The UK Supermarket Market Structure - Essay Example

Critically evaluate the potential applications for bioluminescent-based biosensors and immunoassays in environmental monitoring. Discuss using specific examples, the benefits and shortcomings of these technologies. Bioluminescent-Based Biosensors in Environmental Monitoring The present era witness the age of technological advancements in the manufacturing, types and application of biosensors. Biosensors have found a wide range of applications encompassing clinical and non-clinical diagnostics, detection of the presence of environment pollutants and for monitoring defense mechanism. They could be molecular biosensors, antibodies, enzymes, ion channels, nucleic acids or cell based bio-sensors that include microbial cells, tissues, cell receptors and various biologically derived materials. Biosensors or bioreporters are genetically engineered live microbial cells that generate a measurable signal in response to a particular chemical or physical agent in their immediate environment (King, 1990). Thus, biosensors are sensing components that are capable of generating beneficial signals for further processing. These signals are generated by reporter genes that are activated in response to the physical or chemical agents. Expressions of these genes are recorded as colorimetric, fluorescent, luminescent, chemiluminescent or electrochemical signals. Biosensors are therefore analytical devices that possess biological substances and work through the bio-recognition progression either by way of affinity or through metabolism. The recognized signals are then read through transducers to relay electrical signals. Various categories of biosensors/ bioreporters: LuxCDABE bioreporters: LuxCDABE bioreporters are used in detection methodologies ranging from the sensing of environmental contaminants to the real-time monitoring of pathogen infections in living mice. Nonspecific lux bioreporters: Nonspecific lux bioreporters are characteristically used for the detection of chemical toxins. They are engineered for constant bioluminescence. The level of bioluminescence can be correlated to relative levels of toxicity (Hermens, 1985). Firefly luciferase (Luc): Firefly luciferase catalyzes a reaction that produces visible light in the 550 – 575 nm range. Numerous luc-based bioreporters have been constructed for the detection of a wide array of inorganic and organic compounds of environmental concern. Uroporphyrinogen (Urogen) III Methyltransferase (UMT): UMT catalyzes a reaction that yields two fluorescent products which produce a red-orange fluorescence in the 590 - 770 nm range when illuminated with ultraviolet light (Sattler, 1995). GFP, the green fluorescent protein does not require any additional exogenous substrates. UMT has been used as a bioreporter for the selection of recombinant plasmids, as a marker for gene transcription in bacterial, yeast, and mammalian cells, and for the detection of toxic salts such as arsenite and antimonite. Example of lux-based bioreporters in use: Monitoring environmental contaminants in a groundwater plumeA groundwater research facility at Columbus Air Force Base, Mississippi was contaminated with a simulated jet fuel mixture consisting of naphthalene, toluene, ethylbenzene, and p-xylene (Stapleton, 1998). Two bioreporters were used, Pseudomonas fluorescens 5RL, a bioreporter for naphthalene, and Pseudomonas putida TVA8, a bioreporter for toluene11, 12. Analysis occurred on-site, where bioreporters were simply combined with groundwater samples and allowed to incubate for a set time. Resulting bioluminescence was measured using a field portable photomultiplier unit interfaced to a laptop computer. Duplicate samples were sent to an off-site laboratory for GC/MS determination of toluene and naphthalene concentrations. Bioluminescent bioreporters consistently predicted contaminant concentrations within 50% of the GC/MS analytic measurements. Although in this case not highly quantitative, bioluminescent bioreporters did provide a rapid, general assessment of contaminant presence within the groundwater aquifer, and established an overall snapshot of plume dynamics within a few hours of initial sampling at a cost of approximately 1/10 of that of GC/MS analysis. Luciferases in Environmental research Applications as biosensors: Hollis et al., in 1999 transformed a Saccharomyces cerevisiae with firefly luciferase gene from Photinus pyralis to be used as a biosensor (Hollis, 2000). They studied the cell health upon exposure to toxins directly correlating with the endogenous supply of energy by ATP. A bioluminescent plasmid reporter that shows a sensitive response towards 2-4-Dichlorophenoxyacetic acid and 2, 4-Dichlorophenol in soil was constructed and introduced into the chromosome of Ralstonia eutropha. The transformed bacterium is capable of detecting the concentrations of 1.2 mM 2, 4-D and 1.1X102 μM of 2, 4- dichlorophenol (Hay et al., 2000). Pellinen et al., (2002) developed Escherichia coli K-12 strain for specific detection of the tetracycline family of antimicrobial agents (Pellinen, 2002). It was optimized to work with fish samples. The biosensing strain contains a plasmid incorporating the bacterial luciferase operon of Photorhabdus luminescens under the control of the tetracycline responsive element from transposon Tn10. The lowest levels of detection of tetracycline and oxytetracycline from spiked fish tissue were 20 and 50 μg/kg, respectively, in a 2-h assay. The inherent strength in the use of bioassays, including those based on genetically engineered whole-cell bioreporters, is the ability to quantify global biological effects such as toxicity, mutagenicity, or bioavailability Immunoassays in environmental monitoring: Immunoassay test kits are ideally suited for testing environmental samples - in soil, water or plants - when speed, simplicity, sensitivity and low cost are important criteria. Immunoassays are appropriate when specific chemicals, or families of chemicals, are known or suspect and the objective is to determine their presence, absence, or quantity contained within the sample. By using immunoassay kits for environmental testing, large numbers of samples can be screened quickly and cost effectively, substantially increasing the number of samples feasible within a specific program or budget by limiting the use of high-cost GC or HPLC to site characterization and confirmatory testing, as desired. Its application encompass: Source Water Protection: Drinking Water Monitoring Point Source Testing Effluent Monitoring Run-off Assessment and Monitoring Pesticide Run-off Advantages of biosensors and immunoassays encompass- selectivity, sensitivity (detects ppm concentration), portability, rapid turnaround time, improved data quality, and overall cost effectiveness. Environmental monitoring includes the measurement of heavy metals, priority pollutants, pesticides, BOD, nitrogen, phosphorus, volatile organics, pathogens, carcinogens and toxicity in air, water or soil. Environmental monitoring is important for health and safety, to meet compliance levels established by Federal or Provincial regulatory agencies, and to monitor the efficacy of physical, chemical or biological pollution control technology. Biosensors have advantages over large devices, they are highly targeted and perform measurements at faster pace and they match with various analytical methods for monitoring environmental pollutants. Shortcomings of biosensors and immunoassays: Besides much research and funds being assigned to the development of biosensors very little could gain progress in commercial markets. In recent times they are merged with the new technologies and nanomaterials are being incorporated with the biosensors. It is essential that the detection should be performed even at low concentrations. It is observed that chemical detectors work better under some set of conditions to detect environmental pollutants as biological agents do require recovery time and are little sensitive under some set of conditions. Moreover living material does require appropriate handling and temperature control mechanism else they face threat of survival. It is also seen that the effectiveness of recovery from concentration and various removal measures can differ and influence detection limits, also, sample size, number, and distribution is also influenced if the transport time and method is time consuming, particularly for fastidious, living microbes that may require specific environmental and nutritional conditions for survival (Eggins). Conclusion It is true that biosensor technology has the prospective to accelerate the detection by enhancing specificity and sensitivity but in the presence of a certain molecules the biological system has the potential to change the environment. The measuring device sensitive to this change sends a signal which could be sensed and this could be due to the altered metabolism (Eggins). Moreover the response time also varies if the environmental conditions in which the biological elements are present, changes, as biological entities require recovery time also so it is essential to understand that biosensors are effective in terms where uniformity of the effluents are maintained provided the environment niche is not altered along with no alteration in physiological conditions where the biosensors are placed. The advent of technology is always appreciated in lab but when it comes to work under practical environment then it becomes mandatory that validation of the technology is performed. Shortcomings of biosensors encompassing tailor-made genetically modified microorganisms if ruled out they are the boon to the evaluation of environmental pollutants. References 1. Eggins, B. R. 2002. Chemical Sensors and Biosensors. Wiley Publication. 2. Hay, A. G., Rice, J. F., Applegate, B. M., Bright, N. G., Sayler, G. S. 2000. A Bioluminescent Whole-Cell Reporter for Detection of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol in Soil Applied and Environmental Microbiology, October 2000, p.4589-4594, Vol. 66, No. 10. 3. Hermens, J., Busser, F., Leeuwangh, P., Musch. A. 1985. Quantitative structure-activity relationships and mixture toxicity of organic chemicals in Photobacterium phosphoreum: the Microtox test. Ecotoxicol. Environ. Saf. 9, 17-25 4. Hollis, R. P., Killham, K., Glover, L. A. 2000. Design and Application of a Biosensor for Monitoring Toxicity of Compounds to Eukaryotes Appl Environ Microbiol 66 (4): 1676–1679 5. King, J. M. H., DiGrazia, P. M., Applegate, B., Burlage, R., Sanseverino, J., Dunbar, P., Larimer, F., Sayler, G. S. 1990. Rapid, sensitive bioluminescence reporter technology for naphthalene exposure and biodegradation. Science 249, 778-781. 6. Pellinen, T., Bylund, R., Virta, M., Niemi, A., Matti, K. 2002. Detection of Traces of Tetracyclines from Fish with a Bioluminescent Sensor Strain Incorporating Bacterial Luciferase Reporter Genes. J. Agric. Food Chem. 50(17), 4812-4815. 7. Sattler, I., Roessner, C. A., Stolowich, N. J., Hardin, S. H., Harris-Haller, L. W., Yokubaitis, N. T., Murooka, Y., Hashimoto, Y., Scott, A. I. 1995. Cloning, sequencing, and expression of the uroporphyrinogen-III methyltransferase cobA gene of Propionibacterium freudenreichii (shermanii). J. Bacteriol. 177, 1564-1569. 8. Stapleton, R. D., Sayler, G. S. 1998. Assessment of the microbiological potential for natural attenuation of petroleum hydrocarbons in a shallow aquifer system. Microb. Ecol. 36, 349-361 Read More