Membrane filtration

Definition

Membrane filtration is a physical method used to remove microorganisms from liquids by passing them through a filter with pores small enough to retain bacteria and other microbes. This technique is essential for sterilizing heat-sensitive solutions and for microbial analysis.

5 Must Know Facts For Your Next Test

1. Membrane filters typically have pore sizes ranging from 0.1 to 0.45 micrometers, suitable for trapping bacteria and larger microorganisms.
2. Membrane filtration can be used in both laboratory settings for microbial analysis and in industrial processes such as water treatment.
3. This method does not kill organisms but physically removes them from the solution.
4. Common materials used for membrane filters include cellulose acetate, polycarbonate, and nylon.
5. Filtration efficiency depends on factors like pore size, filter material, and the nature of the liquid being filtered.

Review Questions

• What is the typical pore size range for membrane filters used in microbiology?
• Why is membrane filtration preferred for sterilizing heat-sensitive solutions?
• List three common materials used to make membrane filters.

Related terms

Sterilization:

The process of eliminating all forms of life, including bacterial spores, from an object or environment.

HEPA Filter: A type of air filter that can trap particulate matter down to very small sizes, often used in cleanrooms and laboratories.

Autoclaving:

A sterilization method that uses high-pressure steam at temperatures above boiling point to kill all microorganisms.