Lactose permease and β-galactosidase are required for the production of acid in the lactose fermentation test. What are the specific actions of these two enzymes that help bacteria in fermenting lactose and why does some bacteria are considered as late lactose fermenters?
It is said that the ability of bacteria to ferment lactose is through two enzymes namely permease and beta-galactosidase. Permease allows lactose to enter the bacterial cell wall, where it is then broken down into glucose and galactose by beta-galactosidase. The glucose and galactose will then be metabolized by the bacteria.
Reference:
Aryal, S. (2019, June 14). ONPG Test - Principle, Procedure, Uses and Interpretation. Retrieved October 20, 2020, from https://microbiologyinfo.com/onpg-test/
Some bacteria are considered late lactose fermenters because they have the ability to ferment lactose by producing the intracellular enzyme but they lack beta-galactosidase-permease enzyme. After some time (about 48 hours), these organisms produce mutant cells which possess beta-galactosidase-permease enzyme along with nonlactose fermenting cells, thus, late lactose fermentation is observed.
Reference:
Fermenters, L. (n.d.). Retrieved October 20, 2020, from https://www.microbiologyinpictures.com/bacteria-photos/escherichia-coli-photos/lactose-delayed-e.coli.html
Permease and beta-galactosidase are the two enzymes used for bacteria to ferment lactose. Permease is the one responsible for the movement of lactose across the bacterial cell wall. And once the lactose is inside the cell, it will then broken down into glucose and galactose by beta-galactosidase.
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