, 156 women), prolongation of gestational age (days) (MD 9.00; 95% CI 8.20 to 9.80; one trial, 156 women) and birthweight (grams) (MD 342.13; 95% CI 293.04 to 391.22; one trial, 156 women).Different frequency of dosing of antibiotics was assessed in one small trial and showed no significant difference for any outcome assessed. Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. The overall risk of PTB was not significantly reduced. This review provides little evidence that screening and treating all pregnant women with bacterial

Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach

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

Economou, Nicoleta J.; Zentner, Isaac J.; Lazo, Edwin

2013-04-01

Using a carrier-protein strategy, the structure of teicoplanin bound to its bacterial cell-wall target has been determined. The structure reveals the molecular determinants of target recognition, flexibility in the antibiotic backbone and intrinsic radiation sensitivity of teicoplanin. Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a d-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein–peptide–antibiotic complex.more » The 2.05 Å resolution MBP–peptide–teicoplanin structure shows that teicoplanin recognizes its ligand through a combination of five hydrogen bonds and multiple van der Waals interactions. Comparison of this teicoplanin structure with that of unliganded teicoplanin reveals a flexibility in the antibiotic peptide backbone that has significant implications for ligand recognition. Diffraction experiments revealed an X-ray-induced dechlorination of the sixth amino acid of the antibiotic; it is shown that teicoplanin is significantly more radiation-sensitive than other similar antibiotics and that ligand binding increases radiosensitivity. Insights derived from this new teicoplanin structure may contribute to the development of next-generation antibacterials designed to overcome bacterial resistance.« less

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.

[Therapeutic regimens for treating bacterial vaginosis in pregnant women].

PubMed

Borisov, I; Dimitrova, V; Mazneĭkova, V; Shopova, E

1999-01-01

The study comprises 128 pregnant women examined at different gestational weeks. The diagnosis of bacterial vaginosis was made using: a) the complex clinical criteria--vaginal discharge, vaginal pH, amine test and "clue cells" b) Nugent scoring system c) Spiegel criteria. Two therapeutic regimens were compared--intravaginal 2% clindamycin creme (Dalacin V) 5 g three consecutive days and intravaginal metronidazole (Flagyl) 500 mg once daily for 5 consecutive days. Control examination was carried out 5-7 days after completion of therapy using the same protocol. 28 women from the first group and 31 women from the second group had the control examination. Bacterial vaginosis was eradicated in 93% of women using intravaginal clindamycin and in 87% of women using intravaginal metronidazole. Both regimes were more effective compared to treatment with oral ampicillin for 7 days, where the cure rate was 62%.

Inhaled phage therapy: a promising and challenging approach to treat bacterial respiratory infections.

PubMed

Bodier-Montagutelli, Elsa; Morello, Eric; L'Hostis, Guillaume; Guillon, Antoine; Dalloneau, Emilie; Respaud, Renaud; Pallaoro, Nikita; Blois, Hélène; Vecellio, Laurent; Gabard, Jérôme; Heuzé-Vourc'h, Nathalie

2017-08-01

Bacterial respiratory tract infections (RTIs) are increasingly difficult to treat due to evolving antibiotic resistance. In this context, bacteriophages (or phages) are part of the foreseen alternatives or combination therapies. Delivering phages through the airways seems more relevant to accumulate these natural antibacterial viruses in proximity to their bacterial host, within the infectious site. Areas covered: This review addresses the potential of phage therapy to treat RTIs and discusses preclinical and clinical results of phages administration in this context. Recent phage formulation and aerosolization attempts are also reviewed, raising technical challenges to achieve efficient pulmonary deposition via inhalation. Expert opinion: Overall, the inhalation of phages as antibacterial treatment seems both clinically relevant and technically feasible. Several crucial points still need to be investigated, such as phage product pharmacokinetics and immunogenicity. Furthermore, given phage-specific features, appropriate regulatory and manufacturing guidelines will need to be defined. Finally, randomized controlled clinical trials should be carried out to establish phage therapy's clinical positioning in the antimicrobial arsenal against RTIs.

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.

Bacterial community shift during the startup of a full-scale oxidation ditch treating sewage.

PubMed

Chen, Yajun; Ye, Lin; Zhao, Fuzheng; Xiao, Lin; Cheng, Shupei; Zhang, Xu-Xiang

2016-10-06

Oxidation ditch (OD) is one of the most widely used processes for treating municipal wastewater. However, the microbial communities in the OD systems have not been well characterized and little information about the shift of bacterial community during the startup process of the OD systems is available. In this study, we investigated the bacterial community changes during the startup period (over 100 days) of a full-scale OD. The results showed that the bacterial community dramatically changed during the startup period. Similar to the activated sludge samples in other studies, Proteobacteria (accounting for 26.3%~48.4%) was the most dominant bacterial phylum in the OD system but its relative abundance declined nearly 40% during the startup process. It was also found that Planctomycetes proliferated greatly (from 4.79% to 13.5%) and finally replaced Bacteroidetes as the second abundant phylum in the OD system. Specifically, some bacteria affiliated with Flavobacterium genus of exhibited remarkable decreasing trends, while bacterial species belonging to OD1 candidate division and Saprospiraceae family were found to increase during the startup process. Despite of the bacterial community shift, the organic matter, nitrogen and phosphorus in the effluent were always in low concentrations, suggesting the functional redundancy of the bacterial community. Moreover, by comparing with the bacterial community in other municipal wastewater treatment bioreactors, some potentially novel bacterial species were found to be present in the OD system. Collectively, this study improved our understandings of bacterial community structure and the microbial ecology during the startup of full-scale wastewater treatment bioreactor.

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

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

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...

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.

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.

Entrapped cells-based-anaerobic membrane bioreactor treating domestic wastewater: Performances, fouling, and bacterial community structure.

PubMed

Juntawang, Chaipon; Rongsayamanont, Chaiwat; Khan, Eakalak

2017-11-01

A laboratory scale study on treatment performances and fouling of entrapped cells-based-anaerobic membrane bioreactor (E-AnMBR) in comparison with suspended cells-based-bioreactor (S-AnMBR) treating domestic wastewater was conducted. The difference between E-AnMBR and S-AnMBR was the uses of cells entrapped in phosphorylated polyvinyl alcohol versus planktonic cells. Bulk organic removal efficiencies by the two AnMBRs were comparable. Lower concentrations of suspended biomass, bound extracellular polymeric substances and soluble microbial products in E-AnMBR resulted in less fouling compared to S-AnMBR. S-AnMBR provided 7 days of operation time versus 11 days for E-AnMBR before chemical cleaning was required. The less frequent chemical cleaning potentially leads to a longer membrane life-span for E-AnMBR compared to S-AnMBR. Phyla Proteobacteria, Chloroflexi, Bacteroidetes and Acidobacteria were dominant in cake sludge from both AnMBRs but their abundances were different between the two AnMBRs, suggesting influence of cell entrapment on the bacteria community. Copyright © 2017 Elsevier Ltd. All rights reserved.

Immunomodulators targeting MARCO expression improve resistance to postinfluenza bacterial pneumonia.

PubMed

Wu, Muzo; Gibbons, John G; DeLoid, Glen M; Bedugnis, Alice S; Thimmulappa, Rajesh K; Biswal, Shyam; Kobzik, Lester

2017-07-01

Downregulation of the alveolar macrophage (AM) receptor with collagenous structure (MARCO) leads to susceptibility to postinfluenza bacterial pneumonia, a major cause of morbidity and mortality. We sought to determine whether immunomodulation of MARCO could improve host defense and resistance to secondary bacterial pneumonia. RNAseq analysis identified a striking increase in MARCO expression between days 9 and 11 after influenza infection and indicated important roles for Akt and Nrf2 in MARCO recovery. In vitro, primary human AM-like monocyte-derived macrophages (AM-MDMs) and THP-1 macrophages were treated with IFNγ to model influenza effects. Activators of Nrf2 (sulforaphane) or Akt (SC79) caused increased MARCO expression and a MARCO-dependent improvement in phagocytosis in IFNγ-treated cells and improved survival in mice with postinfluenza pneumococcal pneumonia. Transcription factor analysis also indicated a role for transcription factor E-box (TFEB) in MARCO recovery. Overexpression of TFEB in THP-1 cells led to marked increases in MARCO. The ability of Akt activation to increase MARCO expression in IFNγ-treated AM-MDMs was abrogated in TFEB-knockdown cells, indicating Akt increases MARCO expression through TFEB. Increasing MARCO expression by targeting Nrf2 signaling or the Akt-TFEB-MARCO pathway are promising strategies to improve bacterial clearance and survival in postinfluenza bacterial pneumonia. Copyright © 2017 the American Physiological Society.

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.

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.

Atomic Force Microscope Investigations of Bacterial Biofilms Treated with Gas Discharge Plasmas

NASA Astrophysics Data System (ADS)

Vandervoort, Kurt; Zelaya, Anna; Brelles-Marino, Graciela

2012-02-01

We present investigations of bacterial biofilms before and after treatment with gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve biofilm communities, where bacteria grow embedded in an exopolysaccharide matrix, and cooperative interactions between cells make organisms less susceptible to standard inactivation methods. In this study, biofilms formed by the opportunistic bacterium Pseudomonas aeruginosa were imaged before and after plasma treatment using an atomic force microscope (AFM). Through AFM images and micromechanical measurements we observed bacterial morphological damage and reduced AFM tip-sample surface adhesion following plasma treatment.

Bacterial lysate increases the percentage of natural killer T cells in peripheral blood and alleviates asthma in children.

PubMed

Lu, Yanming; Li, Yaqin; Xu, Lingyun; Xia, Min; Cao, Lanfang

2015-01-01

To assess the efficacy of conventional treatment combined with bacterial lysate [OM-85 Broncho-Vaxom (BV)] in the prevention of asthma in children as well as its influence on the number of natural killer T (NKT) cells and their cytokine production. Sixty children diagnosed with asthma were divided into either a BV-treated group (with oral OM-85 BV) or a conventional inhaled corticosteroid (ICS) group. The numbers of NKT cells and CD4+ NKT cells were measured in the peripheral blood by flow cytometry. The levels of IFN-γ, IL-4, and IL-10 after the blood cells had been cultured with an NKT cell agonist were detected by ELISA. After therapy, asthma attacks were significantly decreased compared with before therapy in both groups. However, after therapy, respiratory tract infections were reduced compared with before therapy in the BV-treated group only. Additionally, the frequency of asthma attacks and use of antibiotics in the BV-treated group were lower than in the ICS group. With BV treatment, the numbers of peripheral blood NKT cells and CD4+ NKT cells were higher after therapy than before therapy. After therapy, the ratio of IFN-γ/IL-4 and IL-10 levels were increased in the BV-treated group, whereas IL-4 was reduced in the BV-treated group compared with the ICS group. BV combined with conventional asthma treatment can prevent recurrent respiratory tract infections and suppress the severity of asthma attacks, possibly by altering the rates and cytokines of NKT cells. © 2015 S. Karger AG, Basel

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

Micro Corona Ionizer as an Ozone Source for Bacterial Cell Lysis

NASA Astrophysics Data System (ADS)

Lee, Eun-Hee; Lim, Hyun Jeong; Chua, Beelee; Son, Ahjeong

2015-04-01

DNA extraction is a critical process of DNA assays including polymerase chain reaction (PCR), microarrays, molecular cloning, and DNA hybridization which has been well established and can be implemented by commercial kits. DNA extraction involves cell lysis, precipitation, and purification through the combination of physical and chemical processes. Cell lysis is essential to high DNA recovery yield which can be achieved via a variety of physical, chemical, and enzymatic methods. However, these methods were originally developed for bioassays that were labor intensive, time consuming, and vulnerable to contamination and inhibition. Here, we proposed to employ a micro corona ionizer as an ozone source to lyse bacterial cells. Ozone has been well known and used as a disinfectant which allows cell lysis and DNA extraction. Previously, we have shown that a micro corona ionizer is capable of generating a significant amount of ozone. In this study, we employed the micro corona ionizer for the bacterial cell lysis which consists of a 50 μm diameter cantilever wire as the discharge cathode and a 50 μm thick copper foil as anode. Applied voltages varied from 1900 to 2200 V with corresponding corona currents from 16 to 28 μA. The resultant ozone (concentration > 0.14 ppm) generated from the micro corona ionizer was bubbled into the sample via a miniature pump. We demonstrated the cell lysis of Pseudomonas putida as the target bacterium using the micro corona ionizer. At a flow rate of 38 ml/min and applied corona voltage of 2000 V, 98.5 ± 0.2% lysis (normalized to sonication result) was achieved after 10 min. In comparison, untreated and air-treated samples showed normalized % lysis of 11.9 ± 2.4 and 36.1 ± 1.7%, respectively. We also showed that the cell lysis efficiency could be significantly increased by increasing the flow rate and the applied corona voltage. By comparing the experimental results for continuous and pulsed treatment, we verified that the percentage of

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.

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

Concentration-Dependent Multiple Binding Sites on Saliva-Treated Hydroxyapatite for Streptococcus sanguis

PubMed Central

Gibbons, R. J.; Moreno, E. C.; Etherden, I.

1983-01-01

The influence of bacterial cell concentration on estimates of the number of binding sites and the affinity for the adsorption of a strain of Streptococcus sanguis to saliva-treated hydroxyapatite was determined, and the possible presence of multiple binding sites for this organism was tested. The range of concentrations of available bacteria varied from 4.7 × 106 to 5,960 × 106 cells per ml. The numbers of adsorbed bacteria increased over the entire range tested, but a suggestion of a break in an otherwise smooth adsorption isotherm was evident. Values for the number of binding sites and the affinity varied considerably depending upon the range of available bacterial concentrations used to estimate them; high correlation coefficients were obtained in all cases. The use of low bacterial cell concentrations yielded lower values for the number of sites and much higher values for the affinity constant than did the use of high bacterial cell concentrations. When data covering the entire range of bacterial concentrations were employed, values for the number of sites and the affinity were similar to those obtained by using only high bacterial cell concentrations. The simplest explanation for these results is that there are multiple binding sites for S. sanguis on saliva-treated hydroxyapatite surfaces. When present in low concentration, the streptococci evidently attach to more specific high-affinity sites which become saturated when higher bacterial concentrations are employed. The possibility of multiple binding sites was substantiated by comparing estimates of the adsorption parameters from a computer-simulated isotherm with those derived from the experimentally generated isotherm. A mathematical model describing bacterial adsorption to binary binding sites was further evidence for the existence of at least two classes of binding sites for S. sanguis. Far fewer streptococci adsorbed to experimental pellicles prepared from saliva depleted of bacterial aggregating

The effect of treating bacterial vaginosis on preterm labor.

PubMed

Tebes, Christine C; Lynch, Catherine; Sinnott, John

2003-01-01

Multiple studies suggest that bacterial vaginosis (BV) causes preterm labor; yet its routine treatment remains controversial. In order to help to elucidate this controversy, we performed a thorough review of studies with levels of evidence ranging from I to II-II. We searched for all of the studies from the years 1994 to 2001 via Medline's database, including MD Consult and Ovid Mednet. Several trials discovered a decrease in the incidence of preterm labor when BV was treated, but most of those trials were performed on women with a history of preterm labor. However, the majority of trials reviewed advise against treatment of a general low-risk obstetric population, as there was no significant decrease in preterm labor. Therefore, based on the above studies and the current guidelines of the Centers for Disease Control and Prevention (CDC), treating pregnant women in high-risk populations who are diagnosed with BV provides the clinician with an opportunity to possibly prevent preterm labor in this population. In nulliparous women without a history of preterm birth, treatment is recommended if other risk factors are present (e.g. gonorrhea or chlamydia). However, in the general low-risk populations, routine screening is not indicated.

Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species

PubMed Central

Brinkman, Cassandra L.; Schmidt-Malan, Suzannah M.; Karau, Melissa J.; Greenwood-Quaintance, Kerryl; Hassett, Daniel J.; Mandrekar, Jayawant N.

2016-01-01

Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the ‘electricidal effect’, in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS. PMID:27992529

Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species.

PubMed

Brinkman, Cassandra L; Schmidt-Malan, Suzannah M; Karau, Melissa J; Greenwood-Quaintance, Kerryl; Hassett, Daniel J; Mandrekar, Jayawant N; Patel, Robin

2016-01-01

Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the 'electricidal effect', in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS.

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.

Deciphering the Bacterial Microbiome in Huanglongbing-Affected Citrus Treated with Thermotherapy and Sulfonamide Antibiotics

PubMed Central

Powell, Charles A.; Duan, Yongping; Shatters, Robert; Fang, Jingping; Zhang, Muqing

2016-01-01

Huanglongbing (HLB) is a serious citrus disease that threatens the citrus industry. In previous studies, sulfonamide antibiotics and heat treatment suppressed ‘Candidatus Liberibacter asiaticus’ (Las), but did not completely eliminate the Las. Furthermore, there are few reports studying the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. In this study, combinations of heat (45°C or 40°C) and sulfonamide treatment (sulfathiazole sodium–STZ, or sulfadimethoxine sodium—SDX) were applied to HLB-affected citrus. The bacterial microbiome of HLB-affected citrus following thermotherapy and/or chemotherapy was characterized by PhyloChipTMG3-based metagenomics. Our results showed that the combination of thermotherapy at 45°C and chemotherapy with STZ and SDX was more effective against HLB than thermotherapy alone, chemotherapy alone, or a combination of thermotherapy at 40°C and chemotherapy. The PhyloChipTMG3-based results indicated that 311 empirical Operational Taxonomic Units (eOTUs) were detected in 26 phyla. Cyanobacteria (18.01%) were dominant after thermo-chemotherapy. Thermotherapy at 45°C decreased eOTUs (64.43%) in leaf samples, compared with thermotherapy at 40°C (73.96%) or without thermotherapy (90.68%) and it also reduced bacterial family biodiversity. The eOTU in phylum Proteobacteria was reduced significantly and eOTU_28, representing “Candidatus Liberibacter,” was not detected following thermotherapy at 45°C. Following antibiotic treatment with SDX and STZ, there was enhanced abundance of specific eOTUs belonging to the families Streptomycetaceae, Desulfobacteraceae, Chitinophagaceae, and Xanthomonadaceae, which may be implicated in increased resistance to plant pathogens. Our study further develops an integrated strategy for combating HLB, and also provides new insight into the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. PMID:27171468

Inflammatory tinea pedis with bacterial superinfection effectively treated with isoconazole nitrate and diflucortolone valerate combination therapy.

PubMed

Friedrich, Markus

2013-05-01

Undetected tinea pedis in a patient with diabetes can lead to serious bacterial infections with potentially serious consequences, such as foot amputations. Here we report on a 60-year-old patient with diabetes presenting with pain, severe pruritus, and malodour in the foot's interdigital area, and subsequently, diagnosed with inflammatory tinea pedis with bacterial superinfection. The patient was successfully treated with Travocort cream containing isoconazole nitrate 1% and diflucortolone valerate 0.1%; marked improvement occurred within 5 days. © 2013 Blackwell Verlag GmbH.

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

Evolving issues in understanding and treating bacterial vaginosis.

PubMed

Marrazzo, Jeanne M

2004-12-01

Bacterial vaginosis is a synergistic polymicrobial syndrome characterized by depletion of Lactobacillus spp., especially those that produce hydrogen peroxide, and an intense increase in the quantity of commensal vaginal anaerobic bacteria to 100- to 1000-fold above normal levels. While the bacterial spectrum of these organisms has long been known to include Gardnerella vaginalis, Prevotella spp., anaerobic Gram-positive cocci, Mobiluncus spp. and Mycoplasma hominis, innovative use of molecular diagnostics has identified novel species apparently associated with this syndrome, including Atopobium vaginalis. Effecting resolution of bacterial vaginosis is important, in particular for the 8 to 23% of women afflicted with symptomatic disease during their reproductive years. Bacterial vaginosis has been consistently associated with numerous adverse sequelae related to the upper genital tract, including pelvic inflammatory disease and postsurgical infection in the setting of invasive gynecologic procedures, and may increase women's risk of acquiring HIV infection. Pregnant women with bacterial vaginosis experience a higher rate of preterm delivery and low-birth-weight infants. While antibiotics with activity against anaerobes--typically, metronidazole and clindamycin applied vaginally or taken orally--are the mainstays of therapy, bacterial vaginosis frequently recurs. For these reasons, innovative approaches to therapy are urgently required.

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

Nociceptor sensory neurons suppress neutrophil and γδ T cell responses in bacterial lung infections and lethal pneumonia.

PubMed

Baral, Pankaj; Umans, Benjamin D; Li, Lu; Wallrapp, Antonia; Bist, Meghna; Kirschbaum, Talia; Wei, Yibing; Zhou, Yan; Kuchroo, Vijay K; Burkett, Patrick R; Yipp, Bryan G; Liberles, Stephen D; Chiu, Isaac M

2018-05-01

Lung-innervating nociceptor sensory neurons detect noxious or harmful stimuli and consequently protect organisms by mediating coughing, pain, and bronchoconstriction. However, the role of sensory neurons in pulmonary host defense is unclear. Here, we found that TRPV1 + nociceptors suppressed protective immunity against lethal Staphylococcus aureus pneumonia. Targeted TRPV1 + -neuron ablation increased survival, cytokine induction, and lung bacterial clearance. Nociceptors suppressed the recruitment and surveillance of neutrophils, and altered lung γδ T cell numbers, which are necessary for immunity. Vagal ganglia TRPV1 + afferents mediated immunosuppression through release of the neuropeptide calcitonin gene-related peptide (CGRP). Targeting neuroimmunological signaling may be an effective approach to treat lung infections and bacterial pneumonia.

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.

Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 reduces bacterial translocation in rats treated with carbon tetrachloride

PubMed Central

Sánchez, Elisabet; Nieto, Juan C.; Vidal, Silvia; Santiago, Alba; Martinez, Xavier; Sancho, Francesc J.; Sancho-Bru, Pau; Mirelis, Beatriz; Corominola, Helena; Juárez, Candido; Manichanh, Chaysavanh; Guarner, Carlos; Soriano, German

2017-01-01

Probiotics can prevent pathological bacterial translocation by modulating intestinal microbiota and improving the gut barrier. The aim was to evaluate the effect of a fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 on bacterial translocation in rats with carbon tetrachloride (CCl4)-induced cirrhosis. Sprague-Dawley rats treated with CCl4 were randomized into a probiotic group that received fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 in drinking water or a water group that received water only. Laparotomy was performed one week after ascites development. We evaluated bacterial translocation, intestinal microbiota, the intestinal barrier and cytokines in mesenteric lymph nodes and serum. Bacterial translocation decreased and gut dysbiosis improved in the probiotic group compared to the water group. The ileal β-defensin-1 concentration was higher and ileal malondialdehyde levels were lower in the probiotic group than in water group. There were no differences between groups in serum cytokines but TNF-α levels in mesenteric lymph nodes were lower in the probiotic group than in the water group. Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 decreases bacterial translocation, gut dysbiosis and ileal oxidative damage and increases ileal β-defensin-1 expression in rats treated with CCl4, suggesting an improvement in the intestinal barrier integrity. PMID:28368023

The oral administration of bacterial extracts prevents asthma via the recruitment of regulatory T cells to the airways.

PubMed

Navarro, S; Cossalter, G; Chiavaroli, C; Kanda, A; Fleury, S; Lazzari, A; Cazareth, J; Sparwasser, T; Dombrowicz, D; Glaichenhaus, N; Julia, V

2011-01-01

The prevalence of asthma has steadily increased during the last decade, probably as the result of changes in the environment, including reduced microbial exposure during infancy. Accordingly, experimental studies have shown that deliberate infections with live pathogens prevent the development of allergic airway diseases in mice. Bacterial extracts are currently used in children suffering from repeated upper respiratory tract infections. In the present study, we have investigated whether bacterial extracts, commercially available as Broncho-Vaxom (BV), could prevent allergic airway disease in mice. Oral treatment with BV suppressed airway inflammation through interleukin-10 (IL-10)-dependent and MyD88 (myeloid differentiation primary response gene (88))-dependent mechanisms and induced the conversion of FoxP3 (forkhead box P3)(-) T cells into FoxP3(+) regulatory T cells. Furthermore, CD4(+) T cells purified from the trachea of BV-treated mice conferred protection against airway inflammation when adoptively transferred into sensitized mice. Therefore, treatment with BV could possibly be a safe and efficient strategy to prevent the development of allergic diseases in children.

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

The Effect of Treating Bacterial Vaginosis on Preterm Labor

PubMed Central

Tebes, Christine C.; Lynch, Catherine

2003-01-01

Objective: Multiple studies suggest that bacterial vaginosis (BV) causes preterm labor; yet its routine treatment remains controversial. In order to help to elucidate this controversy, we performed a thorough review of studies with levels of evidence ranging from I to II–II. Methods: We searched for all of the studies from the years 1994 to 2001 via Medline’s database, including MD Consult and Ovid Mednet. Results: Several trials discovered a decrease in the incidence of preterm labor when BV was treated, but most of those trials were performed on women with a history of preterm labor. However, the majority of trials reviewed advise against treatment of a general low-risk obstetric population, as there was no significant decrease in preterm labor. Conclusions: Therefore, based on the above studies and the current guidelines of the Centers for Disease Control and Prevention (CDC), treating pregnant women in high-risk populations who are diagnosed with BV provides the clinician with an opportunity to possibly prevent preterm labor in this population. In nulliparous women without a history of preterm birth, treatment is recommended if other risk factors are present (e.g. gonorrhea or chlamydia). However, in the general low-risk populations, routine screening is not indicated. PMID:14627219

Biodegradation and decolourization of anaerobically treated distillery spent wash by a novel bacterial consortium.

PubMed

Mohana, Sarayu; Desai, Chirayu; Madamwar, Datta

2007-01-01

The aim of this study was to isolate microorganisms capable of decolourizing and degrading anaerobically treated distillery spent wash. A bacterial consortium DMC comprising of three bacterial cultures was selected on the basis of rapid effluent decolourization and degradation, which exhibited 67 +/- 2% decolourization within 24 h and 51 +/- 2% chemical oxygen demand reduction within 72 h when incubated at 37 degrees C under static condition in effluent supplemented with 0.5% glucose, 0.1% KH(2)PO(4), 0.05% KCl and 0.05% MgSO(4) x 7H(2)O. Addition of organic or inorganic nitrogen sources did not support decolourization. The cultures were identified as Pseudomonas aeruginosa PAO1, Stenotrophomonas maltophila and Proteus mirabilis by the 16S rDNA analysis.

Shape Changes and Interaction Mechanism of Escherichia coli Cells Treated with Sericin and Use of a Sericin-Based Hydrogel for Wound Healing.

PubMed

Xue, Rui; Liu, Yalong; Zhang, Qingsong; Liang, Congcong; Qin, Huazhen; Liu, Pengfei; Wang, Ke; Zhang, Xiaoyong; Chen, Li; Wei, Yen

2016-08-01

To verify the interaction mechanism between sericin and Escherichia coli, especially the morphological and structural changes in the bacterial cells, the antimicrobial activity of sericin against E. coli as a model for Gram-negative bacteria was investigated. The antibacterial activity of sericin on E. coli and the interaction mechanism were investigated in this study by analyzing the growth, integrity, and morphology of the bacterial cells following treatment with sericin. The changes in morphology and cellular compositions of bacterial cells treated with sericin were observed by an inverted fluorescence microscope, scanning electron microscopy, and transmission electron microscopy. Changes in electrical conductivity, total sugar concentration of the broth for the bacteria, and protein expression of the bacteria were determined to investigate the permeability of the cell membrane. A sericin-based hydrogel was prepared for an in vivo study of wound dressing. The results showed that the antibacterial activity of the hydrogel increased with the increase in the concentration of sericin from 10 g/liter to 40 g/liter. The introduction of sericin induces membrane blebbing of E. coli cells caused by antibiotic action on the cell membrane. The cytoplasm shrinkage phenomenon was accompanied by blurring of the membrane wall boundaries. When E. coli cells were treated with sericin, release of intracellular components quickly increased. The electrical conductivity assay indicated that the charged ions are reduced after exposure to sericin so that the integrity of the cell membrane is weakened and metabolism is blocked. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that sericin hinders the expression of bacterial protein. Sericin may damage the integrity of the bacterial cell membrane, thereby eventually inhibiting the growth and reproduction of E. coli Compared to sterile gauze, the sericin-based hydrogel promoted fibroblast cell

Shape Changes and Interaction Mechanism of Escherichia coli Cells Treated with Sericin and Use of a Sericin-Based Hydrogel for Wound Healing

PubMed Central

Xue, Rui; Liu, Yalong; Liang, Congcong; Qin, Huazhen; Liu, Pengfei; Wang, Ke; Zhang, Xiaoyong; Chen, Li

2016-01-01

ABSTRACT To verify the interaction mechanism between sericin and Escherichia coli, especially the morphological and structural changes in the bacterial cells, the antimicrobial activity of sericin against E. coli as a model for Gram-negative bacteria was investigated. The antibacterial activity of sericin on E. coli and the interaction mechanism were investigated in this study by analyzing the growth, integrity, and morphology of the bacterial cells following treatment with sericin. The changes in morphology and cellular compositions of bacterial cells treated with sericin were observed by an inverted fluorescence microscope, scanning electron microscopy, and transmission electron microscopy. Changes in electrical conductivity, total sugar concentration of the broth for the bacteria, and protein expression of the bacteria were determined to investigate the permeability of the cell membrane. A sericin-based hydrogel was prepared for an in vivo study of wound dressing. The results showed that the antibacterial activity of the hydrogel increased with the increase in the concentration of sericin from 10 g/liter to 40 g/liter. The introduction of sericin induces membrane blebbing of E. coli cells caused by antibiotic action on the cell membrane. The cytoplasm shrinkage phenomenon was accompanied by blurring of the membrane wall boundaries. When E. coli cells were treated with sericin, release of intracellular components quickly increased. The electrical conductivity assay indicated that the charged ions are reduced after exposure to sericin so that the integrity of the cell membrane is weakened and metabolism is blocked. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that sericin hinders the expression of bacterial protein. Sericin may damage the integrity of the bacterial cell membrane, thereby eventually inhibiting the growth and reproduction of E. coli. Compared to sterile gauze, the sericin-based hydrogel promoted fibroblast cell

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.

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

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

Performance and bacterial compositions of aged refuse reactors treating mature landfill leachate.

PubMed

Xie, Bing; Xiong, Shunzi; Liang, Shaobo; Hu, Chong; Zhang, Xiaojun; Lu, Jun

2012-01-01

Aged landfill leachates become more refractory over time and difficulty to treat. Recently, aged refuse bioreactors show great promise in treating leachates. In this study, aged refuse bioreactors were constructed to simulate landfill leachate degradation process. The characteristics of leachate were: CODcr, ∼2200 mg/L; BOD5, ∼280 mg/L; total nitrogen, ∼2030 mg/L; and ammonia, ∼1900 mg/L. Results showed that bioreactor could remove leachate pollutants effectively at hydraulic loading of 20 L/m3 d. The removal rate reduced when hydraulic loading doubled or temperature lowered. Effluent recirculation could alleviate the temperature effect. Combining aged refuse and slag biofilters could treat leachate more efficiently. Pyrosequencing analysis indicated that bacteria from Pseudomonas, Lysobacter, Bacillus and δ-proteobacter, Flexibacteraceae were more abundant in the samples. The Shannon index decreased at lower temperature, while evenness and equitability increased with recirculation. We suggest that filter medium and temperature may be the main factors for shaping bacterial community structure. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Bacterial Cell Growth Inhibitors Targeting Undecaprenyl Diphosphate Synthase and Undecaprenyl Diphosphate Phosphatase.

PubMed

Wang, Yang; Desai, Janish; Zhang, Yonghui; Malwal, Satish R; Shin, Christopher J; Feng, Xinxin; Sun, Hong; Liu, Guizhi; Guo, Rey-Ting; Oldfield, Eric

2016-10-19

We synthesized a series of benzoic acids and phenylphosphonic acids and investigated their effects on the growth of Staphylococcus aureus and Bacillus subtilis. One of the most active compounds, 5-fluoro-2-(3-(octyloxy)benzamido)benzoic acid (7, ED 50 ∼0.15 μg mL -1 ) acted synergistically with seven antibiotics known to target bacterial cell-wall biosynthesis (a fractional inhibitory concentration index (FICI) of ∼0.35, on average) but had indifferent effects in combinations with six non-cell-wall biosynthesis inhibitors (average FICI∼1.45). The most active compounds were found to inhibit two enzymes involved in isoprenoid/bacterial cell-wall biosynthesis: undecaprenyl diphosphate synthase (UPPS) and undecaprenyl diphosphate phosphatase (UPPP), but not farnesyl diphosphate synthase, and there were good correlations between bacterial cell growth inhibition, UPPS inhibition, and UPPP inhibition. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Cytotoxicity and genotoxicity of bacterial magnetosomes against human retinal pigment epithelium cells

NASA Astrophysics Data System (ADS)

Qi, Lei; Lv, Xiujuan; Zhang, Tongwei; Jia, Peina; Yan, Ruiying; Li, Shuli; Zou, Ruitao; Xue, Yuhua; Dai, Liming

2016-06-01

A variety of nanomaterials have been developed for ocular diseases. The ability of these nanomaterials to pass through the blood-ocular barrier and their biocompatibility are essential characteristics that must be considered. Bacterial magnetosomes (BMs) are a type of biogenic magnetic nanomaterials synthesized by magnetotactic bacteria. Due to their unique biomolecular membrane shell and narrow size distribution of approximately 30 nm, BMs can pass through the blood-brain barrier. The similarity of the blood-ocular barrier to the blood-brain barrier suggests that BMs have great potential as treatments for ocular diseases. In this work, BMs were isolated from magnetotactic bacteria and evaluated in various cytotoxicity and genotoxicity studies in human retinal pigment epithelium (ARPE-19) cells. The BMs entered ARPE-19 cells by endocytosis after a 6-h incubation and displayed much lower cytotoxicity than chemically synthesized magnetic nanoparticles (MNPs). MNPs exhibited significantly higher genotoxicity than BMs and promoted the expression of Bax (the programmed cell death acceleration protein) and the induction of greater cell necrosis. In BM-treated cells, apoptosis tended to be suppressed via increased expression of the Bcl-2 protein. In conclusion, BMs display excellent biocompatibility and potential for use in the treatment of ocular diseases.

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.

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.

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.

[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.

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.

Bacterial community analysis of swine manure treated with autothermal thermophilic aerobic digestion.

PubMed

Han, Il; Congeevaram, Shankar; Ki, Dong-Won; Oh, Byoung-Taek; Park, Joonhong

2011-02-01

Due to the environmental problems associated with disposal of livestock sludge, many stabilization studies emphasizing on the sludge volume reduction were performed. However, little is known about the microbial risk present in sludge and its stabilized products. This study microbiologically explored the effects of anaerobic lagoon fermentation (ALF) and autothermal thermophilic aerobic digestion (ATAD) on pathogen-related risk of raw swine manure by using culture-independent 16S rDNA cloning and sequencing methods. In raw swine manure, clones closely related to pathogens such as Dialister pneumosintes, Erysipelothrix rhusiopathiae, Succinivibrioan dextrinosolvens, and Schineria sp. were detected. Meanwhile, in the mesophilic ALF-treated swine manure, bacterial community clones closely related to pathogens such as Schineria sp. and Succinivibrio dextrinosolvens were still detected. Interestingly, the ATAD treatment resulted in no detection of clones closely related to pathogens in the stabilized thermophilic bacterial community, with the predominance of novel Clostridia class populations. These findings support the superiority of ATAD in selectively reducing potential human and animal pathogens compared to ALF, which is a typical manure stabilization method used in livestock farms.

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.

Spatial Patterning of Newly-Inserted Material during Bacterial Cell Growth

NASA Astrophysics Data System (ADS)

Ursell, Tristan

2012-02-01

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

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.

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)

[Using cell technologies to treat urologic diseases].

PubMed

Glybochko, P V; Olefir, Yu V; Alyaev, Yu G; Butnaru, D V; Bezrukov, E A; Chaplenko, A A; Zharikova, T M

2016-08-01

Stem and progenitor cells being introduced into the body have the ability to stimulate regeneration of tissues and organs by differentiating into specialized cells. Stem cell therapy is used in urology to treat various disorders, including erectile dysfunction, urinary incontinence, Peyronies disease, and male infertility. This review presents the results of international preclinical and clinical research on stem cell based medications for treating the above diseases. The most promising appears to be the use of adipose tissue-derived mesenchymal stem cells.

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.

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

Femtosecond laser induced surface modification for prevention of bacterial adhesion on 45S5 bioactive glass

NASA Astrophysics Data System (ADS)

Shaikh, Shazia; Singh, Deepti; Subramanian, Mahesh; Kedia, Sunita; Singh, Anil Kumar; Singh, Kulwant; Gupta, Nidhi; Sinha, Sucharita

2018-02-01

Bacterial attachment and biofilm formation on implant surface has been a major concern in hospital and industrial environment. Prevention of bacterial infections of implant surface through surface treatment could be a potential solution and hence this has become a key area of research. In the present study, the antibacterial and biocompatible properties of femtosecond laser surface treated 45S5 bioactive glass (BG) have been investigated. Adhesion and sustainability of both gram positive S. aureus and gram negative P.aeruginosa and E. coli nosocomial bacteria on untreated and laser treated BG samples has been explored. An imprint method has been used to visualize the growth of bacteria on the sample surface. We observed complete bacterial rejection potentially reducing risk of biofilm formation on laser treated surface. This was correlated with surface roughness, wettability and change in surface chemical composition of the samples before and after laser treatment. Biocompatibility of the laser treated BG was demonstrated by studying the anchoring and growth of human cervix cell line INT407. Our results demonstrate that, laser surface modification of BG enables enhanced bacterial rejection without affecting its biocompatibility towards growth of human cells on it. These results open a significantly potential approach towards use of laser in successfully imparting desirable characteristics to BG based bio-implants and devices.

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...

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.

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.

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 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.

Binding mechanism of patulin to heat-treated yeast cell.

PubMed

Guo, C; Yuan, Y; Yue, T; Hatab, S; Wang, Z

2012-12-01

This study aims to assess the removal mechanism of patulin using heat-treated Saccharomyces cerevisiae cells and identify the role of different cell wall components in the binding process. In order to understand the binding mechanism, viable cells, heat-treated cells, cell wall and intracellular extract were performed to assess their ability to remove patulin. Additionally, the effects of chemical and enzymatic treatments of yeast on the binding ability were tested. The results showed that there was no significant difference between viable (53·28%) and heat-treated yeast cells (51·71%) in patulin binding. In addition, the cell wall fraction decreased patulin by 35·05%, and the cell extract nearly failed to bind patulin. Treatments with protease E, methanol, formaldehyde, periodate or urea significantly decreased (P < 0·05) the ability of heat-treated cells to remove patulin. Fourier transform infrared (FTIR) analysis indicated that more functional groups were involved in the binding process of heat-treated cells. Polysaccharides and protein are important components of yeast cell wall involved in patulin removal. In addition, hydrophobic interactions play a major role in binding processes. Heat-treated S. cerevisiae cells could be used to control patulin contamination in the apple juice industry. Also, our results proof that the patulin removal process is based mainly on the adsorption not degradation. © 2012 The Society for Applied Microbiology.

Berberine promotes recovery of colitis and inhibits inflammatory responses in colonic macrophages and epithelial cells in DSS-treated mice

PubMed Central

Wang, Lihong; Shi, Yan; Cao, Hanwei; Liu, Liping; Washington, M. Kay; Chaturvedi, Rupesh; Israel, Dawn A.; Cao, Hailong; Wang, Bangmao; Peek, Richard M.; Wilson, Keith T.; Polk, D. Brent

2012-01-01

Inflammatory bowel disease (IBD) results from dysregulation of intestinal mucosal immune responses to microflora in genetically susceptible hosts. A major challenge for IBD research is to develop new strategies for treating this disease. Berberine, an alkaloid derived from plants, is an alternative medicine for treating bacterial diarrhea and intestinal parasite infections. Recent studies suggest that berberine exerts several other beneficial effects, including inducing anti-inflammatory responses. This study determined the effect of berberine on treating dextran sulfate sodium (DSS)-induced intestinal injury and colitis in mice. Berberine was administered through gavage to mice with established DSS-induced intestinal injury and colitis. Clinical parameters, intestinal integrity, proinflammatory cytokine production, and signaling pathways in colonic macrophages and epithelial cells were determined. Berberine ameliorated DSS-induced body weight loss, myeloperoxidase activity, shortening of the colon, injury, and inflammation scores. DSS-upregulated proinflammatory cytokine levels in the colon, including TNF, IFN-γ, KC, and IL-17 were reduced by berberine. Berberine decreased DSS-induced disruption of barrier function and apoptosis in the colon epithelium. Furthermore, berberine inhibited proinflammatory cytokine production in colonic macrophages and epithelial cells in DSS-treated mice and promoted apoptosis of colonic macrophages. Activation of signaling pathways involved in stimulation of proinflammatory cytokine production, including MAPK and NF-κB, in colonic macrophages and epithelial cells from DSS-treated mice was decreased by berberine. In summary, berberine promotes recovery of DSS-induced colitis and exerts inhibitory effects on proinflammatory responses in colonic macrophages and epithelial cells. Thus berberine may represent a new therapeutic approach for treating gastrointestinal inflammatory disorders. PMID:22173918

Morphological and chemical changes of aerosolized E. coli treated with a dielectric barrier discharge

DOE PAGES

Romero-Mangado, Jaione; Nordlund, Dennis; Soberon, Felipe; ...

2016-02-12

This paper presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure(NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure.more » The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.« less

Hsp70 facilitates trans-membrane transport of bacterial ADP-ribosylating toxins into the cytosol of mammalian cells.

PubMed

Ernst, Katharina; Schmid, Johannes; Beck, Matthias; Hägele, Marlen; Hohwieler, Meike; Hauff, Patricia; Ückert, Anna Katharina; Anastasia, Anna; Fauler, Michael; Jank, Thomas; Aktories, Klaus; Popoff, Michel R; Schiene-Fischer, Cordelia; Kleger, Alexander; Müller, Martin; Frick, Manfred; Barth, Holger

2017-06-02

Binary enterotoxins Clostridium (C.) botulinum C2 toxin, C. perfringens iota toxin and C. difficile toxin CDT are composed of a transport (B) and a separate non-linked enzyme (A) component. Their B-components mediate endocytic uptake into mammalian cells and subsequently transport of the A-components from acidic endosomes into the cytosol, where the latter ADP-ribosylate G-actin resulting in cell rounding and cell death causing clinical symptoms. Protein folding enzymes, including Hsp90 and peptidyl-prolyl cis/trans isomerases facilitate transport of the A-components across endosomal membranes. Here, we identified Hsp70 as a novel host cell factor specifically interacting with A-components of C2, iota and CDT toxins to facilitate their transport into the cell cytosol. Pharmacological Hsp70-inhibition specifically prevented pH-dependent trans-membrane transport of A-components into the cytosol thereby protecting living cells and stem cell-derived human miniguts from intoxication. Thus, Hsp70-inhibition might lead to development of novel therapeutic strategies to treat diseases associated with bacterial ADP-ribosylating toxins.

PMA-Linked Fluorescence for Rapid Detection of Viable Bacterial Endospores

NASA Technical Reports Server (NTRS)

LaDuc, Myron T.; Venkateswaran, Kasthuri; Mohapatra, Bidyut

2012-01-01

The most common approach for assessing the abundance of viable bacterial endospores is the culture-based plating method. However, culture-based approaches are heavily biased and oftentimes incompatible with upstream sample processing strategies, which make viable cells/spores uncultivable. This shortcoming highlights the need for rapid molecular diagnostic tools to assess more accurately the abundance of viable spacecraft-associated microbiota, perhaps most importantly bacterial endospores. Propidium monoazide (PMA) has received a great deal of attention due to its ability to differentiate live, viable bacterial cells from dead ones. PMA gains access to the DNA of dead cells through compromised membranes. Once inside the cell, it intercalates and eventually covalently bonds with the double-helix structures upon photoactivation with visible light. The covalently bound DNA is significantly altered, and unavailable to downstream molecular-based manipulations and analyses. Microbiological samples can be treated with appropriate concentrations of PMA and exposed to visible light prior to undergoing total genomic DNA extraction, resulting in an extract comprised solely of DNA arising from viable cells. This ability to extract DNA selectively from living cells is extremely powerful, and bears great relevance to many microbiological arenas.

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

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.

Activation of mouse liver natural killer cells and NK1.1(+) T cells by bacterial superantigen-primed Kupffer cells.

PubMed

Dobashi, H; Seki, S; Habu, Y; Ohkawa, T; Takeshita, S; Hiraide, H; Sekine, I

1999-08-01

Although bacterial superantigens have been well characterized as potent stimulators of T cells, their role in natural killer (NK)-type cells remains largely unknown. In the present study, we examined the effect of bacterial superantigens on mouse liver NK cells and NK1.1 Ag(+) (NK1(+)) T cells. C57BL/6 mice were intravenously injected with staphylococcal enterotoxin B (SEB) or streptococcal pyrogenic exotoxin A (SPE-A), and mononuclear cells (MNC) of various organs were obtained from mice 4 hours after being injected with superantigen. MNC were cultured for 48 hours, and interferon gamma (IFN-gamma) levels of supernatants were measured. The antitumor cytotoxicities of the liver and spleen MNC were also evaluated 24 hours after the mice were injected with superantigen. Liver MNC produced more IFN-gamma than did splenocytes, and peripheral blood and lung MNC did not produce any detectable IFN-gamma. In addition, liver MNC acquired a potent antitumor cytotoxicity by the SEB injection, and both NK cells and NK1(+)T cells but not cluster of differentiation (CD)8(+) T cells were responsible for the cytotoxicity as demonstrated by either in vivo or in vitro cell depletion experiments, and the NK-type cells were partly responsible for the increased serum IFN-gamma. Activation of liver NK-type cells was also supported by the fact that liver NK cells proportionally increased and NK1(+) T cells augmented their CD11a expressions after SEB injection. The pretreatment of mice with anti-IFN-gamma Ab and/or with anti-interleukin-12 (IL-12) Ab diminished the SEB-induced cytotoxicity of liver MNC. Furthermore, the in vivo depletion of Kupffer cells decreased the SEB-induced cytotoxicity of liver MNC. Consistent with these results, liver MNC stimulated with superantigens in the presence of Kupffer cells in vitro produced a greater amount of IFN-gamma than did the liver MNC without Kupffer cells or splenocytes. Our results suggest that bacterial superantigen-primed Kupffer cells

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

Multiscale modeling of bacterial colonies: how pili mediate the dynamics of single cells and cellular aggregates

NASA Astrophysics Data System (ADS)

Pönisch, Wolfram; Weber, Christoph A.; Juckeland, Guido; Biais, Nicolas; Zaburdaev, Vasily

2017-01-01

Neisseria gonorrhoeae is the causative agent of one of the most common sexually transmitted diseases, gonorrhea. Over the past two decades there has been an alarming increase of reported gonorrhea cases where the bacteria were resistant to the most commonly used antibiotics thus prompting for alternative antimicrobial treatment strategies. The crucial step in this and many other bacterial infections is the formation of microcolonies, agglomerates consisting of up to several thousands of cells. The attachment and motility of cells on solid substrates as well as the cell-cell interactions are primarily mediated by type IV pili, long polymeric filaments protruding from the surface of cells. While the crucial role of pili in the assembly of microcolonies has been well recognized, the exact mechanisms of how they govern the formation and dynamics of microcolonies are still poorly understood. Here, we present a computational model of individual cells with explicit pili dynamics, force generation and pili-pili interactions. We employ the model to study a wide range of biological processes, such as the motility of individual cells on a surface, the heterogeneous cell motility within the large cell aggregates, and the merging dynamics and the self-assembly of microcolonies. The results of numerical simulations highlight the central role of pili generated forces in the formation of bacterial colonies and are in agreement with the available experimental observations. The model can quantify the behavior of multicellular bacterial colonies on biologically relevant temporal and spatial scales and can be easily adjusted to include the geometry and pili characteristics of various bacterial species. Ultimately, the combination of the microbiological experimental approach with the in silico model of bacterial colonies might provide new qualitative and quantitative insights on the development of bacterial infections and thus pave the way to new antimicrobial treatments.

Oral Bacterial Deactivation Using a Low-Temperature Atmospheric Argon Plasma Brush

PubMed Central

Yang, Bo; Chen, Jierong; Yu, Qingsong; Li, Hao; Lin, Mengshi; Mustapha, Azlin; Hong, Liang; Wang, Yong

2010-01-01

Summary Objectives To study the plasma treatment effects on deactivation effectiveness of oral bacteria. Methods A low temperature atmospheric argon plasma brush were used to study the oral bacterial deactivation effects in terms of plasma conditions, plasma exposure time, and bacterial supporting media. Oral bacteria of Streptococcus mutans and Lactobacillus acidophilus with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. Scanning electron microscopy was used to examine the morphological changes of the plasma treated bacteria. Optical absorption was used to determine the leakage of intracellular proteins and DNAs of the plasma treated bacteria. Results The experimental data indicated that the argon atmospheric plasma brush was very effective in deactivating oral bacteria. The plasma exposure time for a 99.9999% cell reduction was less than 15 seconds for S. mutans and within 5 minutes for L. acidophilus. It was found that the plasma deactivation efficiency was also dependent on the bacterial supporting media. With plasma exposure, significant damages to bacterial cell structures were observed with both bacterium species. Leakage of intracellular proteins and DNAs after plasma exposure was observed through monitoring the absorbance peaks at wavelengths of 280nm and 260nm, respectively. Conclusion The experimental results from this study indicated that low temperature atmospheric plasma treatment was very effective in deactivation of oral bacteria and could be a promising technique in various dental clinical applications such as bacterial disinfection and caries early prevention, etc. PMID:20951184

In-vitro analysis of APA microcapsules for oral delivery of live bacterial cells.

PubMed

Chen, H; Ouyang, W; Jones, M; Haque, T; Lawuyi, B; Prakash, S

2005-08-01

Oral administration of microcapsules containing live bacterial cells has potential as an alternative therapy for several diseases. This article evaluates the suitability of the alginate-poly-L-lysine-alginate (APA) microcapsules for oral delivery of live bacterial cells, in-vitro, using a dynamic simulated human gastro-intestinal (GI) model. Results showed that the APA microcapsules were morphologically stable in the simulated stomach conditions, but did not retain their structural integrity after a 3-day exposure in simulated human GI media. The microbial populations of the tested bacterial cells and the activities of the tested enzymes in the simulated human GI suspension were not substantially altered by the presence of the APA microcapsules, suggesting that there were no significant adverse effects of oral administration of the APA microcapsules on the flora of the human gastrointestinal tract. When the APA microcapsules containing Lactobacillus plantarum 80 (LP80) were challenged in the simulated gastric medium (pH = 2.0), 80.0% of the encapsulated cells remained viable after a 5-min incubation; however, the viability decreased considerably (8.3%) after 15 min and dropped to 2.6% after 30 min and lower than 0.2% after 60 min, indicating the limitations of the currently obtainable APA membrane for oral delivery of live bacteria. Further in-vivo studies are required before conclusions can be made concerning the inadequacy of APA microcapsules for oral delivery of live bacterial cells.

Sequential Super-Resolution Imaging of Bacterial Regulatory Proteins: The Nucleoid and the Cell Membrane in Single, Fixed E. coli Cells.

PubMed

Spahn, Christoph; Glaesmann, Mathilda; Gao, Yunfeng; Foo, Yong Hwee; Lampe, Marko; Kenney, Linda J; Heilemann, Mike

2017-01-01

Despite their small size and the lack of compartmentalization, bacteria exhibit a striking degree of cellular organization, both in time and space. During the last decade, a group of new microscopy techniques emerged, termed super-resolution microscopy or nanoscopy, which facilitate visualizing the organization of proteins in bacteria at the nanoscale. Single-molecule localization microscopy (SMLM) is especially well suited to reveal a wide range of new information regarding protein organization, interaction, and dynamics in single bacterial cells. Recent developments in click chemistry facilitate the visualization of bacterial chromatin with a resolution of ~20 nm, providing valuable information about the ultrastructure of bacterial nucleoids, especially at short generation times. In this chapter, we describe a simple-to-realize protocol that allows determining precise structural information of bacterial nucleoids in fixed cells, using direct stochastic optical reconstruction microscopy (dSTORM). In combination with quantitative photoactivated localization microscopy (PALM), the spatial relationship of proteins with the bacterial chromosome can be studied. The position of a protein of interest with respect to the nucleoids and the cell cylinder can be visualized by super-resolving the membrane using point accumulation for imaging in nanoscale topography (PAINT). The combination of the different SMLM techniques in a sequential workflow maximizes the information that can be extracted from single cells, while maintaining optimal imaging conditions for each technique.

Visual outcomes in treated bacterial keratitis: four years of prospective follow-up.

PubMed

McClintic, Scott M; Prajna, Namperumalsamy V; Srinivasan, Muthiah; Mascarenhas, Jeena; Lalitha, Prajna; Rajaraman, Revathi; Oldenburg, Catherine E; O'Brien, Kieran S; Ray, Kathryn J; Acharya, Nisha R; Lietman, Thomas M; Keenan, Jeremy D

2014-05-02

We described the change in visual acuity experienced by eyes successfully treated for bacterial keratitis. This was a prospective cohort study of a subset of study participants who had previously enrolled in the Steroids for Corneal Ulcers Trial (SCUT). All study participants had been diagnosed with culture-proven bacterial keratitis before enrollment in SCUT and subsequently were randomized to adjunctive topical corticosteroids or placebo. During SCUT, we monitored study participants at enrollment, 3 weeks, 3 months, and 12 months. We invited a subset to complete a comprehensive eye examination approximately 4 years after enrollment in SCUT. Certified refractionists assessed best spectacle-corrected visual acuity (BSCVA) using the same protocol at each study visit. We examined 50 SCUT participants at 4 years after enrollment. Among those in this cohort, mean logMAR BSCVA at enrollment was 0.85 (Snellen equivalent, 20/160; 95% confidence interval [CI], 0.71-0.99). On average, visual acuity improved by 2.9 logMAR lines from enrollment to 3 weeks (P < 0.001), 1.2 lines from 3 weeks to 3 months (P = 0.002), and 0.8 lines from 3 to 12 months (P = 0.01). The BSCVA did not change significantly between 12 months and 4 years (0.04-line improvement, P = 0.88). After controlling for visual acuity at enrollment, BSCVA was not significantly different between the corticosteroid and placebo groups at 4 years (P = 0.53). Cases of bacterial keratitis may continue to demonstrate improvements in visual acuity up to 12 months following diagnosis, but further improvements are unlikely. These findings may guide the appropriate timing of surgical intervention in these patients. (ClinicalTrials.gov number, NCT00324168.).

Procalcitonin as a Biomarker of Bacterial Infection in Sickle Cell Vaso-Occlusive Crisis

PubMed Central

Patel, Dilip Kumar; Mohapatra, Manoj Kumar; Thomas, Ancil George; Patel, Siris; Purohit, Prasanta

2014-01-01

Sickle cell anaemia (SCA) patients with vaso-occlusive crisis (VOC) have signs of inflammation and it is often difficult to diagnose a bacterial infection in them. This study was undertaken to evaluate the role of serum procalcitonin (PCT) as a biomarker of bacterial infection in acute sickle cell vaso-occlusive crisis. Hundred homozygous SCA patients were studied at Sickle Cell Clinic and Molecular Biology Laboratory, V.S.S. Medical College, Burla, Odisha, India. All the patients were divided into three categories namely category-A (VOC/ACS with SIRS but without evidence of bacterial infection - 66 patients), category-B (VOC/ACS with SIRS and either proven or suspected bacterial infection - 24 patients) and category-C (SCA patients in steady state without VOC/ACS or SIRS - 10 patients). Complete blood count, C-reactive protein (CRP) estimation and PCT measurement were done in all the patients. There was no significant difference in TLC and CRP values between category-A and B. In category-A, the PCT level was <0.5 ng/mL in 83.3% and 0.5–2 ng/mL in 16.7% of cases. In category-B, all the patients had PCT value >0.5 ng/mL with 87.5% of patients having >2 ng/mL. In category-C, PCT value was <0.5 ng/mL. PCT had a high sensitivity (100%) and negative predictive value (100%) for bacterial infection at a cutoff value of 0.5 ng/mL; whereas the specificity is excellent at a cut-off value of 2 ng/mL. SCA patients with VOC/ACS and SIRS having a PCT level of <0.5 ng/mL have a low probability of bacterial infection whereas PCT value of >2 ng/mL is indicative of bacterial infection necessitating early antimicrobial therapy. PMID:24678395

A nanovehicle developed for treating deep-seated bacteria using low-dose X-ray.

PubMed

Pan, Chien-Lin; Chen, Ming-Hong; Tung, Fu-I; Liu, Tse-Ying

2017-01-01

Many non-antibiotic strategies, such as photocatalysis and photodynamic therapy, have been proposed to inhibit and/or kill bacteria. However, these approaches still have drawbacks such as insufficient bacterial specificity and the limited penetration depth of ultraviolet and near-infrared light. To overcome these limitations, we developed a bacteria-specific anti-bacterial technique via using low-dose X-ray. Graphene oxide quantum dots (GQDs, a multifunctional vehicle) conjugated with vancomycin (Van, a bacteria-targeting ligand) were assembled with Protoporphyrin IX (PpIX, a photo/radiation sensitizer) to yield a novel Van-GQDs/PpIX complex that specifically attached to Escherichia coli and efficiently generated intracellular reactive oxygen species following X-ray activation. Delivery using GQDs increased the PpIX/Van ratio in the target bacterial cell, damaged bacterial cell wall, and enhanced X-ray-induced PpIX activation. Hence, this approach allowed for the use of a low-dose X-ray to efficiently activate the Van-GQDs/PpIX complex to exert its bactericidal effects on Escherichia coli without damaging normal cells. Furthermore, the E. coli did not develop resistance to the proposed approach for at least 7 rounds of repeated administration during one week. Thus, this proposed vehicle exhibiting bacteria-specific X-ray-triggered toxicity is a promising alternative to antibiotics for treating serious bacterial infections occurring in deep-seated tissues/organs (e.g., osteomyelitis and peritonitis). Administration of antibiotics is the most common treatment modality for bacterial infections. However, in some cases, patient attributes such as age, health, tolerance to antibiotics do not allow for the use of high-dose antibiotics. In addition, some bacteria develop resistance to antibiotics because of improper and long-term use of these agents. Therefore, non-antibiotic strategies to treat deeply situated bacterial infections, such as osteomyelitis, are urgently

Anti-bacterial activity of Achatina CRP and its mechanism of action.

PubMed

Mukherjee, Sandip; Barman, Soma; Mandal, Narayan Chandra; Bhattacharya, Shelley

2014-07-01

The physiological role of C-reactive protein (CRP), the classical acute-phase protein, is not well documented, despite many reports on biological effects of CRP in vitro and in model systems in vivo. It has been suggested that CRP protects mice against lethal toxicity of bacterial infections by implementing immunological responses. In Achatina fulica CRP is a constitutive multifunctional protein in haemolymph and considered responsible for their survival in the environment for millions of years. The efficacy of Achatina CRP (ACRP) was tested against both Salmonella typhimurium and Bacillus subtilis infections in mice where endogenous CRP level is negligible even after inflammatory stimulus. Further, growth curves of the bacteria revealed that ACRP (50 microg/mL) is bacteriostatic against gram negative salmonellae and bactericidal against gram positive bacilli. ACRP induced energy crises in bacterial cells, inhibited key carbohydrate metabolic enzymes such as phosphofructokinase in glycolysis, isocitrate dehydrogenase in TCA cycle, isocitrate lyase in glyoxylate cycle and fructose-1,6-bisphosphatase in gluconeogenesis. ACRP disturbed the homeostasis of cellular redox potential as well as reduced glutathione status, which is accompanied by an enhanced rate of lipid peroxidation. Annexin V-Cy3/CFDA dual staining clearly showed ACRP induced apoptosis-like death in bacterial cell population. Moreover, immunoblot analyses also indicated apoptosis-like death in ACRP treated bacterial cells, where activation of poly (ADP-ribose) polymerase-1 (PARP) and caspase-3 was noteworthy. It is concluded that metabolic impairment by ACRP in bacterial cells is primarily due to generation of reactive oxygen species and ACRP induced anti-bacterial effect is mediated by metabolic impairment leading to apoptosis-like death in bacterial cells.

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.

Contribution of bacterial cells to lacustrine organic matter based on amino sugars and D-amino acids

NASA Astrophysics Data System (ADS)

Carstens, Dörte; Köllner, Krista E.; Bürgmann, Helmut; Wehrli, Bernhard; Schubert, Carsten J.

2012-07-01

Amino sugars (ASs), D-amino acids (D-AAs), and bacterial cell counts were measured in two Swiss lakes to study the contribution of bacterial cells to organic matter (OM) and the fate of ASs and bacterial amino biomarkers during OM degradation. Concentrations of individual ASs (glucosamine, galactosamine, muramic acid, and mannosamine) in the particulate and total OM pools were analyzed in water-column profiles of Lake Brienz (oligotrophic and oxic throughout the entire water column) and Lake Zug (eutrophic, stratified, and permanently anoxic below 170 m) in spring and in fall. Generally, carbon-normalized AS concentrations decreased with water depth, indicating the preferential decomposition of ASs. For Lake Brienz the relative loss of particulate ASs was higher than in Lake Zug, suggesting enhanced AS turnover in an oligotrophic environment. AS ratio changes in the water column revealed a replacement of plankton biomass with OM from heterotrophic microorganisms with increasing water depth. Similar to the ASs, highest carbon normalized D-AA concentrations were found in the upper water column with decreasing concentrations with depth and an increase close to the sediments. In Lake Zug, an increase in the percentage of D-AAs also showed the involvement of bacteria in OM degradation. Estimations of OM derived from bacterial cells using cell counts and the bacterial biomarkers muramic acid and D-AAs gave similar results. For Lake Brienz 0.2-14% of the organic carbon pool originated from bacterial cells, compared to only 0.1-5% in Lake Zug. Based on our estimates, muramic acid appeared primarily associated with bacterial biomass and not with refractory bacterial necromass. Our study underscores that bacteria are not only important drivers of OM degradation in lacustrine systems, they also represent a significant source of OM themselves, especially in oligotrophic lakes.

Identification of a Supramolecular Functional Architecture of Streptococcus mutans Adhesin P1 on the Bacterial Cell Surface*

PubMed Central

Heim, Kyle P.; Sullan, Ruby May A.; Crowley, Paula J.; El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Tang, Wenxing; Besingi, Richard; Dufrene, Yves F.; Brady, L. Jeannine

2015-01-01

P1 (antigen I/II) is a sucrose-independent adhesin of Streptococcus mutans whose functional architecture on the cell surface is not fully understood. S. mutans cells subjected to mechanical extraction were significantly diminished in adherence to immobilized salivary agglutinin but remained immunoreactive and were readily aggregated by fluid-phase salivary agglutinin. Bacterial adherence was restored by incubation of postextracted cells with P1 fragments that contain each of the two known adhesive domains. In contrast to untreated cells, glutaraldehyde-treated bacteria gained reactivity with anti-C-terminal monoclonal antibodies (mAbs), whereas epitopes recognized by mAbs against other portions of the molecule were masked. Surface plasmon resonance experiments demonstrated the ability of apical and C-terminal fragments of P1 to interact. Binding of several different anti-P1 mAbs to unfixed cells triggered release of a C-terminal fragment from the bacterial surface, suggesting a novel mechanism of action of certain adherence-inhibiting antibodies. We also used atomic force microscopy-based single molecule force spectroscopy with tips bearing various mAbs to elucidate the spatial organization and orientation of P1 on living bacteria. The similar rupture lengths detected using mAbs against the head and C-terminal regions, which are widely separated in the tertiary structure, suggest a higher order architecture in which these domains are in close proximity on the cell surface. Taken together, our results suggest a supramolecular organization in which additional P1 polypeptides, including the C-terminal segment originally identified as antigen II, associate with covalently attached P1 to form the functional adhesive layer. PMID:25666624

Identification of a supramolecular functional architecture of Streptococcus mutans adhesin P1 on the bacterial cell surface.

PubMed

Heim, Kyle P; Sullan, Ruby May A; Crowley, Paula J; El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Tang, Wenxing; Besingi, Richard; Dufrene, Yves F; Brady, L Jeannine

2015-04-03

P1 (antigen I/II) is a sucrose-independent adhesin of Streptococcus mutans whose functional architecture on the cell surface is not fully understood. S. mutans cells subjected to mechanical extraction were significantly diminished in adherence to immobilized salivary agglutinin but remained immunoreactive and were readily aggregated by fluid-phase salivary agglutinin. Bacterial adherence was restored by incubation of postextracted cells with P1 fragments that contain each of the two known adhesive domains. In contrast to untreated cells, glutaraldehyde-treated bacteria gained reactivity with anti-C-terminal monoclonal antibodies (mAbs), whereas epitopes recognized by mAbs against other portions of the molecule were masked. Surface plasmon resonance experiments demonstrated the ability of apical and C-terminal fragments of P1 to interact. Binding of several different anti-P1 mAbs to unfixed cells triggered release of a C-terminal fragment from the bacterial surface, suggesting a novel mechanism of action of certain adherence-inhibiting antibodies. We also used atomic force microscopy-based single molecule force spectroscopy with tips bearing various mAbs to elucidate the spatial organization and orientation of P1 on living bacteria. The similar rupture lengths detected using mAbs against the head and C-terminal regions, which are widely separated in the tertiary structure, suggest a higher order architecture in which these domains are in close proximity on the cell surface. Taken together, our results suggest a supramolecular organization in which additional P1 polypeptides, including the C-terminal segment originally identified as antigen II, associate with covalently attached P1 to form the functional adhesive layer. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Staphylococcus epidermidis adhesion on surface-treated open-cell Ti6Al4V foams.

PubMed

Türkan, Uğur; Güden, Mustafa; Sudağıdan, Mert

2016-06-01

The effect of alkali and nitric acid surface treatments on the adhesion of Staphylococcus epidermidis to the surface of 60% porous open-cell Ti6Al4V foam was investigated. The resultant surface roughness of foam particles was determined from the ground flat surfaces of thin foam specimens. Alkali treatment formed a porous, rough Na2Ti5O11 surface layer on Ti6Al4V particles, while nitric acid treatment increased the number of undulations on foam flat and particle surfaces, leading to the development of finer surface topographical features. Both surface treatments increased the nanometric-scale surface roughness of particles and the number of bacteria adhering to the surface, while the adhesion was found to be significantly higher in alkali-treated foam sample. The significant increase in the number of bacterial attachment on the alkali-treated sample was attributed to the formation of a highly porous and nanorough Na2Ti5O11 surface layer.

New method for estimating bacterial cell abundances in natural samples by use of sublimation

NASA Technical Reports Server (NTRS)

Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

2004-01-01

We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples, including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert, were heated to a temperature of 500 degrees C for several seconds under reduced pressure. The sublimate was collected on a cold finger, and the amount of adenine released from the samples was then determined by high-performance liquid chromatography with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approximately 10(5) to 10(9) E. coli cell equivalents per gram. For most of these samples, the sublimation-based cell counts were in agreement with total bacterial counts obtained by traditional DAPI (4,6-diamidino-2-phenylindole) staining.

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

Vehicles, Replicators, and Intercellular Movement of Genetic Information: Evolutionary Dissection of a Bacterial Cell

PubMed Central

Jalasvuori, Matti

2012-01-01

Prokaryotic biosphere is vastly diverse in many respects. Any given bacterial cell may harbor in different combinations viruses, plasmids, transposons, and other genetic elements along with their chromosome(s). These agents interact in complex environments in various ways causing multitude of phenotypic effects on their hosting cells. In this discussion I perform a dissection for a bacterial cell in order to simplify the diversity into components that may help approach the ocean of details in evolving microbial worlds. The cell itself is separated from all the genetic replicators that use the cell vehicle for preservation and propagation. I introduce a classification that groups different replicators according to their horizontal movement potential between cells and according to their effects on the fitness of their present host cells. The classification is used to discuss and improve the means by which we approach general evolutionary tendencies in microbial communities. Moreover, the classification is utilized as a tool to help formulating evolutionary hypotheses and to discuss emerging bacterial pathogens as well as to promote understanding on the average phenotypes of different replicators in general. It is also discussed that any given biosphere comprising prokaryotic cell vehicles and genetic replicators may naturally evolve to have horizontally moving replicators of various types. PMID:22567533

Gut microbial translocation corrupts myeloid cell function to control bacterial infection during liver cirrhosis.

PubMed

Hackstein, Carl-Philipp; Assmus, Lisa Mareike; Welz, Meike; Klein, Sabine; Schwandt, Timo; Schultze, Joachim; Förster, Irmgard; Gondorf, Fabian; Beyer, Marc; Kroy, Daniela; Kurts, Christian; Trebicka, Jonel; Kastenmüller, Wolfgang; Knolle, Percy A; Abdullah, Zeinab

2017-03-01

Patients with liver cirrhosis suffer from increased susceptibility to life-threatening bacterial infections that cause substantial morbidity. Experimental liver fibrosis in mice induced by bile duct ligation or CCl 4 application was used to characterise the mechanisms determining failure of innate immunity to control bacterial infections. In murine liver fibrosis, translocation of gut microbiota induced tonic type I interferon (IFN) expression in the liver. Such tonic IFN expression conditioned liver myeloid cells to produce high concentrations of IFN upon intracellular infection with Listeria that activate cytosolic pattern recognition receptors. Such IFN-receptor signalling caused myeloid cell interleukin (IL)-10 production that corrupted antibacterial immunity, leading to loss of infection-control and to infection-associated mortality. In patients with liver cirrhosis, we also found a prominent liver IFN signature and myeloid cells showed increased IL-10 production after bacterial infection. Thus, myeloid cells are both source and target of IFN-induced and IL-10-mediated immune dysfunction. Antibody-mediated blockade of IFN-receptor or IL-10-receptor signalling reconstituted antibacterial immunity and prevented infection-associated mortality in mice with liver fibrosis. In severe liver fibrosis and cirrhosis, failure to control bacterial infection is caused by augmented IFN and IL-10 expression that incapacitates antibacterial immunity of myeloid cells. Targeted interference with the immune regulatory host factors IL-10 and IFN reconstitutes antibacterial immunity and may be used as therapeutic strategy to control bacterial infections in patients with liver cirrhosis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

[Changes and clinical significance of peripheral blood natural killer cells in neonates with bacterial pneumonia].

PubMed

Li, Qiuling; Weng, Kaizhi; Zhu, Ling; Mei, Xuqiao; Xu, Liping; Lin, Jiehua

2014-10-01

To detect the percentage of total natural killer (NK) cells and its different populations in the peripheral blood from neonates with bacterial pneumonia and discuss the clinical significance of NK cells in the pathogenesis of bacterial pneumonia. Flow cytometry was performed to detect the percentages of NK cells and its subsets in peripheral blood lymphocytes from 38 cases of neonatal bacterial pneumonias and 18 cases of normal neonates. Patients recruited were divided into two groups according to hospitalization days and numbers of peripheral leukocytes: hospitalization days within 10 days (including 10 days) as group A, and more than 10 days as group B; the number of peripheral blood leukocytes <5.0×10(9)/L or >20.0×10(9)/L as severe infection group, and 5.0×10(9)/L< number of peripheral blood leukocytes <20.0×10(9)/L as mild infection group. The percentages of peripheral blood NK cells and CD3(-)CD56(neg)CD16(bright) subset in the neonates with bacterial pneumonia were significantly lower than those of the normal newborns (P<0.01), but there were no statistically significant differences in CD3(-)CD56(bright)CD16(neg/dim) and CD3(-)CD56(dim)CD16(bright) subsets. The percentage of CD3(-)CD56(neg)CD16(bright) subset in group A was significantly lower than that of the normal newborns (P<0.01), while the percentages of the total NK cells and other subsets had no statistical significance. The neonates with bacterial pneumonia had significantly lower percentages of the total NK cells and CD3(-)CD56(neg)CD16(bright) subset in group B as compared with the normal neonates (P<0.01). And the percentages of the total NK cells and its subsets in group B were also lower than those in group A (P<0.05). The percentages of NK cells and each subset in severe infection group were significantly lower than those in mild infection group (P<0.05). To the neonates who suffer from bacterial pneumonia, the more serious and the longer hospital stay, the lower the percentages of NK

Chemical Changes in Nonthermal Plasma-Treated N-Acetylcysteine (NAC) Solution and Their Contribution to Bacterial Inactivation.

PubMed

Ercan, Utku K; Smith, Josh; Ji, Hai-Feng; Brooks, Ari D; Joshi, Suresh G

2016-02-02

In continuation of our previous reports on the broad-spectrum antimicrobial activity of atmospheric non-thermal dielectric barrier discharge (DBD) plasma treated N-Acetylcysteine (NAC) solution against planktonic and biofilm forms of different multidrug resistant microorganisms, we present here the chemical changes that mediate inactivation of Escherichia coli. In this study, the mechanism and products of the chemical reactions in plasma-treated NAC solution are shown. UV-visible spectrometry, FT-IR, NMR, and colorimetric assays were utilized for chemical characterization of plasma treated NAC solution. The characterization results were correlated with the antimicrobial assays using determined chemical species in solution in order to confirm the major species that are responsible for antimicrobial inactivation. Our results have revealed that plasma treatment of NAC solution creates predominantly reactive nitrogen species versus reactive oxygen species, and the generated peroxynitrite is responsible for significant bacterial inactivation.

Biosensors of bacterial cells.

PubMed

Burlage, Robert S; Tillmann, Joshua

2017-07-01

Biosensors are devices which utilize both an electrical component (transducer) and a biological component to study an environment. They are typically used to examine biological structures, organisms and processes. The field of biosensors has now become so large and varied that the technology can often seem impenetrable. Yet the principles which underlie the technology are uncomplicated, even if the details of the mechanisms are elusive. In this review we confine our analysis to relatively current advancements in biosensors for the detection of whole bacterial cells. This includes biosensors which rely on an added labeled component and biosensors which do not have a labeled component and instead detect the binding event or bound structure on the transducer. Methods to concentrate the bacteria prior to biosensor analysis are also described. The variety of biosensor types and their actual and potential uses are described. Copyright © 2016 Elsevier B.V. All rights reserved.

Visual Outcomes in Treated Bacterial Keratitis: Four Years of Prospective Follow-up

PubMed Central

McClintic, Scott M.; Prajna, Namperumalsamy V.; Srinivasan, Muthiah; Mascarenhas, Jeena; Lalitha, Prajna; Rajaraman, Revathi; Oldenburg, Catherine E.; O'Brien, Kieran S.; Ray, Kathryn J.; Acharya, Nisha R.; Lietman, Thomas M.; Keenan, Jeremy D.

2014-01-01

Purpose. We described the change in visual acuity experienced by eyes successfully treated for bacterial keratitis. Methods. This was a prospective cohort study of a subset of study participants who had previously enrolled in the Steroids for Corneal Ulcers Trial (SCUT). All study participants had been diagnosed with culture-proven bacterial keratitis before enrollment in SCUT and subsequently were randomized to adjunctive topical corticosteroids or placebo. During SCUT, we monitored study participants at enrollment, 3 weeks, 3 months, and 12 months. We invited a subset to complete a comprehensive eye examination approximately 4 years after enrollment in SCUT. Certified refractionists assessed best spectacle-corrected visual acuity (BSCVA) using the same protocol at each study visit. Results. We examined 50 SCUT participants at 4 years after enrollment. Among those in this cohort, mean logMAR BSCVA at enrollment was 0.85 (Snellen equivalent, 20/160; 95% confidence interval [CI], 0.71–0.99). On average, visual acuity improved by 2.9 logMAR lines from enrollment to 3 weeks (P < 0.001), 1.2 lines from 3 weeks to 3 months (P = 0.002), and 0.8 lines from 3 to 12 months (P = 0.01). The BSCVA did not change significantly between 12 months and 4 years (0.04-line improvement, P = 0.88). After controlling for visual acuity at enrollment, BSCVA was not significantly different between the corticosteroid and placebo groups at 4 years (P = 0.53). Conclusions. Cases of bacterial keratitis may continue to demonstrate improvements in visual acuity up to 12 months following diagnosis, but further improvements are unlikely. These findings may guide the appropriate timing of surgical intervention in these patients. (ClinicalTrials.gov number, NCT00324168.) PMID:24618327

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

Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms.

PubMed

Sugano, Marika; Morisaki, Hirobumi; Negishi, Yoichi; Endo-Takahashi, Yoko; Kuwata, Hirotaka; Miyazaki, Takashi; Yamamoto, Matsuo

2016-01-01

Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail. The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms. Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy. The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms. In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

PubMed Central

Kapasi, Anokhi J.; Dittrich, Sabine; González, Iveth J.; Rodwell, Timothy C.

2016-01-01

Background In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics. Methods Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers. Findings Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections. Discussion This manuscript provides a summary

Continuous monitoring of bacterial attachment

NASA Technical Reports Server (NTRS)

Koeing, D. W.; Mishra, S. K.; Pierson, D. L.

1994-01-01

A major concern with the Space Station Freedom (SSF) water supply system is the control of longterm microbial contamination and biofilm development in the water storage and distribution systems. These biofilms have the potential for harboring pathogens as well as microbial strains containing resistance factors that could negatively influence crew health. The proposed means for disinfecting the water system on SSF (iodine) may encourage the selection of resistant strains. In fact, biofilm bacteria were observed in water lines from the Space Shuttle Columbia (OV-102); therefore, an alternative remediation method is required to disinfect spacecraft water lines. A thorough understanding of colonization events and the physiological parameters that will influence bacteria adhesion is required. The limiting factor for development of this technology is the ability to continuously monitor adhesion events and the effects of biocides on sessile bacteria. Methods were developed to allow bacterial adhesion and subsequent biocidal treatment to be monitored continuously. This technique couples automated image analysis with a continuous flow of a bacterial suspension through an optical flow cell. A strain of Pseudomonas cepacia isolated from the water supply of the Space Shuttle Discovery (OV-103) during STS-39 was grown in a nitrogen-limited continuous culture. This culture was challenged continuously with iodine during growth, and the adhesion characteristics of this strain was measure with regard to flow rate. Various biocides (ozone, hypochlorite, and iodine) were added to the flow stream to evaluate how well each chemical removed the bacteria. After biocide treatment, a fresh bacterial suspension was introduced into the flow cell, and the attachment rate was evaluated on the previously treated surface. This secondary fouling was again treated with biocide to determine the efficacy of multiple batch chemical treatments in removing biofilm.

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

It is critical to develop highly effective antimicrobial agents that are not harmful to humans and do not present adverse effects on the environment. Although antimicrobial studies of graphene-based nanomaterials are still quite limited, some researchers have paid particular attention to such nanocomposites as promising candidates for the next generation of antimicrobial agents. The polyvinyl-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.It is critical to develop highly effective antimicrobial agents that are not harmful to humans and do not present adverse effects on the environment. Although antimicrobial studies of graphene-based nanomaterials are still quite limited, some researchers have paid particular attention to such nanocomposites as promising candidates for the next generation of antimicrobial agents. The polyvinyl

Dislocation-mediated growth of bacterial cell walls

PubMed Central

Amir, Ariel; Nelson, David R.

2012-01-01

Recent experiments have illuminated a remarkable growth mechanism of rod-shaped bacteria: proteins associated with cell wall extension move at constant velocity in circles oriented approximately along the cell circumference [Garner EC, et al., (2011) Science 333:222–225], [Domínguez-Escobar J, et al. (2011) Science 333:225–228], [van Teeffelen S, et al. (2011) PNAS 108:15822–15827]. We view these as dislocations in the partially ordered peptidoglycan structure, activated by glycan strand extension machinery, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Generation and motion of these interacting defects lead to surprising effects arising from the cylindrical geometry, with important implications for growth. We also discuss how long range elastic interactions and turgor pressure affect the dynamics of the fraction of actively moving dislocations in the bacterial cell wall. PMID:22660931

Chemical Changes in Nonthermal Plasma-Treated N-Acetylcysteine (NAC) Solution and Their Contribution to Bacterial Inactivation

PubMed Central

Ercan, Utku K.; Smith, Josh; Ji, Hai-Feng; Brooks, Ari D.; Joshi, Suresh G.

2016-01-01

In continuation of our previous reports on the broad-spectrum antimicrobial activity of atmospheric non-thermal dielectric barrier discharge (DBD) plasma treated N-Acetylcysteine (NAC) solution against planktonic and biofilm forms of different multidrug resistant microorganisms, we present here the chemical changes that mediate inactivation of Escherichia coli. In this study, the mechanism and products of the chemical reactions in plasma-treated NAC solution are shown. UV-visible spectrometry, FT-IR, NMR, and colorimetric assays were utilized for chemical characterization of plasma treated NAC solution. The characterization results were correlated with the antimicrobial assays using determined chemical species in solution in order to confirm the major species that are responsible for antimicrobial inactivation. Our results have revealed that plasma treatment of NAC solution creates predominantly reactive nitrogen species versus reactive oxygen species, and the generated peroxynitrite is responsible for significant bacterial inactivation. PMID:26832829

Bacterial actin MreB assembles in complex with cell shape protein RodZ.

PubMed

van den Ent, Fusinita; Johnson, Christopher M; Persons, Logan; de Boer, Piet; Löwe, Jan

2010-03-17

Bacterial actin homologue MreB is required for cell shape maintenance in most non-spherical bacteria, where it assembles into helical structures just underneath the cytoplasmic membrane. Proper assembly of the actin cytoskeleton requires RodZ, a conserved, bitopic membrane protein that colocalises to MreB and is essential for cell shape determination. Here, we present the first crystal structure of bacterial actin engaged with a natural partner and provide a clear functional significance of the interaction. We show that the cytoplasmic helix-turn-helix motif of Thermotoga maritima RodZ directly interacts with monomeric as well as filamentous MreB and present the crystal structure of the complex. In vitro and in vivo analyses of mutant T. maritima and Escherichia coli RodZ validate the structure and reveal the importance of the MreB-RodZ interaction in the ability of cells to propagate as rods. Furthermore, the results elucidate how the bacterial actin cytoskeleton might be anchored to the membrane to help constrain peptidoglycan synthesis in the periplasm.

The interaction of bacterial magnetosomes and human liver cancer cells in vitro

NASA Astrophysics Data System (ADS)

Wang, Pingping; Chen, Chuanfang; Chen, Changyou; Li, Yue; Pan, Weidong; Song, Tao

2017-04-01

As the biogenic magnetic nanomaterial, bacterial magnetic nanoparticles, namely magnetosomes, provide many advantages for potential biomedical applications. As such, interactions among magnetosomes and target cells should be elucidated to develop their bioapplications and evaluate their biocompatibilities. In this study, the interaction of magnetosomes and human liver cancer HepG2 cells was examined. Prussian blue staining revealed numerous stained particles in or on the cells. Intracellular iron concentrations, measured through inductively coupled plasma optical emission spectroscopy, increased with the increasing concentration of the magnetosomes. Transmission electron microscopy images showed that magnetosomes could be internalized in cells, mainly encapsulated in membrane vesicles, such as endosomes and lysosomes, and partly found as free particles in the cytosol. Some of the magnetosomes on cellular surfaces were encapsulated through cell membrane ruffling, which is the initiating process of endocytosis. Applying low temperature treatment and using specific endocytic inhibitors, we validated that macropinocytosis and clathrin-mediated endocytosis were involved in magnetosome uptake by HepG2 cells. Consequently, we revealed the interaction and intrinsic endocytic mechanisms of magnetosomes and HepG2 cells. This study provides a basis for the further research on bacterial magnetosome applications in liver diseases.

One Bacterial Cell, One Complete Genome

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

Woyke, Tanja; Tighe, Damon; Mavrommatis, Konstantinos

2010-04-26

While the bulk of the finished microbial genomes sequenced to date are derived from cultured bacterial and archaeal representatives, the vast majority of microorganisms elude current culturing attempts, severely limiting the ability to recover complete or even partial genomes from these environmental species. Single cell genomics is a novel culture-independent approach, which enables access to the genetic material of an individual cell. No single cell genome has to our knowledge been closed and finished to date. Here we report the completed genome from an uncultured single cell of Candidatus Sulcia muelleri DMIN. Digital PCR on single symbiont cells isolated frommore » the bacteriome of the green sharpshooter Draeculacephala minerva bacteriome allowed us to assess that this bacteria is polyploid with genome copies ranging from approximately 200?900 per cell, making it a most suitable target for single cell finishing efforts. For single cell shotgun sequencing, an individual Sulcia cell was isolated and whole genome amplified by multiple displacement amplification (MDA). Sanger-based finishing methods allowed us to close the genome. To verify the correctness of our single cell genome and exclude MDA-derived artifacts, we independently shotgun sequenced and assembled the Sulcia genome from pooled bacteriomes using a metagenomic approach, yielding a nearly identical genome. Four variations we detected appear to be genuine biological differences between the two samples. Comparison of the single cell genome with bacteriome metagenomic sequence data detected two single nucleotide polymorphisms (SNPs), indicating extremely low genetic diversity within a Sulcia population. This study demonstrates the power of single cell genomics to generate a complete, high quality, non-composite reference genome within an environmental sample, which can be used for population genetic analyzes.« less

Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure.

PubMed

Li, Jiabao; Rui, Junpeng; Yao, Minjie; Zhang, Shiheng; Yan, Xuefeng; Wang, Yuanpeng; Yan, Zhiying; Li, Xiangzhen

2015-01-01

The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: [Formula: see text] (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters.

Assessment of temporal and spatial evolution of bacterial communities in a biological sand filter mesocosm treating winery wastewater.

PubMed

Ramond, J-B; Welz, P J; Tuffin, M I; Burton, S G; Cowan, D A

2013-07-01

To assess the impact of winery wastewater (WW) on biological sand filter (BSF) bacterial community structures, and to evaluate whether BSFs can constitute alternative and valuable treatment- processes to remediate WW. During 112 days, WW was used to contaminate a BSF mesocosm (length 173 cm/width 106 cm/depth 30 cm). The effect of WW on bacterial communities of four BSF microenvironments (surface/deep, inlet/outlet) was investigated using terminal-restriction fragment length polymorphism (T-RFLP). BSF achieved high Na (95·1%), complete Cl and almost complete chemical oxygen demand (COD) (98·0%) and phenolic (99·2%) removals. T-RFLP analysis combined with anosim revealed that WW significantly modified the surface and deep BSF bacterial communities. BSF provided high COD, phenolic and salt removals throughout the experiment. WW-selected bacterial communities were thus able to tolerate and/or degrade WW, suggesting that community composition does not alter BSF performances. However, biomass increased significantly in the WW-impacted surface sediments, which could later lead to system clogging and should thus be monitored. BSFs constitute alternatives to constructed wetlands to treat agri effluents such as WW. To our knowledge, this study is the first unravelling the responses of BSF bacterial communities to contamination and suggests that WW-selected BSF communities maintained high removal performances. Journal of Applied Microbiology © 2013 The Society for Applied Microbiology.

Determination and Variation of Core Bacterial Community in a Two-Stage Full-Scale Anaerobic Reactor Treating High-Strength Pharmaceutical Wastewater.

PubMed

Ma, Haijun; Ye, Lin; Hu, Haidong; Zhang, Lulu; Ding, Lili; Ren, Hongqiang

2017-10-28

Knowledge on the functional characteristics and temporal variation of anaerobic bacterial populations is important for better understanding of the microbial process of two-stage anaerobic reactors. However, owing to the high diversity of anaerobic bacteria, close attention should be prioritized to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. In this study, using MiSeq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a two-stage upflow blanket filter reactor treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct, in that the FS core bacterial community was indicated to be more related to a higher-level fermentation process, and the SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of the FS and SS core bacterial communities to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the Order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales, and Thermotogales might play key roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advance our knowledge about the core bacterial community and its temporal variability for future comparative research and improvement of the two-stage anaerobic system operation.

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.

The Disruptive Effect of Lysozyme on the Bacterial Cell Wall Explored by an "In-Silico" Structural Outlook

ERIC Educational Resources Information Center

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…

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

Human Lung Fibroblasts Present Bacterial Antigens to Autologous Lung Th Cells.

PubMed

Hutton, Andrew J; Polak, Marta E; Spalluto, C Mirella; Wallington, Joshua C; Pickard, Chris; Staples, Karl J; Warner, Jane A; Wilkinson, Tom M A

2017-01-01

Lung fibroblasts are key structural cells that reside in the submucosa where they are in contact with large numbers of CD4 + Th cells. During severe viral infection and chronic inflammation, the submucosa is susceptible to bacterial invasion by lung microbiota such as nontypeable Haemophilus influenzae (NTHi). Given their proximity in tissue, we hypothesized that human lung fibroblasts play an important role in modulating Th cell responses to NTHi. We demonstrate that fibroblasts express the critical CD4 + T cell Ag-presentation molecule HLA-DR within the human lung, and that this expression can be recapitulated in vitro in response to IFN-γ. Furthermore, we observed that cultured lung fibroblasts could internalize live NTHi. Although unable to express CD80 and CD86 in response to stimulation, fibroblasts expressed the costimulatory molecules 4-1BBL, OX-40L, and CD70, all of which are related to memory T cell activation and maintenance. CD4 + T cells isolated from the lung were predominantly (mean 97.5%) CD45RO + memory cells. Finally, cultured fibroblasts activated IFN-γ and IL-17A cytokine production by autologous, NTHi-specific lung CD4 + T cells, and cytokine production was inhibited by a HLA-DR blocking Ab. These results indicate a novel role for human lung fibroblasts in contributing to responses against bacterial infection through activation of bacteria-specific CD4 + T cells. Copyright © 2016 by The American Association of Immunologists, Inc.

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.

Antimicrobial activity of endemic Crataegus tanacetifolia (Lam.) Pers and observation of the inhibition effect on bacterial cells.

PubMed

Benli, Mehlika; Yiğit, Nazife; Geven, Fatmagül; Güney, Kerim; Bingöl, Umit

2008-12-01

Up to now an increasing number of antibiotic-resistant bacteria have been reported and thus new natural therapeutic agents are needed in order to eradicate these pathogens. Through the discovery of plants such as Crataegus tanacetifolia (Lam.) Pers that have antimicrobial activity, it will be possible to discover new natural drugs serving as chemotherapeutic agents for the treatment of nosocomial pathogens and take these antibiotic-resistant bacteria under control. The objective of the present study was to determine antimicrobial activity and the activity mechanism of C. tanacetifolia plant extract. The leaves of C. tanacetifolia, which is an endemic plant, were extracted using methanol and tested against 10 bacterial and 4 yeast strains by using a drop method. It was observed that the plant extract had antibacterial effects on Bacillus subtilis, Shigella, Staphylococcus aureus, and Listeria monocytogenes among the microorganisms that were tested. Minimum inhibitory concentration (MIC) results obtained at the end of an incubation of 24 h were found to be > or =6.16 mg ml(-1) for B. subtilis, < 394 mg ml(-1) for Shigella, and > or =3.08 mg ml(-1) for L. monocytogenes and S. aureus and minimum bactericidal concentration (MBC) were found as > or =24.63 mg ml(-1) for B. subtilis, > or =394 mg ml(-1) for Shigella, > or =6.16 mg ml(-1) for L. monocytogenes, and > or =98.5 mg ml(-1) for S. aureus. According to the MBC results, it was found that the plant extract had bactericidal effects and in order to explain the activity mechanism and cell deformation of bacterial strains treated with plant extract, the scanning electron microscopy (SEM) was used. The results of SEM showed that the treated cells appeared shrunken and there was degradation of the cell walls. This study, in which the antibacterial effect of C. tanacetifolia was demonstrated, will be a base for further investigations on advanced purification and effect mechanism of action of its active compounds.

Bacterial Immobilization for Imaging by Atomic Force Microscopy

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

Allison, David P; Sullivan, Claretta; Mortensen, Ninell P

2011-01-01

AFM is a high-resolution (nm scale) imaging tool that mechanically probes a surface. It has the ability to image cells and biomolecules, in a liquid environment, without the need to chemically treat the sample. In order to accomplish this goal, the sample must sufficiently adhere to the mounting surface to prevent removal by forces exerted by the scanning AFM cantilever tip. In many instances, successful imaging depends on immobilization of the sample to the mounting surface. Optimally, immobilization should be minimally invasive to the sample such that metabolic processes and functional attributes are not compromised. By coating freshly cleaved micamore » surfaces with porcine (pig) gelatin, negatively charged bacteria can be immobilized on the surface and imaged in liquid by AFM. Immobilization of bacterial cells on gelatin-coated mica is most likely due to electrostatic interaction between the negatively charged bacteria and the positively charged gelatin. Several factors can interfere with bacterial immobilization, including chemical constituents of the liquid in which the bacteria are suspended, the incubation time of the bacteria on the gelatin coated mica, surface characteristics of the bacterial strain and the medium in which the bacteria are imaged. Overall, the use of gelatin-coated mica is found to be generally applicable for imaging microbial cells.« less

Homogenizing bacterial cell factories: Analysis and engineering of phenotypic heterogeneity.

PubMed

Binder, Dennis; Drepper, Thomas; Jaeger, Karl-Erich; Delvigne, Frank; Wiechert, Wolfgang; Kohlheyer, Dietrich; Grünberger, Alexander

2017-07-01

In natural habitats, microbes form multispecies communities that commonly face rapidly changing and highly competitive environments. Thus, phenotypic heterogeneity has evolved as an innate and important survival strategy to gain an overall fitness advantage over cohabiting competitors. However, in defined artificial environments such as monocultures in small- to large-scale bioreactors, cell-to-cell variations are presumed to cause reduced production yields as well as process instability. Hence, engineering microbial production toward phenotypic homogeneity is a highly promising approach for synthetic biology and bioprocess optimization. In this review, we discuss recent studies that have unraveled the cell-to-cell heterogeneity observed during bacterial gene expression and metabolite production as well as the molecular mechanisms involved. In addition, current single-cell technologies are briefly reviewed with respect to their applicability in exploring cell-to-cell variations. We highlight emerging strategies and tools to reduce phenotypic heterogeneity in biotechnological expression setups. Here, strain or inducer modifications are combined with cell physiology manipulations to achieve the ultimate goal of equalizing bacterial populations. In this way, the majority of cells can be forced into high productivity, thus reducing less productive subpopulations that tend to consume valuable resources during production. Modifications in uptake systems, inducer molecules or nutrients represent valuable tools for diminishing heterogeneity. Finally, we address the challenge of transferring homogeneously responding cells into large-scale bioprocesses. Environmental heterogeneity originating from extrinsic factors such as stirring speed and pH, oxygen, temperature or nutrient distribution can significantly influence cellular physiology. We conclude that engineering microbial populations toward phenotypic homogeneity is an increasingly important task to take biotechnological

Dysregulated luminal bacterial antigen-specific T-cell responses and antigen-presenting cell function in HLA-B27 transgenic rats with chronic colitis

PubMed Central

Qian, Bi-Feng; Tonkonogy, Susan L; Hoentjen, Frank; Dieleman, Levinus A; Sartor, R Balfour

2005-01-01

HLA-B27/β2 microglobulin transgenic (TG) rats spontaneously develop T-cell-mediated colitis when colonized with normal commensal bacteria, but remain disease-free under germ-free conditions. We investigated regulation of in vitro T-cell responses to enteric bacterial components. Bacterial lysates prepared from the caecal contents of specific pathogen-free (SPF) rats stimulated interferon-γ (IFN-γ) production by TG but not non-TG mesenteric lymph node (MLN) cells. In contrast, essentially equivalent amounts of interleukin-10 (IL-10) were produced by TG and non-TG cells. However, when cells from MLNs of non-TG rats were cocultured with TG MLN cells, no suppression of IFN-γ production was noted. Both non-TG and TG antigen-presenting cells (APC) pulsed with caecal bacterial lysate were able to induce IFN-γ production by TG CD4+ cells, although non-TG APC were more efficient than TG APC. Interestingly, the addition of exogenous IL-10 inhibited non-TG APC but not TG APC stimulation of IFN-γ production by cocultured TG CD4+ lymphocytes. Conversely, in the presence of exogenous IFN-γ, production of IL-10 was significantly lower in the supernatants of TG compared to non-TG APC cultures. We conclude that commensal luminal bacterial components induce exaggerated in vitro IFN-γ responses in HLA-B27 TG T cells, which may in turn inhibit the production of regulatory molecules, such as IL-10. Alterations in the production of IFN-γ, and in responses to this cytokine, as well as possible resistance of TG cells to suppressive regulation could together contribute to the development of chronic colitis in TG rats. PMID:16108823

Enhanced Toxic Metal Accumulation in Engineered Bacterial Cells Expressing Arabidopsis thaliana Phytochelatin Synthase

PubMed Central

Sauge-Merle, Sandrine; Cuiné, Stéphan; Carrier, Patrick; Lecomte-Pradines, Catherine; Luu, Doan-Trung; Peltier, Gilles

2003-01-01

Phytochelatins (PCs) are metal-binding cysteine-rich peptides, enzymatically synthesized in plants and yeasts from glutathione in response to heavy metal stress by PC synthase (EC 2.3.2.15). In an attempt to increase the ability of bacterial cells to accumulate heavy metals, the Arabidopsis thaliana gene encoding PC synthase (AtPCS) was expressed in Escherichia coli. A marked accumulation of PCs was observed in vivo together with a decrease in the glutathione cellular content. When bacterial cells expressing AtPCS were placed in the presence of heavy metals such as cadmium or the metalloid arsenic, cellular metal contents were increased 20- and 50-fold, respectively. We discuss the possibility of using genes of the PC biosynthetic pathway to design bacterial strains or higher plants with increased abilities to accumulate toxic metals, and also arsenic, for use in bioremediation and/or phytoremediation processes. PMID:12514032

Chemical and Enzymatic Strategies for Bacterial and Mammalian Cell Surface Engineering.

PubMed

Bi, Xiaobao; Yin, Juan; Chen Guanbang, Ashley; Liu, Chuan-Fa

2018-06-07

The cell surface serves important functions such as the regulation of cell-cell and cell-environment interactions. The understanding and manipulation of the cell surface is important for a wide range of fundamental studies of cellular behavior and for biotechnological and medical applications. With the rapid advance of biology, chemistry and materials science, many strategies have been developed for the functionalization of bacterial and mammalian cell surfaces. Here, we review the recent development of chemical and enzymatic approaches to cell surface engineering with particular emphasis on discussing the advantages and limitations of each of these strategies. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple and novel modification of comet assay for determination of bacteriophage mediated bacterial cell lysis.

PubMed

Khairnar, Krishna; Sanmukh, Swapnil; Chandekar, Rajshree; Paunikar, Waman

2014-07-01

The comet assay is the widely used method for in vitro toxicity testing which is also an alternative to the use of animal models for in vivo testing. Since, its inception in 1984 by Ostling and Johansson, it is being modified frequently for a wide range of application. In spite of its wide applicability, unfortunately there is no report of its application in bacteriophages research. In this study, a novel application of comet assay for the detection of bacteriophage mediated bacterial cell lysis was described. The conventional methods in bacteriophage research for studying bacterial lysis by bacteriophages are plaque assay method. It is time consuming, laborious and costly. The lytic activity of bacteriophage devours the bacterial cell which results in the release of bacterial genomic material that gets detected by ethidium bromide staining method by the comet assay protocol. The objective of this study was to compare efficacy of comet assay with different assay used to study phage mediated bacterial lysis. The assay was performed on culture isolates (N=80 studies), modified comet assay appear to have relatively higher sensitivity and specificity than other assay. The results of the study showed that the application of comet assay can be an economical, time saving and less laborious alternative to conventional plaque assay for the detection of bacteriophage mediated bacterial cell lysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure

PubMed Central

Li, Jiabao; Rui, Junpeng; Yao, Minjie; Zhang, Shiheng; Yan, Xuefeng; Wang, Yuanpeng; Yan, Zhiying; Li, Xiangzhen

2015-01-01

The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: NH4+-N (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters. PMID:26648921

Bacterial genome engineering and synthetic biology: combating pathogens.

PubMed

Krishnamurthy, Malathy; Moore, Richard T; Rajamani, Sathish; Panchal, Rekha G

2016-11-04

The emergence and prevalence of multidrug resistant (MDR) pathogenic bacteria poses a serious threat to human and animal health globally. Nosocomial infections and common ailments such as pneumonia, wound, urinary tract, and bloodstream infections are becoming more challenging to treat due to the rapid spread of MDR pathogenic bacteria. According to recent reports by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), there is an unprecedented increase in the occurrence of MDR infections worldwide. The rise in these infections has generated an economic strain worldwide, prompting the WHO to endorse a global action plan to improve awareness and understanding of antimicrobial resistance. This health crisis necessitates an immediate action to target the underlying mechanisms of drug resistance in bacteria. The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic and treatment plans to monitor and treat widespread recalcitrant bacterial infections. Key advances in genetic engineering approaches can successfully aid in targeting and editing pathogenic bacterial genomes for understanding and mitigating drug resistance mechanisms. In this review, we discuss the application of specific genome engineering and SB methods such as recombineering, clustered regularly interspaced short palindromic repeats (CRISPR), and bacterial cell-cell signaling mechanisms for pathogen targeting. The utility of these tools in developing antibacterial strategies such as novel antibiotic production, phage therapy, diagnostics and vaccine production to name a few, are also highlighted. The prevalent use of antibiotics and the spread of MDR bacteria raise the prospect of a post-antibiotic era, which underscores the need for developing novel therapeutics to target MDR pathogens. The development of enabling SB technologies offers promising solutions to deliver safe and effective antibacterial therapies.

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

PubMed

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

2018-01-01

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

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.

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

The acoustic sensor for rapid analysis of bacterial cells in the conductive suspensions.

PubMed

Borodina, I A; Zaitsev, B D; Guliy, O; Teplykh, A A; Shikhabudinov, A M

2017-11-01

The possibility of using the acoustic sensor on the basis of a two-channel delay line for rapid analysis of bacterial cells in the conductive suspensions was investigated. The dependencies of change in phase and insertion loss of output signal of the sensor on conductivity of buffer solution with various concentrations of cells due to a specific interaction "bacterial cells - mini-antibodies" for electrically open and electrically shorted channels of delay line were measured. It has been found that these changes have the most values for the electrically open channel. It has been also shown that the sensor rapidly responds to the specific interaction and the time stabilization of the phase and insertion loss of output signal is less than 10min. Copyright © 2017 Elsevier B.V. All rights reserved.

Diethylaminoethyl-cellulose-bacterial cell immunoadsorbent columns: preparation of serotype-specific globulin and immunofluorescent conjugates for Streptococcus mutans serotypes a and d.

PubMed

McKinney, R M; Thacker, L

1976-04-01

Diethylaminoethyl (DEAE)-cellulose was used as a support material for preparing bacterial cell columns. Pretreatment of the bacterial cells with formalin was essential in obtaining satisfactory adherence of the cells to DEAE-cellulose. Cross-reacting antibodies were removed from antibody preparations against strains of Streptococcus mutans serotypes a and d by adsorption on appropriate bacterial cell columns. S. mutans serotype d was further divided into two subtypes on the basis of immunofluorescent staining with conjugates of immunospecifically adsorbed immunoglobulin G. The DEAE-cellulose-bacterial cell columns were regenerated after use by desorbing the cross-reacting antibodies with low-pH buffer and were used repeatedly over and 18-month period with no detectable loss in effectiveness.

A novel biological recovery approach for PHA employing selective digestion of bacterial biomass in animals.

PubMed

Ong, Su Yean; Zainab-L, Idris; Pyary, Somarajan; Sudesh, Kumar

2018-03-01

Polyhydroxyalkanoate (PHA) is a family of microbial polyesters that is completely biodegradable and possesses the mechanical and thermal properties of some commonly used petrochemical-based plastics. Therefore, PHA is attractive as a biodegradable thermoplastic. It has always been a challenge to commercialize PHA due to the high cost involved in the biosynthesis of PHA via bacterial fermentation and the subsequent purification of the synthesized PHA from bacterial cells. Innovative enterprise by researchers from various disciplines over several decades successfully reduced the cost of PHA production through the efficient use of cheap and renewable feedstock, precisely controlled fermentation process, and customized bacterial strains. Despite the fact that PHA yields have been improved tremendously, the recovery and purification processes of PHA from bacterial cells remain exhaustive and require large amounts of water and high energy input besides some chemicals. In addition, the residual cell biomass ends up as waste that needs to be treated. We have found that some animals can readily feed on the dried bacterial cells that contain PHA granules. The digestive system of the animals is able to assimilate the bacterial cells but not the PHA granules which are excreted in the form of fecal pellets, thus resulting in partial recovery and purification of PHA. In this mini-review, we will discuss this new concept of biological recovery, the selection of the animal model for biological recovery, and the properties and possible applications of the biologically recovered PHA.

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

[Preoperatiove Airway Bacterial Colonization: the Missing Link between Non-small Cell Lung Cancer Following Lobectomy and Postoperative Pneumonia?

PubMed

Gao, Ke; Lai, Yutian; Huang, Jian; Wang, Yifan; Wang, Xiaowei; Che, Guowei

2017-04-20

Surgical procedure is the main method of treating lung cancer. Meanwhile, postoperative pneumonia (POP) is the major cause of perioperative mortality in lung cancer surgery. The preoperative pathogenic airway bacterial colonization is an independent risk factor causing postoperative pulmonary complications (PPC). This cross-sectional study aimed to explore the relationship between preoperative pathogenic airway bacterial colonization and POP in lung cancer and to identify the high-risk factors of preoperative pathogenic airway bacterial colonization. A total of 125 patients with non-small cell lung cancer (NSCLC) underwent thoracic surgery in six hospitals of Chengdu between May 2015 and January 2016. Preoperative pathogenic airway bacterial colonization was detected in all patients via fiber bronchoscopy. Patients' PPC, high-risk factors, clinical characteristics, and the serum surfactant protein D (SP-D) level were also analyzed. The incidence of preoperative pathogenic airway bacterial colonization among NSCLC patients was 15.2% (19/125). Up to 22 strains were identified in the colonization positive group, with Gram-negative bacteria being dominant (86.36%, 19/22). High-risk factors of pathogenic airway bacterial colonization were age (≥75 yr) and smoking index (≥400 cigarettes/year). PPC incidence was significantly higher in the colonization-positive group (42.11%, 8/19) than that in the colonization-negative group (16.04%, 17/106)(P=0.021). POP incidence was significantly higher in the colonization-positive group (26.32%, 5/19) than that in the colonization-negative group (6.60%, 7/106)(P=0.019). The serum SP-D level of patients in the colonization-positive group was remarkably higher than that in the colonization-negative group [(31.25±6.09) vs (28.17±5.23)](P=0.023). The incidence of preoperative pathogenic airway bacterial colonization among NSCLC patients with POP was 41.67% (5/12). This value was 3.4 times higher than that among the patients without

PECAM-1 is involved in neutrophil transmigration across Histophilus somni treated bovine brain endothelial cells.

PubMed

Tiwari, Raksha; Sullivan, J; Czuprynski, C J

2009-09-01

Histophilus somni (H. somni) is a gram-negative bacterial pathogen that causes respiratory, reproductive, and central nervous system disease in cattle. The hallmark of systemic H. somni infection is diffused vasculitis that can lead to an acute central nervous system disease known as thrombotic meningoencephalitis (TME). Because platelet endothelial cell adhesion molecule-1 (PECAM-1) and endothelial nitric oxide synthase (eNOS) play fundamental roles in maintaining homeostasis in blood vessels, we sought to determine if PECAM-1 and eNOS expression play a role in events related to the pathogenesis of TME. Our findings demonstrate that neutrophil transmigration across H. somni-treated TBBEC (SV-40 transformed bovine brain endothelial cell line) was reduced by treatment with anti-PECAM-1 antibodies. Confocal microscopy indicated that H. somni treatment leads to redistribution of PECAM-1 and eNOS on the surface of TBBEC. These findings suggest that PECAM-1 and eNOS may play a role in the early pathogenesis of TME.

Heterologous Expression of Toxins from Bacterial Toxin-Antitoxin Systems in Eukaryotic Cells: Strategies and Applications

PubMed Central

Yeo, Chew Chieng; Abu Bakar, Fauziah; Chan, Wai Ting; Espinosa, Manuel; Harikrishna, Jennifer Ann

2016-01-01

Toxin-antitoxin (TA) systems are found in nearly all prokaryotic genomes and usually consist of a pair of co-transcribed genes, one of which encodes a stable toxin and the other, its cognate labile antitoxin. Certain environmental and physiological cues trigger the degradation of the antitoxin, causing activation of the toxin, leading either to the death or stasis of the host cell. TA systems have a variety of functions in the bacterial cell, including acting as mediators of programmed cell death, the induction of a dormant state known as persistence and the stable maintenance of plasmids and other mobile genetic elements. Some bacterial TA systems are functional when expressed in eukaryotic cells and this has led to several innovative applications, which are the subject of this review. Here, we look at how bacterial TA systems have been utilized for the genetic manipulation of yeasts and other eukaryotes, for the containment of genetically modified organisms, and for the engineering of high expression eukaryotic cell lines. We also examine how TA systems have been adopted as an important tool in developmental biology research for the ablation of specific cells and the potential for utility of TA systems in antiviral and anticancer gene therapies. PMID:26907343

Lipopolysaccharide structure impacts the entry kinetics of bacterial outer membrane vesicles into host cells

PubMed Central

Hadis, Mohammed; Alderwick, Luke

2017-01-01

Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections. PMID:29186191

Isoprenoid Biosynthesis Inhibitors Targeting Bacterial Cell Growth.

PubMed

Desai, Janish; Wang, Yang; Wang, Ke; Malwal, Satish R; Oldfield, Eric

2016-10-06

We synthesized potential inhibitors of farnesyl diphosphate synthase (FPPS), undecaprenyl diphosphate synthase (UPPS), or undecaprenyl diphosphate phosphatase (UPPP), and tested them in bacterial cell growth and enzyme inhibition assays. The most active compounds were found to be bisphosphonates with electron-withdrawing aryl-alkyl side chains which inhibited the growth of Gram-negative bacteria (Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa) at ∼1-4 μg mL -1 levels. They were found to be potent inhibitors of FPPS; cell growth was partially "rescued" by the addition of farnesol or overexpression of FPPS, and there was synergistic activity with known isoprenoid biosynthesis pathway inhibitors. Lipophilic hydroxyalkyl phosphonic acids inhibited UPPS and UPPP at micromolar levels; they were active (∼2-6 μg mL -1 ) against Gram-positive but not Gram-negative organisms, and again exhibited synergistic activity with cell wall biosynthesis inhibitors, but only indifferent effects with other inhibitors. The results are of interest because they describe novel inhibitors of FPPS, UPPS, and UPPP with cell growth inhibitory activities as low as ∼1-2 μg mL -1 . © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The physical boundaries of public goods cooperation between surface-attached bacterial cells

PubMed Central

Weigert, Michael; Kümmerli, Rolf

2017-01-01

Bacteria secrete a variety of compounds important for nutrient scavenging, competition mediation and infection establishment. While there is a general consensus that secreted compounds can be shared and therefore have social consequences for the bacterial collective, we know little about the physical limits of such bacterial social interactions. Here, we address this issue by studying the sharing of iron-scavenging siderophores between surface-attached microcolonies of the bacterium Pseudomonas aeruginosa. Using single-cell fluorescent microscopy, we show that siderophores, secreted by producers, quickly reach non-producers within a range of 100 µm, and significantly boost their fitness. Producers in turn respond to variation in sharing efficiency by adjusting their pyoverdine investment levels. These social effects wane with larger cell-to-cell distances and on hard surfaces. Thus, our findings reveal the boundaries of compound sharing, and show that sharing is particularly relevant between nearby yet physically separated bacteria on soft surfaces, matching realistic natural conditions such as those encountered in soft tissue infections. PMID:28701557

Analysis of gene expression levels in individual bacterial cells without image segmentation

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

Kwak, In Hae; Son, Minjun; Hagen, Stephen J., E-mail: sjhagen@ufl.edu

2012-05-11

Highlights: Black-Right-Pointing-Pointer We present a method for extracting gene expression data from images of bacterial cells. Black-Right-Pointing-Pointer The method does not employ cell segmentation and does not require high magnification. Black-Right-Pointing-Pointer Fluorescence and phase contrast images of the cells are correlated through the physics of phase contrast. Black-Right-Pointing-Pointer We demonstrate the method by characterizing noisy expression of comX in Streptococcus mutans. -- Abstract: Studies of stochasticity in gene expression typically make use of fluorescent protein reporters, which permit the measurement of expression levels within individual cells by fluorescence microscopy. Analysis of such microscopy images is almost invariably based on amore » segmentation algorithm, where the image of a cell or cluster is analyzed mathematically to delineate individual cell boundaries. However segmentation can be ineffective for studying bacterial cells or clusters, especially at lower magnification, where outlines of individual cells are poorly resolved. Here we demonstrate an alternative method for analyzing such images without segmentation. The method employs a comparison between the pixel brightness in phase contrast vs fluorescence microscopy images. By fitting the correlation between phase contrast and fluorescence intensity to a physical model, we obtain well-defined estimates for the different levels of gene expression that are present in the cell or cluster. The method reveals the boundaries of the individual cells, even if the source images lack the resolution to show these boundaries clearly.« less

Cellular damage in bacterial meningitis: an interplay of bacterial and host driven toxicity.

PubMed

Weber, Joerg R; Tuomanen, Elaine I

2007-03-01

Bacterial meningitis is still an important infectious disease causing death and disability. Invasive bacterial infections of the CNS generate some of the most powerful inflammatory responses known in medicine. Although the components of bacterial cell surfaces are now chemically defined in exquisite detail and the interaction with several receptor pathways has been discovered, it is only very recently that studies combining these advanced biochemical and cell biological tools have been done. Additional to the immunological response direct bacterial toxicity has been identified as an important contributor to neuronal damage. A detailed understanding of the complex interaction of bacterial toxicity and host response may generate opportunities for innovative and specific neuroprotective therapies.

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.

Engineering bacterial motility towards hydrogen-peroxide.

PubMed

Virgile, Chelsea; Hauk, Pricila; Wu, Hsuan-Chen; Shang, Wu; Tsao, Chen-Yu; Payne, Gregory F; Bentley, William E

2018-01-01

Synthetic biologists construct innovative genetic/biological systems to treat environmental, energy, and health problems. Many systems employ rewired cells for non-native product synthesis, while a few have employed the rewired cells as 'smart' devices with programmable function. Building on the latter, we developed a genetic construct to control and direct bacterial motility towards hydrogen peroxide, one of the body's immune response signaling molecules. A motivation for this work is the creation of cells that can target and autonomously treat disease, the latter signaled by hydrogen peroxide release. Bacteria naturally move towards a variety of molecular cues (e.g., nutrients) in the process of chemotaxis. In this work, we engineered bacteria to recognize and move towards hydrogen peroxide, a non-native chemoattractant and potential toxin. Our system exploits oxyRS, the native oxidative stress regulon of E. coli. We first demonstrated H2O2-mediated upregulation motility regulator, CheZ. Using transwell assays, we showed a two-fold increase in net motility towards H2O2. Then, using a 2D cell tracking system, we quantified bacterial motility descriptors including velocity, % running (of tumble/run motions), and a dynamic net directionality towards the molecular cue. In CheZ mutants, we found that increased H2O2 concentration (0-200 μM) and induction time resulted in increased running speeds, ultimately reaching the native E. coli wild-type speed of ~22 μm/s with a ~45-65% ratio of running to tumbling. Finally, using a microfluidic device with stable H2O2 gradients, we characterized responses and the potential for "programmed" directionality towards H2O2 in quiescent fluids. Overall, the synthetic biology framework and tracking analysis in this work will provide a framework for investigating controlled motility of E. coli and other 'smart' probiotics for signal-directed treatment.

Bacterial Quorum Sensing and Microbial Community Interactions

PubMed Central

2018-01-01

ABSTRACT Many bacteria use a cell-cell communication system called quorum sensing to coordinate population density-dependent changes in behavior. Quorum sensing involves production of and response to diffusible or secreted signals, which can vary substantially across different types of bacteria. In many species, quorum sensing modulates virulence functions and is important for pathogenesis. Over the past half-century, there has been a significant accumulation of knowledge of the molecular mechanisms, signal structures, gene regulons, and behavioral responses associated with quorum-sensing systems in diverse bacteria. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have revealed how quorum sensing coordinates interactions both within a species and between species. Such studies of quorum sensing as a social behavior have relied on the development of “synthetic ecological” models that use nonclonal bacterial populations. In this review, we discuss some of these models and recent advances in understanding how microbes might interact with one another using quorum sensing. The knowledge gained from these lines of investigation has the potential to guide studies of microbial sociality in natural settings and the design of new medicines and therapies to treat bacterial infections. PMID:29789364

Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions.

PubMed

Hesketh, Andy; Vergnano, Marta; Wan, Chris; Oliver, Stephen G

2017-07-25

We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection. IMPORTANCE During infections, pathogenic bacteria can release nucleotides into the cells of their eukaryotic hosts. These nucleotides are recognized as signals that contribute to the initiation of defensive immune responses that help the infected

Bacterial reduction by cell salvage washing and leukocyte depletion filtration.

PubMed

Waters, Jonathan H; Tuohy, Marion J; Hobson, Donna F; Procop, Gary

2003-09-01

Blood conservation techniques are being increasingly used because of the increased cost and lack of availability of allogeneic blood. Cell salvage offers great blood savings opportunities but is thought to be contraindicated in a number of areas (e.g., blood contaminated with bacteria). Several outcome studies have suggested the safety of this technique in trauma and colorectal surgery, but many practitioners are still hesitant to apply cell salvage in the face of frank bacterial contamination. This study was undertaken to assess the efficacy of bacterial removal when cell salvage was combined with leukocyte depletion filtration. Expired packed erythrocytes were obtained and inoculated with a fixed amount of a stock bacteria (Escherichia coli American Type Culture Collections [ATCC] 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, or Bacteroides fragilis ATCC 25285) in amounts ranging from 2,000 to 4,000 colony forming units/ml. The blood was processed via a cell salvage machine. The washed blood was then filtered using a leukocyte reduction filter. The results for blood taken during each step of processing were compared using a repeated-measures design. Fifteen units of blood were contaminated with each of the stock bacteria. From the prewash sample to the postfiltration sample, 99.0%, 99.6%, 100%, and 97.6% of E. coli, S. aureus, P. aeruginosa, and B. fragilis were removed, respectively. Significant but not complete removal of contaminating bacteria was seen. An increased level of patient safety may be added to cell salvage by including a leukocyte depletion filter when salvaging blood that might be grossly contaminated with bacteria.

Measuring masses of single bacterial whole cells with a quadrupole ion trap.

PubMed

Peng, Wen-Ping; Yang, Yi-Chang; Kang, Ming-Wei; Lee, Yuan T; Chang, Huan-Cheng

2004-09-29

A novel method has been developed to precisely measure the masses of single bacterial whole cells using a quadrupole ion trap as an electrodynamic balance. The bacterial cells were introduced into the ion trap by matrix-assisted laser desorption/ionization, confined in space by audio frequency ac fields, and detected by elastic light scattering. Mass measurement accuracy approaching 0.1% was achieved for Escherichia coli K-12 with a mass distribution of +/-3% from 60 repetitive measurements of the particles and their clusters. This is the first high-precision mass measurement reported for any intact microorganisms with masses greater than 1 x 1010 Da. The method opens new avenues for high-precision mass measurement of single microbial particles and offers an alternative approach for rapid identification of microorganisms by mass spectrometry.

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

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

PubMed

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

2013-01-01

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

Temperate Bacterial Viruses as Double-Edged Swords in Bacterial Warfare

PubMed Central

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

2013-01-01

It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a “replicating toxin”. However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails. PMID:23536852

Live cell imaging of actin dynamics in dexamethasone-treated porcine trabecular meshwork cells.

PubMed

Fujimoto, Tomokazu; Inoue, Toshihiro; Inoue-Mochita, Miyuki; Tanihara, Hidenobu

2016-04-01

The regulation of the actin cytoskeleton in trabecular meshwork (TM) cells is important for controlling outflow of the aqueous humor. In some reports, dexamethasone (DEX) increased the aqueous humor outflow resistance and induced unusual actin structures, such as cross-linked actin networks (CLAN), in TM cells. However, the functions and dynamics of CLAN in TM cells are not completely known, partly because actin stress fibers have been observed only in fixed cells. We conducted live-cell imaging of the actin dynamics in TM cells with or without DEX treatment. An actin-green fluorescent protein (GFP) fusion construct with a modified insect virus was transfected into porcine TM cells. Time-lapse imaging of live TM cells treated with 25 μM Y-27632 and 100 nM DEX was performed using an inverted fluorescence microscope. Fluorescent images were recorded every 15 s for 30 min after Y-27632 treatment or every 30 min for 72 h after DEX treatment. The GFP-actin was expressed in 22.7 ± 10.9% of the transfected TM cells. In live TM cells, many actin stress fibers were observed before the Y-27632 treatment. Y-27632 changed the cell shape and decreased stress fibers in a time-dependent manner. In fixed cells, CLAN-like structures were seen in 26.5 ± 1.7% of the actin-GFP expressed PTM cells treated with DEX for 72 h. In live imaging, there was 28% CLAN-like structure formation at 72 h after DEX treatment, and the lifetime of CLAN-like structures increased after DEX treatment. The DEX-treated cells with CLAN-like structures showed less migration than DEX-treated cells without CLAN-like structures. Furthermore, the control cells (without DEX treatment) with CLAN-like structures also showed less migration than the control cells without CLAN-like structures. These results suggested that CLAN-like structure formation was correlated with cell migration in TM cells. Live cell imaging of the actin cytoskeleton provides valuable information on the actin dynamics in TM

Hydroxychavicol, a key ingredient of Piper betle induces bacterial cell death by DNA damage and inhibition of cell division.

PubMed

Singh, Deepti; Narayanamoorthy, Shwetha; Gamre, Sunita; Majumdar, Ananda Guha; Goswami, Manish; Gami, Umesh; Cherian, Susan; Subramanian, Mahesh

2018-05-20

Antibiotic resistance is a global problem and there is an urgent need to augment the arsenal against pathogenic bacteria. The emergence of different drug resistant bacteria is threatening human lives to be pushed towards the pre-antibiotic era. Botanical sources remain a vital source of diverse organic molecules that possess antibacterial property as well as augment existing antibacterial molecules. Piper betle, a climber, is widely used in south and south-east Asia whose leaves and nuts are consumed regularly. Hydroxychavicol (HC) isolated from Piper betle has been reported to possess antibacterial activity. It is currently not clear how the antibacterial activity of HC is manifested. In this investigation we show HC generates superoxide in E. coli cells. Antioxidants protected E. coli against HC induced cell death while gshA mutant was more sensitive to HC than wild type. DNA damage repair deficient mutants are hypersensitive to HC and HC induces the expression of DNA damage repair genes that repair oxidative DNA damage. HC treated E. coli cells are inhibited from growth and undergo DNA condensation. In vitro HC binds to DNA and cleaves it in presence of copper. Our data strongly indicates HC mediates bacterial cell death by ROS generation and DNA damage. Damage to iron sulfur proteins in the cells contribute to amplification of oxidative stress initiated by HC. Further HC is active against a number of Gram negative bacteria isolated from patients with a wide range of clinical symptoms and varied antibiotic resistance profiles. Copyright © 2018 Elsevier Inc. All rights reserved.

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

Seasonal and spatial distribution of bacterial biomass and the percentage of viable cells in a reservoir of Alabama

USGS Publications Warehouse

Tietjen, T.E.; Wetzel, R.G.

2003-01-01

Spatial community dynamics of bacterioplankton were evaluated along the length of the former stream channel of Elledge Lake, a small reservoir in western Alabama. The reservoir was strongly stratified from April to October with up to a 10??C temperature difference across the 1 m deep metalimnion. Bacterial biomass was highest during late summer, with a general pattern of increasing abundance from the inflowing river (???10 ??g C l-1) to the dam (???20-30 ??g C l-1). Bacterial numbers also increased following a >10-fold increase in turbidity associated with a major precipitation event, although only ???10% of these cells were viable. The percentage of viable cells generally increased through the stratified period with 50-70% viable cells in late summer. Overall, an average of 38% of bacterial cells were viable, with a range from <20 to 70%. Although these values were similar to those found by others, additional patterns were identified that have not been previously observed: a marked decline in viable cells was found following turbid storm inflows and increases in the percentage of viable cells occurred during spring warming and following autumnal mixing events. Although a modest increase in abundance occurred along the gradient from inflow down-reservoir to the dam, bacterial abundance did not increase near the dam in a pattern coincident with the commonly observed increased algal biomass in the lacustrine portion of reservoir ecosystems. The increases observed in bacterial viability moving from the inflowing rivers towards the dam and later in stratified periods stress the importance of differences in environmental conditions in time and space in regulating bacterial biomass and development, as well as of shifts that would be anticipated accompanying altered hydrological regimes under climatic change.

Quantitative microbiological analysis of bacterial community shifts in a high-rate anaerobic bioreactor treating sulfite evaporator condensate.

PubMed

Ney, U; Macario, A J; Conway de Macario, E; Aivasidis, A; Schoberth, S M; Sahm, H

1990-08-01

The bacterial population of a high-rate, anaerobic, fixed-bed loop reactor treating sulfite evaporator condensate from the pulp industry was studied over a 14-month period. This period was divided into seven cycles that included a startup at the beginning of each cycle. Some 82% of the total biomass was immobilized on and between the porous glass rings filling the reactor. The range of the total number of microorganisms in these biofilms was 2 x 10 to 7 x 10 cells per ml. Enumeration and characterization by microbiological methods and by phase-contrast, epifluorescence, and electron microscopy showed that the samples consisted mainly of the following methanogens: a Methanobacterium sp., a Methanosarcina sp., a Methanobrevibacter sp., and a Methanothrix sp., as well as furfural-degrading sulfate-reducing bacteria resembling Desulfovibrio furfuralis. Viable counts of hydrogenotrophic methanogens were relatively stable (mostly within the range of 3.2 x 10 to 7.5 x 10 cells per ml), but Methanobrevibacter cells increased from <5 to 30% of the total hydrogenotrophic count after transfer of the fixed bed into a second reactor vessel. Acetotrophic methanogens reached their highest numbers of 1.3 x 10 to 2.6 x 10 cells per ml in the last fermentation cycles. They showed a morphological shift from sarcinalike packets in early samples to single coccoid forms in later phases of the fermentation. Furfural-degrading sulfate reducers reached counts of 1 x 10 to 5.8 x 10 cells per ml. The distribution of the chief metabolic groups between free fluid and biofilms was analyzed in the fifth fermentation cycle: 4.5 times more furfural degraders were found in the free fluid than in the biofilms. In contrast, 5.8 times more acetotrophic and 16.6 times more hydrogenotrophic methanogens were found in the biofilms than in the free liquid. The data concerning time shifts of morphotypes among the trophic groups of methanogens corroborated the trends observed by using immunological assays on

Quantitative Microbiological Analysis of Bacterial Community Shifts in a High-Rate Anaerobic Bioreactor Treating Sulfite Evaporator Condensate

PubMed Central

Ney, U.; Macario, A. J. L.; de Macario, E. Conway; Aivasidis, A.; Schoberth, S. M.; Sahm, H.

1990-01-01

The bacterial population of a high-rate, anaerobic, fixed-bed loop reactor treating sulfite evaporator condensate from the pulp industry was studied over a 14-month period. This period was divided into seven cycles that included a startup at the beginning of each cycle. Some 82% of the total biomass was immobilized on and between the porous glass rings filling the reactor. The range of the total number of microorganisms in these biofilms was 2 × 109 to 7 × 109 cells per ml. Enumeration and characterization by microbiological methods and by phase-contrast, epifluorescence, and electron microscopy showed that the samples consisted mainly of the following methanogens: a Methanobacterium sp., a Methanosarcina sp., a Methanobrevibacter sp., and a Methanothrix sp., as well as furfural-degrading sulfate-reducing bacteria resembling Desulfovibrio furfuralis. Viable counts of hydrogenotrophic methanogens were relatively stable (mostly within the range of 3.2 × 108 to 7.5 × 108 cells per ml), but Methanobrevibacter cells increased from <5 to 30% of the total hydrogenotrophic count after transfer of the fixed bed into a second reactor vessel. Acetotrophic methanogens reached their highest numbers of 1.3 × 108 to 2.6 × 108 cells per ml in the last fermentation cycles. They showed a morphological shift from sarcinalike packets in early samples to single coccoid forms in later phases of the fermentation. Furfural-degrading sulfate reducers reached counts of 1 × 107 to 5.8 × 107 cells per ml. The distribution of the chief metabolic groups between free fluid and biofilms was analyzed in the fifth fermentation cycle: 4.5 times more furfural degraders were found in the free fluid than in the biofilms. In contrast, 5.8 times more acetotrophic and 16.6 times more hydrogenotrophic methanogens were found in the biofilms than in the free liquid. The data concerning time shifts of morphotypes among the trophic groups of methanogens corroborated the trends observed by using

Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

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

Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia

2010-08-04

Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MSmore » displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.« less

Detection of Only Viable Bacterial Spores Using a Live/Dead Indicator in Mixed Populations

NASA Technical Reports Server (NTRS)

Behar, Alberto E.; Stam, Christina N.; Smiley, Ronald

2013-01-01

This method uses a photoaffinity label that recognizes DNA and can be used to distinguish populations of bacterial cells from bacterial spores without the use of heat shocking during conventional culture, and live from dead bacterial spores using molecular-based methods. Biological validation of commercial sterility using traditional and alternative technologies remains challenging. Recovery of viable spores is cumbersome, as the process requires substantial incubation time, and the extended time to results limits the ability to quickly evaluate the efficacy of existing technologies. Nucleic acid amplification approaches such as PCR (polymerase chain reaction) have shown promise for improving time to detection for a wide range of applications. Recent real-time PCR methods are particularly promising, as these methods can be made at least semi-quantitative by correspondence to a standard curve. Nonetheless, PCR-based methods are rarely used for process validation, largely because the DNA from dead bacterial cells is highly stable and hence, DNA-based amplification methods fail to discriminate between live and inactivated microorganisms. Currently, no published method has been shown to effectively distinguish between live and dead bacterial spores. This technology uses a DNA binding photoaffinity label that can be used to distinguish between live and dead bacterial spores with detection limits ranging from 109 to 102 spores/mL. An environmental sample suspected of containing a mixture of live and dead vegetative cells and bacterial endospores is treated with a photoaffinity label. This step will eliminate any vegetative cells (live or dead) and dead endospores present in the sample. To further determine the bacterial spore viability, DNA is extracted from the spores and total population is quantified by real-time PCR. The current NASA standard assay takes 72 hours for results. Part of this procedure requires a heat shock step at 80 degC for 15 minutes before the

Does the high nucleic acid content of individual bacterial cells allow us to discriminate between active cells and inactive cells in aquatic systems?

PubMed

Lebaron, P; Servais, P; Agogué, H; Courties, C; Joux, F

2001-04-01

The nucleic acid contents of individual bacterial cells as determined with three different nucleic acid-specific fluorescent dyes (SYBR I, SYBR II, and SYTO 13) and flow cytometry were compared for different seawater samples. Similar fluorescence patterns were observed, and bacteria with high apparent nucleic acid contents (HNA) could be discriminated from bacteria with low nucleic acid contents (LNA). The best discrimination between HNA and LNA cells was found when cells were stained with SYBR II. Bacteria in different water samples collected from seven freshwater, brackish water, and seawater ecosystems were prelabeled with tritiated leucine and then stained with SYBR II. After labeling and staining, HNA, LNA, and total cells were sorted by flow cytometry, and the specific activity of each cellular category was determined from leucine incorporation rates. The HNA cells were responsible for most of the total bacterial production, and the specific activities of cells in the HNA population varied between samples by a factor of seven. We suggest that nucleic acid content alone can be a better indicator of the fraction of growing cells than total counts and that this approach should be combined with other fluorescent physiological probes to improve detection of the most active cells in aquatic systems.

Does the High Nucleic Acid Content of Individual Bacterial Cells Allow Us To Discriminate between Active Cells and Inactive Cells in Aquatic Systems?

PubMed Central

Lebaron, Philippe; Servais, Pierre; Agogué, Helene; Courties, Claude; Joux, Fabien

2001-01-01

The nucleic acid contents of individual bacterial cells as determined with three different nucleic acid-specific fluorescent dyes (SYBR I, SYBR II, and SYTO 13) and flow cytometry were compared for different seawater samples. Similar fluorescence patterns were observed, and bacteria with high apparent nucleic acid contents (HNA) could be discriminated from bacteria with low nucleic acid contents (LNA). The best discrimination between HNA and LNA cells was found when cells were stained with SYBR II. Bacteria in different water samples collected from seven freshwater, brackish water, and seawater ecosystems were prelabeled with tritiated leucine and then stained with SYBR II. After labeling and staining, HNA, LNA, and total cells were sorted by flow cytometry, and the specific activity of each cellular category was determined from leucine incorporation rates. The HNA cells were responsible for most of the total bacterial production, and the specific activities of cells in the HNA population varied between samples by a factor of seven. We suggest that nucleic acid content alone can be a better indicator of the fraction of growing cells than total counts and that this approach should be combined with other fluorescent physiological probes to improve detection of the most active cells in aquatic systems. PMID:11282632

Interactions of plaunotol with bacterial membranes.

PubMed

Koga, T; Watanabe, H; Kawada, H; Takahashi, K; Utsui, Y; Domon, H; Ishii, C; Narita, T; Yasuda, H

1998-08-01

Plaunotol, a cytoprotective antiulcer agent, has a bactericidal effect against Helicobacter pylori, which may result from interaction of this compound with the bacterial cell membrane. The purpose of the present study was to confirm that plaunotol interacts with the H. pylori membrane. Membrane fluidities were measured using two stearic acid spin labels, namely 5-doxyl-stearic acid (in which the nitroxide group is located in the upper portion of the bacterial cell membrane) and 16-doxyl-stearic acid methyl ester (in which the nitroxide group is located deeper in the bacterial cell membrane), by means of electron spin resonance. The membrane fluidities of plaunotol-treated cells were significantly increased in the measurements made using the two spin labels. We also attempted to isolate plaunotol-resistant H. pylori in vitro by two different methods. To assess the level of resistance that could be reached, H. pylori was passaged five times on an agar plate containing subinhibitory concentrations of plaunotol or metronidazole. To measure the rate of development of resistance, H. pylori was grown with subinhibitory concentrations (0.25 x MIC) of plaunotol or metronidazole, and quantitatively plated on to medium containing 4 x MIC of the compounds. This treatment was repeated once more. No plaunotol-resistant colonies were selected by the two methods. H. pylori developed resistance to metronidazole easily and at a relatively high rate. The mechanism by which plaunotol directly fluidizes and destroys the H. pylori membrane might make it difficult for this organism to develop resistance to plaunotol. It was confirmed that the bactericidal effects of plaunotol were also shown against Staphylococcus aureus, Streptococcus pneumoniae, Neisseria gonorrhoeae, Moraxella catarrhalis and Haemophilus influenzae. No such effect was seen against Escherichia coli and Pseudomonas aeruginosa.

Ultraviolet micro-Raman spectrograph for the detection of small numbers of bacterial cells

NASA Astrophysics Data System (ADS)

Chadha, S.; Nelson, W. H.; Sperry, J. F.

1993-11-01

The construction of a practical UV micro-Raman spectrograph capable of selective excitation of bacterial cells and other microscopic samples has been described. A reflective objective is used to focus cw laser light on a sample and at the same time collect the scattered light at 180°. With the aid of a quartz lens the image produced is focused on the slits of a spectrograph equipped with a single 2400 grooves/mm grating optimized for 250 nm. Spectra were detected by means of a blue-intensified diode array detector. Resonance Raman spectra of Bacillus subtilis and Flavobacterium capsulatum excited by the 257.2 nm output of a cw laser were recorded in the 900-1800 cm-1 region. Bacterial cells were immobilized on a quartz plate by means of polylysine and were counted visually. Cooling was required to retard sample degradation. Sample sizes ranged from 1 to 50 cells with excitation times varying from 15 to 180 s. Excellent spectra have been obtained from 20 cells in 15 s using a spectrograph having only 3% throughput.

The basics of cell therapy to treat cardiovascular disease: one cell does not fit all.

PubMed

Taylor, Doris A; Robertson, Matthew J

2009-09-01

Cardiovascular disease represents a continuum of disease entities whose medical treatments differ. Cell therapy is a 21st century approach to treating cardiovascular disease and is being applied worldwide. However, no concerted approach exists for defining the best cell population(s) to use, or the best treatment conditions. It is naïve to believe that a single treatment -even a stem cell- can be found to treat the entire spectrum of cardiovascular disease. We describe the continuum of ischemic heart disease, the potential uses of cells for treating this continuum, and the basic issues that must be considered when contemplating cardiovascular cell therapy. The clinical goal is cardiac and vascular regeneration. Whether cells can deliver this remains to be determined. The correct cell, the ideal therapeutic window, and the patient likewise are open to debate. This article is designed to provide insights into the early, middle, and later stages of cardiovascular disease and how cells might be used differently for treatment at each stage.

Plasma Assisted Decontamination of Bacterial Spores

PubMed Central

Kuo, Spencer P

2008-01-01

The efficacy and mechanism of killing bacterial spores by a plasma torch is studied. Bacterial-spore (Bacillus cereus) suspension is inoculated onto glass/paper slide-coupons and desiccated into dry samples, and inoculated into well-microplate as wet sample. The exposure distance of all samples is 4 cm from the nozzle of the torch. In the experiment, paper slide-coupon is inserted inside an envelope. The kill times on spores in three types of samples are measured to be about 3, 9, and 24 seconds. The changes in the morphology and shape of still viable spores in treated wet samples are recorded by scanning electron and atomic force microscopes. The loss of appendages and exosporium in the structure and squashed/flattened cell shape are observed. The emission spectroscopy of the torch indicates that the plasma effluent carries abundant reactive atomic oxygen, which is responsible for the destruction of spores. PMID:19662115

Interlinkages between bacterial populations dynamics and the operational parameters in a moving bed membrane bioreactor treating urban sewage.

PubMed

Reboleiro-Rivas, P; Martín-Pascual, J; Morillo, J A; Juárez-Jiménez, B; Poyatos, J M; Rodelas, B; González-López, J

2016-01-01

Bacteria are key players in biological wastewater treatments (WWTs), thus a firm knowledge of the bacterial population dynamics is crucial to understand environmental/operational factors affecting the efficiency and stability of the biological depuration process. Unfortunately, little is known about the microbial ecology of the advanced biological WWTs combining suspended biomass (SB) and attached biofilms (AB). This study explored in depth the bacterial community structure and population dynamics in each biomass fraction from a pilot-scale moving bed membrane bioreactor (MBMBR) treating municipal sewage, by means of temperature-gradient gel electrophoresis (TGGE) and 454-pyrosequencing. Eight experimental phases were conducted, combining different carrier filling ratios, hydraulic retention times and concentrations of mixed liquor total suspended solids. The bacterial community, dominated by Proteobacteria (20.9-53.8%) and Actinobacteria (20.6-57.6%), was very similar in both biomass fractions and able to maintain its functional stability under all the operating conditions, ensuring a successful and steady depuration process. Multivariate statistical analysis demonstrated that solids concentration, carrier filling ratio, temperature and organic matter concentration in the influent were the significant factors explaining population dynamics. Bacterial diversity increased as carrier filling ratio increased (from 20% to 35%, v/v), and solids concentration was the main factor triggering the shifts of the community structure. These findings provide new insights on the influence of operational parameters on the biology of the innovative MBMBRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

A comparative study of fungal and bacterial biofiltration treating a VOC mixture.

PubMed

Estrada, José M; Hernández, Sergio; Muñoz, Raúl; Revah, Sergio

2013-04-15

Bacterial biofilters usually exhibit a high microbial diversity and robustness, while fungal biofilters have been claimed to better withstand low moisture contents and pH values, and to be more efficient coping with hydrophobic volatile organic compounds (VOCs). However, there are only few systematic evaluations of both biofiltration technologies. The present study compared fungal and bacterial biofiltration for the treatment of a VOC mixture (propanal, methyl isobutyl ketone-MIBK, toluene and hexanol) under the same operating conditions. Overall, fungal biofiltration supported lower elimination capacities than its bacterial counterpart (27.7 ± 8.9 vs 40.2 ± 5.4 gCm(-3) reactor h(-1)), which exhibited a final pressure drop 60% higher than that of the bacterial biofilter due to mycelial growth. The VOC mineralization ratio was also higher in the bacterial bed (≈ 63% vs ≈ 43%). However, the substrate biodegradation preference order was similar for both biofilters (propanal>hexanol>MIBK>toluene) with propanal partially inhibiting the consumption of the rest of the VOCs. Both systems supported an excellent robustness versus 24h VOC starvation episodes. The implementation of a fungal/bacterial coupled system did not significantly improve the VOC removal performance compared to the individual biofilter performances. Copyright © 2013 Elsevier B.V. All rights reserved.

Small Bowel Bacterial Overgrowth Associated with Persistence of Abdominal Symptoms in Children Treated with a Proton Pump Inhibitor.

PubMed

Sieczkowska, Agnieszka; Landowski, Piotr; Zagozdzon, Pawel; Kaminska, Barbara; Lifschitz, Carlos

2015-05-01

Small bowel bacterial overgrowth (SBBO) was diagnosed in 22.5% of 40 children treated for 3 months with a proton pump inhibitor (PPI). Compared with those without SBBO, children with SBBO had higher frequency of abdominal pain, bloating, eructation, and flatulence. Patients with gastrointestinal symptoms after PPI treatment should be evaluated for SBBO rather than empirically prolonging PPI therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Modulating bacterial and gut mucosal interactions with engineered biofilm matrix proteins.

PubMed

Duraj-Thatte, Anna M; Praveschotinunt, Pichet; Nash, Trevor R; Ward, Frederick R; Joshi, Neel S

2018-02-22

Extracellular appendages play a significant role in mediating communication between bacteria and their host. Curli fibers are a class of bacterial fimbria that is highly amenable to engineering. We demonstrate the use of engineered curli fibers to rationally program interactions between bacteria and components of the mucosal epithelium. Commensal E. coli strains were engineered to produce recombinant curli fibers fused to the trefoil family of human cytokines. Biofilms formed from these strains bound more mucins than those producing wild-type curli fibers, and modulated mucin rheology as well. When treated with bacteria producing the curli-trefoil fusions mammalian cells behaved identically in terms of their migration behavior as when they were treated with the corresponding soluble trefoil factors. Overall, this demonstrates the potential utility of curli fibers as a scaffold for the display of bioactive domains and an untapped approach to rationally modulating host-microbe interactions using bacterial matrix proteins.

Bacterial Outer Membrane Vesicles Induce Plant Immune Responses.

PubMed

Bahar, Ofir; Mordukhovich, Gideon; Luu, Dee Dee; Schwessinger, Benjamin; Daudi, Arsalan; Jehle, Anna Kristina; Felix, Georg; Ronald, Pamela C

2016-05-01

Gram-negative bacteria continuously pinch off portions of their outer membrane, releasing membrane vesicles. These outer membrane vesicles (OMVs) are involved in multiple processes including cell-to-cell communication, biofilm formation, stress tolerance, horizontal gene transfer, and virulence. OMVs are also known modulators of the mammalian immune response. Despite the well-documented role of OMVs in mammalian-bacterial communication, their interaction with plants is not well studied. To examine whether OMVs of plant pathogens modulate the plant immune response, we purified OMVs from four different plant pathogens and used them to treat Arabidopsis thaliana. OMVs rapidly induced a reactive oxygen species burst, medium alkalinization, and defense gene expression in A. thaliana leaf discs, cell cultures, and seedlings, respectively. Western blot analysis revealed that EF-Tu is present in OMVs and that it serves as an elicitor of the plant immune response in this form. Our results further show that the immune coreceptors BAK1 and SOBIR1 mediate OMV perception and response. Taken together, our results demonstrate that plants can detect and respond to OMV-associated molecules by activation of their immune system, revealing a new facet of plant-bacterial interactions.

Lipopolysaccharide Clearance, Bacterial Clearance, and Systemic Inflammatory Responses Are Regulated by Cell Type–Specific Functions of TLR4 during Sepsis

PubMed Central

Deng, Meihong; Loughran, Patricia; Gibson, Gregory; Sodhi, Chhinder; Watkins, Simon; Hackam, David

2013-01-01

The morbidity associated with bacterial sepsis is the result of host immune responses to pathogens, which are dependent on pathogen recognition by pattern recognition receptors, such as TLR4. TLR4 is expressed on a range of cell types, yet the mechanisms by which cell-specific functions of TLR4 lead to an integrated sepsis response are poorly understood. To address this, we generated mice in which TLR4 was specifically deleted from myeloid cells (LysMTLR4KO) or hepatocytes (HCTLR4KO) and then determined survival, bacterial counts, host inflammatory responses, and organ injury in a model of cecal ligation and puncture (CLP), with or without antibiotics. LysM-TLR4 was required for phagocytosis and efficient bacterial clearance in the absence of antibiotics. Survival, the magnitude of the systemic and local inflammatory responses, and liver damage were associated with bacterial levels. HCTLR4 was required for efficient LPS clearance from the circulation, and deletion of HCTLR4 was associated with enhanced macrophage phagocytosis, lower bacterial levels, and improved survival in CLP without antibiotics. Antibiotic administration during CLP revealed an important role for hepatocyte LPS clearance in limiting sepsis-induced inflammation and organ injury. Our work defines cell type–selective roles for TLR4 in coordinating complex immune responses to bacterial sepsis and suggests that future strategies for modulating microbial molecule recognition should account for varying roles of pattern recognition receptors in multiple cell populations. PMID:23562812

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

PubMed

Luo, Gang; Angelidaki, Irini

2014-09-01

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

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.

Stopping bacterial adhesion: a novel approach to treating infections.

PubMed

Bavington, C; Page, C

2005-01-01

Adhesion and colonization are prerequisites for the establishment of bacterial pathogenesis. The prevention of adhesion is an attractive target for the development of new therapies in the prevention of infection. Bacteria have developed a multiplicity of adhesion mechanisms commonly targeting surface carbohydrate structures, but our ability to rationally design effective antiadhesives is critically affected by the limitations of our knowledge of the human 'glycome' and of the bacterial function in relation to it. The potential for the future development of carbohydrate-based antiadhesives has been demonstrated by a significant number of in vitro and in vivo studies. Such therapies will be particularly relevant for infections of mucosal surfaces where topical application or delivery is possible. (c) 2005 S. Karger AG, Basel

Potential nitrification and denitrification and the corresponding composition of the bacterial communities in a compact constructed wetland treating landfill leachates.

PubMed

Sundberg, C; Tonderski, K; Lindgren, P E

2007-01-01

Constructed wetlands can be used to decrease the high ammonium concentrations in landfill leachates. We investigated nitrification/denitrification activity and the corresponding bacterial communities in landfill leachate that was treated in a compact constructed wetland, Tveta Recycling Facility, Sweden. Samples were collected at three depths in a filter bed and the sediment from a connected open pond in July, September and November 2004. Potential ammonia oxidation was measured by short-term incubation method and potential denitrification by the acetylene inhibition technique. The ammonia-oxidising and the denitrifying bacterial communities were investigated using group-specific PCR primers targeting 16S rRNA genes and the functional gene nosZ, respectively. PCR products were analysed by denaturing gradient gel electrophoresis and nucleotide sequencing. The same degree of nitrification activity was observed in the pond sediment and at all levels in the filter bed, whereas the denitrification activity decreased with filter bed depth. Denitrification rates were higher in the open pond, even though the denitrifying bacterial community was more diverse in the filter bed. The ammonia-oxidising community was also more varied in the filter bed. In the filter bed and the open pond, there was no obvious relationship between the nitrification/denitrification activities and the composition of the corresponding bacterial communities.

Cultivating stem cells for treating amyotrophic lateral sclerosis

PubMed Central

Li, Shengwen Calvin; Yin, Hong Zhen; Loudon, William G; Weiss, John H

2012-01-01

This editorial addresses the current challenges and future directions in the use of stem cells as an approach for treating amyotrophic lateral sclerosis. A wide variety of literature has been reviewed to enlighten the reader on the many facets of stem cell research that are important to consider before using them for a cell based therapy. PMID:23516096

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 Species and Biochemical Characteristic Investigations of Nostoc flagelliforme Concentrates during its Storage.

PubMed

Yue, Lifang; Lv, Hexin; Zhen, Jing; Jiang, Shengping; Jia, Shiru; Shen, Shigang; Gao, Lu; Dai, Yujie

2016-04-28

Preservation of fresh algae plays an important role in algae seed subculture and aquaculture. The determination and examination of the changes of cell viability, composition, and bacterial species during storage would help to take suitable preservation methods to prolong the preservation time of fresh algae. Nostoc flagelliforme is a kind of edible cyanobacterium with important herbal and dietary values. This article investigated the changes of bacterial species and biochemical characteristics of fresh N. flagelliforme concentrate during natural storage. It was found that the viability of cells decreased along with the storage time. Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE and were grouped into four phyla, including Cyanobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among them, Enterococcus viikkiensis may be a concern in the preservation. Eleven volatile organic compounds were identified from N. flagelliforme cells, in which geosmin could be treated as an indicator of the freshness of N. flagelliforme. The occurrence of indole compound may be an indicator of the degradation of cells.

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.

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

PubMed Central

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

2015-01-01

ABSTRACT 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. PMID:26220963

Humidity-dependent bacterial cells functional morphometry investigations using atomic force microscope.

PubMed

Nikiyan, Hike; Vasilchenko, Alexey; Deryabin, Dmitry

2010-01-01

The effect of a relative humidity (RH) in a range of 93-65% on morphological and elastic properties of Bacillus cereus and Escherichia coli cells was evaluated using atomic force microscopy. It is shown that gradual dehumidification of bacteria environment has no significant effect on cell dimensional features and considerably decreases them only at 65% RH. The increasing of the bacteria cell wall roughness and elasticity occurs at the same time. Observed changes indicate that morphological properties of B. cereus are rather stable in wide range of relative humidity, whereas E. coli are more sensitive to drying, significantly increasing roughness and stiffness parameters at RH cell wall structure of gram-positive and gram-negative bacterial cells.

Humidity-Dependent Bacterial Cells Functional Morphometry Investigations Using Atomic Force Microscope

PubMed Central

Nikiyan, Hike; Vasilchenko, Alexey; Deryabin, Dmitry

2010-01-01

The effect of a relative humidity (RH) in a range of 93–65% on morphological and elastic properties of Bacillus cereus and Escherichia coli cells was evaluated using atomic force microscopy. It is shown that gradual dehumidification of bacteria environment has no significant effect on cell dimensional features and considerably decreases them only at 65% RH. The increasing of the bacteria cell wall roughness and elasticity occurs at the same time. Observed changes indicate that morphological properties of B. cereus are rather stable in wide range of relative humidity, whereas E. coli are more sensitive to drying, significantly increasing roughness and stiffness parameters at RH ≤ 84% RH. It is discussed the dependence of the response features on differences in cell wall structure of gram-positive and gram-negative bacterial cells. PMID:20652040

Bone marrow-derived cells participate in stromal remodeling of the lung following acute bacterial pneumonia in mice.

PubMed

Serikov, Vladimir B; Mikhaylov, Viatcheslav M; Krasnodembskay, Anna D; Matthay, Michael A

2008-01-01

Bone marrow-derived cells (BMDC) have been shown to graft injured tissues, differentiate in specialized cells, and participate in repair. The importance of these processes in acute lung bacterial inflammation and development of fibrosis is unknown. The goal of this study was to investigate the temporal sequence and lineage commitment of BMDC in mouse lungs injured by bacterial pneumonia. We transplanted GFP-tagged BMDC into 5-Gy-irradiated C57BL/6 mice. After 3 months of recovery, mice were subjected to LD(50) intratracheal instillation of live E. coli (controls received saline) which produced pneumonia and subsequent areas of fibrosis. Lungs were investigated by immunohistology for up to 6 months. At the peak of lung inflammation, the predominant influx of BMDC were GFP(+) leukocytes. Postinflammatory foci of lung fibrosis were evident after 1-2 months. The fibrotic foci in lung stroma contained clusters of GFP(+) CD45(+) cells, GFP(+) vimentin-positive cells, and GFP(+) collagen I-positive fibroblasts. GFP(+) endothelial or epithelial cells were not identified. These data suggest that following 5-Gy irradiation and acute bacterial pneumonia, BMDC may temporarily participate in lung postinflammatory repair and stromal remodeling without long-term engraftment as specialized endothelial or epithelial cells.

Eradication of bacterial species via photosensitization

NASA Astrophysics Data System (ADS)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1999-02-01

Photosensitization and inactivation efficacy of three bacterial species: Prevotella nigrescens, Staphylococcus aureus and Escherichia coli have been investigated. Samples of Staphylococcus aureus and Escherichia coli were treated with the triphenylmethane dye malachite green isothiocyanate and exposed to light from a variety of continuous and pulsed light sauces at a wavelength of approximately 630 nm. Inactivation of the Gram-positive species Staphylococcus aureus was found to increase with radiation dose, whilst Gram-negative Escherichia coli was resistant to such treatment. Samples of the pigmented species Prevotella nigrescens were found to be inactivated by exposure to light alone. The mechanism of photosensitization and inactivation of Staphylococcus aureus with malachite green isothiocyanate is addressed. The possible roles of the excited triplet state of the photosensitizer, the involvement of molecular oxygen, and the bacterial cell wall are discussed. Photosensitization may provide a way of eliminating naturally pigmented species responsible for a variety of infections, including oral diseases such as gingivitis and periodontitis.

An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

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

Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.

2015-02-09

Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has beenmore » observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.« less

An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

NASA Astrophysics Data System (ADS)

Song, Zhen; Kenney, Janice P. L.; Fein, Jeremy B.; Bunker, Bruce A.

2012-06-01

Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.

Effect of Micro- and Nanoscale Topography on the Adhesion of Bacterial Cells to Solid Surfaces

PubMed Central

Hsu, Lillian C.; Fang, Jean; Borca-Tasciuc, Diana A.; Worobo, Randy W.

2013-01-01

Attachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, including Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials. PMID:23416997

An experimental study of Au removal from solution by non-metabolizing bacterial cells and their exudates

NASA Astrophysics Data System (ADS)

Kenney, Janice P. L.; Song, Zhen; Bunker, Bruce A.; Fein, Jeremy B.

2012-06-01

In this study, we examine the initial interactions between aqueous Au(III)-hydroxide-chloride aqueous complexes and bacteria by measuring the effects of non-metabolizing cells on the speciation and distribution of Au. We conducted batch Au(III) removal experiments, measuring the kinetics and pH dependence of Au removal, and tracking valence state transformations and binding environments using XANES spectroscopy. These experiments were conducted using non-metabolizing cells of Bacillus subtilis or Pseudomonas putida suspended in a 5 ppm Au(III)-(hydroxide)-chloride starting solution of 0.1 M NaClO4 to buffer ionic strength. Both bacterial species removed greater than 85% of the Au from solution after 2 h of exposure time below approximately pH 5. Above pH 5, the extent of Au removed from solution decreased with increasing pH, with less than approximately 10% removal of Au from solution above pH 7.5. Kinetics experiments indicated that the Au removal with both bacterial species was rapid at pH 3, and slowed with increasing pH. Reversibility experiments demonstrated that (1) once the Au was removed from solution, adjusting 35 the pH alone did not remobilize the Au into solution and (2) the presence of cysteine in solution in the reversibility experiments caused Au to desorb, suggesting that the Au was not internalized within the bacterial cells. Our results suggest that Au removal occurs as a two-step pH-dependent adsorption reduction process. The speciation of the aqueous Au and the bacterial surface appears to control the rate of Au removal from solution. Under low pH conditions, the cell walls are only weakly negatively charged and aqueous Au complexes adsorb readily and rapidly. With increasing pH, the cell wall becomes more negatively charged, slowing adsorption significantly. The XANES data demonstrate that the reduction of Au(III) by bacterial exudates is slower and less extensive than the reduction observed in the bacteria-bearing systems, and we conclude that

Bacterial interactions in dental biofilm development.

PubMed

Hojo, K; Nagaoka, S; Ohshima, T; Maeda, N

2009-11-01

Recent analyses with ribosomal RNA-based technologies have revealed the diversity of bacterial populations within dental biofilms, and have highlighted their important contributions to oral health and disease. Dental biofilms are exceedingly complex and multispecies ecosystems, where oral bacteria interact cooperatively or competitively with other members. Bacterial interactions that influence dental biofilm communities include various different mechanisms. During the early stage of biofilm formation, it is known that planktonic bacterial cells directly attach to surfaces of the oral cavity or indirectly bind to other bacterial cells that have already colonized. Adherence through co-aggregation may be critical for the temporary retention of bacteria on dental surfaces, and may facilitate eventual bacterial colonization. It is likely that metabolic communication, genetic exchange, production of inhibitory factors (e.g., bacteriocins, hydrogen peroxide, etc.), and quorum-sensing are pivotal regulatory factors that determine the bacterial composition and/or metabolism. Since each bacterium can easily access a neighboring bacterial cell and its metabolites, genetic exchanges and metabolic communication may occur frequently in dental biofilms. Quorum-sensing is defined as gene regulation in response to cell density, which influences various functions, e.g., virulence and bacteriocin production. In this review, we discuss these important interactions among oral bacteria within the dental biofilm communities.

PARAMETERS OF TREATED STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION

EPA Science Inventory

Use of materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial attachment. Surface char...

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 host and reporter gene optimization for genetically encoded whole cell biosensors.

PubMed

Brutesco, Catherine; Prévéral, Sandra; Escoffier, Camille; Descamps, Elodie C T; Prudent, Elsa; Cayron, Julien; Dumas, Louis; Ricquebourg, Manon; Adryanczyk-Perrier, Géraldine; de Groot, Arjan; Garcia, Daniel; Rodrigue, Agnès; Pignol, David; Ginet, Nicolas

2017-01-01

Whole-cell biosensors based on reporter genes allow detection of toxic metals in water with high selectivity and sensitivity under laboratory conditions; nevertheless, their transfer to a commercial inline water analyzer requires specific adaptation and optimization to field conditions as well as economical considerations. We focused here on both the influence of the bacterial host and the choice of the reporter gene by following the responses of global toxicity biosensors based on constitutive bacterial promoters as well as arsenite biosensors based on the arsenite-inducible P ars promoter. We observed important variations of the bioluminescence emission levels in five different Escherichia coli strains harboring two different lux-based biosensors, suggesting that the best host strain has to be empirically selected for each new biosensor under construction. We also investigated the bioluminescence reporter gene system transferred into Deinococcus deserti, an environmental, desiccation- and radiation-tolerant bacterium that would reduce the manufacturing costs of bacterial biosensors for commercial water analyzers and open the field of biodetection in radioactive environments. We thus successfully obtained a cell survival biosensor and a metal biosensor able to detect a concentration as low as 100 nM of arsenite in D. deserti. We demonstrated that the arsenite biosensor resisted desiccation and remained functional after 7 days stored in air-dried D. deserti cells. We also report here the use of a new near-infrared (NIR) fluorescent reporter candidate, a bacteriophytochrome from the magnetotactic bacterium Magnetospirillum magneticum AMB-1, which showed a NIR fluorescent signal that remained optimal despite increasing sample turbidity, while in similar conditions, a drastic loss of the lux-based biosensors signal was observed.

Adipose derived mesenchymal stem cells partially rescue mitomycin C treated ARPE19 cells from death in co-culture condition.

PubMed

Singh, Amar K; Srivastava, Girish K; García-Gutiérrez, María T; Pastor, J Carlos

2013-12-01

Age-related macular degeneration is a retinal disease with important damage at the RPE layer. This layer is considered a target for therapeutical approaches. Stem cell transplantation is a promising option for retinal diseases. Adipose derived mesenchymal stem cells secret growth factors which might play a significant role in RPE maintenance. This study aimed to evaluate human AD-MSCs ability to rescue mitomycin C treated dying ARPE19 cells in co-culture condition. ARPE19 cells were treated with MMC (50 μg/ml, 100 μg/ml and 200 μg/ml) for 2 hours to induce cell death. These treated cells were co-cultured with hAD-MSCs in indirect co-culture system for 3 days and 3 weeks. Then the viability, growth and proliferation of these ARPE19 cells were evaluated by a cell viability/cytotoxicity assay kit and Alamar Blue (AB) assay. Untreated ARPE19 cells and human skin fibroblasts (HSF) were used as controls. MMC blocked ARPE19 cell proliferation significantly in 3 days and cells were almost completely dead after 3 weeks. Cell toxicity of MMC increased significantly with concentration. When these cells were co-cultured with hAD-MSCs, a significant growth difference was observed in treated cells compared to untreated cells. hAD-MSCs rescue capacity was also significantly higher than HSF for treated ARPE19 cells. This study showed that hAD-MSCs rescued MMC treated ARPE19 cells from death. It probably occurred due to undefined growth factors secreted by hAD-MSCs in the medium, shared by treated ARPE19 cells in co-culture conditions. This study supports further evaluation of the effect of hAD-MSCs subretinal transplantation over the RPE degeneration process in AMD patients.

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation.

PubMed

Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand; Apte, Shree Kumar

2016-08-15

Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

PubMed Central

Kulkarni, Sayali; Misra, Chitra Seetharam; Gupta, Alka; Ballal, Anand

2016-01-01

ABSTRACT Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCE The present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous

BT-benzo-29 inhibits bacterial cell proliferation by perturbing FtsZ assembly.

PubMed

Ray, Shashikant; Jindal, Bhavya; Kunal, Kishore; Surolia, Avadhesha; Panda, Dulal

2015-10-01

We have identified a potent antibacterial agent N-(4-sec-butylphenyl)-2-(thiophen-2-yl)-1H-benzo[d]imidazole-4-carboxamide (BT-benzo-29) from a library of benzimidazole derivatives that stalled bacterial division by inhibiting FtsZ assembly. A short (5 min) exposure of BT-benzo-29 disassembled the cytokinetic Z-ring in Bacillus subtilis cells without affecting the cell length and nucleoids. BT-benzo-29 also perturbed the localization of early and late division proteins such as FtsA, ZapA and SepF at the mid-cell. Further, BT-benzo-29 bound to FtsZ with a dissociation constant of 24 ± 3 μm and inhibited the assembly and GTPase activity of purified FtsZ. A docking analysis suggested that BT-benzo-29 may bind to FtsZ at the C-terminal domain near the T7 loop. BT-benzo-29 displayed significantly weaker inhibitory effects on the assembly and GTPase activity of two mutants (L272A and V275A) of FtsZ supporting the prediction of the docking analysis. Further, BT-benzo-29 did not appear to inhibit DNA duplication and nucleoid segregation and it did not perturb the membrane potential of B. subtilis cells. The results suggested that BT-benzo-29 exerts its potent antibacterial activity by inhibiting FtsZ assembly. Interestingly, BT-benzo-29 did not affect the membrane integrity of mammalian red blood cells. BT-benzo-29 bound to tubulin with a much weaker affinity than FtsZ and exerted significantly weaker effects on mammalian cells than on the bacterial cells indicating that the compound may have a strong antibacterial potential. © 2015 FEBS.

Raman spectroscopy for bacterial identification and characterization

NASA Astrophysics Data System (ADS)

Bernatová, Silvie; Samek, Ota; Pilát, Zdeněk.; Šerý, Mojmír.; Ježek, Jan; Krzyžánek, Vladislav; Zemánek, Pavel; Ružička, Filip

2012-01-01

The main goal of our investigation is to use Raman tweezers technique so that the responce of Raman scattering on microorganisms suspended in liquid media (bacteria, algae and yeast cells in microfluidic chips) can be used to identify different species. The investigations presented here include identification of different bacteria strains (biofilm-positive and biofilm-negative) and yeast cells by using principal component analysis (PCA). The main driving force behind our investigation was a common problem in the clinical microbiology laboratory - how to distinguish between contaminant and invasive isolates. Invasive bacterial/yeast isolates can be assumed to form a biofilm, while isolates which do not form a biofilm can be treated as contaminant. Thus, the latter do not represent an important virulence factor.

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

PubMed Central

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

2015-01-01

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

RNA Imaging with Dimeric Broccoli in Live Bacterial and Mammalian Cells

PubMed Central

Filonov, Grigory S.

2016-01-01

RNA spatial dynamics play a crucial role in cell physiology and thus the ability to monitor RNA localization in live cells can provide insight into important biological problems. This article focuses on imaging RNAs using an “RNA mimic of GFP”. This approach relies on a RNA aptamer, called dimeric Broccoli, which binds to and switches on the fluorescence of DFHBI, a small molecule mimicking the fluorophore in GFP. Dimeric Broccoli is tagged to heterologously expressed RNAs and upon DFHBI binding the fluorescent signal of dimeric Broccoli reports the transcript’s localization in cells. This protocol describes the process of validating the fluorescence of dimeric Broccoli-labeled transcripts in vitro and in cells, flow cytometry analysis to determine overall fluorescence levels in cells, and fluorescence imaging in bacterial and mammalian cells. Overall, the current protocol should be useful for researchers seeking to image high abundance RNAs, such as transcribed off the T7 promoter in bacteria or off Pol III-dependent promoters in mammalian cells. PMID:26995352

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

Flow cytometric bacterial cell counts challenge conventional heterotrophic plate counts for routine microbiological drinking water monitoring.

PubMed

Van Nevel, S; Koetzsch, S; Proctor, C R; Besmer, M D; Prest, E I; Vrouwenvelder, J S; Knezev, A; Boon, N; Hammes, F

2017-04-15

Drinking water utilities and researchers continue to rely on the century-old heterotrophic plate counts (HPC) method for routine assessment of general microbiological water quality. Bacterial cell counting with flow cytometry (FCM) is one of a number of alternative methods that challenge this status quo and provide an opportunity for improved water quality monitoring. After more than a decade of application in drinking water research, FCM methodology is optimised and established for routine application, supported by a considerable amount of data from multiple full-scale studies. Bacterial cell concentrations obtained by FCM enable quantification of the entire bacterial community instead of the minute fraction of cultivable bacteria detected with HPC (typically < 1% of all bacteria). FCM measurements are reproducible with relative standard deviations below 3% and can be available within 15 min of samples arriving in the laboratory. High throughput sample processing and complete automation are feasible and FCM analysis is arguably less expensive than HPC when measuring more than 15 water samples per day, depending on the laboratory and selected staining procedure(s). Moreover, many studies have shown FCM total (TCC) and intact (ICC) cell concentrations to be reliable and robust process variables, responsive to changes in the bacterial abundance and relevant for characterising and monitoring drinking water treatment and distribution systems. The purpose of this critical review is to initiate a constructive discussion on whether FCM could replace HPC in routine water quality monitoring. We argue that FCM provides a faster, more descriptive and more representative quantification of bacterial abundance in drinking water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions

PubMed Central

Vergnano, Marta; Wan, Chris

2017-01-01

ABSTRACT We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection. PMID:28743817

CD8+ T cells and Risk for Bacterial Pneumonia and All-Cause Mortality Among HIV-infected Women

PubMed Central

Gohil, Shruti; Heo, Moonseong; Schoenbaum, Ellie; Celentano, David; Pirofski, Liise-anne

2012-01-01

Background Bacterial pneumonia risk is disproportionately high among those infected with Human Immunodeficiency Virus (HIV). This risk is present across all CD4+ T cell levels (TCL), suggesting additional factors govern susceptibility. This study examines CD8+ TCL and risk for HIV-associated bacterial pneumonia and all-cause mortality. Methods Demographic, clinical, and laboratory data were obtained for 885 HIV-infected (HIV+) women enrolled in the HIV Epidemiologic Research Study (HERS). Bacterial pneumonia cases were identified using clinical, microbiologic, and radiographic criteria. CD8+ TCLs were assessed at 6-month intervals. Statistical methods included Cox proportional hazards regression modeling and covariate-adjusted survival estimates. Results Relative to a referent CD8+ TCL 401–800 cells/mm3, risk for bacterial pneumonia was significantly higher when CD8+ TCLs were ≤ 400 (hazard ratio 1.65, p=0.017, 95% CI 1.10–2.49), after adjusting for age, CD4+ TCL, viral load, and antiretroviral use. There was also a significantly higher risk of death when CD8+ TCLs were ≤ 400 cells/mm3 (hazard ratio 1.45, p=0.04, 95% CI 1.02–2.06). Covariate-adjusted survival estimates revealed shorter time to pneumonia and death in this CD8+ TCL category and the overall association of the categorized CD8+TCL with bacterial pneumonia and all-cause mortality were each statistically significant (p=0.017 and p<0.0001, respectively). Conclusions CD8+ TCL ≤ 400 cells/mm3 was associated with increased risk for pneumonia and all-cause mortality in HIV-infected women in the HERS Cohort, suggesting that CD8+ TCL could serve as an adjunctive biomarker of pneumonia risk and mortality in HIV-infected individuals. PMID:22334070

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.

Evaluation of an in vitro cell assay to select attenuated bacterial mutants of Aeromonas hydrophila and Edwardsiella tarda to channel catfish

USDA-ARS?s Scientific Manuscript database

To evaluate the feasibility of using an in vitro cell assay to select attenuated bacterial mutants. Using catfish gill cells G1B, the feasibility of using an in vitro assay instead of in vivo virulence assay using live fish to select attenuated bacterial mutants was evaluated in this study. Pearson ...

Physical impaction injury effects on bacterial cells during spread plating influenced by cell characteristics of the organisms.

PubMed

Thomas, P; Mujawar, M M; Sekhar, A C; Upreti, R

2014-04-01

To understand the factors that contribute to the variations in colony-forming units (CFU) in different bacteria during spread plating. Employing a mix culture of vegetative cells of ten organisms varying in cell characteristics (Gram reaction, cell shape and cell size), spread plating to the extent of just drying the agar surface (50-60 s) was tested in comparison with the alternate spotting-and-tilt-spreading (SATS) approach where 100 μl inoculum was distributed by mere tilting of plate after spotting as 20-25 microdrops. The former imparted a significant reduction in CFU by 20% over the spreader-independent SATS approach. Extending the testing to single organisms, Gram-negative proteobacteria with relatively larger cells (Escherichia, Enterobacter, Agrobacterium, Ralstonia, Pantoea, Pseudomonas and Sphingomonas spp.) showed significant CFU reduction with spread plating except for slow-growing Methylobacterium sp., while those with small rods (Xenophilus sp.) and cocci (Acinetobacter sp.) were less affected. Among Gram-positive nonspore formers, Staphylococcus epidermidis showed significant CFU reduction while Staphylococcus haemolyticus and actinobacteria (Microbacterium, Cellulosimicrobium and Brachybacterium spp.) with small rods/cocci were unaffected. Vegetative cells of Bacillus pumilus and B. subtilis were generally unaffected while others with larger rods (B. thuringiensis, Brevibacillus, Lysinibacillus and Paenibacillus spp.) were significantly affected. A simulated plating study coupled with live-dead bacterial staining endorsed the chances of cell disruption with spreader impaction in afflicted organisms. Significant reduction in CFU could occur during spread plating due to physical impaction injury to bacterial cells depending on the spreader usage and the variable effects on different organisms are determined by Gram reaction, cell size and cell shape. The inoculum spreader could impart physical disruption of vegetative cells against a hard surface

Low-energy plasma immersion ion implantation to induce DNA transfer into bacterial E. coli

NASA Astrophysics Data System (ADS)

Sangwijit, K.; Yu, L. D.; Sarapirom, S.; Pitakrattananukool, S.; Anuntalabhochai, S.

2015-12-01

Plasma immersion ion implantation (PIII) at low energy was for the first time applied as a novel biotechnology to induce DNA transfer into bacterial cells. Argon or nitrogen PIII at low bias voltages of 2.5, 5 and 10 kV and fluences ranging from 1 × 1012 to 1 × 1017 ions/cm2 treated cells of Escherichia coli (E. coli). Subsequently, DNA transfer was operated by mixing the PIII-treated cells with DNA. Successes in PIII-induced DNA transfer were demonstrated by marker gene expressions. The induction of DNA transfer was ion-energy, fluence and DNA-size dependent. The DNA transferred in the cells was confirmed functioning. Mechanisms of the PIII-induced DNA transfer were investigated and discussed in terms of the E. coli cell envelope anatomy. Compared with conventional ion-beam-induced DNA transfer, PIII-induced DNA transfer was simpler with lower cost but higher efficiency.

Parenteral irons versus transfused red blood cells for treatment of anemia during canine experimental bacterial pneumonia.

PubMed

Suffredini, Dante A; Xu, Wanying; Sun, Junfeng; Barea-Mendoza, Jesús; Solomon, Steven B; Brashears, Samuel L; Perlegas, Andreas; Kim-Shapiro, Daniel B; Klein, Harvey G; Natanson, Charles; Cortés-Puch, Irene

2017-10-01

No studies have been performed comparing intravenous (IV) iron with transfused red blood cells (RBCs) for treating anemia during infection. In a previous report, transfused older RBCs increased free iron release and mortality in infected animals when compared to fresher cells. We hypothesized that treating anemia during infection with transfused fresh RBCs, with minimal free iron release, would prove superior to IV iron therapy. Purpose-bred beagles (n = 42) with experimental Staphylococcus aureus pneumonia rendered anemic were randomized to be transfused RBCs stored for 7 days or one of two IV iron preparations (7 mg/kg), iron sucrose, a widely used preparation, or ferumoxytol, a newer formulation that blunts circulating iron levels. Both irons increased the alveolar-arterial oxygen gradient at 24 to 48 hours (p = 0.02-0.001), worsened shock at 16 hours (p = 0.02-0.003, respectively), and reduced survival (transfusion 56%; iron sucrose 8%, p = 0.01; ferumoxytol 9%, p = 0.04). Compared to fresh RBC transfusion, plasma iron measured by non-transferrin-bound iron levels increased with iron sucrose at 7, 10, 13, 16, 24, and 48 hours (p = 0.04 to p < 0.0001) and ferumoxytol at 7, 24, and 48 hours (p = 0.04 to p = 0.004). No significant differences in cardiac filling pressures or performance, hemoglobin (Hb), or cell-free Hb were observed. During canine experimental bacterial pneumonia, treatment of mild anemia with IV iron significantly increased free iron levels, shock, lung injury, and mortality compared to transfusion of fresh RBCs. This was true for iron preparations that do or do not blunt circulating free iron level elevations. These findings suggest that treatment of anemia with IV iron during infection should be undertaken with caution. © 2017 AABB.

Tobramycin mediated silver nanospheres/graphene oxide composite for synergistic therapy of bacterial infection.

PubMed

Ullah, Sadeeq; Ahmad, Aftab; Subhan, Fazli; Jan, Aminullah; Raza, Muslim; Khan, Arif Ullah; Rahman, Aziz-Ur; Khan, Usman Ali; Tariq, Muhammad; Yuan, Qipeng

2018-06-01

Graphene-based materials have attracted a significant attention in constructing hybrid systems for drug delivery with enhanced antimicrobial activities. In our work, we demonstrated the formation of silver nanoparticles (AgNPs) on graphene oxide (GO) using tobramycin (TOB), an aminoglycoside antibiotic, as reducing and decorating agent. The TOB decorated GO AgNPs (TOB-GO-Ag) composite was used as an antibacterial agent against multi-drug resistant Gram-negative E-coli (BL21 DE3). The reversal of surface potential from -30 mV (GO) to +20 mV confirms the successful reduction of GO by TOB. Atomic force microscopy (AFM) and high-resolution transmission electron microscopic (HRTEM) analyses confirmed the formation of uniformly distributed AgNPs on the reduced GO with an approximate particle size of 5 nm. The as-synthesized nanocomposite displayed significant antibacterial activity as compared to pure AgNPs and TOB. The positively charged TOB-GO-Ag interacts with the negatively charged E. coli membrane and inhibit bacterial growth by the antibacterial actions of the released silver, GO and tobramycin from the TOB-GO-Ag composite. The significant loss of bacterial membrane potential from -52 ± 2 mV (control) to -2 ± 1 mV (treated) indicates a severe cell wall damage caused by TOB-GO-Ag composite. Furthermore, fluorescence study also demonstrated a severe membrane disruption in bacterial cells treated with TOB-GO-Ag composite as compared to pure AgNPs and GO. In conclusion, the development of such hybrid systems would help in enhancing the efficacy of available drugs and eradicating the emerging bacterial resistance. Copyright © 2018 Elsevier B.V. All rights reserved.

A prospective study of risk factors for neurological complications in childhood bacterial meningitis.

PubMed

Namani, Sadie; Milenković, Zvonko; Koci, Bulëza

2013-01-01

To prospectively analyze the prognostic factors for neurological complications of childhood bacterial meningitis. This prospective study enrolled 77 children from 1 month until 16 years of age, treated for bacterial meningitis during the period of January 1, 2009 through December 31, 2010. 16 relevant predictors were chosen to analyze their association with the incidence of neurological complications. p-values < 0.05 were considered statistically significant. Of the 77 children treated for bacterial meningitis, 33 patients developed neurological complications (43%), and two children died (2.6%). The etiology of bacterial meningitis cases was proven in 57/77 (74%) cases: 32 meningococci, eight pneumococci, six Gram-negative bacilli, five H. influenzae, five staphylococci, and one S. viridans isolates were found. Factors found to be associated with increased risk of development of neurological complications were age < 12 months, altered mental status, seizures prior to admission, initial therapy with two antibiotics, dexamethasone use, presence of focal neurological deficit on admission and increased proteins in cerebrospinal fluid (CSF) (p < 0.05). Initial pleocytosis > 5,000 cells/mm(3), pleocytosis > 5,000 cells/mm(3) after 48 hours, CSF/blood glucose ratio < 0.20, female gender, previous treatment with antibiotics, community-acquired infection, duration of illness > 48 hours, presence of comorbidity, and primary focus of infection were not associated with increased risk for the development of neurological complications. Age < 12 months and severity of clinical presentation at admission were identified as the strongest predictors of neurological complications and may be of value in selecting patients for more intensive care and treatment. Copyright © 2013 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Development of Rare Bacterial Monosaccharide Analogs for Metabolic Glycan Labeling in Pathogenic Bacteria.

PubMed

Clark, Emily L; Emmadi, Madhu; Krupp, Katharine L; Podilapu, Ananda R; Helble, Jennifer D; Kulkarni, Suvarn S; Dube, Danielle H

2016-12-16

Bacterial glycans contain rare, exclusively bacterial monosaccharides that are frequently linked to pathogenesis and essentially absent from human cells. Therefore, bacterial glycans are intriguing molecular targets. However, systematic discovery of bacterial glycoproteins is hampered by the presence of rare deoxy amino sugars, which are refractory to traditional glycan-binding reagents. Thus, the development of chemical tools that label bacterial glycans is a crucial step toward discovering and targeting these biomolecules. Here, we explore the extent to which metabolic glycan labeling facilitates the studying and targeting of glycoproteins in a range of pathogenic and symbiotic bacterial strains. We began with an azide-containing analog of the naturally abundant monosaccharide N-acetylglucosamine and discovered that it is not broadly incorporated into bacterial glycans, thus revealing a need for additional azidosugar substrates to broaden the utility of metabolic glycan labeling in bacteria. Therefore, we designed and synthesized analogs of the rare deoxy amino d-sugars N-acetylfucosamine, bacillosamine, and 2,4-diacetamido-2,4,6-trideoxygalactose and established that these analogs are differentially incorporated into glycan-containing structures in a range of pathogenic and symbiotic bacterial species. Further application of these analogs will refine our knowledge of the glycan repertoire in diverse bacteria and may find utility in treating a variety of infectious diseases with selectivity.

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

PubMed Central

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

2010-01-01

We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiography. Our results showed that leucine was taken up by 70–80% of Bacteria-positive cells, whereas only 15–43% of Bacteria-positive cells were able to take up thymidine. When a saturating substrate concentration in combination with a short incubation was used, 80–90% of Betaproteobacteria and 67–79% of Actinobacteria were positive for leucine uptake, whereas thymidine was taken up by < 10% of Betaproteobacteria and by < 1% of the R-BT subgroup that dominated this bacterial group. Bacterial abundance was a good predictor of the relative contribution of bacterial groups to leucine uptake, whereas when thymidine was used Actinobacteria represented the large majority (> 80%) of the cells taking up this substrate. Increasing the substrate concentration to 100 nM did not affect the percentage of R-BT cells taking up leucine (> 90% even at low concentrations), but moderately increased the fraction of thymidine-positive R-BT cells to a maximum of 35% of the hybridized cells. Our results show that even at very high concentrations, thymidine is not taken up by all, otherwise active, bacterial cells. PMID:19725866

Controlled graphene encapsulation: a nanoscale shield for characterising single bacterial cells in liquid.

PubMed

Li, Jiayao; Zheng, Changxi; Liu, Boyin; Chou, Tsengming; Kim, Yeonuk; Qiu, Shi; Li, Jian; Yan, Wenyi; Fu, Jing

2018-06-11

High-resolution single-cell imaging in their native or near-native state has received considerable interest for decades. In this research, we present an innovative approach that can be employed to study both morphological and nano-mechanical properties of hydrated single bacterial cells. The proposed strategy is to encapsulate wet cells with monolayer graphene with a newly developed water membrane approach, followed by imaging with both electron microscopy (EM) and atomic force microscopy (AFM). A computational framework was developed to provide additional insights, with the detailed nanoindentation process on graphene modeled based on finite element method. The model was first validated by calibration with polymer materials of known properties, and the contribution of graphene was then studied and corrected to determine the actual moduli of the encapsulated hydrated sample. Aapplication of the proposed approach was performed on hydrated bacterial cells (Klebsiella pneumoniae) to correlate the structural and mechanical information. EM and EDS (energy-dispersive X-ray spectroscopy) imaging confirmed that the cells in their near-native stage can be studied inside the miniatured environment enabled with graphene encapsulation. The actual moduli of the encapsulated hydrated cells were determined based on the developed computational model in parallel, with results comparable with those acquired with Wet-AFM. It is expected that the successful establishment of controlled graphene encapsulation offers a new route for probing liquid/live cells with scanning probe microscopy, as well as correlative imaging of hydrated samples for both biological and material sciences. © 2018 IOP Publishing Ltd.

Cell Cycle Inhibition To Treat Sleeping Sickness.

PubMed

Epting, Conrad L; Emmer, Brian T; Du, Nga Y; Taylor, Joann M; Makanji, Ming Y; Olson, Cheryl L; Engman, David M

2017-09-19

African trypanosomiasis is caused by infection with the protozoan parasite Trypanosoma brucei During infection, this pathogen divides rapidly to high density in the bloodstream of its mammalian host in a manner similar to that of leukemia. Like all eukaryotes, T. brucei has a cell cycle involving the de novo synthesis of DNA regulated by ribonucleotide reductase (RNR), which catalyzes the conversion of ribonucleotides into their deoxy form. As an essential enzyme for the cell cycle, RNR is a common target for cancer chemotherapy. We hypothesized that inhibition of RNR by genetic or pharmacological means would impair parasite growth in vitro and prolong the survival of infected animals. Our results demonstrate that RNR inhibition is highly effective in suppressing parasite growth both in vitro and in vivo These results support drug discovery efforts targeting the cell cycle, not only for African trypanosomiasis but possibly also for other infections by eukaryotic pathogens. IMPORTANCE The development of drugs to treat infections with eukaryotic pathogens is challenging because many key virulence factors have closely related homologues in humans. Drug toxicity greatly limits these development efforts. For pathogens that replicate at a high rate, especially in the blood, an alternative approach is to target the cell cycle directly, much as is done to treat some hematologic malignancies. The results presented here indicate that targeting the cell cycle via inhibition of ribonucleotide reductase is effective at killing trypanosomes and prolonging the survival of infected animals. Copyright © 2017 Epting et al.

Stem cell transplantation for treating Parkinson's disease: Literature analysis based on the Web of Science.

PubMed

Li, Runhui

2012-06-05

To identify global research trends of stem cell transplantation for treating Parkinson's disease using a bibliometric analysis of the Web of Science. We performed a bibliometric analysis of data retrievals for stem cell transplantation for treating Parkinson's disease from 2002 to 2011 using the Web of Science. (a) peer-reviewed articles on stem cell transplantation for treating Parkinson's disease which were published and indexed in the Web of Science; (b) type of articles: original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material and news items; (c) year of publication: 2002-2011. (a) articles that required manual searching or telephone access; (b) we excluded documents that were not published in the public domain; (c) we excluded a number of corrected papers from the total number of articles. (1) Type of literature; (2) annual publication output; (3) distribution according to journals; (4) distribution according to subject areas; (5) distribution according to country; (6) distribution according to institution; (7) comparison of countries that published the most papers on stem cell transplantation from different cell sources for treating Parkinson's disease; (8) comparison of institutions that published the most papers on stem cell transplantation from different cell sources for treating Parkinson's disease in the Web of Science from 2002 to 2011; (9) comparison of studies on stem cell transplantation from different cell sources for treating Parkinson's disease. In total, 1 062 studies on stem cell transplantation for treating Parkinson's disease appeared in the Web of Science from 2002 to 2011, almost one third of which were from American authors and institutes. The number of studies on stem cell transplantation for treating Parkinson's disease had gradually increased over the past 10 years. Papers on stem cell transplantation for treating Parkinson's disease appeared in journals such as Stem Cells and

Altered Virome and Bacterial Microbiome in Human Immunodeficiency Virus-Associated Acquired Immunodeficiency Syndrome

PubMed Central

Monaco, Cynthia L.; Gootenberg, David B.; Zhao, Guoyan; Handley, Scott A.; Ghebremichael, Musie S.; Lim, Efrem S.; Lankowski, Alex; Baldridge, Megan T.; Wilen, Craig B.; Flagg, Meaghan; Norman, Jason M.; Keller, Brian C.; Luévano, Jesús Mario; Wang, David; Boum, Yap; Martin, Jeffrey N.; Hunt, Peter W.; Bangsberg, David R.; Siedner, Mark J.; Kwon, Douglas S.; Virgin, Herbert W.

2016-01-01

SUMMARY Human immunodeficiency virus (HIV) infection is associated with increased intestinal translocation of microbial products and enteropathy as well as alterations in gut bacterial communities. However, whether the enteric virome contributes to this infection and resulting immunodeficiency remains unknown. We characterized the enteric virome and bacterial microbiome in a cohort of Ugandan patients, including HIV-uninfected or HIV-infected subjects and those either treated with anti-retroviral therapy (ART) or untreated. Low peripheral CD4 T cell counts were associated with an expansion of enteric adenovirus sequences and this increase was independent of ART treatment. Additionally, the enteric bacterial microbiome of patients with lower CD4 T counts exhibited reduced phylogenetic diversity and richness with specific bacteria showing differential abundance, including increases in Enterobacteriaceae, which have been associated with inflammation. Thus, immunodeficiency in progressive HIV infection is associated with alterations in the enteric virome and bacterial microbiome, which may contribute to AIDS-associated enteropathy and disease progression. PMID:26962942

Altered Virome and Bacterial Microbiome in Human Immunodeficiency Virus-Associated Acquired Immunodeficiency Syndrome.

PubMed

Monaco, Cynthia L; Gootenberg, David B; Zhao, Guoyan; Handley, Scott A; Ghebremichael, Musie S; Lim, Efrem S; Lankowski, Alex; Baldridge, Megan T; Wilen, Craig B; Flagg, Meaghan; Norman, Jason M; Keller, Brian C; Luévano, Jesús Mario; Wang, David; Boum, Yap; Martin, Jeffrey N; Hunt, Peter W; Bangsberg, David R; Siedner, Mark J; Kwon, Douglas S; Virgin, Herbert W

2016-03-09

Human immunodeficiency virus (HIV) infection is associated with increased intestinal translocation of microbial products and enteropathy as well as alterations in gut bacterial communities. However, whether the enteric virome contributes to this infection and resulting immunodeficiency remains unknown. We characterized the enteric virome and bacterial microbiome in a cohort of Ugandan patients, including HIV-uninfected or HIV-infected subjects and those either treated with anti-retroviral therapy (ART) or untreated. Low peripheral CD4 T cell counts were associated with an expansion of enteric adenovirus sequences and this increase was independent of ART treatment. Additionally, the enteric bacterial microbiome of patients with lower CD4 T counts exhibited reduced phylogenetic diversity and richness with specific bacteria showing differential abundance, including increases in Enterobacteriaceae, which have been associated with inflammation. Thus, immunodeficiency in progressive HIV infection is associated with alterations in the enteric virome and bacterial microbiome, which may contribute to AIDS-associated enteropathy and disease progression. Copyright © 2016 Elsevier Inc. All rights reserved.

Raman spectroscopic analysis of cytotoxic effect of cisplatin-treated leukemic cells

NASA Astrophysics Data System (ADS)

Lin, Juqiang; Li, Yongzeng; Feng, Shangyuan; Chen, Rong; Chen, Guannan; Chen, Qisong; Pan, Jianji; Lin, Shaojun; Yu, Yun

2009-08-01

An antitumor drug cisplatin was employed to treat the leukemic cells and induce apoptosis of the cancer cells. Confocal Raman micro-spectroscopy has been applied to investigate the effectiveness of the treatment using near-infrared laser (785nm) excitation, scanning range from 500 to 2000 cm-1. The Raman spectra of leukemic cell treated with cisplatin for 4, 6, 8, 12 and 14 h were measured separately. The major difference of the apoptotic cells from the cancer cells are the reduction in intensities of vibration bands generated by cellular lipids, proteins and nucleic acids. In particular, large intensity reduction in nucleic vibrations at 782, 1092, 1320, 1340, and 1578 cm-1 was observed upon apoptosis of the leukemic cells. Up to 45% reduction in the magnitude of the 782 cm-1 peak in Raman spectra of the apoptotic cells was observed, which suggests the breakdown of phosphodiester bonds and DNA bases. We showed that the principal components analysis (PCA), a multivariate statistical tool, can be used to distinguish single apoptotic cells and leukemic cells based on their Raman spectra. Our results indicate that the Raman spectroscopy with PCA is a novel, nondestructive mean for studying the cisplatin -treated leukemic cells, which could also provide useful data for clinical dosage optimization for cisplatin.

Emerging Microtechnologies and Automated Systems for Rapid Bacterial Identification and Antibiotic Susceptibility Testing

PubMed Central

Li, Yiyan; Yang, Xing; Zhao, Weian

2018-01-01

Rapid bacterial identification (ID) and antibiotic susceptibility testing (AST) are in great demand due to the rise of drug-resistant bacteria. Conventional culture-based AST methods suffer from a long turnaround time. By necessity, physicians often have to treat patients empirically with antibiotics, which has led to an inappropriate use of antibiotics, an elevated mortality rate and healthcare costs, and antibiotic resistance. Recent advances in miniaturization and automation provide promising solutions for rapid bacterial ID/AST profiling, which will potentially make a significant impact in the clinical management of infectious diseases and antibiotic stewardship in the coming years. In this review, we summarize and analyze representative emerging micro- and nanotechnologies, as well as automated systems for bacterial ID/AST, including both phenotypic (e.g., microfluidic-based bacterial culture, and digital imaging of single cells) and molecular (e.g., multiplex PCR, hybridization probes, nanoparticles, synthetic biology tools, mass spectrometry, and sequencing technologies) methods. We also discuss representative point-of-care (POC) systems that integrate sample processing, fluid handling, and detection for rapid bacterial ID/AST. Finally, we highlight major remaining challenges and discuss potential future endeavors toward improving clinical outcomes with rapid bacterial ID/AST technologies. PMID:28850804

Emerging Microtechnologies and Automated Systems for Rapid Bacterial Identification and Antibiotic Susceptibility Testing.

PubMed

Li, Yiyan; Yang, Xing; Zhao, Weian

2017-12-01

Rapid bacterial identification (ID) and antibiotic susceptibility testing (AST) are in great demand due to the rise of drug-resistant bacteria. Conventional culture-based AST methods suffer from a long turnaround time. By necessity, physicians often have to treat patients empirically with antibiotics, which has led to an inappropriate use of antibiotics, an elevated mortality rate and healthcare costs, and antibiotic resistance. Recent advances in miniaturization and automation provide promising solutions for rapid bacterial ID/AST profiling, which will potentially make a significant impact in the clinical management of infectious diseases and antibiotic stewardship in the coming years. In this review, we summarize and analyze representative emerging micro- and nanotechnologies, as well as automated systems for bacterial ID/AST, including both phenotypic (e.g., microfluidic-based bacterial culture, and digital imaging of single cells) and molecular (e.g., multiplex PCR, hybridization probes, nanoparticles, synthetic biology tools, mass spectrometry, and sequencing technologies) methods. We also discuss representative point-of-care (POC) systems that integrate sample processing, fluid handling, and detection for rapid bacterial ID/AST. Finally, we highlight major remaining challenges and discuss potential future endeavors toward improving clinical outcomes with rapid bacterial ID/AST technologies.

Parkin induces G2/M cell cycle arrest in TNF-α-treated HeLa cells.

PubMed

Lee, Min Ho; Cho, Yoonjung; Jung, Byung Chul; Kim, Sung Hoon; Kang, Yeo Wool; Pan, Cheol-Ho; Rhee, Ki-Jong; Kim, Yoon Suk

2015-08-14

Parkin is a known tumor suppressor. However, the mechanism by which parkin acts as a tumor suppressor remains to be fully elucidated. Previously, we reported that parkin expression induces caspase-dependent apoptotic cell death in TNF-α-treated HeLa cells. However, at that time, we did not consider the involvement of parkin in cell cycle control. In the current study, we investigated whether parkin is involved in cell cycle regulation and suppression of cancer cell growth. In our cell cycle analyses, parkin expression induced G2/M cell cycle arrest in TNF-α-treated HeLa cells. To elucidate the mechanism(s) by which parkin induces this G2/M arrest, we analyzed cell cycle regulatory molecules involved in the G2/M transition. Parkin expression induced CDC2 phosphorylation which is known to inhibit CDC2 activity and cause G2/M arrest. Cyclin B1, which is degraded during the mitotic transition, accumulated in response to parkin expression, thereby indicating parkin-induced G2/M arrest. Next, we established that Myt1, which is known to phosphorylate and inhibit CDC2, increased following parkin expression. In addition, we found that parkin also induces increased Myt1 expression, G2/M arrest, and reduced cell viability in TNF-α-treated HCT15 cells. Furthermore, knockdown of parkin expression by parkin-specific siRNA decreased Myt1 expression and phosphorylation of CDC2 and resulted in recovered cell viability. These results suggest that parkin acts as a crucial molecule causing cell cycle arrest in G2/M, thereby suppressing tumor cell growth. Copyright © 2015 Elsevier Inc. All rights reserved.

Immune Cells Are Required for Cutaneous Ulceration in a Swine Model of Chancroid

PubMed Central

San Mateo, Lani R.; Toffer, Kristen L.; Orndorff, Paul E.; Kawula, Thomas H.

1999-01-01

Cutaneous lesions of the human sexually transmitted genital ulcer disease chancroid are characterized by the presence of intraepidermal pustules, keratinocyte cytopathology, and epidermal and dermal erosion. These lesions are replete with neutrophils, macrophages, and CD4+ T cells and contain very low numbers of cells of Haemophilus ducreyi, the bacterial agent of chancroid. We examined lesion formation by H. ducreyi in a pig model by using cyclophosphamide (CPA)-induced immune cell deficiency to distinguish between host and bacterial contributions to chancroid ulcer formation. Histologic presentation of H. ducreyi-induced lesions in CPA-treated pigs differed from ulcers that developed in immune-competent animals in that pustules did not form and surface epithelia remained intact. However, these lesions had significant suprabasal keratinocyte cytotoxicity. These results demonstrate that the host immune response was required for chancroid ulceration, while bacterial products were at least partially responsible for the keratinocyte cytopathology associated with chancroid lesions in the pig. The low numbers of H. ducreyi present in lesions in humans and immune-competent pigs have prevented localization of these organisms within skin. However, H. ducreyi organisms were readily visualized in lesion biopsies from infected CPA-treated pigs by immunoelectron microscopy. These bacteria were extracellular and associated with necrotic host cells in the epidermis and dermis. The relative abundance of H. ducreyi in inoculated CPA-treated pig skin suggests control of bacterial replication by host immune cells during natural human infection. PMID:10456960

Immune cells are required for cutaneous ulceration in a swine model of chancroid.

PubMed

San Mateo, L R; Toffer, K L; Orndorff, P E; Kawula, T H

1999-09-01

Cutaneous lesions of the human sexually transmitted genital ulcer disease chancroid are characterized by the presence of intraepidermal pustules, keratinocyte cytopathology, and epidermal and dermal erosion. These lesions are replete with neutrophils, macrophages, and CD4(+) T cells and contain very low numbers of cells of Haemophilus ducreyi, the bacterial agent of chancroid. We examined lesion formation by H. ducreyi in a pig model by using cyclophosphamide (CPA)-induced immune cell deficiency to distinguish between host and bacterial contributions to chancroid ulcer formation. Histologic presentation of H. ducreyi-induced lesions in CPA-treated pigs differed from ulcers that developed in immune-competent animals in that pustules did not form and surface epithelia remained intact. However, these lesions had significant suprabasal keratinocyte cytotoxicity. These results demonstrate that the host immune response was required for chancroid ulceration, while bacterial products were at least partially responsible for the keratinocyte cytopathology associated with chancroid lesions in the pig. The low numbers of H. ducreyi present in lesions in humans and immune-competent pigs have prevented localization of these organisms within skin. However, H. ducreyi organisms were readily visualized in lesion biopsies from infected CPA-treated pigs by immunoelectron microscopy. These bacteria were extracellular and associated with necrotic host cells in the epidermis and dermis. The relative abundance of H. ducreyi in inoculated CPA-treated pig skin suggests control of bacterial replication by host immune cells during natural human infection.

Growth of Bacterial Colonies

NASA Astrophysics Data System (ADS)

Warren, Mya; Hwa, Terence

2013-03-01

On hard agar gel, there is insufficient surface hydration for bacteria to swim or swarm. Instead, growth occurs in colonies of close-packed cells, which expand purely due to repulsive interactions: individual bacteria push each other out of the way through the force of their growth. In this way, bacterial colonies represent a new type of ``active'' granular matter. In this study, we investigate the physical, biochemical, and genetic elements that determine the static and dynamic aspects of this mode of bacterial growth for E. coli. We characterize the process of colony expansion empirically, and use discrete and continuum models to examine the extent to which our observations can be explained by the growth characteristics of non-communicating cells, coupled together by physical forces, nutrients, and waste products. Our results challenge the commonly accepted modes of bacterial colony growth and provide insight into sources of growth limitation in crowded bacterial communities.

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.

Treating B-cell cancer with T cells expressing anti-CD19 chimeric antigen receptors.

PubMed

Kochenderfer, James N; Rosenberg, Steven A

2013-05-01

Most B-cell malignancies express CD19, and a majority of patients with B-cell malignancies are not cured by current standard therapies. Chimeric antigen receptors (CARs) are fusion proteins consisting of antigen recognition moieties and T-cell activation domains. T cells can be genetically modified to express CARs, and adoptive transfer of anti-CD19 CAR T cells is now being tested in clinical trials. Effective clinical treatment with anti-CD19 CAR T cells was first reported in 2010 after a patient with advanced-stage lymphoma treated at the NCI experienced a partial remission of lymphoma and long-term eradication of normal B cells. Additional patients have subsequently obtained long-term remissions of advanced-stage B-cell malignancies after infusions of anti-CD19 CAR T cells. Long-term eradication of normal CD19(+) B cells from patients receiving infusions of anti-CD19 CAR T cells demonstrates the potent antigen-specific activity of these T cells. Some patients treated with anti-CD19 CAR T cells have experienced acute adverse effects, which were associated with increased levels of serum inflammatory cytokines. Although anti-CD19 CAR T cells are at an early stage of development, the potent antigen-specific activity observed in patients suggests that infusions of anti-CD19 CAR T cells might become a standard therapy for some B-cell malignancies.

The effect of metal loading on Cd adsorption onto Shewanella oneidensis bacterial cell envelopes: The role of sulfhydryl sites

NASA Astrophysics Data System (ADS)

Yu, Qiang; Fein, Jeremy B.

2015-10-01

The adsorption and desorption of Cd onto Shewanella oneidensis bacterial cells with and without blocking of sulfhydryl sites was measured in order to determine the effect of metal loading and to understand the role of sulfhydryl sites in the adsorption reactions. The observed adsorption/desorption behaviors display strong dependence on metal loading. Under a high loading of 40 μmol Cd/g bacterial cells, blocking the sulfhydryl sites within the cell envelope by exposure of the biomass to monobromo(trimethylammonio)bimane bromide (qBBr) does not significantly affect the extent of Cd adsorption, and we observed fully reversible adsorption under this condition. In contrast, under a low metal loading of 1.3 μmol Cd/g bacterial cells, the extent of Cd adsorption onto sulfhydryl-blocked S. oneidensis cells was significantly lower than that onto untreated cells, and only approximately 50-60% of the adsorbed Cd desorbed from the cells upon acidification. In conjunction with previous EXAFS results, our findings demonstrate that Cd adsorption onto S. oneidensis under low metal loading conditions is dominated by sulfhydryl binding, and thus is controlled by a distinct adsorption mechanism from the non-sulfhydryl site binding which controls Cd adsorption under high metal loading conditions. We use the data to develop a surface complexation model that constrains the values of the stability constants for individual Cd-sulfhydryl and Cd-non-sulfhydryl bacterial complexes, and we use this approach to account for the Cd adsorption behavior as a function of both pH and metal loading. This approach is crucial in order to predict metal adsorption onto bacteria under environmentally relevant metal loading conditions where sulfhydryl binding sites can dominate the adsorption reaction.

DNA-crosslinker cisplatin eradicates bacterial persister cells.

PubMed

Chowdhury, Nityananda; Wood, Thammajun L; Martínez-Vázquez, Mariano; García-Contreras, Rodolfo; Wood, Thomas K

2016-09-01

For all bacteria, nearly every antimicrobial fails since a subpopulation of the bacteria enter a dormant state known as persistence, in which the antimicrobials are rendered ineffective due to the lack of metabolism. This tolerance to antibiotics makes microbial infections the leading cause of death worldwide and makes treating chronic infections, including those of wounds problematic. Here, we show that the FDA-approved anti-cancer drug cisplatin [cis-diamminodichloroplatinum(II)], which mainly forms intra-strand DNA crosslinks, eradicates Escherichia coli K-12 persister cells through a growth-independent mechanism. Additionally, cisplatin is more effective at killing Pseudomonas aeruginosa persister cells than mitomycin C, which forms inter-strand DNA crosslinks, and cisplatin eradicates the persister cells of several pathogens including enterohemorrhagic E. coli, Staphylococcus aureus, and P. aeruginosa. Cisplatin was also highly effective against clinical isolates of S. aureus and P. aeruginosa. Therefore, cisplatin has broad spectrum activity against persister cells. Biotechnol. Bioeng. 2016;113: 1984-1992. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Impact of bacteria and bacterial components on osteogenic and adipogenic differentiation of adipose-derived mesenchymal stem cells

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

Fiedler, Tomas, E-mail: tomas.fiedler@med.uni-rostock.de; Salamon, Achim; Adam, Stefanie

Adult mesenchymal stem cells (MSC) are present in several tissues, e.g. bone marrow, heart muscle, brain and subcutaneous adipose tissue. In invasive infections MSC get in contact with bacteria and bacterial components. Not much is known about how bacterial pathogens interact with MSC and how contact to bacteria influences MSC viability and differentiation potential. In this study we investigated the impact of three different wound infection relevant bacteria, Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes, and the cell wall components lipopolysaccharide (LPS; Gram-negative bacteria) and lipoteichoic acid (LTA; Gram-positive bacteria) on viability, proliferation, and osteogenic as well as adipogenic differentiationmore » of human adipose tissue-derived mesenchymal stem cells (adMSC). We show that all three tested species were able to attach to and internalize into adMSC. The heat-inactivated Gram-negative E. coli as well as LPS were able to induce proliferation and osteogenic differentiation but reduce adipogenic differentiation of adMSC. Conspicuously, the heat-inactivated Gram-positive species showed the same effects on proliferation and adipogenic differentiation, while its cell wall component LTA exhibited no significant impact on adMSC. Therefore, our data demonstrate that osteogenic and adipogenic differentiation of adMSC is influenced in an oppositional fashion by bacterial antigens and that MSC-governed regeneration is not necessarily reduced under infectious conditions. - Highlights: • Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli bind to and internalize into adMSC. • Heat-inactivated cells of these bacterial species trigger proliferation of adMSC. • Heat-inactivated E. coli and LPS induce osteogenic differentiation of adMSC. • Heat-inactivated E. coli and LPS reduce adipogenic differentiation of adMSC. • LTA does not influence adipogenic or osteogenic differentiation of adMSC.« less

Efficiency of fluorescence in situ hybridization for bacterial cell identification in temporary river sediments with contrasting water content.

PubMed

Fazi, Stefano; Amalfitano, Stefano; Pizzetti, Ilaria; Pernthaler, Jakob

2007-09-01

We studied the efficiency of two hybridization techniques for the analysis of benthic bacterial community composition under varying sediment water content. Microcosms were set up with sediments from four European temporary rivers. Wet sediments were dried, and dry sediments were artificially rewetted. The percentage of bacterial cells detected by fluorescence in situ hybridization with fluorescently monolabeled probes (FISH) significantly increased from dry to wet sediments, showing a positive correlation with the community activity measured via incorporation of (3)H leucine. FISH and signal amplification by catalyzed reporter deposition (CARD-FISH) could significantly better detect cells with low activity in dried sediments. Through the application of an optimized cell permeabilization protocol, the percentage of hybridized cells by CARD-FISH showed comparable values in dry and wet conditions. This approach was unrelated to (3)H leucine incorporation rates. Moreover, the optimized protocol allowed a significantly better visualization of Gram-positive Actinobacteria in the studied samples. CARD-FISH is, therefore, proposed as an effective technique to compare bacterial communities residing in sediments with contrasting water content, irrespective of differences in the activity state of target cells. Considering the increasing frequencies of flood and drought cycles in European temporary rivers, our approach may help to better understand the dynamics of microbial communities in such systems.

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.

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.

Rapid Antibiotic Susceptibility Testing of Uropathogenic E. coli by Tracking Submicron Scale Motion of Single Bacterial Cells.

PubMed

Syal, Karan; Shen, Simon; Yang, Yunze; Wang, Shaopeng; Haydel, Shelley E; Tao, Nongjian

2017-08-25

To combat antibiotic resistance, a rapid antibiotic susceptibility testing (AST) technology that can identify resistant infections at disease onset is required. Current clinical AST technologies take 1-3 days, which is often too slow for accurate treatment. Here we demonstrate a rapid AST method by tracking sub-μm scale bacterial motion with an optical imaging and tracking technique. We apply the method to clinically relevant bacterial pathogens, Escherichia coli O157: H7 and uropathogenic E. coli (UPEC) loosely tethered to a glass surface. By analyzing dose-dependent sub-μm motion changes in a population of bacterial cells, we obtain the minimum bactericidal concentration within 2 h using human urine samples spiked with UPEC. We validate the AST method using the standard culture-based AST methods. In addition to population studies, the method allows single cell analysis, which can identify subpopulations of resistance strains within a sample.

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

Impact of commonly used agrochemicals on bacterial diversity in cultivated soils.

PubMed

Ampofo, J A; Tetteh, W; Bello, M

2009-09-01

The effects of three selected agrochemicals on bacterial diversity in cultivated soil have been studied. The selected agrochemicals are Cerox (an insecticide), Ceresate and Paraquat (both herbicides). The effect on bacterial population was studied by looking at the total heterotrophic bacteria presence and the effect of the agrochemicals on some selected soil microbes. The soil type used was loamy with pH of 6.0-7.0. The soil was placed in opaque pots and bambara bean (Vigna subterranean) seeds cultivated in them. The agrochemicals were applied two weeks after germination of seeds at concentrations based on manufacturer's recommendation. Plant growth was assessed by weekly measurement of plant height, foliage appearance and number of nodules formed after one month. The results indicated that the diversity index (Di) among the bacteria populations in untreated soil and that of Cerox-treated soils were high with mean diversity index above 0.95. Mean Di for Ceresate-treated soil was 0.88, and that for Paraquattreated soil was 0.85 indicating low bacterial populations in these treatment-type soils. The study also showed that application of the agrochemicals caused reduction in the number of total heterotrophic bacteria population sizes in the soil. Ceresate caused 82.50% reduction in bacteria number from a mean of 40 × 10(5) cfu g(-1) of soil sample to 70 × 10(4) cfu g(-1). Paraquat-treated soil showed 92.86% reduction, from a mean of 56 × 10(5) cfu g(-1) to 40 × 10(4) cfu g(-1). Application of Cerox to the soil did not have any remarkable reduction in bacterial population number. Total viable cell count studies using Congo red yeast-extract mannitol agar indicated reduction in the number of Rhizobium spp. after application of the agrochemicals. Mean number of Rhizobium population numbers per gram of soil was 180 × 10(4) for the untreated soil. Cerox-treated soil recorded mean number of 138 × 10(4) rhizobial cfu g(-1) of soil, a 23.33% reduction. Ceresate- and

Spatial variation in the bacterial and denitrifying bacterial community in a biofilter treating subsurface agricultural drainage.

PubMed

Andrus, J Malia; Porter, Matthew D; Rodríguez, Luis F; Kuehlhorn, Timothy; Cooke, Richard A C; Zhang, Yuanhui; Kent, Angela D; Zilles, Julie L

2014-02-01

Denitrifying biofilters can remove agricultural nitrates from subsurface drainage, reducing nitrate pollution that contributes to coastal hypoxic zones. The performance and reliability of natural and engineered systems dependent upon microbially mediated processes, such as the denitrifying biofilters, can be affected by the spatial structure of their microbial communities. Furthermore, our understanding of the relationship between microbial community composition and function is influenced by the spatial distribution of samples.In this study we characterized the spatial structure of bacterial communities in a denitrifying biofilter in central Illinois. Bacterial communities were assessed using automated ribosomal intergenic spacer analysis for bacteria and terminal restriction fragment length polymorphism of nosZ for denitrifying bacteria.Non-metric multidimensional scaling and analysis of similarity (ANOSIM) analyses indicated that bacteria showed statistically significant spatial structure by depth and transect,while denitrifying bacteria did not exhibit significant spatial structure. For determination of spatial patterns, we developed a package of automated functions for the R statistical environment that allows directional analysis of microbial community composition data using either ANOSIM or Mantel statistics.Applying this package to the biofilter data, the flow path correlation range for the bacterial community was 6.4 m at the shallower, periodically in undated depth and 10.7 m at the deeper, continually submerged depth. These spatial structures suggest a strong influence of hydrology on the microbial community composition in these denitrifying biofilters. Understanding such spatial structure can also guide optimal sample collection strategies for microbial community analyses.

Impacts of Long-Term Irrigation of Domestic Treated Wastewater on Soil Biogeochemistry and Bacterial Community Structure

PubMed Central

Wafula, Denis; White, John R.; Canion, Andy; Jagoe, Charles; Pathak, Ashish

2015-01-01

Freshwater scarcity and regulations on wastewater disposal have necessitated the reuse of treated wastewater (TWW) for soil irrigation, which has several environmental and economic benefits. However, TWW irrigation can cause nutrient loading to the receiving environments. We assessed bacterial community structure and associated biogeochemical changes in soil plots irrigated with nitrate-rich TWW (referred to as pivots) for periods ranging from 13 to 30 years. Soil cores (0 to 40 cm) were collected in summer and winter from five irrigated pivots and three adjacently located nonirrigated plots. Total bacterial and denitrifier gene abundances were estimated by quantitative PCR (qPCR), and community structure was assessed by 454 massively parallel tag sequencing (MPTS) of small-subunit (SSU) rRNA genes along with terminal restriction fragment length polymorphism (T-RFLP) analysis of nirK, nirS, and nosZ functional genes responsible for denitrification of the TWW-associated nitrate. Soil physicochemical analyses showed that, regardless of the seasons, pH and moisture contents (MC) were higher in the irrigated (IR) pivots than in the nonirrigated (NIR) plots; organic matter (OM) and microbial biomass carbon (MBC) were higher as a function of season but not of irrigation treatment. MPTS analysis showed that TWW loading resulted in the following: (i) an increase in the relative abundance of Proteobacteria, especially Betaproteobacteria and Gammaproteobacteria; (ii) a decrease in the relative abundance of Actinobacteria; (iii) shifts in the communities of acidobacterial groups, along with a shift in the nirK and nirS denitrifier guilds as shown by T-RFLP analysis. Additionally, bacterial biomass estimated by genus/group-specific real-time qPCR analyses revealed that higher numbers of total bacteria, Acidobacteria, Actinobacteria, Alphaproteobacteria, and the nirS denitrifier guilds were present in the IR pivots than in the NIR plots. Identification of the nir

Probing Prokaryotic Social Behaviors with Bacterial “Lobster Traps”

PubMed Central

Connell, Jodi L.; Wessel, Aimee K.; Parsek, Matthew R.; Ellington, Andrew D.; Whiteley, Marvin; Shear, Jason B.

2010-01-01

Bacteria are social organisms that display distinct behaviors/phenotypes when present in groups. These behaviors include the abilities to construct antibiotic-resistant sessile biofilm communities and to communicate with small signaling molecules (quorum sensing [QS]). Our understanding of biofilms and QS arises primarily from in vitro studies of bacterial communities containing large numbers of cells, often greater than 108 bacteria; however, in nature, bacteria often reside in dense clusters (aggregates) consisting of significantly fewer cells. Indeed, bacterial clusters containing 101 to 105 cells are important for transmission of many bacterial pathogens. Here, we describe a versatile strategy for conducting mechanistic studies to interrogate the molecular processes controlling antibiotic resistance and QS-mediated virulence factor production in high-density bacterial clusters. This strategy involves enclosing a single bacterium within three-dimensional picoliter-scale microcavities (referred to as bacterial “lobster traps”) defined by walls that are permeable to nutrients, waste products, and other bioactive small molecules. Within these traps, bacteria divide normally into extremely dense (1012 cells/ml) clonal populations with final population sizes similar to that observed in naturally occurring bacterial clusters. Using these traps, we provide strong evidence that within low-cell-number/high-density bacterial clusters, QS is modulated not only by bacterial density but also by population size and flow rate of the surrounding medium. We also demonstrate that antibiotic resistance develops as cell density increases, with as few as ~150 confined bacteria exhibiting an antibiotic-resistant phenotype similar to biofilm bacteria. Together, these findings provide key insights into clinically relevant phenotypes in low-cell-number/high-density bacterial populations. PMID:21060734

Stem Cell Therapy to Treat Diabetes Mellitus

PubMed Central

Liew, Chee Gee; Andrews, Peter W.

2008-01-01

Transplantation of pancreatic islets offers a direct treatment for type 1 diabetes and in some cases, insulin-dependent type 2 diabetes. However, its widespread use is hampered by a shortage of donor organs. Many extant studies have focused on deriving β-cell progenitors from pancreas and pluripotent stem cells. Efforts to generate β-cells in vitro will help elucidate the mechanisms of β-cell formation and thus provide a versatile in vivo system to evaluate the therapeutic potential of these cells to treat diabetes. Various successful experiments using β-cells in animal models have generated extensive interest in using human embryonic stem cells to restore normoglycemia in diabetic patients. While new techniques are continually unveiled, the success of β-cell generation rests upon successful manipulation of culture conditions and the induction of key regulatory genes implicated in pancreas development. In this review, we compare successfully conducted protocols, highlight essential steps and identify some of the remarkable shortfalls common to these methods. In addition, we discuss recent advancements in the derivation of patient-specific pluripotent stem cells that may facilitate the use of autologous β-cells in stem cell therapy. PMID:19290381

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

Phylogenetic and Metagenomic Analyses of Substrate-Dependent Bacterial Temporal Dynamics in Microbial Fuel Cells

PubMed Central

Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

2014-01-01

Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate. PMID:25202990

Phylogenetic and metagenomic analyses of substrate-dependent bacterial temporal dynamics in microbial fuel cells.

PubMed

Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

2014-01-01

Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate.

Noninvasive Measurement of Bacterial Intracellular pH on a Single-Cell Level with Green Fluorescent Protein and Fluorescence Ratio Imaging Microscopy

PubMed Central

Olsen, Katja N.; Budde, Birgitte B.; Siegumfeldt, Henrik; Rechinger, K. Björn; Jakobsen, Mogens; Ingmer, Hanne

2002-01-01

We show that a pH-sensitive derivative of the green fluorescent protein, designated ratiometric GFP, can be used to measure intracellular pH (pHi) in both gram-positive and gram-negative bacterial cells. In cells expressing ratiometric GFP, the excitation ratio (fluorescence intensity at 410 and 430 nm) is correlated to the pHi, allowing fast and noninvasive determination of pHi that is ideally suited for direct analysis of individual bacterial cells present in complex environments. PMID:12147523

'Drugs from bugs': bacterial effector proteins as promising biological (immune-) therapeutics.

PubMed

Rüter, Christian; Hardwidge, Philip R

2014-02-01

Immune system malfunctions cause many of the most severe human diseases. The immune system has evolved primarily to control bacterial, viral, fungal, and parasitic infections. In turn, over millions of years of coevolution, microbial pathogens have evolved various mechanisms to control and modulate the host immune system for their own benefit and survival. For example, many bacterial pathogens use virulence proteins to modulate and exploit target cell mechanisms. Our understanding of these bacterial strategies opens novel possibilities to exploit 'microbial knowledge' to control excessive immune reactions. Gaining access to strategies of microbial pathogens could lead to potentially huge benefits for the therapy of inflammatory diseases. Most work on bacterial pathogen effector proteins has the long-term aim of neutralizing the infectious capabilities of the pathogen. However, attenuated pathogens and microbial products have been used for over a century with overwhelming success in the form of vaccines to induce specific immune responses that protect against the respective infectious diseases. In this review, we focus on bacterial effector and virulence proteins capable of modulating and suppressing distinct signaling pathways with potentially desirable immune-modulating effects for treating unrelated inflammatory diseases. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

OmpA: A Flexible Clamp for Bacterial Cell Wall Attachment.

PubMed

Samsudin, Firdaus; Ortiz-Suarez, Maite L; Piggot, Thomas J; Bond, Peter J; Khalid, Syma

2016-12-06

The envelope of Gram-negative bacteria is highly complex, containing separate outer and inner membranes and an intervening periplasmic space encompassing a peptidoglycan (PGN) cell wall. The PGN scaffold is anchored non-covalently to the outer membrane via globular OmpA-like domains of various proteins. We report atomically detailed simulations of PGN bound to OmpA in three different states, including the isolated C-terminal domain (CTD), the full-length monomer, or the complete full-length dimeric form. Comparative analysis of dynamics of OmpA CTD from different bacteria helped to identify a conserved PGN-binding mode. The dynamics of full-length OmpA, embedded within a realistic representation of the outer membrane containing full-rough (Ra) lipopolysaccharide, phospholipids, and cardiolipin, suggested how the protein may provide flexible mechanical support to the cell wall. An accurate model of the heterogeneous bacterial cell envelope should facilitate future efforts to develop antibacterial agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Palladium-bacterial cellulose membranes for fuel cells.

PubMed

Evans, Barbara R; O'Neill, Hugh M; Malyvanh, Valerie P; Lee, Ida; Woodward, Jonathan

2003-07-01

Bacterial cellulose is a versatile renewable biomaterial that can be used as a hydrophilic matrix for the incorporation of metals into thin, flexible, thermally stable membranes. In contrast to plant cellulose, we found it catalyzed the deposition of metals within its structure to generate a finely divided homogeneous catalyst layer. Experimental data suggested that bacterial cellulose possessed reducing groups capable of initiating the precipitation of palladium, gold, and silver from aqueous solution. Since the bacterial cellulose contained water equivalent to at least 200 times the dry weight of the cellulose, it was dried to a thin membranous structure suitable for the construction of membrane electrode assemblies (MEAs). Results of our study with palladium-cellulose showed that it was capable of catalyzing the generation of hydrogen when incubated with sodium dithionite and generated an electrical current from hydrogen in an MEA containing native cellulose as the polyelectrolyte membrane (PEM). Advantages of using native and metallized bacterial cellulose membranes in an MEA over other PEMs such as Nafion 117 include its higher thermal stability to 130 degrees C and lower gas crossover.

Protein expression of preferred human codon-optimized Gaussia luciferase genes with an artificial open-reading frame in mammalian and bacterial cells.

PubMed

Inouye, Satoshi; Suzuki, Takahiro

2016-12-01

The protein expressions of three preferred human codon-optimized Gaussia luciferase genes (pGLuc, EpGLuc, and KpGLuc) were characterized in mammalian and bacterial cells by comparing them with those of wild-type Gaussia luciferase gene (wGLuc) and human codon-optimized Gaussia luciferase gene (hGLuc). Two synthetic genes of EpGLuc and KpGLuc containing the complete preferred human codons have an artificial open-reading frame; however, they had the similar protein expression levels to those of pGLuc and hGLuc in mammalian cells. In bacterial cells, the protein expressions of pGLuc, EpGLuc, and KpGLuc with approximately 65% GC content were the same and showed approximately 60% activities of wGLuc and hGLuc. The artificial open-reading frame in EpGLuc and KpGLuc did not affect the protein expression in mammalian and bacterial cells. Copyright © 2016 Elsevier Inc. All rights reserved.

Bacterially mediated mineralization of vaterite

NASA Astrophysics Data System (ADS)

Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

2007-03-01

Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

Formation and dissolution of bacterial colonies.

PubMed

Weber, Christoph A; Lin, Yen Ting; Biais, Nicolas; Zaburdaev, Vasily

2015-09-01

Many organisms form colonies for a transient period of time to withstand environmental pressure. Bacterial biofilms are a prototypical example of such behavior. Despite significant interest across disciplines, physical mechanisms governing the formation and dissolution of bacterial colonies are still poorly understood. Starting from a kinetic description of motile and interacting cells we derive a hydrodynamic equation for their density on a surface, where most of the kinetic coefficients are estimated from experimental data for N. gonorrhoeae bacteria. We use it to describe the formation of multiple colonies with sizes consistent with experimental observations. Finally, we show how the changes in the cell-to-cell interactions lead to the dissolution of the bacterial colonies. The successful application of kinetic theory to a complex far from equilibrium system such as formation and dissolution of living bacterial colonies potentially paves the way for the physical quantification of the initial stages of biofilm formation.

Mycoplasma pneumoniae, an Underutilized Model for Bacterial Cell Biology

PubMed Central

2014-01-01

In recent decades, bacterial cell biology has seen great advances, and numerous model systems have been developed to study a wide variety of cellular processes, including cell division, motility, assembly of macromolecular structures, and biogenesis of cell polarity. Considerable attention has been given to these model organisms, which include Escherichia coli, Bacillus subtilis, Caulobacter crescentus, and Myxococcus xanthus. Studies of these processes in the pathogenic bacterium Mycoplasma pneumoniae and its close relatives have also been carried out on a smaller scale, but this work is often overlooked, in part due to this organism's reputation as minimalistic and simple. In this minireview, I discuss recent work on the role of the M. pneumoniae attachment organelle (AO), a structure required for adherence to host cells, in these processes. The AO is constructed from proteins that generally lack homology to those found in other organisms, and this construction occurs in coordination with cell cycle events. The proteins of the M. pneumoniae AO share compositional features with proteins with related roles in model organisms. Once constructed, the AO becomes activated for its role in a form of gliding motility whose underlying mechanism appears to be distinct from that of other gliding bacteria, including Mycoplasma mobile. Together with the FtsZ cytoskeletal protein, motility participates in the cell division process. My intention is to bring this deceptively complex organism into alignment with the better-known model systems. PMID:25157081

Bacterial surface adaptation

NASA Astrophysics Data System (ADS)

Utada, Andrew

2014-03-01

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

Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria

PubMed Central

Mistou, Michel-Yves; Sutcliffe, Iain C.; van Sorge, Nina M.

2016-01-01

The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.

PubMed

Mistou, Michel-Yves; Sutcliffe, Iain C; van Sorge, Nina M

2016-07-01

The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. © FEMS 2016.

Bacterial computing with engineered populations.

PubMed

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

2015-07-28

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

Invasion of human cells by a bacterial pathogen.

PubMed

Edwards, Andrew M; Massey, Ruth C

2011-03-21

Here we will describe how we study the invasion of human endothelial cells by bacterial pathogen Staphylococcus aureus . The general protocol can be applied to the study of cell invasion by virtually any culturable bacterium. The stages at which specific aspects of invasion can be studied, such as the role of actin rearrangement or caveolae, will be highlighted. Host cells are grown in flasks and when ready for use are seeded into 24-well plates containing Thermanox coverslips. Using coverslips allows subsequent removal of the cells from the wells to reduce interference from serum proteins deposited onto the sides of the wells (to which S. aureus would attach). Bacteria are grown to the required density and washed to remove any secreted proteins (e.g. toxins). Coverslips with confluent layers of endothelial cells are transferred to new 24-well plates containing fresh culture medium before the addition of bacteria. Bacteria and cells are then incubated together for the required amount of time in 5% CO(2) at 37°C. For S. aureus this is typically between 15-90 minutes. Thermanox coverslips are removed from each well and dip-washed in PBS to remove unattached bacteria. If total associated bacteria (adherent and internalised) are to be quantified, coverslips are then placed in a fresh well containing 0.5% Triton X-100 in PBS. Gentle pipetting leads to complete cell lysis and bacteria are enumerated by serial dilution and plating onto agar. If the number of bacteria that have invaded the cells is needed, coverslips are added to wells containing 500 μl tissue culture medium supplemented with gentamicin and incubation continued for 1 h, which will kill all external bacteria. Coverslips can then be washed, cells lysed and bacteria enumerated by plating onto agar as described above. If the experiment requires direct visualisation, coverslips can be fixed and stained for light, fluorescence or confocal microscopy or prepared for electron microscopy.

Electrically-receptive and thermally-responsive paper-based sensor chip for rapid detection of bacterial cells.

PubMed

Khan, Muhammad S; Misra, Santosh K; Dighe, Ketan; Wang, Zhen; Schwartz-Duval, Aaron S; Sar, Dinabandhu; Pan, Dipanjan

2018-07-01

Although significant technological advancements have been made in the development of analytical biosensor chips for detecting bacterial strains (E. coli, S. Mutans and B. Subtilis), critical requirements i.e. limit of detection (LOD), fast time of response, ultra-sensitivity with high reproducibility and good shelf-life with robust sensing capability have yet to be met within a single sensor chip. In order to achieve these criteria, we present an electrically-receptive thermally-responsive (ER-TR) sensor chip comprised of simple filter paper used as substrate coated with composite of poly(N-isopropylacrylamide) polymer (PNIPAm) - graphene nanoplatelet (GR) followed by evaporation of Au electrodes for capturing both Gram-positive (S. mutans and B. subtilis) and Gram-negative (E. coli) bacterial cells in real-time. Autoclave water, tap water, lake water and milk samples were tested with ER-TR chip with and without bacterial strains at varying concentration range 10 1 -10 5 cells/mL. The sensor was integrated with in-house built printed circuit board (PCB) to transmit/receive electrical signals. The interaction of E. coli, S. mutans and B. subtilis cells with fibers of PNIPAm-GR resulted in a change of electrical resistance and the readout was monitored wirelessly in real-time using MATLAB algorithm. Finally, prepared ER-TR chip exhibited the reproducibility of 85-97% with shelf-life of up to four weeks after testing with lake water sample. Copyright © 2018 Elsevier B.V. All rights reserved.

Immune response in the lungs following oral immunization with bacterial lysates of respiratory pathogens.

PubMed Central

Ruedl, C; Frühwirth, M; Wick, G; Wolf, H

1994-01-01

We have investigated the local immune response of the BALB/c mouse respiratory tract after oral immunization with a bacterial lysate of seven common respiratory pathogens. After two immunization on five consecutive days, we examined the immunoglobulin (immunoglobulin G [IgG], IgM, and IgA) secretion rates of cells isolated from the lungs and compared them with those of spleen cells of orally immunized and nonimmunized animals by using a new test system based on time-resolved fluorescence. The procedure followed the principle of the classical ELISPOT test with nitrocellulose-bottomed microtiter plates, but europium (Eu3+)-linked streptavidin rather than enzyme-conjugated streptavidin was used, with the advantage of quantifying secreted immunoglobulins instead of detecting single antibody-secreting cells. Lymphocytes isolated from the lungs of treated animals revealed significant increases in total and antigen-specific IgA synthesis compared with the rates of the controls, whereas IgG and IgM production rates showed no remarkable differences. In addition, the sera of treated mice revealed higher antigen-specific IgA titers but not increased IgM and IgG levels. We conclude that priming the gut-associated lymphoid tissue with bacterial antigens of pneumotropic microorganisms can elicit an enhanced IgA response in a distant mucosal effector site, such as the respiratory tract, according to the concept of a common mucosa-associated immune system. PMID:7496936

Immune response in the lungs following oral immunization with bacterial lysates of respiratory pathogens.

PubMed

Ruedl, C; Frühwirth, M; Wick, G; Wolf, H

1994-03-01

We have investigated the local immune response of the BALB/c mouse respiratory tract after oral immunization with a bacterial lysate of seven common respiratory pathogens. After two immunization on five consecutive days, we examined the immunoglobulin (immunoglobulin G [IgG], IgM, and IgA) secretion rates of cells isolated from the lungs and compared them with those of spleen cells of orally immunized and nonimmunized animals by using a new test system based on time-resolved fluorescence. The procedure followed the principle of the classical ELISPOT test with nitrocellulose-bottomed microtiter plates, but europium (Eu3+)-linked streptavidin rather than enzyme-conjugated streptavidin was used, with the advantage of quantifying secreted immunoglobulins instead of detecting single antibody-secreting cells. Lymphocytes isolated from the lungs of treated animals revealed significant increases in total and antigen-specific IgA synthesis compared with the rates of the controls, whereas IgG and IgM production rates showed no remarkable differences. In addition, the sera of treated mice revealed higher antigen-specific IgA titers but not increased IgM and IgG levels. We conclude that priming the gut-associated lymphoid tissue with bacterial antigens of pneumotropic microorganisms can elicit an enhanced IgA response in a distant mucosal effector site, such as the respiratory tract, according to the concept of a common mucosa-associated immune system.

CD4+ T Cells Reactive to Enteric Bacterial Antigens in Spontaneously Colitic C3H/HeJBir Mice: Increased T Helper Cell Type 1 Response and Ability to Transfer Disease

PubMed Central

Cong, Yingzi; Brandwein, Steven L.; McCabe, Robert P.; Lazenby, A.; Birkenmeier, Edward H.; Sundberg, John P.; Elson, Charles O.

1998-01-01

C3H/HeJBir mice are a new substrain that spontaneously develop colitis early in life. This study was done to determine the T cell reactivity of C3H/HeJBir mice to candidate antigens that might be involved in their disease. C3H/HeJBir CD4+ T cells were strongly reactive to antigens of the enteric bacterial flora, but not to epithelial or food antigens. The stimulatory material in the enteric bacteria was trypsin sensitive and restricted by class II major histocompatibility complex molecules, but did not have the properties of a superantigen. The precursor frequency of interleuken (IL)-2–producing, bacterial-reactive CD4+ T cells in colitic mice was 1 out of 2,000 compared to 1 out of 20,000–25,000 in noncolitic control mice. These T cells produced predominately IL-2 and interferon γ, consistent with a T helper type 1 cell response and were present at 3–4 wk, the age of onset of the colitis. Adoptive transfer of bacterial-antigen–activated CD4+ T cells from colitic C3H/HeJBir but not from control C3H/HeJ mice into C3H/HeSnJ scid/scid recipients induced colitis. These data represent a direct demonstration that T cells reactive with conventional antigens of the enteric bacterial flora can mediate chronic inflammatory bowel disease. PMID:9500788

Pilot Screening to Determine Antimicrobial Synergies in a Multidrug-Resistant Bacterial Strain Library

PubMed Central

Kim, Si-Hyun; Park, Chulmin; Chun, Hye-Sun; Choi, Jae-Ki; Lee, Hyo-Jin; Cho, Sung-Yeon; Park, Sun Hee; Choi, Su-Mi; Choi, Jung-Hyun; Yoo, Jin-Hong

2016-01-01

With the rise in multidrug-resistant (MDR) bacterial infections, there has been increasing interest in combinations of ≥2 antimicrobial agents with synergistic effects. We established an MDR bacterial strain library to screen for in vitro antimicrobial synergy by using a broth microdilution checkerboard method and high-throughput luciferase-based bacterial cell viability assay. In total, 39 MDR bacterial strains, including 23 carbapenem-resistant gram-negative bacteria, 9 vancomycin-intermediate Staphylococcus aureus, and 7 vancomycin-resistant Enterococcus faecalis, were used to screen for potential antimicrobial synergies. Synergies were more frequently identified with combinations of imipenem plus trimethoprim–sulfamethoxazole for carbapenem-resistant Acinetobacter baumannii in the library. To verify this finding, we tested 34 A. baumannii clinical isolates resistant to both imipenem and trimethoprim–sulfamethoxazole by the checkerboard method. The imipenem plus trimethoprim–sulfamethoxazole combination showed synergy in the treatment of 21 (62%) of the clinical isolates. The results indicate that pilot screening for antimicrobial synergy in the MDR bacterial strain library could be valuable in the selection of combination therapeutic regimens to treat MDR bacterial infections. Further studies are warranted to determine whether this screening system can be useful to screen for the combined effects of conventional antimicrobials and new-generation antimicrobials or nonantimicrobials. PMID:26974861

Cr(VI) sorption by free and immobilised chromate-reducing bacterial cells in PVA-alginate matrix: equilibrium isotherms and kinetic studies.

PubMed

Rawat, Monica; Rawat, A P; Giri, Krishna; Rai, J P N

2013-08-01

Chromate-resistant bacterial strain isolated from the soil of tannery was studied for Cr(VI) bioaccumulation in free and immobilised cells to evaluate its applicability in chromium removal from aqueous solution. Based on the comparative analysis of the 16S rRNA gene, and phenotypic and biochemical characterization, this strain was identified as Paenibacillus xylanilyticus MR12. Mechanism of Cr adsorption was also ascertained by chemical modifications of the bacterial biomass followed by Fourier transform infrared spectroscopy analysis of the cell wall constituents. The equilibrium biosorption analysed using isotherms (Langmuir, Freundlich and Dubinin-Redushkevich) and kinetics models (pseudo-first-order, second-order and Weber-Morris) revealed that the Langmuir model best correlated to experimental data, and Weber-Morris equation well described Cr(VI) biosorption kinetics. Polyvinyl alcohol alginate immobilised cells had the highest Cr(VI) removal efficiency than that of free cells and could also be reused four times for Cr(VI) removal. Complete reduction of chromate in simulated effluent containing Cu(2+), Mg(2+), Mn(2+) and Zn(2+) by immobilised cells, demonstrated potential applications of a novel immobilised bacterial strain MR12, as a vital bioresource in Cr(VI) bioremediation technology.

Axially substituted silicon(IV) phthalocyanine and its quaternized derivative as photosensitizers towards tumor cells and bacterial pathogens.

PubMed

Ömeroğlu, İpek; Kaya, Esra Nur; Göksel, Meltem; Kussovski, Vesselin; Mantareva, Vanya; Durmuş, Mahmut

2017-10-15

Axially di-(alpha,alpha-diphenyl-4-pyridylmethoxy) silicon(IV) phthalocyanine (3) and its quaternized derivative (3Q) were synthesized and tested as photosensitizers against tumor and bacterial cells. These new phthalocyanines were characterized by elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF and 1 H NMR. The photophysical properties such as absorption and fluorescence, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated in solutions. The obtained values were compared to the values obtained with unsubstituted silicon(IV) phthalocyanine dichloride (SiPcCl 2 ). The addition of two di-(alpha,alpha-diphenyl-4-pyridylmethanol) groups as axial ligands showed an improvement of the photophysical and photochemical properties and an increasement of the singlet oxygen quantum yield (Φ Δ ) from 0.15 to 0.33 was determined. The photodynamic efficacy of synthesized photosensitizers (3 and 3Q) were evaluated with promising photocytotoxicity (17% cell survival for 3 and 28% for 3Q) against the cervical cancer cell line (HeLa). The photodynamic inactivation of pathogenic bacterial strains Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa suggested a high susceptibility with quaternized derivative (3Q). The both Gram-positive bacterial strains were fully photoinactivated with 11μM 3Q and mild light dose 50J.cm -2 . In case of P. aeruginosa the effect was negligible for concentrations up to 22μM 3Q and light dose 100J.cm -2 . The results suggested that the novel axially substituted silicon(IV) phthalocyanines have promising characteristic as photosensitizer towards tumor cells. The quaternized derivative 3Q has high potential for photoinactivation of pathogenic bacterial species. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Bone marrow mesenchymal stem cells suppress E coli-induced bacterial prostatitis in rats].

PubMed

Han, Guang-wei; Liu, Cheng-cheng; Gao, Wen-hong; Cui, Dong; Yi, Shan-hong

2015-04-01

To investigate the inhibitory effect of bone marrow mesenchymal stem cells (BMSCs) on E coliinduced prostatitis in rats. BMSCs were isolated, cultured and amplified by the attached choice method. Fifty SD rats were randomized into five groups of equal number: normal control, acute bacterial prostatitis (ABP) , chronic bacterial prostatitis (CBP), ABP + BMSCs, and CBP + BMSCs, and the animals in the latter four groups were injected with E. coli into both sides of the prostate under ultrasound guidance for 1 - 14 days to induce ABP and for 4 - 12 weeks to induce CBP. The control rats were injected with the same amount of PBS. Two weeks after injection of BMSCs into the prostates, pathomorphological changes in the prostate were observed under the light microscope and the mRNA and protein levels of IL-1β and TNF-α determined by RT-PCR and ELISA, respectively, followed by statistical analysis with SPSS 18.0. Histopathological evaluation showed typical pathological inflammatory changes in the prostates of the rats in the ABP and CBP groups, including glandular structural changes, interstitial edema, inflammatory cell infiltration, and fibrous hyperplasia, which were all remarkably relieved after treated with BMSCs. The mRNA and protein levels of IL-β ([0.829 ± 0.121] and [271.75 ± 90.59] pg/ml) and TNF-α ([0.913 ± 0. 094] and [105.78 ± 19. 05] pg/ml) in the ABP and those of IL-1β ([0. 975 ± 0. 114] and [265. 31 ± 71. 34] pg/ml) and TNF-α ([0. 886 ± 0. 084] and [107. 45 ± 26. 11 ] pg/ml) in the CBP groups were significantly higher than those in the control rats ([0. 342 ± 0.087] and [45.76 17. 99] pg/ml, P <0. 05); ([0.247 ± 0.054] and ([19.42 ± 7. 75] pg/ml, P <0. 01) as well as than those in the ABP + BMSCs ([0. 433 ± 0. 072] and [51. 34 ± 22. 13] pg/ml, P < 0. 05 ) ; ( [0. 313 ± 0. 076] and [28. 38 ± 8. 78] pg/ml, P < 0. 01) and the CBP + BMSCs group ([0.396 ± 0.064] and [56.37 ± 21.22] pg/ml, P <0.05); ([0.417 ± 0.068] and [29.21 ± 10.22] pg

A bacterial type III secretion-based protein delivery tool for broad applications in cell biology.

PubMed

Ittig, Simon J; Schmutz, Christoph; Kasper, Christoph A; Amstutz, Marlise; Schmidt, Alexander; Sauteur, Loïc; Vigano, M Alessandra; Low, Shyan Huey; Affolter, Markus; Cornelis, Guy R; Nigg, Erich A; Arrieumerlou, Cécile

2015-11-23

Methods enabling the delivery of proteins into eukaryotic cells are essential to address protein functions. Here we propose broad applications to cell biology for a protein delivery tool based on bacterial type III secretion (T3S). We show that bacterial, viral, and human proteins, fused to the N-terminal fragment of the Yersinia enterocolitica T3S substrate YopE, are effectively delivered into target cells in a fast and controllable manner via the injectisome of extracellular bacteria. This method enables functional interaction studies by the simultaneous injection of multiple proteins and allows the targeting of proteins to different subcellular locations by use of nanobody-fusion proteins. After delivery, proteins can be freed from the YopE fragment by a T3S-translocated viral protease or fusion to ubiquitin and cleavage by endogenous ubiquitin proteases. Finally, we show that this delivery tool is suitable to inject proteins in living animals and combine it with phosphoproteomics to characterize the systems-level impact of proapoptotic human truncated BID on the cellular network. © 2015 Ittig et al.

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

Bacterial adherence to periurethral epithelial cells in girls prone to urinary-tract infections.

PubMed

Källenius, G; Winberg, J

1978-09-09

Bacterial adherence to epithelial cells from the periurethral region of 48 healthy girls aged over 2 years and of 76 girls with repeated urinary-tract infections was investigated. The infection-prone girls had a significantly higher mean number of adhering bacteria than the healthy controls ( P less than 0.01). This difference was valid irrespective of whether or not the infection-prone girls had urinary-tract infections at the time of investigation. Furthermore, statistically significantly higher numbers of a pyelonephritic strain of Escherichia coli (075:H-:K-non-typable) were found to adhere to washed periurethral cells from infection-prone girls than to cells from healthy controls. These characteristics of the periurethral epithelial cells may facilitate the primary periurethral colonisation which precedes infection of the urinary tract.

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 1--Bacterial adherence.

PubMed

Sharma, Priya; Mickel, André K; Chogle, Sami; Sharma, Prem Nath; Han, Yiping W; Jones, Jefferson J

2008-02-01

To compare the adherence of Prevotella melaninogenica and Enterococcus faecalis to 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial adherence compared to Lambone and Atrisorb. The barriers were suspended in trypticase soy broth containing an inoculum of either P melaninogenica or E faecalis. The samples were incubated under appropriate conditions for 6, 24, and 48 hours. Following incubation, each membrane was mixed in fresh media in a vortex machine to dislodge adherent bacteria. The vortexed media was quantitatively assessed using serial dilutions for viable cell count. E faecalis exhibited higher adherence compared to P melaninogenica with time. Of the membranes tested, Lambone displayed the least bacterial adherence. An analysis of the results indicated that bacterial adherence was time-dependent for all membranes. Membrane structure, chemical configuration, hydrophobicity, and bacterial cell surface structure were suggested as factors contributing to variance in bacterial adherence.

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

PubMed

Mellouk, Nora; Enninga, Jost

2016-01-01

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

Activity and Phylogenetic Diversity of Bacterial Cells with High and Low Nucleic Acid Content and Electron Transport System Activity in an Upwelling Ecosystem

PubMed Central

Longnecker, K.; Sherr, B. F.; Sherr, E. B.

2005-01-01

We evaluated whether bacteria with higher cell-specific nucleic acid content (HNA) or an active electron transport system, i.e., positive for reduction of 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), were responsible for the bulk of bacterioplankton metabolic activity. We also examined whether the phylogenetic diversity of HNA and CTC-positive cells differed from the diversity of Bacteria with low nucleic acid content (LNA). Bacterial assemblages were sampled both in eutrophic shelf waters and in mesotrophic offshore waters in the Oregon coastal upwelling region. Cytometrically sorted HNA, LNA, and CTC-positive cells were assayed for their cell-specific [3H]leucine incorporation rates. Phylogenetic diversity in sorted non-radioactively labeled samples was assayed using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes. Cell-specific rates of leucine incorporation of HNA and CTC-positive cells were on average only slightly greater than the cell-specific rates of LNA cells. HNA cells accounted for most bacterioplankton substrate incorporation due to high abundances, while the low abundances of CTC-positive cells resulted in only a small contribution by these cells to total bacterial activity. The proportion of the total bacterial leucine incorporation attributable to LNA cells was higher in offshore regions than in shelf waters. Sequence data obtained from DGGE bands showed broadly similar phylogenetic diversity across HNA, LNA, and CTC-positive cells, with between-sample and between-region variability in the distribution of phylotypes. Our results suggest that LNA bacteria are not substantially different from HNA bacteria in either cell-specific rates of substrate incorporation or phylogenetic composition and that they can be significant contributors to bacterial metabolism in the sea. PMID:16332746

Activity and phylogenetic diversity of bacterial cells with high and low nucleic acid content and electron transport system activity in an upwelling ecosystem.

PubMed

Longnecker, K; Sherr, B F; Sherr, E B

2005-12-01

We evaluated whether bacteria with higher cell-specific nucleic acid content (HNA) or an active electron transport system, i.e., positive for reduction of 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), were responsible for the bulk of bacterioplankton metabolic activity. We also examined whether the phylogenetic diversity of HNA and CTC-positive cells differed from the diversity of Bacteria with low nucleic acid content (LNA). Bacterial assemblages were sampled both in eutrophic shelf waters and in mesotrophic offshore waters in the Oregon coastal upwelling region. Cytometrically sorted HNA, LNA, and CTC-positive cells were assayed for their cell-specific [3H]leucine incorporation rates. Phylogenetic diversity in sorted non-radioactively labeled samples was assayed using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes. Cell-specific rates of leucine incorporation of HNA and CTC-positive cells were on average only slightly greater than the cell-specific rates of LNA cells. HNA cells accounted for most bacterioplankton substrate incorporation due to high abundances, while the low abundances of CTC-positive cells resulted in only a small contribution by these cells to total bacterial activity. The proportion of the total bacterial leucine incorporation attributable to LNA cells was higher in offshore regions than in shelf waters. Sequence data obtained from DGGE bands showed broadly similar phylogenetic diversity across HNA, LNA, and CTC-positive cells, with between-sample and between-region variability in the distribution of phylotypes. Our results suggest that LNA bacteria are not substantially different from HNA bacteria in either cell-specific rates of substrate incorporation or phylogenetic composition and that they can be significant contributors to bacterial metabolism in the sea.

Simultaneous selection of soil electroactive bacterial communities associated to anode and cathode in a two-chamber Microbial Fuel Cell

NASA Astrophysics Data System (ADS)

Chiellini, Carolina; Bacci, Giovanni; Fani, Renato; Mocali, Stefano

2016-04-01

Different bacteria have evolved strategies to transfer electrons over their cell surface to (or from) their extracellular environment. This electron transfer enables the use of these bacteria in bioelectrochemical systems (BES) such as Microbial Fuel Cells (MFCs). In MFC research the biological reactions at the cathode have long been a secondary point of interest. However, bacterial biocathodes in MFCs represent a potential advantage compared to traditional cathodes, for both their low costs and their low impact on the environment. The main challenge in biocathode set-up is represented by the selection of a bacterial community able to efficiently accept electrons from the electrode, starting from an environmental matrix. In this work, a constant voltage was supplied on a two-chamber MFC filled up with soil over three weeks in order to simultaneously select an electron donor bacterial biomass on the anode and an electron acceptor biomass on the cathode, starting from the same soil. Next Generation Sequencing (NGS) analysis was performed to characterize the bacterial community of the initial soil, in the anode, in the cathode and in the control chamber not supplied with any voltage. Results highlighted that both the MFC conditions and the voltage supply affected the soil bacterial communities, providing a selection of different bacterial groups preferentially associated to the anode (Betaproteobacteria, Bacilli and Clostridia) and to the cathode (Actinobacteria and Alphaproteobacteria). These results confirmed that several electroactive bacteria are naturally present within a top soil and, moreover, different soil bacterial genera could provide different electrical properties.

Relationships between soil organic matter, nutrients, bacterial community structure, and the performance of microbial fuel cells.

PubMed

Dunaj, Sara J; Vallino, Joseph J; Hines, Mark E; Gay, Marcus; Kobyljanec, Christine; Rooney-Varga, Juliette N

2012-02-07

Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful renewable resource: soil organic carbon. We analyzed bacterial community structure, MFC performance, and soil characteristics in different microhabitats within MFCs constructed from agricultural or forest soils in order to determine how soil type and bacterial dynamics influence MFC performance. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs. Bacterial community profile data indicate that the bacterial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These results suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic bacterial communities, while the quality of available organic matter may have played a significant role in supporting high performing bacterial communities.

Analysis of gene expression levels in individual bacterial cells without image segmentation.

PubMed

Kwak, In Hae; Son, Minjun; Hagen, Stephen J

2012-05-11

Studies of stochasticity in gene expression typically make use of fluorescent protein reporters, which permit the measurement of expression levels within individual cells by fluorescence microscopy. Analysis of such microscopy images is almost invariably based on a segmentation algorithm, where the image of a cell or cluster is analyzed mathematically to delineate individual cell boundaries. However segmentation can be ineffective for studying bacterial cells or clusters, especially at lower magnification, where outlines of individual cells are poorly resolved. Here we demonstrate an alternative method for analyzing such images without segmentation. The method employs a comparison between the pixel brightness in phase contrast vs fluorescence microscopy images. By fitting the correlation between phase contrast and fluorescence intensity to a physical model, we obtain well-defined estimates for the different levels of gene expression that are present in the cell or cluster. The method reveals the boundaries of the individual cells, even if the source images lack the resolution to show these boundaries clearly. Copyright © 2012 Elsevier Inc. All rights reserved.

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.

Bacterial amelioration of bauxite residue waste of industrial alumina plants.

PubMed

Hamdy, M K; Williams, F S

2001-10-01

The high alkali content of bauxite residue deposits from alumina production plants in industrial nations poses a challenge to reestablish flora and fauna at the deposit sites. The present study demonstrated that low levels of injured bacterial cells in the bauxite residue actively grew using various added nutrients and/or hay. The organisms grew from less than 10 to more than 10(9) cells g(-1) bauxite residue and formed organic acids that lowered the pH from 13 to about 7.0. A total of 150 cultures was isolated from treated bauxite residue and included species of Bacillus, Lactobacillus, Leuconostoc, Micrococcus, Staphylococcus, Pseudomonas, Flavobacterium and Enterobacter. Scanning electron micrographs demonstrated that untreated particles (control) of the bauxite residue were clumped together, and in treated bauxite residue these particles were highly dispersed with microcolonial structures. Furthermore, the treated bauxite residue supported growth of several plants and earthworms that survived for over 300 days. In a test plot bioremediation on a residue deposit at Alcoa Point Comfort, TX, the Bermuda grass hay used was effective mulch material and encouraged water filtration, leading to establishment and growth of salt-tolerant vegetative species.

Patient-Specific B-Cell Antibody Factories to Treat Metastatic Disease

DTIC Science & Technology

2013-08-01

Immortalization of these selected clones using Epstein - Barr viral transformation provides a method to maintain these antibody producing cell lines as a...2013 Please see next page. None provided. Patient-Specific B-Cell Antibody Factories to Treat Metastatic Disease Kevin Claffey University of

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

Bacterial meningitis in hematopoietic stem cell transplant recipients: a population-based prospective study.

PubMed

van Veen, K E B; Brouwer, M C; van der Ende, A; van de Beek, D

2016-11-01

We performed a nationwide prospective cohort study on the epidemiology and clinical features of community-acquired bacterial meningitis. Patients with a medical history of autologous or allogeneic hematopoietic stem cell transplantation (HSCT) were identified from the cohort performed from March 2006 to October 2014. Fourteen of 1449 episodes (1.0%) of bacterial meningitis occurred in patients with a history of HSCT. The incidence of bacterial meningitis in HSCT recipients was 40.4 per 100 000 patients per year (95% confidence interval (CI) 23.9-62.2), which is 30-fold (95% CI 18-51; P<0.001) higher compared with persons without HSCT. Incidence was higher in allogeneic HSCT compared with autologous HSCT (70.0 vs 15.8 per 100 000 patients per year). Causative organisms were Streptococcus pneumoniae in 11 patients, Neisseria meningitidis in two and Streptococcus mitis in one patient. Mortality was 3 of 14 (21%) and 6 of 11 (55%) survivors had sequelae. Nine of 11 patients (82%) with pneumococcal meningitis were infected with a serotype included in the 23-valent pneumococcal polysaccharide vaccine, of whom four developed meningitis despite vaccination. In conclusion, HSCT recipients have a substantially increased risk compared with the general population of acquiring bacterial meningitis, which is mostly due to S. pneumoniae, and disease is associated with high mortality and morbidity. Vaccination is important to prevent disease although vaccine failures did occur.

Insect Gut Symbiont Susceptibility to Host Antimicrobial Peptides Caused by Alteration of the Bacterial Cell Envelope*

PubMed Central

Kim, Jiyeun Kate; Son, Dae Woo; Kim, Chan-Hee; Cho, Jae Hyun; Marchetti, Roberta; Silipo, Alba; Sturiale, Luisa; Park, Ha Young; Huh, Ye Rang; Nakayama, Hiroshi; Fukatsu, Takema; Molinaro, Antonio; Lee, Bok Luel

2015-01-01

The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis. PMID:26116716

Treating Diet-Induced Diabetes and Obesity with Human Embryonic Stem Cell-Derived Pancreatic Progenitor Cells and Antidiabetic Drugs

PubMed Central

Bruin, Jennifer E.; Saber, Nelly; Braun, Natalie; Fox, Jessica K.; Mojibian, Majid; Asadi, Ali; Drohan, Campbell; O’Dwyer, Shannon; Rosman-Balzer, Diana S.; Swiss, Victoria A.; Rezania, Alireza; Kieffer, Timothy J.

2015-01-01

Summary Human embryonic stem cell (hESC)-derived pancreatic progenitor cells effectively reverse hyperglycemia in rodent models of type 1 diabetes, but their capacity to treat type 2 diabetes has not been reported. An immunodeficient model of type 2 diabetes was generated by high-fat diet (HFD) feeding in SCID-beige mice. Exposure to HFDs did not impact the maturation of macroencapsulated pancreatic progenitor cells into glucose-responsive insulin-secreting cells following transplantation, and the cell therapy improved glucose tolerance in HFD-fed transplant recipients after 24 weeks. However, since diet-induced hyperglycemia and obesity were not fully ameliorated by transplantation alone, a second cohort of HFD-fed mice was treated with pancreatic progenitor cells combined with one of three antidiabetic drugs. All combination therapies rapidly improved body weight and co-treatment with either sitagliptin or metformin improved hyperglycemia after only 12 weeks. Therefore, a stem cell-based therapy may be effective for treating type 2 diabetes, particularly in combination with antidiabetic drugs. PMID:25801507

Effect of PDT-treated apoptotic cells on macrophages

NASA Astrophysics Data System (ADS)

Song, Sheng; Xing, Da; Zhou, Fei-fan; Chen, Wei R.

2009-02-01

Recently, the long-term immunological effects of photodynamic therapy have attracted much attention. PDT induced immune response was mainly initiated through necrotic cells and apoptotic cells, as well as immune cells such as macrophages. Nitric oxide (NO) as an important regulatory factor in signal transfer between cells has been wildly studied for generation, development, and metastasis of tumors. NO synthase is a key enzyme in nitric oxide synthesis. However, inducible nitric oxide synthase (iNOS) is usually activated under pathological conditions, such as stress and cancer, which can produce high levels of nitric oxide and contribute to tumor cytotoxicity. In addition, increased NO production by iNOS has been associated with the host immune response and cell apoptosis, which play an important role in many carcinogenesis and anti-carcinoma mechanisms. This study focuses on the NO production in macrophages, induced by mouse breast carcinoma apoptotic cells treated by PDT in vitro, and on the effects of immune response induced by apoptotic cells in tumor cells growth.

Functional effects of the bacterial insecticide Bacillus thuringiensis var. kurstaki on aquatic microbial communities.

PubMed

Kreutzweiser, D P; Gringorten, J L; Thomas, D R; Butcher, J T

1996-04-01

Epilithic microbial communities were colonized on leaf disks and exposed to commercial preparations of Bacillus thuringiensis var. kurstaki (Btk) in aquatic microcosms. Responses in terms of microbial respiration, bacterial cell density, protozoan density, and microbial decomposition activity were measured. Test concentrations for treatments with Dipel 64AF and Dipel 8AF in microcosms were the expected environmental concentration (EEC) of 20 IU/ml, 100x the EEC, and 1000x the EEC. Bacterial cell density in the biofilm of leaf disks was significantly increased at concentrations as low as the EEC. There were no concomitant alterations in protozoan density. Microbial respiration was significantly increased, and decomposition activity was significantly decreased, but only at the artificially high concentration of 1000x the EEC. This effect was attributed to the spore-crystal component rather than formulation ingredients. Microbial decomposition of leaf material was also determined in outdoor stream channels treated at concentrations ranging from the EEC to 100x the EEC. Although there tended to be reduced decomposition activity in treated channels, there were no significant differences in mass loss of leaf material between treated and control channels. Various regression, classification, and ordination procedures were applied to the experimental data, and none indicated significant treatment effects. These results from laboratory and controlled field experiments indicate that contamination of watercourses with Btk is unlikely to result in significant adverse effects on microbial community function in terms of detrital decomposition.

Computer simulation of the processes of inactivation of bacterial cells by dynamic low-coherent speckles

NASA Astrophysics Data System (ADS)

Ulianova, Onega V.; Ulyanov, Sergey S.; Sazanova, Elena V.; Zhihong, Zhang; Sibo, Zhou; Luo, Qingming; Zudina, Irina; Bednov, Andrey

2006-05-01

Biochemical, biophysical and optical aspects of interaction of low-coherent light with bacterial cells have been discussed. Influence of low-coherent speckles on the colonies grows is investigated. It has been demonstrated that effects of light on the inhibition of cells (Francisella Tularensis) are connected with speckle dynamics. The regimes of illumination of cell suspension with purpose of devitalization of hazard bacteria, caused very dangerous infections, such as tularemia, are found. Mathematical model of interaction of low-coherent laser radiation with bacteria suspension has been proposed. Computer simulations of the processes of laser-cells interaction have been carried out.

Assessment of in vitro cyto/genotoxicity of sequentially treated electroplating effluent on the human hepatocarcinoma HuH-7 cell line.

PubMed

Naik, Umesh Chandra; Das, Mihir Tanay; Sauran, Swati; Thakur, Indu Shekhar

2014-03-01

The present study compares in vitro toxicity of electroplating effluent after the batch treatment process with that obtained after the sequential treatment process. Activated charcoal prepared from sugarcane bagasse through chemical carbonization, and tolerant indigenous bacteria, Bacillus sp. strain IST105, were used individually and sequentially for the treatment of electroplating effluent. The sequential treatment involving activated charcoal followed by bacterial treatment removed 99% of Cr(VI) compared with the batch processes, which removed 40% (charcoal) and 75% (bacteria), respectively. Post-treatment in vitro cyto/genotoxicity was evaluated by the MTT test and the comet assay in human HuH-7 hepatocarcinoma cells. The sequentially treated sample showed an increase in LC50 value with a 6-fold decrease in comet-assay DNA migration compared with that of untreated samples. A significant decrease in DNA migration and an increase in LC50 value of treated effluent proved the higher effectiveness of the sequential treatment process over the individual batch processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Influenza viral neuraminidase primes bacterial coinfection through TGF-β-mediated expression of host cell receptors.

PubMed

Li, Ning; Ren, Aihui; Wang, Xiaoshuang; Fan, Xin; Zhao, Yong; Gao, George F; Cleary, Patrick; Wang, Beinan

2015-01-06

Influenza infection predisposes the host to secondary bacterial pneumonia, which is a major cause of mortality during influenza epidemics. The molecular mechanisms underlying the bacterial coinfection remain elusive. Neuraminidase (NA) of influenza A virus (IAV) enhances bacterial adherence and also activates TGF-β. Because TGF-β can up-regulate host adhesion molecules such as fibronectin and integrins for bacterial binding, we hypothesized that activated TGF-β during IAV infection contributes to secondary bacterial infection by up-regulating these host adhesion molecules. Flow cytometric analyses of a human lung epithelial cell line indicated that the expression of fibronectin and α5 integrin was up-regulated after IAV infection or treatment with recombinant NA and was reversed through the inhibition of TGF-β signaling. IAV-promoted adherence of group A Streptococcus (GAS) and other coinfective pathogens that require fibronectin for binding was prevented significantly by the inhibition of TGF-β. However, IAV did not promote the adherence of Lactococcus lactis unless this bacterium expressed the fibronectin-binding protein of GAS. Mouse experiments showed that IAV infection enhanced GAS colonization in the lungs of wild-type animals but not in the lungs of mice deficient in TGF-β signaling. Taken together, these results reveal a previously unrecognized mechanism: IAV NA enhances the expression of cellular adhesins through the activation of TGF-β, leading to increased bacterial loading in the lungs. Our results suggest that TGF-β and cellular adhesins may be potential pharmaceutical targets for the prevention of coinfection.

Light scattering on PHA granules protects bacterial cells against the harmful effects of UV radiation.

PubMed

Slaninova, Eva; Sedlacek, Petr; Mravec, Filip; Mullerova, Lucie; Samek, Ota; Koller, Martin; Hesko, Ondrej; Kucera, Dan; Marova, Ivana; Obruca, Stanislav

2018-02-01

Numerous prokaryotes accumulate polyhydroxyalkanoates (PHA) in the form of intracellular granules. The primary function of PHA is the storage of carbon and energy. Nevertheless, there are numerous reports that the presence of PHA granules in microbial cells enhances their stress resistance and fitness when exposed to various stress factors. In this work, we studied the protective mechanism of PHA granules against UV irradiation employing Cupriavidus necator as a model bacterial strain. The PHA-accumulating wild type strain showed substantially higher UV radiation resistance than the PHA non-accumulating mutant. Furthermore, the differences in UV-Vis radiation interactions with both cell types were studied using various spectroscopic approaches (turbidimetry, absorption spectroscopy, and nephelometry). Our results clearly demonstrate that intracellular PHA granules efficiently scatter UV radiation, which provides a substantial UV-protective effect for bacterial cells and, moreover, decreases the intracellular level of reactive oxygen species in UV-challenged cells. The protective properties of the PHA granules are enhanced by the fact that granules specifically bind to DNA, which in turn provides shield-like protection of DNA as the most UV-sensitive molecule. To conclude, the UV-protective action of PHA granules adds considerable value to their primary storage function, which can be beneficial in numerous environments.

Biological consequences and advantages of asymmetric bacterial growth.

PubMed

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

2013-01-01

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

Bacterial adhesion force quantification by fluidic force microscopy

NASA Astrophysics Data System (ADS)

Potthoff, Eva; Ossola, Dario; Zambelli, Tomaso; Vorholt, Julia A.

2015-02-01

Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology.Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many

Copper effects on bacterial activity of estuarine silty sediments

NASA Astrophysics Data System (ADS)

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

2007-07-01

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

Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell

USDA-ARS?s Scientific Manuscript database

Microbial fuel cells (MFCs) are a technology that provides electrical energy from the microbial oxidation of organic compounds. Most MFCs use oxygen as the oxidant in the cathode chamber. The present study examined the formation in culture of an unidentified bacterial oxidant and investigated the ...

Effects of Chinese Propolis in Protecting Bovine Mammary Epithelial Cells against Mastitis Pathogens-Induced Cell Damage.

PubMed

Wang, Kai; Jin, Xiao-Lu; Shen, Xiao-Ge; Sun, Li-Ping; Wu, Li-Ming; Wei, Jiang-Qin; Marcucci, Maria Cristina; Hu, Fu-Liang; Liu, Jian-Xin

2016-01-01

Chinese propolis (CP), an important hive product, can alleviate inflammatory responses. However, little is known regarding the potential of propolis treatment for mastitis control. To investigate the anti-inflammatory effects of CP on bovine mammary epithelial cells (MAC-T), we used a range of pathogens to induce cellular inflammatory damage. Cell viability was determined and expressions of inflammatory/antioxidant genes were measured. Using a cell-based reporter assay system, we evaluated CP and its primary constituents on the NF-κB and Nrf2-ARE transcription activation. MAC-T cells treated with bacterial endotoxin (lipopolysaccharide, LPS), heat-inactivated Escherichia coli, and Staphylococcus aureus exhibited significant decreases in cell viability while TNF-α and lipoteichoic acid (LTA) did not. Pretreatment with CP prevented losses in cell viability associated with the addition of killed bacteria or bacterial endotoxins. There were also corresponding decreases in expressions of proinflammatory IL-6 and TNF-α mRNA. Compared with the mastitis challenged cells, enhanced expressions of antioxidant genes HO-1, Txnrd-1, and GCLM were observed in CP-treated cells. CP and its polyphenolic active components (primarily caffeic acid phenethyl ester and quercetin) had strong inhibitive effects against NF-κB activation and increased the transcriptional activity of Nrf2-ARE. These findings suggest that propolis may be valuable in the control of bovine mastitis.

Effects of Chinese Propolis in Protecting Bovine Mammary Epithelial Cells against Mastitis Pathogens-Induced Cell Damage

PubMed Central

Jin, Xiao-Lu; Shen, Xiao-Ge; Sun, Li-Ping; Wu, Li-Ming; Wei, Jiang-Qin; Marcucci, Maria Cristina; Hu, Fu-Liang; Liu, Jian-Xin

2016-01-01

Chinese propolis (CP), an important hive product, can alleviate inflammatory responses. However, little is known regarding the potential of propolis treatment for mastitis control. To investigate the anti-inflammatory effects of CP on bovine mammary epithelial cells (MAC-T), we used a range of pathogens to induce cellular inflammatory damage. Cell viability was determined and expressions of inflammatory/antioxidant genes were measured. Using a cell-based reporter assay system, we evaluated CP and its primary constituents on the NF-κB and Nrf2-ARE transcription activation. MAC-T cells treated with bacterial endotoxin (lipopolysaccharide, LPS), heat-inactivated Escherichia coli, and Staphylococcus aureus exhibited significant decreases in cell viability while TNF-α and lipoteichoic acid (LTA) did not. Pretreatment with CP prevented losses in cell viability associated with the addition of killed bacteria or bacterial endotoxins. There were also corresponding decreases in expressions of proinflammatory IL-6 and TNF-α mRNA. Compared with the mastitis challenged cells, enhanced expressions of antioxidant genes HO-1, Txnrd-1, and GCLM were observed in CP-treated cells. CP and its polyphenolic active components (primarily caffeic acid phenethyl ester and quercetin) had strong inhibitive effects against NF-κB activation and increased the transcriptional activity of Nrf2-ARE. These findings suggest that propolis may be valuable in the control of bovine mastitis. PMID:27433029

Solid-state NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization.

PubMed

Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine

2013-04-03

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.

Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

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

Lemmer, Kimberly C.; Zhang, Weiping; Langer, Samantha J.

ABSTRACT Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation inRhodobacter sphaeroides. By screening anR. sphaeroidesTn5mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their totalmore » lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCEThis paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these

Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production.

PubMed

Lemmer, Kimberly C; Zhang, Weiping; Langer, Samantha J; Dohnalkova, Alice C; Hu, Dehong; Lemke, Rachelle A; Piotrowski, Jeff S; Orr, Galya; Noguera, Daniel R; Donohue, Timothy J

2017-05-23

Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides By screening an R. sphaeroides Tn 5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCE This paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these alterations can be

Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

DOE PAGES

Lemmer, Kimberly C.; Zhang, Weiping; Langer, Samantha J.; ...

2017-05-23

ABSTRACT Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation inRhodobacter sphaeroides. By screening anR. sphaeroidesTn5mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their totalmore » lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCEThis paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these

Evaluation of quantitative PCR measurement of bacterial colonization of epithelial cells.

PubMed

Schmidt, Marcin T; Olejnik-Schmidt, Agnieszka K; Myszka, Kamila; Borkowska, Monika; Grajek, Włodzimierz

2010-01-01

Microbial colonization is an important step in establishing pathogenic or probiotic relations to host cells and in biofilm formation on industrial or medical devices. The aim of this work was to verify the applicability of quantitative PCR (Real-Time PCR) to measure bacterial colonization of epithelial cells. Salmonella enterica and Caco-2 intestinal epithelial cell line was used as a model. To verify sensitivity of the assay a competition of the pathogen cells to probiotic microorganism was tested. The qPCR method was compared to plate count and radiolabel approach, which are well established techniques in this area of research. The three methods returned similar results. The best quantification accuracy had radiolabel method, followed by qPCR. The plate count results showed coefficient of variation two-times higher than this of qPCR. The quantitative PCR proved to be a reliable method for enumeration of microbes in colonization assay. It has several advantages that make it very useful in case of analyzing mixed populations, where several different species or even strains can be monitored at the same time.

Spatially Correlated Gene Expression in Bacterial Groups: The Role of Lineage History, Spatial Gradients, and Cell-Cell Interactions.

PubMed

van Vliet, Simon; Dal Co, Alma; Winkler, Annina R; Spriewald, Stefanie; Stecher, Bärbel; Ackermann, Martin

2018-04-25

Gene expression levels in clonal bacterial groups have been found to be spatially correlated. These correlations can partly be explained by the shared lineage history of nearby cells, although they could also arise from local cell-cell interactions. Here, we present a quantitative framework that allows us to disentangle the contributions of lineage history, long-range spatial gradients, and local cell-cell interactions to spatial correlations in gene expression. We study pathways involved in toxin production, SOS stress response, and metabolism in Escherichia coli microcolonies and find for all pathways that shared lineage history is the main cause of spatial correlations in gene expression levels. However, long-range spatial gradients and local cell-cell interactions also contributed to spatial correlations in SOS response, amino acid biosynthesis, and overall metabolic activity. Together, our data show that the phenotype of a cell is influenced by its lineage history and population context, raising the question of whether bacteria can arrange their activities in space to perform functions they cannot achieve alone. Copyright © 2018 Elsevier Inc. All rights reserved.

FT-Raman spectroscopic analysis of enhanced activity of supercritical carbon dioxide treated bacterial alpha-amylase.

PubMed

Paul, Kaninika; Dutta, Sayantani; Bhattacharjee, Paramita

2017-09-01

Our previous investigation on high pressure supercritical carbon dioxide treatment of a bacterial α-amylase had revealed enhanced activity of the same. 1 H NMR analysis of the activity enhanced enzyme led the authors to hypothesize that the enhancement was possibly owing to alterations in the active site of the enzyme. In the present study, the changes in the active site of the treated enzyme was analysed by Fourier-transform Raman (FT-Raman) spectroscopy. The spectra obtained revealed shifting of bands in the active site of α-amylase indicating a nudging effect of the bonds in this region consequent to high pressure treatment. Also, shifts in bands in the OH stretching vibration of water were observed in the enzyme spectra. These variations in the spectra confirmed changes in the active site as well as in the water associated with the same that perhaps had a concerted effect on the increased activity of α-amylase. Copyright © 2017 Elsevier Inc. All rights reserved.

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

PubMed

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

2017-02-01

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

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm

PubMed Central

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it. PMID:27092296

HYPOTONIC SWELLING OF SALICYLATE-TREATED COCHLEAR OUTER HAIR CELLS

PubMed Central

Zhi, Man; Ratnanather, J. Tilak; Ceyhan, Elvan; Popel, Aleksander S.; Brownell, William E.

2007-01-01

The outer hair cell (OHC) is a hydrostat with a low hydraulic conductivity of Pf = 3×10−4 cm/s across the plasma membrane (PM) and subsurface cisterna (SSC) that make up the OHC's lateral wall. The SSC is structurally and functionally a transport barrier in normal cells that is known to be disrupted by salicylate. The effect of sodium salicylate on Pf is determined from osmotic experiments in which isolated, control and salicylate-treated OHCs were exposed to hypotonic solutions in a constant flow chamber. The value of Pf = 3.5±0.5 ×10−4 cm/s (mean ± s.e.m, n = 34) for salicylate-treated OHCs was not significantly different from Pf = 2.4±0.3 ×10−4 cm/s (mean ± s.e.m, n = 31) for untreated OHCs (p=.3302). Thus Pf is determined by the PM and is unaffected by salicylate treatment. The ratio of longitudinal strain to radial strain εz/εc = −0.76 for salicylate-treated OHCs was significantly smaller (p = .0143) from −0.72 for untreated OHCs, and is also independent of the magnitude of the applied osmotic challenge. Salicylate-treated OHCs took longer to attain a steady-state volume which is larger than that for untreated OHCs and increased in volume by 8-15% prior to hypotonic perfusion unlike sodium α-ketoglutarate treated OHCs. It is suggested that depolymerization of cytoskeletal proteins and/or glycogen maybe responsible for the large volume increase in salicylate-treated OHCs as well as the different responses to different modes of application of the hypotonic solution. PMID:17400411

Neutrophilic NLRP3 inflammasome-dependent IL-1β secretion regulates the γδT17 cell response in respiratory bacterial infections.

PubMed

Hassane, M; Demon, D; Soulard, D; Fontaine, J; Keller, L E; Patin, E C; Porte, R; Prinz, I; Ryffel, B; Kadioglu, A; Veening, J-W; Sirard, J-C; Faveeuw, C; Lamkanfi, M; Trottein, F; Paget, C

2017-07-01

Traditionally regarded as simple foot soldiers of the innate immune response limited to the eradication of pathogens, neutrophils recently emerged as more complex cells endowed with a set of immunoregulatory functions. Using a model of invasive pneumococcal disease, we highlighted an unexpected key role for neutrophils as accessory cells in innate interleukin (IL)-17A production by lung resident Vγ6Vδ1 + T cells via nucleotide-binding oligomerization domain receptor, pyrin-containing 3 (NLRP3) inflammasome-dependent IL-1β secretion. In vivo activation of the NLRP3 inflammasome in neutrophils required both host-derived and bacterial-derived signals. Elaborately, it relies on (i) alveolar macrophage-secreted TNF-α for priming and (ii) subsequent exposure to bacterial pneumolysin for activation. Interestingly, this mechanism can be translated to human neutrophils. Our work revealed the cellular and molecular dynamic events leading to γδT17 cell activation, and highlighted for the first time the existence of a fully functional NLRP3 inflammasome in lung neutrophils. This immune axis thus regulates the development of a protective host response to respiratory bacterial infections.

Duodenal bacterial overgrowth during treatment in outpatients with omeprazole.

PubMed Central

Fried, M; Siegrist, H; Frei, R; Froehlich, F; Duroux, P; Thorens, J; Blum, A; Bille, J; Gonvers, J J; Gyr, K

1994-01-01

The extent of duodenal bacterial overgrowth during the pronounced inhibition of acid secretion that occurs with omeprazole treatment is unknown. The bacterial content of duodenal juice of patients treated with omeprazole was therefore examined in a controlled prospective study. Duodenal juice was obtained under sterile conditions during diagnostic upper endoscopy. Aspirates were plated quantitatively for anaerobic and aerobic organisms. Twenty five outpatients with peptic ulcer disease were investigated after a 5.7 (0.5) weeks (mean (SEM)) treatment course with 20 mg (nine patients) or 40 mg (16 patients). The control group consisted of 15 outpatients referred for diagnostic endoscopy without prior antisecretory treatment. No patient in the control group had duodenal bacterial overgrowth. In the omeprazole group bacterial overgrowth (> or = 10(5) cfu/ml) was found in 14 (56%) patients (p = 0.0003). The number of bacteria (log10) in duodenal juice in patients treated with omeprazole was distinctly higher (median 5.7; range < 2-8.7) when compared with the control group (median < 2; range < 2-5.0; p = 0.0004). As well as orally derived bacteria, faecal type bacteria were found in seven of 14 and anaerobic bacteria in three of 14 patients. Bacterial overgrowth was similar with the two doses of omeprazole. These results indicate that duodenal bacterial overgrowth of both oral and faecal type bacteria occurs often in ambulatory patients treated with omeprazole. Further studies are needed to determine the clinical significance of these findings, particularly in high risk groups during long term treatment with omeprazole. PMID:8307444

Detection and quantification of intracellular bacterial colonies by automated, high-throughput microscopy.

PubMed

Ernstsen, Christina L; Login, Frédéric H; Jensen, Helene H; Nørregaard, Rikke; Møller-Jensen, Jakob; Nejsum, Lene N

2017-08-01

To target bacterial pathogens that invade and proliferate inside host cells, it is necessary to design intervention strategies directed against bacterial attachment, cellular invasion and intracellular proliferation. We present an automated microscopy-based, fast, high-throughput method for analyzing size and number of intracellular bacterial colonies in infected tissue culture cells. Cells are seeded in 48-well plates and infected with a GFP-expressing bacterial pathogen. Following gentamicin treatment to remove extracellular pathogens, cells are fixed and cell nuclei stained. This is followed by automated microscopy and subsequent semi-automated spot detection to determine the number of intracellular bacterial colonies, their size distribution, and the average number per host cell. Multiple 48-well plates can be processed sequentially and the procedure can be completed in one working day. As a model we quantified intracellular bacterial colonies formed by uropathogenic Escherichia coli (UPEC) during infection of human kidney cells (HKC-8). Urinary tract infections caused by UPEC are among the most common bacterial infectious diseases in humans. UPEC can colonize tissues of the urinary tract and is responsible for acute, chronic, and recurrent infections. In the bladder, UPEC can form intracellular quiescent reservoirs, thought to be responsible for recurrent infections. In the kidney, UPEC can colonize renal epithelial cells and pass to the blood stream, either via epithelial cell disruption or transcellular passage, to cause sepsis. Intracellular colonies are known to be clonal, originating from single invading UPEC. In our experimental setup, we found UPEC CFT073 intracellular bacterial colonies to be heterogeneous in size and present in nearly one third of the HKC-8 cells. This high-throughput experimental format substantially reduces experimental time and enables fast screening of the intracellular bacterial load and cellular distribution of multiple

Bioremediation of treated wood with bacteria

Treesearch

Carol A. Clausen

2006-01-01

This chapter reviews prior research in the field of bacterial bioremediation for wood treated with oilborne and inorganic preservatives. Current state of the art is summarized along with potential benefits and pitfalls of a pilot-scale bioremediation process for CCA-treated waste wood.

Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB

PubMed Central

Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D.; Garner, Ethan C.; Walker, Suzanne

2014-01-01

Summary The bacterial actin homolog MreB, which is critical for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of lipid-linked peptidoglycan precursors. When precursors are depleted, MreB filaments disassemble into the cytoplasm and peptidoglycan synthesis becomes disorganized. In cells that lack wall teichoic acids, but continue to make peptidoglycan, dynamic MreB filaments are observed, although their presence is not sufficient to establish a rod shape. We propose that the cell regulates MreB filament association with the membrane, allowing rapid and reversible inactivation of cell wall enzyme complexes in response to the inhibition of cell wall synthesis. PMID:25402772

Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB.

PubMed

Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D; Garner, Ethan C; Walker, Suzanne

2015-01-01

The bacterial actin homolog MreB, which is crucial for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of lipid-linked peptidoglycan precursors. When precursors are depleted, MreB filaments disassemble into the cytoplasm, and peptidoglycan synthesis becomes disorganized. In cells that lack wall teichoic acids but continue to make peptidoglycan, dynamic MreB filaments are observed, although their presence is not sufficient to establish a rod shape. We propose that the cell regulates MreB filament association with the membrane, allowing rapid and reversible inactivation of cell wall enzyme complexes in response to the inhibition of cell wall synthesis.

Accumulation of Poly(3-hydroxybutyrate) Helps Bacterial Cells to Survive Freezing

PubMed Central

Krzyzanek, Vladislav; Mravec, Filip; Hrubanova, Kamila; Samek, Ota; Kucera, Dan; Benesova, Pavla; Marova, Ivana

2016-01-01

Accumulation of polyhydroxybutyrate (PHB) seems to be a common metabolic strategy adopted by many bacteria to cope with cold environments. This work aimed at evaluating and understanding the cryoprotective effect of PHB. At first a monomer of PHB, 3-hydroxybutyrate, was identified as a potent cryoprotectant capable of protecting model enzyme (lipase), yeast (Saccharomyces cerevisiae) and bacterial cells (Cupriavidus necator) against the adverse effects of freezing-thawing cycles. Further, the viability of the frozen–thawed PHB accumulating strain of C. necator was compared to that of the PHB non-accumulating mutant. The presence of PHB granules in cells was revealed to be a significant advantage during freezing. This might be attributed to the higher intracellular level of 3-hydroxybutyrate in PHB accumulating cells (due to the action of parallel PHB synthesis and degradation, the so-called PHB cycle), but the cryoprotective effect of PHB granules seems to be more complex. Since intracellular PHB granules retain highly flexible properties even at extremely low temperatures (observed by cryo-SEM), it can be expected that PHB granules protect cells against injury from extracellular ice. Finally, thermal analysis indicates that PHB-containing cells exhibit a higher rate of transmembrane water transport, which protects cells against the formation of intracellular ice which usually has fatal consequences. PMID:27315285

Bacterial cell motility of Burkholderia gut symbiont is required to colonize the insect gut.

PubMed

Lee, Jun Beom; Byeon, Jin Hee; Jang, Ho Am; Kim, Jiyeun Kate; Yoo, Jin Wook; Kikuchi, Yoshitomo; Lee, Bok Luel

2015-09-14

We generated a Burkholderia mutant, which is deficient of an N-acetylmuramyl-l-alanine amidase, AmiC, involved in peptidoglycan degradation. When non-motile ΔamiC mutant Burkholderia cells harboring chain form were orally administered to Riptortus insects, ΔamiC mutant cells were unable to establish symbiotic association. But, ΔamiC mutant complemented with amiC gene restored in vivo symbiotic association. ΔamiC mutant cultured in minimal medium restored their motility with single-celled morphology. When ΔamiC mutant cells harboring single-celled morphology were administered to the host insect, this mutant established normal symbiotic association, suggesting that bacterial motility is essential for the successful symbiosis between host insect and Burkholderia symbiont. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Bacterial cell surface properties: role of loosely bound extracellular polymeric substances (LB-EPS).

PubMed

Zhao, Wenqiang; Yang, Shanshan; Huang, Qiaoyun; Cai, Peng

2015-04-01

This study investigated the effect of loosely bound extracellular polymeric substances (LB-EPS) on the comprehensive surface properties of four bacteria (Bacillus subtilis, Streptococcus suis, Escherichia coli and Pseudomonas putida). The removal of LB-EPS from bacterial surfaces by high-speed centrifugation (12,000×g) was confirmed by SEM images. Viability tests showed that the percentages of viable cells ranged from 95.9% to 98.0%, and no significant difference was found after treatment (P>0.05). FTIR spectra revealed the presence of phosphodiester, carboxylic, phosphate, and amino functional groups on bacteria surfaces, and the removal of LB-EPS did not alter the types of cell surface functional groups. Potentiometric titration results suggested the total site concentrations on the intact bacteria were higher than those on LB-EPS free bacteria. Most of the acidity constants (pKa) were almost identical, except the increased pKa values of phosphodiester groups on LB-EPS free S. suis and E. coli surfaces. The electrophoretic mobilities and hydrodynamic diameters of the intact and LB-EPS free bacteria were statistically unchanged (P>0.05), indicating LB-EPS had no influence on the net surface charges and size distribution of bacteria. However, LB-ESP could enhance cell aggregation processes. The four LB-EPS free bacteria all exhibited fewer hydrophobicity values (26.1-65.0%) as compared to the intact cells (47.4-69.3%), suggesting the removal of uncharged nonpolar compounds (e.g., carbohydrates) in LB-EPS. These findings improve our understanding of the changes in cell surface characterizations induced by LB-EPS, and have important implications for assessing the role of LB-EPS in bacterial adhesion and transport behaviors. Copyright © 2015 Elsevier B.V. All rights reserved.

Single Cell-Based Vector Tracing in Patients with ADA-SCID Treated with Stem Cell Gene Therapy.

PubMed

Igarashi, Yuka; Uchiyama, Toru; Minegishi, Tomoko; Takahashi, Sirirat; Watanabe, Nobuyuki; Kawai, Toshinao; Yamada, Masafumi; Ariga, Tadashi; Onodera, Masafumi

2017-09-15

Clinical improvement in stem cell gene therapy (SCGT) for primary immunodeficiencies depends on the engraftment levels of genetically corrected cells, and tracing the transgene in each hematopoietic lineage is therefore extremely important in evaluating the efficacy of SCGT. We established a single cell-based droplet digital PCR (sc-ddPCR) method consisting of the encapsulation of a single cell into each droplet, followed by emulsion PCR with primers and probes specific for the transgene. A fluorescent signal in a droplet indicates the presence of a single cell carrying the target gene in its genome, and this system can clearly determine the ratio of transgene-positive cells in the entire population at the genomic level. Using sc-ddPCR, we analyzed the engraftment of vector-transduced cells in two patients with severe combined immunodeficiency (SCID) who were treated with SCGT. Sufficient engraftment of the transduced cells was limited to the T cell lineage in peripheral blood (PB), and a small percentage of CD34 + cells exhibited vector integration in bone marrow, indicating that the transgene-positive cells in PB might have differentiated from a small population of stem cells or lineage-restricted precursor cells. sc-ddPCR is a simplified and powerful tool for the detailed assessment of transgene-positive cell distribution in patients treated with SCGT.

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.

The effect of natural organic matter on the adsorption of mercury to bacterial cells

NASA Astrophysics Data System (ADS)

Dunham-Cheatham, Sarrah; Mishra, Bhoopesh; Myneni, Satish; Fein, Jeremy B.

2015-02-01

We investigated the ability of non-metabolizing Bacillus subtilis, Shewanella oneidensis MR-1, and Geobacter sulfurreducens bacterial species to adsorb mercury in the absence and presence of Suwanee River fulvic acid (FA). Bulk adsorption and X-ray absorption spectroscopy (XAS) experiments were conducted at three pH conditions, and the results indicate that the presence of FA decreases the extent of Hg adsorption to biomass under all of the pH conditions studied. Hg XAS results show that the presence of FA does not alter the binding environment of Hg adsorbed onto the biomass regardless of pH or FA concentration, indicating that ternary bacteria-Hg-FA complexes do not form to an appreciable extent under the experimental conditions, and that Hg binding on the bacteria is dominated by sulfhydryl binding. We used the experimental results to calculate apparent partition coefficients, Kd, for Hg under each experimental condition. The calculations yield similar coefficients for Hg onto each of the bacterial species studies, suggesting there is no significant difference in Hg partitioning between the three bacterial species. The calculations also indicate similar coefficients for Hg-bacteria and Hg-FA complexes. S XAS measurements confirm the presence of sulfhydryl sites on both the FA and bacterial cells, and demonstrate the presence of a wide range of S moieties on the FA in contrast to the bacterial biomass, whose S sites are dominated by thiols. Our results suggest that although FA can compete with bacterial binding sites for aqueous Hg, because of the relatively similar partition coefficients for the types of sorbents, the competition is not dominated by either bacteria or FA unless the concentration of one type of site greatly exceeds that of the other.