R.O Lecture 6 Flashcards
Biosensors
Conventional analytical instruments often do not facilitate real-time analytical measurements in the field
- size, weight, fragility
Analyte-specific techniques
- require lengthy extraction and sample preparation steps
-bioassays traditionally performed using whole animals or tissue cultures
In what way can bacteria be used as biosensors
-Demonstrate the toxicity of a variety of environmental media including soil,
sediment, and water
- Quantify specific analytes in a sample (e.g. ethanol, antibiotics etc.)
What are bacterial biosensors paired with/
Engineered by pairing a reporter gene that generates a signal with a contaminant-sensing component that responds to chemical or physical change, such as exposure to a specific
analyte
What occurs when a biosensor paired with a reporter gene is exposed to change?
The sensing component stimulates the reporter gene through a biochemical pathway in the cell.
The reporter gene then produces a measurable response, such as emitting visible light, which is indicative of the degree of chemical or physical change.
Goal of sensor research (biosensors)
- to provide continuous quantitative and/or qualitative analysis
- thereby eliminating delay
- preserving precision and accuracy
Give an example of whole-cell optical fibre-based biosensors.
Gu MB, Gil GC (2001) Biosens Bioelectron 16:661-666
Monitoring system for continuous analysis of aqueous samples
- 4 bioluminescent strains of E. coli to assist in toxin classification
- Light emitted from bioluminescent bacteria transmitted through optical fibres to luminometers for analysis
phenol – protein-damaging agent
mitomycin C – DNA-damaging agent
cerulenin – cell membrane-damaging agent
Bacterial biosensors constructed using Shigella Sonnei and E.Coli
*The bacterial biosensors constructed using Shigella sonnei and E. coli, were found to be sensitive to the toxicity of the wastewater effluents.
*A linear increase in bioluminescence with increasing concentration of heavy metals and inorganic pollutants in water was observed.
*These bacterial biosensors could provide appropriate alternatives for a rapid, sensitive and cost-effective detection of wastewater quality.
What are the improvements made to biosensor devices
To extend storage lifetime of whole cells and increase portability of apparatus
-freeze dried bioluminescent bacteria
-bacteria rehydrated with water and incubated for 30 min at 30
C before use
Bio-mining
An efficient and environmentally friendly method for extracting minerals from ores using microorganisms that leach them out.
Give an example of a bacterium used for Bio-mining
*Thiobacillus ferrooxidans to leach copper from mine
tailings has improved recovery rates and reduced operating costs
Describe Thiobacillus ferroxidans
- chemolithotropic (inorganic substances as source of energy i.e. rock eaters) bacteria
- find food source in pyrite (FeS2) and other sulphides in mine soils exposed to the atmosphere
- have a slime layer (glycocalyx), that allows them to survive in the toxic environment (acidic) they create
*present in certain sulphur- containing material
*get energy by oxidizing inorganic material such as copper sulphide minerals
Why are thermophilic bacteria necessary in bio-mining
*To increase the efficiency of bio-mining
*thermophilic bacteria found in hot springs
What do heavy metals such as mercury, cadmium, and arsenic do?
poison microbes and slows the bioprocessing
Scientists are attempting to genetically engineer bacterial strains that can stand up to heavy metals.
Advantages of Bio-mining
*Biomining is cost-effective.
*Biomining can sometimes be carried out in situ. Recovery of the metal can be conducted without bringing vast quantities of ore and waste rock to the surface
*Bio-mining consumes minimal energy
*Biomining generates limited hazardous waste
