Rationally-assembled multispecies biofilms could benefit applied processes including mixed waste biodegradation and drug biosynthesis by combining complementary metabolic pathways into single functional communities. We hypothesized that the cellular composition of mature multispecies biofilms could be manipulated by controlling the number of each cell type present on newly colonized surfaces. To ...

Assessment of physiological states of individual bacterial cells can be useful in the monitoring of the biotechnological processes. Physiological heterogeneity of Escherichia coli population by respiration activity and membrane potential during growth and starvation in batch cultures was evaluated using 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and bis-(1,3-dibutylbarbituric acid) trimethine oxo (DiBAC(4))(3) ...

Methionine aminopeptidase (MetAP) is a promising target for the development of novel antibiotics. However, many potent inhibitors of the purified enzyme failed to show significant antibacterial activity. It is uncertain which divalent metal MetAP uses as its native cofactor in bacterial cells. Herein, we describe a cell-based assay that monitors ...

Rod-shaped bacteria such as Escherichia coli divide by binary fission. They inherit an old pole from the parent cell. The new pole is recently derived from the septum. Because the chemoreceptor accumulates linearly with time on the cell pole, the old pole carries more receptors than does the new pole. ...

We present a fluorescence recovery after photobleaching-based method for monitoring the progression of septal Z-ring contraction in dividing Escherichia coli cells. In a large number of cells undergoing division, we irreversibly bleached cytosolically expressed Enhanced Green Fluorescent Protein on one side of the septal invagination and followed the fluorescence relaxation ...

To assess the functions of the three human MutT-type enzymes, MTH1, MTH2, and NUDT5, mutation induction by an oxidized form of dGTP, 8-hydroxy-2'-deoxyguanosine 5'-triphosphate (8-OH-dGTP; 7,8-dihydro-8-oxo-2'-deoxyguanosine 5'-triphosphate), was examined using human 293T cells treated with their specific siRNAs. Shuttle plasmid DNA containing the supF gene was first transfected into the ...

AIM: Gynecological douches may contain various molecules that need to cover and be retained by cutaneous and mucosal cells if they are to act efficaciously in treating local conditions. The aim of this study was to investigate the possibility of directly visualising the ability of a commercial medical gynecological douche ...

Escherichia coli chemotaxis has long served as a simple model of environmental signal processing, and bacterial responses to single chemical gradients are relatively well understood. Less is known about the chemotactic behavior of E. coli in multiple chemical gradients. In their native environment, cells are often exposed to multiple chemical ...

The photodynamic inactivation (PDI) of Escherichia coli and Streptococcus mitis sensitized by cationic phthalocyanines was studied in different media containing blood derivatives. First, the activity of zinc(II) tetramethyltetrapyridino[3,4-b:3',4'-g:3'',4''-l:3''',4'''-q]porphyrazinium (ZnAPc4+), zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc4+) and zinc(II) 2,9,16,23-tetrakis[2-(N,N,N-trimethylamino)ethoxy]phthalocyanine (ZnEPc4+) were compared to photoinactivate these bacteria in saline solutions. After visible light irradiation, a ...

This study investigated the quorum sensing, biofilm and type three secretion system (TTSS) inhibitory properties of citrus flavonoids. Flavonoids were tested for their ability to inhibit quorum sensing using Vibrio harveyi reporter assay. Biofilm assays were carried out in 96-well plates. Inhibition of biofilm formation in Escherichia coli O157:H7 and ...

To study the swimming of a peritrichous bacterium such as Escherichia coli, which is able to change its swimming direction actively, we simulate the "run-and-tumble" motion by using a bead-spring model to account for: 1), the hydrodynamic and the mechanical interactions among the cell body and multiple flagella; 2), the ...

BACKGROUND: In the process of developing a microplate-based growth assay, we discovered that our test organism, a native E. coli isolate, displayed very uniform doubling times (tau) only up to a certain threshold cell density. Below this cell concentration (<or= 100 -1,000 CFU mL-1 ; <or= 27-270 CFU well-1) we ...

Bacillus subtilis quercetin 2,3-dioxygenase (QdoI) catalyzes the C-ring cleavage of quercetin to yield 2-protocatechuoyl-phloroglucinol carboxylic acid and carbon monoxide. The recombinant QdoI effectively decomposed several flavonols, including quercetin, whereas its activity toward fisetin was low, suggesting that the 5-hydroxyl group at the A-ring is critical for substrate recognition. A B. ...

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 ...

Matrix metalloproteinases (MMPs) modulate cell-cell and cell-matrix interactions and the membrane-type MMPs (MT-MMPs) are especially important for pericellular proteolysis. Understanding the activity, regulation, and function of MT-MMPs would provide important insight for ongoing research in many diseases including cancer, fibrosis, and autoimmune diseases. In this chapter, we introduce the methods ...

Tetherin (BST-2/CD317/HM1.24) is an interferon (IFN)-inducible factor of the innate immune system, recently shown to exert antiviral activity against HIV-1 and other enveloped viruses by tethering nascent viral particles to the cell surface, thereby inhibiting viral release. In HIV-1 infection, the viral protein U (Vpu) counteracts this antiviral action by ...

Developing cost-effective methods for high throughput production of recombinant baculoviruses in insect cells is very challenging, because the baculovirus DNA preparation and the following transfection procedure are labour-intensive and time consuming. We developed a new method of introducing recombinant Bacmid DNA from bacteria into insect cells simply using invasive diaminopimelate ...

tRNA aminoacylation, or charging, levels can rapidly change within a cell in response to the environment[1]. Changes in tRNA charging levels in both prokaryotic and eukaryotic cells lead to translational regulation which is a major cellular mechanism of stress response. Familiar examples are the stringent response in E. coli and ...

Propidium monoazide can limit the analysis of microbial communities derived from genetic fingerprints to viable cells with intact cell membranes. However, PMA treatment cannot completely suppress polymerase chain reaction (PCR) amplification when the targeted gene is too short. PMA treatment in combination with two-step nested PCR was designed to overcome ...

This paper describes a new approach for labeling intact flagella using the biarsenical dyes FlAsH and ReAsH and imaging their spatial and temporal dynamics on live Escherichia coli cells in swarming communities of bacteria by using epifluorescence microscopy. Using this approach, we observed that (i) bundles of flagella on swarmer ...

In this issue of Molecular Cell, Davies et al. (2009) work out a sequence of active cellular events that lead to the death of Escherichia coli in the presence of the drug hydroxyurea.

F-pili are thin, flexible filaments elaborated by F(+) cells of Escherichia coli. They belong to the class of Gram-negative pili that function in horizontal gene transfer. F-pili are initially required to establish contacts between DNA donor and recipient cells. Beyond that, F-pilus function, and that of other conjugative pili, has ...

Colicin D is a plasmid-encoded antibacterial protein that specifically cleaves the anticodon loops of four Escherichia coli tRNA(Arg) species. Here, we report that the catalytic domain of colicin D, which is expressed in Saccharomyces cerevisiae, impairs cell growth by cleaving specific tRNAs. DNA microarray analysis revealed that mating-related genes were ...

The presence of the resting membrane potential has a strong effect on the dielectric behavior of cell suspensions. Using this observation and a well-established theoretical model, the low frequency dielectric dispersion curves of E. coli cell suspensions are de-convoluted to obtain the resting membrane potential of E. coli cells at ...

Prefoldin is a hexameric chaperone that has been identified in eukaryotic cells and in Archaea. E. coli cells over-expressing the prefoldin gene from the hyperthermophilic, archaeum, Pyrococcus furiosus, grew well at 48 degrees C while control cells were unable to grow above 46 degrees C. The isolated and purified Pfu-prefoldin ...

The inside of the cell is a complex environment that is difficult to simulate when studying proteins and other molecules in vitro. We have developed a device and system that provides a controlled environment for nuclear magnetic resonance (NMR) experiments involving living cells. Our device comprises two main parts, an ...

The development of Escherichia coli biofilm requires the differential expression of various genes implicated in cell signalling, stress responses, motility and the synthesis of structures responsible for cell attachment. The ibpAB operon is among the stress-response genes most induced during growth of the E. coli biofilm. In this study we ...

The sliding clamp proliferating cell nuclear antigen (PCNA) plays vital roles in many aspects of DNA replication and repair in eukaryotic cells and in archaea. Realising the full potential of archaea as a model for PCNA function requires a combination of biochemical and genetic approaches. In order to provide a ...

The risk of infectious diseases has compelled some industries to establish a zero-tolerance standard for the presence of microorganisms in a given sample. Here, we address this issue with a novel reverse-phase immunoassay on impedimetric transducers for the specific detection of extremely low numbers of pathogens (less than 10 cells). ...

The role of extracellular macromolecules on Escherichia coli O157:H7 transport and retention was investigated in saturated porous media. To compare the relative transport and retention of E. coli cells that are macromolecule rich and deficient, macromolecules were partially cleaved using a proteolytic enzyme. Characterization of bacterial cell surfaces, cell aggregation, ...

Toll-like receptor (TLR)-expressing cells, for the first time, detected and identified a microbial contaminant in a product made in Escherichia coli using an old manufacturing process. It was suspected of having a microbial contaminant(s) because, although it tested negative by standard pyrogen assays, it was associated with adverse events in ...

Cell engineering to enable step change improvements in bioprocessing can be directed at targets other than increasing product titer. The physical properties of the process suspension such as viscosity, for example, have a major impact on various downstream processing unit operations. The release of chromosomal DNA during homogenization of Escherichia ...

Microorganisms can complex and sequester heavy metals, rendering them promising living factories for nanoparticle production. Glutathione (GSH) is pivotal in cadmium sulfide (CdS) nanoparticle formation in yeasts and its synthesis necessitates two enzymes: gamma-glutamylcysteine synthetase (gamma-GCS) and glutathione synthetase (GS). Hereby, we constructed two recombinant E. coli ABLE C strains ...

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 induces the formation of filamentous, actin-rich, pedestal-shaped structures beneath bacterial cells that have attached to intestinal epithelial cells. Pedestal formation requires the translocation of EHEC O157:H7 type III effectors. One of these type III effectors, EspFu, consists of an N-terminal signal sequence, which is necessary ...

Candida albicans is the most common fungal pathogen in humans, causing both debilitating mucosal infections and potentially life-threatening systemic infections. Until recently, C. albicans was thought to be strictly asexual, existing only as an obligate diploid. A cryptic mating cycle has since been uncovered in which diploid a and alpha ...

How cells maintain their ploidy is relevant to cellular development and disease. Here, we investigate the mechanism by which the bacterium Bacillus subtilis enforces diploidy as it differentiates into a dormant spore. We demonstrate that a sporulation-induced protein SirA (originally annotated YneE) blocks new rounds of replication by targeting the ...

In this study, we observed a novel property of Escherichia coli Hfq protein: it possibly influenced extracellular indole levels. The extracellular indole concentrations were increased in Hfq mutant cells and decreased in Hfq overexpression cells in a cell density-dependent manner. The decreased extracellular indole levels in Hfq overexpression cells caused ...

Cell-free protein synthesis systems are generally influenced by the nature of the cell extract, which contains various factors on the chromosomal DNA. Some of the Escherichia coli cell extract factors are essential, despite their negative effects on protein synthesis, because they are required during the cell growth and/or extract preparation ...

It was observed that a biocatalyst prepared from dehydrated whole cells of a recombinant Escherichia coli (initially suspended in borate buffer) was able to hydrolyze gaseous 1-chlorobutane in a solid/gas reactor. Nevertheless, at 40 degrees C and for a 0.7 water activity, it rapidly lost its activity. The explanation of ...

AIMS: Adhesion of a micro-organism to a cell surface is often considered to be the first step in pathogenesis. Inhibiting this process may have therapeutic effects in vivo. This study investigates the inhibitory effects of various bovine whey products on the association of Salm. Typhimurium, E. coli O157:H7 and C. ...

The phage shock protein (Psp) response in Gram-negative bacteria counteracts membrane stress. Transcription of the PspF regulon (pspABCDE and pspG) in Escherichia coli is induced upon stresses that dissipate the proton motive force (pmf). Using GFP fusions we have visualized the subcellular localizations of PspA (a negative regulator and effector ...

To understand the mechanism of sigma(E)-dependent cell lysis, we examined the consequences of deletion derivatives of rpoE regulators rseA, rseB and rseC on sigma(E) transcription, on levels of free versus membrane-bound sigma(E) and on OMP-biogenesis limiting factor(s) that could impact cell lysis. RT-PCR showed that individual nonpolar DeltarseA and DeltarseB ...

Bacterial cytokinesis is coupled to the localized synthesis of new peptidoglycan (PG) at the division site. This newly generated septal PG is initially shared by the daughter cells. In Escherichia coli and other gram-negative bacteria, it is split shortly after it is made to promote daughter cell separation and allow ...

DnaA is a replication initiator protein that is conserved among bacteria. It plays a central role in the initiation of DNA replication. In order to monitor its behavior in living Escherichia coli cells, a nonessential portion of the protein was replaced by a fluorescent protein. Such a strain grew normally, ...

The catalytic turnover of cytochrome P450( cam ) from Pseudomonas putida requires two auxiliary reduction partners, putidaredoxin (Pd) and putidaredoxin reductase (PdR). We report the functional expression in Escherichia coli of tricistronic constructs consisting of P450( cam ) encoded by the first cistron and the auxiliary proteins, Pd and PdR ...

Prodrug activation gene therapy is a developing approach to cancer treatment, whereby prodrug-activating enzymes are expressed in tumour cells. After administration of a non-toxic prodrug, its conversion to cytotoxic metabolites directly kills tumour cells expressing the activating enzyme, whereas the local spread of activated metabolites can kill nearby cells lacking ...

DnaA initiates chromosomal replication in Escherichia coli at a well-regulated time in the cell cycle. To determine how the spatial distribution of DnaA is related to the location of chromosomal replication and other cell cycle events, the localization of DnaA in living cells was visualized by confocal fluorescence microscopy. The ...

Chemotaxis is the migration of cells in gradients of chemoeffector molecules. Although multiple, competing gradients must often coexist in nature, conventional approaches for investigating bacterial chemotaxis are suboptimal for quantifying migration in response to gradients of multiple signals. In this work, we developed a microfluidic device for generating precise and ...

The bacterium Escherichia coli is rod-shaped, and a unit cell keeps regular dimensions of about 1.5 microm long and 0.5 microm wide. The rod-shaped cell is composed of two parts: a cylinder in the center and caps at both ends. The length of the cylinder corresponds to the length of ...

Shiga toxin 1 (Stx1) is located in the periplasmic fraction, while Stx2 is found in the extracellular fraction, suggesting that enterohemorrhagic Escherichia coli (EHEC) contains a specific Stx2 release system. Both stx(1) and stx(2) are found within the late operons of Stx-encoding phages. Stx2 production is greatly induced by mitomycin ...