You need to determine if a pure culture of bacteria is gram-positive or gram-negative, but you've just spilled your only solution 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?

Question

Pamela Burnett

Biology

16 May, 02:06

You need to determine if a pure culture of bacteria is gram-positive or gram-negative, but you've just spilled your only solution 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?

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Jonah Salinas · Answer 1

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.