Question

A spectrophotometer can measure the amount of light absorbed by a solution. A cloudy solution absorbs more light than a clear solution. What should happen to the absorption reading of a bacterial solution that is treated with lysozyme? and Why? (See appendix B for more information about spectrophotometry). (Hint: What should be the appropriate word for describing absorption reading value?) Absorption reading will decrease due to less light absorption by lower bacterial population. Absorption reading will remain constant because lysozyme will only kill some bacteria. Absorption reading will get more cloudy since bacteria lyse and the cellular structures are everywhere in the solution. Absorption reading will increase because the wavelength gets longer. Absorption reading will get clearer because more bacteria lysed in the solution. Absorption reading will keep fluctuate (goes up and down) because the bacterial population is unstable in the solution.

Answer 1

Lysozyme kills the bacteria by attacking the links in the cell wall. Lysozyme is more effective against gram-positive bacteria than gram-negative bacteria because gram-positive bacteria contain far more peptidoglycans in their cell wall.

If the lysozyme is added to Gram-Negative bacteria, there will be no change. However, the reading should decrease, indicating a less light absorbed, when the lysozyme is added to Gram-Positive bacteria.

Absorbance is a measure of the quantity of light absorbed by a sample. It is also known as optical density, extinction, or decadic absorbance. If all light passes through a sample, none was absorbed, so the absorbance would be zero and the transmission would be 100%.