Aseptic technique

Sterile technique is used to ensure a "clean" lab environment. It is essential to ensure the reliability of experimental results.

Sterile practices are especially important when working with microorganisms. A single spore or tiny bacterium can overgrow your whole medium and destroy your experiment.

The following steps are used to keep laboratory work sterile:

  • Laboratory doors and windows are kept closed to prevent air currents, preventing surface microorganisms becoming airborne.

  • The wire loop and glass spreader are sterilized before and after use with a Bunsen burner to prevent the introduction of unwanted microorganisms.

  • Lids from bottles and tubes are held when removed, and not placed on the bench during material transfer from one bottle or tube to another.

  • The neck of a bottle or tube must be immediately heated using the Bunsen burner so that any air movement is outward.

  • The bottle or tube are opened for the minimum time possible, and while open, all work is performed close to the Bunsen burner flame.

  • Media and equipment are sterilized to prevent the growth of unwanted microorganisms.

There are two images: on the left, a contaminated petri dish that contains two big fuzzy white fungal growths. On the right, a wire loop is being sterilized by placing it through the flame of a gas burner.

Figures 1: Left- A contaminated petri dish. Various species of fungi have grown in this petri dish. Image Source : Wikimedia Commons. Right- Sterile technique by sterilizing a wire loop through the flame of a gas burner. Image Source : Wikimedia Commons