Papers by Shimshon Belkin
Bookmarks Related papers MentionsView impact
Analytica Chimica Acta, 2010
Electrochemical signal detection can be readily integrated in biosensors and is thus an attractiv... more Electrochemical signal detection can be readily integrated in biosensors and is thus an attractive alternative to optical detection methods. In the field of environmental chemistry and ecotoxicology there is a growing demand for lab-independent devices based on whole cell biosensors for the detection of genotoxic compounds. Because of the broad occurrence of pre-genotoxic compounds that need to be bio-activated, the integration of a system for metabolic activation into such a biosensor is important. The present study evaluates a chrono-amperometric detection method in which para-aminophenyl beta-D-galactopyranoside is used as substrate for a reporter gene assay based on the bacterial SOS-response in comparison to a test system for the determination of genotoxicity in water that is standardized according to the International Organization for Standardization (ISO). The evaluation was done in order to analyze the potential of the electrochemical signal detection to be used as a complementary method for the standard test system and thus to evaluate the usability of electrochemical biosensors for the assessment of genotoxicity of environmental samples. In the present study it is shown that the chrono-amperometric detection of para-aminophenol is specific even in the presence of electro-active species generated by the enzymatic system used for the external bio-activation of contaminants. Under optimized conditions electrochemistry is sufficiently sensitive with a limit of detection that is comparable to the respective ISO-standard.
Bookmarks Related papers MentionsView impact
< A new bacterial bioassay for toxicity of particulate air pollution is presented. < Bioassay res... more < A new bacterial bioassay for toxicity of particulate air pollution is presented. < Bioassay responses indicating toxicity were observed for several PM samples. < These responses suggest oxidative stress, respiration inhibition and Fe deficiency. < A metal chelating treatment of the samples relieved the bioassay's responses. < Bioavailability analysis suggested that Cr was related to these toxic responses. a b s t r a c t Numerous studies have demonstrated that elevated concentrations of suspended atmospheric particulate matter (PM) are associated with adverse health effects. In order to minimize the adverse public health effects of atmospheric PM by exposure management, there is a need for a greater understanding of the toxic mechanisms and the components that are responsible for the toxic effects. The aim of this study was to utilize bioassay techniques to investigate these aspects. For this purpose a reporter panel of 9 genetically engineered bacterial (Escherichia coli) strains was composed. Each panel member was designed to report on a different stress condition with a measurable light signal produced by the luciferase enzyme. Toxic mechanisms and components were studied using six anthropogenic PM source samples, including two vehicle combustion particles, three coal fly ash (CFA) samples and an urban dust sample. The most prominent outcome of the panel exposure results were broad panel responses observed for two of the CFA samples, indicating oxidative stress, respiration inhibition and iron deficiency. These responses were relieved when the samples were treated with EDTA, a non-specific metal chelator, suggesting the involvement of metals in the observed effects. Bioavailability analysis of the samples suggests that chromium was related to the toxic responses induced by two of the CFA samples. Oxidative stress was also observed in several samples of ambient atmospheric aerosols and excess metal toxicity in an urban dust sample collected in a parking lot. The reporter panel approach, as demonstrated in this study, has the potential of providing novel insights as to the mechanisms of atmospheric PM toxicity. Furthermore, combining the panel's results with bioavailability data can enlighten about the role of different PM components in the observed toxicity.
Bookmarks Related papers MentionsView impact
Cellular Origin, Life in Extreme Habitats and Astrobiology, 2010
The surfaces of aboveground parts of plants – the phyllosphere – are normally colonized by a vari... more The surfaces of aboveground parts of plants – the phyllosphere – are normally colonized by a variety of bacteria, yeasts, and fungi (Lindow and Leveau, 2002). Bacteria are the most numerous colonists of leaves, often being found in numbers averaging 106–107 cells/cm2 of leaf (Andrews and Harris, 2000; Beattie and Lindow, 1995; Hirano and Upper, 1989). In spite of their worldwide distribution (Morris and Kinkel, 2002), studies of the composition of bacterial communities on leaves have been relatively limited in scope, mostly focusing on potential pathogens of agriculturally relevant plants (Beattie and Lindow, 1994; Dik, et al., 1992; Ercolani, 1991).
Bookmarks Related papers MentionsView impact
Environmental Toxicology & Water Quality, 1994
... Michael Stieber ... As a direct consequence, the biodegradation of these compounds has been e... more ... Michael Stieber ... As a direct consequence, the biodegradation of these compounds has been extensively studied, and their degradative pathways are known to a large extent (Cer-niglia andHeitkamp, 1989; Morgan and Watkinson, 1989; Mueller et al., 1989, Heitkamp et al ...
Bookmarks Related papers MentionsView impact
NATO Science Series, 2006
At the heart of every biosensor is a biological entity, the purpose of which is to react with the... more At the heart of every biosensor is a biological entity, the purpose of which is to react with the target analyte(s) and generate a readily quantifiable signal. Traditional biosensors are based on the unique specificity of enzymes to their substrates, antibodies to antigens or that of nucleic acids to their complementary sequences.
Bookmarks Related papers MentionsView impact
PLANT PHYSIOLOGY, 1987
The internal pH values of two unicellular cyanobacterial strains were determined with electron sp... more The internal pH values of two unicellular cyanobacterial strains were determined with electron spin resonance probes, over an external pH range of 6 to 9, in the light and in the dark. The slow growing, thylakoid-lacking Gloeobacter violaceus was found to have a low capacity for maintaining a constant internal pH. The distribution pattern of weak acid and amine nitroxide spin probes across the cell membranes of this organism, in the light and in the dark, was consistent with the assumption that it contains a single intracellular compartment. At an external pH of 7.0, intracellular pH was 6.8 in the dark and 7.2 in the light. The cells of Agmenellum quadruplicatum, a marine species, were found to contain two separate compartments; in the dark, the pH of the cytoplasmic and the intrathylakoid spaces were calculated to be 7.2 and 5.5, respectively. Upon illumination, the former increased and the latter decreased by about 0.5 pH units.
Bookmarks Related papers MentionsView impact
Phytochemistry, 1975
Bookmarks Related papers MentionsView impact
FEMS Microbiology Ecology, 2000
Bookmarks Related papers MentionsView impact
Chemosphere, 1999
Bookmarks Related papers MentionsView impact
Biological Bulletin, 1986
Bookmarks Related papers MentionsView impact
Biodegradation, 1992
Bookmarks Related papers MentionsView impact
Archives of Microbiology, 1990
Bookmarks Related papers MentionsView impact
Archives of Microbiology, 1988
Bookmarks Related papers MentionsView impact
Archives of Microbiology, 1985
Bookmarks Related papers MentionsView impact
Archives of Biochemistry and Biophysics, 1987
Bookmarks Related papers MentionsView impact
Fresenius' journal of analytical chemistry
In parallel to the continuous development of increasingly more sophisticated physical and chemica... more In parallel to the continuous development of increasingly more sophisticated physical and chemical analytical technologies for the detection of environmental pollutants, there is a progressively more urgent need also for bioassays which report not only on the presence of a chemical but also on its bioavailability and its biological effects. As a partial fulfillment of that need, there has been a rapid development of biosensors based on genetically engineered bacteria. Such microorganisms typically combine a promoter-operator, which acts as the sensing element, with reporter gene(s) coding for easily detectable proteins. These sensors have the ability to detect global parameters such as stress conditions, toxicity or DNA-damaging agents as well as specific organic and inorganic compounds. The systems described in this review, designed to detect different groups of target chemicals, vary greatly in their detection limits, specificity, response times and more. These variations reflect ...
Bookmarks Related papers MentionsView impact
Microfluidics, BioMEMS, and Medical Microsystems IV, 2006
A novel water chemical toxin sensor has been successfully developed and evaluated as a working po... more A novel water chemical toxin sensor has been successfully developed and evaluated as a working portable laboratory prototype. This sensor relies on a disposable plastic biochip prepared with a 4x4 micro-laboratory (muLab) chambers array of Escherichia coli reporter cells and micro-fluidic channels for liquids translocation. Each bacterial strain has been genetically modified into a bioluminescent reporter that responds to a
Bookmarks Related papers MentionsView impact
Sensors and Actuators B: Chemical, 2011
Bookmarks Related papers MentionsView impact
Research in Microbiology, 2011
Bookmarks Related papers MentionsView impact
Uploads
Papers by Shimshon Belkin