ABSTRACT
p-Nitrophenol is a common structural unit of many pesticides and was chosen as a model compound to monitor genotoxicity during photocatalytic degradation. The genotoxicity of p-nitrophenol (PNP) and its breakdown products was measured using a bioluminescent bacterial bioassay, Vitotox. The genotoxic potential decreased with the concomitant photocatalytic degradation of the parent PNP concentration. The rate of genotoxicity reduction was slower than the rate of removal of the parent PNP, due to the formation of genotoxic by-products. After 6 h of photocatalytic treatment the total genotoxicity was removed. These results indicate that bioassays can be used as a simple and highly sensitive method for monitoring the general toxicity of chemical pollutants before, during and after photocatalytic treatment or other destructive processes.
Subject(s)
Environmental Monitoring/methods , Escherichia coli/genetics , Nitrophenols/toxicity , Water Pollutants/toxicity , Aliivibrio fischeri/genetics , Aliivibrio fischeri/physiology , Biological Assay/methods , Catalysis , Luminescent Measurements , Nitrophenols/analysis , Organisms, Genetically Modified , Photochemistry , Water Pollutants/analysisABSTRACT
A panel of Escherichia coli strains harbouring different stress-responsive promoters fused to a lux reporter system was used to assess the potential toxicity of 17 unknown model water samples. Using liquid cultures, nine out of 14 toxic samples were properly identified as toxic, whereas five were false negatives. All three non-toxic controls were identified correctly (no false positives). Two strains containing promoter-lux fusions were also tested when immobilized onto fibre-optic tips. One genotoxic sample and six toxic samples were correctly identified in this manner. The potential advantages and limitations in the use of genetically engineered bacteria as biosensors for water toxicity are discussed in view of these results.
Subject(s)
Luminescent Proteins/genetics , Toxins, Biological/analysis , Water Supply , Biosensing Techniques , Bioterrorism , Escherichia coli/genetics , Escherichia coli/physiology , False Negative Reactions , Fiber Optic Technology , Luminescent Measurements , Luminescent Proteins/biosynthesis , Organisms, Genetically Modified , Promoter Regions, GeneticABSTRACT
An aerobic bacterium, isolated from a contaminated site, was able to degrade sulfanilic acid (4-aminobenzenesulfonic acid) and was identified as Pseudomonas paucimobilis. The isolate could grow on sulfanilic acid (SA) as its sole carbon and nitrogen source and metabolized the target compound to biomass. The bioconversion capacity depended on the sulfanilic acid concentration; greater than 98% elimination of the hazardous compound was achieved at low (10 mM) sulfanilic acid concentration, and the yield was greater than 70% at 50 mM concentration of the contaminant. The maximum conversion rate was 1.5 mmol sulfanilic acid/h per mg wet cells at 30 degrees C. Ca-alginate-phytagel proved a good matrix for immobilization of P. paucimobilis, with essentially unaltered biodegradation activity. Removal of sulfanilic acid from contaminated industrial waste water was demonstrated. SDS-PAGE analysis of the crude extract revealed novel proteins appearing upon induction with sulfanilic acid and related compounds, which indicated alternative degradation mechanisms involving various inducible enzymes.
Subject(s)
Pseudomonas/metabolism , Sulfanilic Acids/metabolism , Biodegradation, Environmental , Biotechnology/methods , Cells, Immobilized , Culture Media , Pseudomonas/growth & development , Substrate Specificity , Waste Disposal, Fluid/methods , Water Microbiology , Water Pollution, Chemical , Water Purification/methodsABSTRACT
Whole-cell luminescent bioreporter sensors based on immobilized recombinant Escherichia coli are described and evaluated. The sensors were prepared by glutaraldehyde-anchoring of nonspecific anti-E. coli antibodies on aminosylilated gold or silica glass surfaces with subsequent attachment of the probe bacteria. We demonstrate the generality of the concept by attachment of several E. coli strains that express luciferase in response to different physiological stress conditions including heat shock, DNA damage (SOS), fatty acid availability, peroxide and oxidative stress. The sensors can be used either as single- or multiple-use disposable sensing elements or for continuous operation. We show compatibility with optical fiber technology. Storage stability of the sensors exceeded 5 months with no measurable deterioration of the signal. Repeatability on exposure in successive days was <15%, as was sensor to sensor reproducibility. Sensitivity and detection limits of the immobilized cells were comparable to that of non-immobilized bacteria.
ABSTRACT
A fundamental and principal difficulty of the future energy supply is that the formation of fossil fuels is much slower than the rate of their exploitation. Therefore the reserves which can be recovered in an energetically feasible manner are shrinking parallel with an increasing world-wide energy demand. Among the alternative energy carriers, hydrogen is preferred because it is easy to transport and store and it burns to environmentally friendly water vapour when utilized. Hydrogen can be produced in biological systems, however, our understanding of the molecular details is just emerging.
Subject(s)
Biotechnology/trends , Hydrogen , Hydrogenase , Methane/metabolism , Nitro Compounds/metabolismABSTRACT
A fundamental and principal difficulty of the future energy supply is that the formation of fossil fuels is much slower than the rate of their exploitation. Therefore the reserves which can be recovered in an energetically feasible manner are shrinking parallel with an increasing world-wide energy demand. Among the alternative energy carriers, hydrogen is preferred because it is easy to transport and store and it burns to environmentally friendly water vapour when utilized. Hydrogen can be produced in biological systems, however, our understanding of the molecular details is just emerging.
