Tips on Making Bacterial Slides

Thanks to Jordan M. one of our summer interns from Mckinley Technology High School for writing this guest post. 

Making bacteria slides is messy but can be fun! Imagine seeing all the tiny bacteria that grows that nobody gets to see. The end product is amazing and useful. Gram staining is used to help identify infections in your body and to indicate the type of bacteria. Here are some great tips that will help you make beautiful gram stained bacteria slides:

  • Make sure your slides are completely dried so you will not see water droplets under the microscope.
  • Wear protection on your hands and body to avoid getting any bacteria or dye on them and to avoid contaminating the slides. (Lab coat, goggles, closed toed shoes and gloves.)
  • Make sure to not burn your hands when holding a slide over the burner! Hold the slide by its tip and hold in the fire for about 10 seconds.
  • Use as little Gram’s crystal as possible to cover the slides.
  • If the slide is over stained, use more alcohol.
  • Make sure to pat not rub when removing water on a slide.
  • When picking up bacteria on a toothpick do not take too little (hard to see under a microscope) or too much (bacteria looks bunched up).


Here are some examples of the slides that I made during my internship at Edvotek.


This is a picture of Citrobacter frundii that I made using Gram staining.


This is a picture of Escherichia coli also with Gram stain.

Your first slides may not come out as perfect. (I had to try several times before I discovered how to make the slides just right.) However, in the end, your slides will come out looking like a real scientist. Also, the bacteria are beautiful under a microscope. You will be amazed how they look!

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