Question

2. Which would have better tolerance to salt: a sample of microorganisms taken from the Dead Sea or a sample of microorganisms taken from a freshwater stream? 3.What structure(s) in bacteria (or yeasts, if applicable) might provide an ability to withstand salt?

Answer 1

Ans :

2) A sample of organisms taken from the Dead Sea have the capability to tolerate salt better.

The pecularity of Dead Sea is that it contains a large amount of minerals and salts in the water. Therefore the water has high salinity and the microorganisms present in the Dead Sea have special metabolic properties and mechanisms which allow them to adapt to the high salt concentration ang high osmotic pressure in the water. While the freshwater has low salinity and hence the microbes living in them can't tolerate high salinity. If we put sample of microorganisms in freshwater to high salinity condition it will kill them by sucking water out of them in a process known as osmosis, where water passes out of a bacterium so as to balance salt concentrations on each side of its cell membrane.

3) The bacteria have specialized cellular machinery which is adapted to high salt concentrations by having charged amino acids on their surfaces, allowing the retention of water molecules around salt components. These charged amino acids are known as osmoprotectants which are compatible solutes. Osmoprotectants can act as stabilizers which help organisms to survive extreme osmotic stress in high salinity conditions. The bacteria accumulates these osmoprotectants in the cytoplasm and increase the internal osmolarity of the bacterial cell. Another strategy adopted by bacteria is radical adaptation which involves selectively absorbing potassium (K⁺) ions into the cytoplasm.