Slide Prep: Simple Smear

Agar Culture

  • Place a loop full of water onto a clean glass slide. Up to three smears can easily be placed on one slide, spacing them evenly.
  • Flame your loop, pick up a small amount of culture, and mix it into the drop of water, spreading it over the glass. The most common mistake novices make is to use too much culture. The smear should be just barely visible when dry.
  • Flame the loop and set it down. (See Aseptic Techniques: Flaming the Loop)
  • Allow the smear to air-dry completely.
  • Heat fix the smear by passing it briefly through the Bunsen burner flame two or three times. The slide should never become so hot that you cannot touch it.
  • The smear is now ready to stain.

Broth Culture

  • Mix the culture.
  • Use your loop to spread a loop full of culture onto a clean glass slide. Three smears can easily be spaced on one slide.
  • Flame the loop and set it down. (See Aseptic Techniques: Flaming the Loop)
  • Allow the smear to air-dry completely.
  • If the culture is very sparse, you can produce a more concentrated smear by adding another loop of culture over the first air-dried smear.
  • Heat fix the smear by passing it briefly through the Bunsen burner flame two or three times. The slide should never become so hot that you cannot touch it.
  • The smear is now ready to stain.

Take the Quiz

On to Direct Stain