Question

Membrane fluidity for bacteria is critical. What type of fatty acids would you expect bacteria to synthesize as growth temperature increases? Why type of fatty acids would you expect bacteria to synthesize as growth temperature decreases? Why cannot bacteria simply synthesize the same type of fatty acids regardless of temperature?

Answer 1

Fluidity of lipid bilayer depends on chain length and degree of unsaturation of fatty acids. Longer the phospholipid tail, more the interaction between tail, i.e, less fluid the membrane be. Short chain reduces the tendency of interaction between hydrocarbon tails.The presence of double bond in hydrocarbon tail of fatty acid leads to formation of kink. Kink or bend in shape of unsaturated fatty acid prevent them to pack close together.At high temperature it adopt a fluid like random state. At low temperature , the increased proportion of unsaturated to saturated fatty acid in the membrane increases the fluidity of bilayer and it form a gel like organisation. This difference in synthesis of fatty acid in bacteria helps it to maintain it's structure at various temperature and prevent distortion of shape.