Lactose

Definition

Lactose is a disaccharide composed of glucose and galactose, commonly found in milk and dairy products. It plays a significant role in microbial fermentation processes.

5 Must Know Facts For Your Next Test

1. Lactose is hydrolyzed by the enzyme beta-galactosidase (lactase) into glucose and galactose.
2. Certain bacteria, such as Lactobacillus, can ferment lactose to produce lactic acid.
3. Lactose intolerance occurs when there is insufficient production of lactase in the small intestine.
4. In microbiology labs, lactose fermentation is often tested using MacConkey agar to differentiate between lactose-fermenting and non-fermenting bacteria.
5. E. coli is an example of a bacterium that can ferment lactose, often used as an indicator organism for fecal contamination.

Review Questions

• What are the two monosaccharides that make up lactose?
• Which enzyme is responsible for breaking down lactose into its component sugars?
• How does MacConkey agar help in differentiating bacterial species based on their ability to ferment lactose?

Related terms

Beta-galactosidase: An enzyme that hydrolyzes lactose into glucose and galactose.

Lactic Acid Fermentation:

A metabolic process by which certain bacteria convert sugars like lactose into lactic acid.

MacConkey Agar:

A selective and differential culture medium designed to isolate Gram-negative bacteria and differentiate them based on lactose fermentation.