You need to determine if a pure culture of bacteria is gram-positive or gram-negative, but you've just spilled your only solutio
n of crystal violet so you can't do a Gram stain. You decide to try a lysozyme treatment on a sample of each culture and then examine the samples under the microscope. The expected result is?
Gram positive bacteria will be lysed whereas gram negative bacteria will be unaffected.
Explanation:
Lysozyme treatment degrades bacterial cell wall. It destroys the peptidoglycan cell wall by hydrolyzing the glycosidic bond between NAM and NAG sugar residues present in the cell wall.
Gram positive bacteria has a thick peptidoglycan cell wall with only a thin outer layer of techoic acid. So when exposed to lysozyme, the peptidoglycan layer disintegrates and forms debris.
Gram negative bacteria has a thin peptidoglycan cell wall and a tough outer membrane. The outer membrane does not allow the lysozyme to come in contact with the cell wall keeping it intact.
Hence, Gram positive bacteria will be lysed whereas gram negative bacteria will be unaffected by lysozyme treatment.
If water did not expand when freezing, then it would be denser than liquid water when it froze; therefore it would sink and fill lakes or the ocean from bottom to top. Once the oceans filled with ice, life there would not be possible.
