Serial dilution

Definition

Serial dilution is a stepwise dilution of a substance in solution, often used to reduce a dense culture of cells to a more usable concentration. It is frequently employed in microbiology to estimate the number of organisms present in a sample.

5 Must Know Facts For Your Next Test

1. Serial dilution involves multiple dilutions, each reducing the concentration by a consistent factor, typically tenfold.
2. It is essential for quantifying viable microorganisms in samples by counting colony-forming units (CFUs) after plating on agar plates.
3. Dilutions are often performed using sterile saline or broth as the diluent to maintain osmotic balance and avoid microbial death.
4. Serial dilution allows for achieving concentrations low enough to enable accurate enumeration while avoiding overcrowded colonies that can merge.
5. Accurate pipetting and aseptic techniques are crucial for ensuring reliable and reproducible results.

Review Questions

Related terms

Colony-Forming Unit (CFU): A unit used to estimate the number of viable bacteria or fungal cells in a sample.

Aseptic Technique:

Procedures used to prevent contamination by unwanted microorganisms during experiments.

Diluent: A liquid, usually sterile saline or broth, used to dilute a sample during serial dilutions.