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Everything you need to know about biosensors. Some of the most frequently asked questions are as follows:-
Q.1. What are the biosensors?
Ans: The organisms/bacteria which can be used to locate biologically active pollutants are regarded as biosensors.
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Q.2. In the USA, 265 million metric tonnes of hazardous waste is generated by industrial plants. Where does the major part (80 per cent) of it go?
Ans: It is buried into landfills.
Q.3. What is required to monitor the working of a bio-receptor?
Ans: There are two requirements:
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(1) A receptor which is activated in the presence of pollutants.
(2) A reporter to make the change apparent.
Q.4. Name the bacterial species that can be used or engineered to be used as biosensors.
Ans: Vibriofischeri, Photo bacterium, Xanthomonas, Brady rhizobium, Lactococcus and Escherichia coli, etc.
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Q.5. Which characteristics of the bacterium Vibrio or that of Photo bacterium works as a reporter?
Ans: The lux operon of the bacterium that contains inducers or structural genes for the enzyme luciferase.
Q.6. How do biosensors use the lux operon from Vibrio or Photo bacterium?
Ans: The biosensors employ the lux operon from Vibrio or Photo bacterium as a receptor. The operon has structural and inducing genes for the enzyme luciferase. In the presence of a coenzyme known as FMNH2, the luciferase reacts with the molecule to form an enzyme& substrate complex. The enzyme substrate complex emits blue green light which then oxidizes the FMNH2 to form FMN. Therefore, the bacterium containing the lux gene emits visible light when the receptor is activated.
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Q.7. Give two examples of the bacteria to which lux operon has been transferred. Why is it done?
Ans: (1) It has been readily transferred to the plant pathogen Xanthomonas to monitor progression of infection due to it in plants. As the altered bacteria emit light, their presence can be detected on a photographic film.
(2) The Brady rhizobium too has been engineered to contain the Lux gene. It has been done to understand the root nodule formation in soybean.
Q.8. What is the use of Lactococcus containing Lux Operon as a biosensor in dairy microbiology.
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Ans: The Lactococcus containing Lux Operon can be used to detect the presence of antibiotic in milk. This application is useful because if milk contains antibiotics, the cheese starter culture does not grow.
Q.9. How do some Microtox systems developed recently use marine bacterium Photo bacterium directly to detect pollutants?
Ans: The photo bacteria loose their characteristics of emitting light if they are killed by pollutants.
Q.10. What is an operon?
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Ans: It comprises the operator site and the structural genes that it controls.
Q.11. What is luciferase?
Ans: Luciferase is an enzyme that accepts electrons from flavoproteins and emits a photon of light.
