Twelve recombinant bioluminescent bacteria have been immobilized within the wells of a 96-well plate using two different matrices--agar and sol-gel. All 12 strains were immobilized within individual wells of the plates and the sensitivity of the strains and the stability of the responses were determined for select chemicals. Each strain was exposed to seven well-characterized chemicals over a wide range of concentrations to demonstrate their individual selectivity for specific toxicants. Although the sensitivity of the immobilized cells was generally lower than cultures grown in liquid media, they were comparable. For example, strain DPD1710, which responds to DNA damage was able to detect mitomycin C, a genotoxin, at a minimum concentration of 0.6 ppb. When immobilized, the lower limit of detection was between 1 and 10 ppb. Finally, using compounds that are known to elicit a response from each of the strains, the stability of the bioluminescent responses were measured over an extended period of 4 weeks. Although the activity of several strains decreased over time, the majority of the strains used in both immobilized systems were still responsive.
"To better understand the toxic mechanisms, the total cellular RNA was purified from these cultures at set times (10, 30, 60 and 90 min) and used to prepare cDNA. Based on the structural similarities between FA and salicylic acid, it was presumed that FA would lead to a significant heat shock response, as was seen previously with salicylic acid (Mitchell and Gu, 2006). Therefore, the relative expression levels of two heat shock genes, grpE and clpB, were determined for each time point. "
[Show abstract][Hide abstract] ABSTRACT: Aberrations in the growth and transcriptome of Escherichia coli str. BL21(DE3) were determined when exposed to varying concentrations of ferulic acid (0.25-1 g/L), an aromatic carboxylic acid identified within lignin-cellulose hydrolysate samples. The expression of several individual genes (aaeA, aaeB, inaA and marA) was significantly induced, i.e., more than 4-fold, and thus these genes and the heat shock response gene htpG were selected as biomarkers to monitor E. coli's responses to five additional hydrolysate-related compounds, including vanillic acid, coumaric acid, 4-hydroxybenzoic acid, ferulaldehyde and furfural. While all of the biomarkers showed dose-dependent responses to most of the compounds, expression of aaeA and aaeB showed the greatest induction (5-30-fold) for all compounds tested except furfural. Lastly, the marA, inaA and htpG genes all showed higher expression levels when the culture was exposed to spruce hydrolysate samples, demonstrating the potential use of these genes as biomarkers.
[Show abstract][Hide abstract] ABSTRACT: This review deals with the applications of bioluminescent bacteria to the environmental analyses, published during the years 2000-2007. The ecotoxicological assessment, by bioassays, of the environmental risks and the luminescent approaches are reported. The review includes a brief introduction to the characteristics and applications of bioassays, a description of the characteristics and applications of natural bioluminescent bacteria (BLB), and a collection of the main applications to organic and inorganic pollutants. The light-emitting genetically modified bacteria applications, as well as the bioluminescent immobilized systems and biosensors are outlined. Considerations about commercially available BLB and BLB catalogues are also reported. Most of the environmental applications, here mentioned, of luminescent organisms are on wastewater, seawater, surface and ground water, tap water, soil and sediments, air. Comparison to other bioindicators and bioassay has been also made. Various tables have been inserted, to make easier to take a rapid glance at all possible references concerning the topic of specific interest.
[Show abstract][Hide abstract] ABSTRACT: A study was conducted to investigate the effect of toxic mode of silver nanoparticles on cell membrane using stress-specific biloluminescent bacteria. The cytotoxicity of silver nanoparticles in growth inhibition was tested with the wild-type E.coli strain, RFM443. Scientist used high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to identify the effect of silver nanoparticles on bacteria. It was founnd that silver nanoparticles attached to the surface of the cell membrane and penerated inside the cell. A silver nanoparticles generated Ag+ ions, which were partially responsible for the biocidal effect. Scientist also evaluated the cell viability and other effects caused by the silver nanoparticles were analyzed using scanning electron microscopy (SEM). It is concluded that silver nanoparticles cause toxicity through protein/membrane and oxidative damage, but do not result in DNA damage.
Small 06/2008; 4(6):746-50. DOI:10.1002/smll.200700954 · 8.37 Impact Factor
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