For example, bacteria isolated from a highly PAH contaminated area suppose to have a greater PAH degradation capacity. Is it true?
Yes. Enzymes that degrade PAH will be induced when a bacterium forced to use PAH as its sole source of carbon and other essential elements.
Capability is a potential for a specified activity, not the activity itself . . . The induction of PAH metabolizing enzymes upon the exposure to PAH does not change the capability, but merely actualizes the already present potential.
This is a general rule for organic contaminants and is true for pesticide exposure and degradation. It may be a combination of what Alemu has suggested and an improved tolerance to the potentially ecotoxicological effects of the pollutant (ie the population of organisms that can degrade the pollutant would not be as affected compared to a population not previously exposed the the pollutant - therefore degradation capacity would be higher in previously exposed soils).
Nope. Exposure to PAH does not bring about the ability of a bacteria to utilise PAH denovo. Not all possess the bacteria to utilise PAH as a carbon source. Only a few have that ability. In a favourable condition Or in other words if other sources of carbon are available, bacteria do Not produce PAH hydrolysing enzymes. Once PAH becomes the only available source of carbon, the bacteria start producing PAH degrading enzymes. Hence, PAH exposure does not yield any denovo ability to digest PAH rather it just brings the ability the bacteria to limelight. So, first exposure to PAH makes the bacteria more resilient to the subsequent exposures.
Actually, I was thinking from a different point of view. In a highly polluted site, only those bacteria suppose to thrive which are highly capable of degrading the pollutants. In terms of natural selection, either we will find more capable bacteria or no bacteria in a highly contaminated area. Am I right?
Yes Mr. Chowdhury you are right. Bacteria living in among the pollutants will be capable of degrading the pollutants. But it depends on the level pollution. Basically pollutants make the environment unfavourable for bacteria which is a stress. So if the degree of stress is extremely high, then the bacteria succumb to it. If the intensity is moderate, they can endure it. Among the population of bacteria that endure the stress, the clone of bacterial cells previously exposed to the pollunant will be more flexible and can survive. This phenomenon can be better explained in terms of Site directed mutagenesis.
- Badges
- Science topic
- Similar topics
- Biological Science
- Microbiology
- Microorganisms
- Bacteria