Question

*Remember you must recalibrate with a blank of each pH/Sal for that solution. * Questions 1. Of the two methods used to assess microbial growth, which was more qualitative? Quantitative? Nes Rol Mic Mc 2. How do you suppose a fever would be beneficial in fighting a bacterial infection? Shu Ch 3. What would happen to a bacterial cell from a freshwater environment when suddenly placed in a marine environment? Ha Yo 4. What conditions would be best for growing microbes from Monterey Bay? 5. Explain how a 3% saline solution may be isotonic to marine microbes but hypertonic to freshwater microbes. References Brown, Alfred E. 2007. Benson's Microbiological Applications. Laboratoru M 1

Answer 1

1.) Cannot be answered due to insufficient data provided. Which two methods are they talking about ? You may mention it in comments, I'll try answering it then.

2.) Fever is quite beneficial in fighting the bacterial infections. It's the natural immune response of our body. The reason behind this is the fact that most of the bacterial species are able to survive in a very narrow range of temperature only. Upon increasing the body temperature, the chances of survival of the infecting bacteria gets reduced, and hence they ultimately get killed.

3) When bacterial cells from freshwater environment are suddenly placed in marine environment, then the cells will lose water content and shrink. This is because of the difference in osmotic balance. In Marine environment, the salt concentration is higher. So to maintain osmotic balance, the bacteria will release its water content into the environment and then shrink. Ultimately the cell will get lysed due to excessive shrinking.

4) Monterey Bay is located on the Pacific Coast in the west coast of USA. Since it is at Pacific Ocean, so the environment will be marine. Hence the Salt concentration (or Salinity) needs to be quite high, along with temperature in range of 50-65o F to provide best growing conditions for microbes.

5) Marine Microorganisms are osmotolerant and halophiles, i.e. they can easily survive in high salt concentration and high osmolarity. For them, 3% saline solution is isotonic, as their internal ionic concentration is also similar (that's how they can survive high osmolarity by maintaining osmotic balance). On the other hand, there is no such osmotic disbalance caused in freshwater environment and its inhabitant microbes, as the salt concentration is very low. So the internal ionic concentration of such microbes is also quite low.

Now, when freshwater microbes are put in 3% saline solution, then the internal ion concentration is not enough to compensate for osmotic disbalance. Hence the cell will lose its water content due to hypertonic environment, ultimately shrinking and then getting lysed.

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