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Bacterial Biosensor (bacterial + biosensor)

Distribution by Scientific Domains
Life Sciences75%

Selected Abstracts

A new green fluorescent protein-based bacterial biosensor for analysing phenanthrene fluxes

ENVIRONMENTAL MICROBIOLOGY, Issue 4 2006
Robin Tecon
Summary The polycyclic aromatic hydrocarbon (PAH)-degrading strain Burkholderia sp. RP007 served as host strain for the design of a bacterial biosensor for the detection of phenanthrene. RP007 was transformed with a reporter plasmid containing a transcriptional fusion between the phnS putative promoter/operator region and the gene encoding the enhanced green fluorescent protein (GFP). The resulting bacterial biosensor ,Burkholderia sp. strain RP037 , produced significant amounts of GFP after batch incubation in the presence of phenanthrene crystals. Co-incubation with acetate did not disturb the phenanthrene-specific response but resulted in a homogenously responding population of cells. Active metabolism was required for induction with phenanthrene. The magnitude of GFP induction was influenced by physical parameters affecting the phenanthrene flux to the cells, such as the contact surface area between solid phenanthrene and the aqueous phase, addition of surfactant, and slow phenanthrene release from Model Polymer Release System beads or from a water-immiscible oil. These results strongly suggest that the bacterial biosensor can sense different phenanthrene fluxes while maintaining phenanthrene metabolism, thus acting as a genuine sensor for phenanthrene bioavailability. A relationship between GFP production and phenanthrene mass transfer is proposed. [source]

Influence of complexation with chloride on the responses of a lux-marked bacteria bioassay to cadmium, copper, lead, and mercury

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2000
Charoon Sarin
Abstract The toxicity of a heavy metal in solution to a microorganism depends not only on its concentration but also on pH and the concentrations of any aqueous complexing ligands in the microorganism's environment. This paper reports on the use of different inorganic resuscitation media and effect of the chloride ion, Cl,, on the bioluminescence response of a bacterial biosensor, Escherichia coli HB101 (pUCD607), to four metals: Cd, Cu, Hg, and Pb. The toxicity tests were conducted at pH 4, using 0.1 M KNO3 as resuscitation medium and adding KCl to investigate effect of Cl, concentration. The species distributions of metals as a function of Cl, concentration were calculated using GeoChem-PC. Resuscitation in 0.1 M KC1 gave significantly higher light output than that in 0.1 M KNO3, demonstrating that Cl, in the resuscitation medium has a direct effect on the bioluminescence response of the E. coli biosensor. Increasing concentrations of Cl, ions increased the toxicity of Hg, apparently because of the formation of HgCl,3, and increased the toxicity of Pb because of PbCl+ formation. The toxicity of Cu decreased at high Cl, concentrations as free Cu2+ decreased, in accordance with the free ion model. Concentrations of Cl, had no significant effect on the toxicity of Cd. This study clearly demonstrates that the chloro-complexes of some heavy metals can be toxic and, for Pb and Hg, more toxic than the free ion. [source]

The detection of antibacterial actions of whole herb tinctures using luminescent Escherichia coli

PHYTOTHERAPY RESEARCH, Issue 12 2007
Kathryn Watt
Abstract Two whole cell Escherichia coli luminescent biosensors were used to determine the antibacterial actions of 16 herbal tinctures. These bioassays can detect genotoxic (strain DPD2794) and general oxidative stress (DE135) events when challenged with antibacterial substances. Many of the herbal tinctures were active against these Gram-negative bacteria, affecting their metabolism without, in some cases, arresting cell growth or causing cell death. Antibacterial activity ranged from undetectable for Curcuma longa, Cinnamomum zeylanicum and Apium graveolens to highly effective against both E. coli strains in the case of Rosmarinus officinalis. Some of the results were unexpected. Althaea officinalis affected microbial metabolism in spite of the lack of literature precedent, and Cinnamomum zeylanicum did not appear to be antimicrobial, as claimed in some literature. It is concluded that studies using luminescent bacterial biosensors can provide important new insights into the potency and modes of the lethal and sub-lethal antibacterial action of whole herbs, and thereby provide crucial evidence for efficacy demanded by modern science and medicine. Copyright © 2007 John Wiley & Sons, Ltd. [source]