Gram Stain Lab

765 Words4 Pages
Lauren Calso September 29, 2014 BIOL 240 Lab Report Gram Stain Introduction Various methods are used to identify unknown bacteria. A popular method to determine unknown bacteria is called a Gram Stain. A stain is coloring a specimen with dye. A Danish physician named Hans Christian Gram developed the Gram stain method in 1844. He studied at the University of Copenhagen and became a professor of Medicine. When differentiating between two types of pneumonia, he found that most bacteria are either Gram-positive or Gram-negative. This indicated that Gram stain is a called a differential stain. The bacteria is Gram-positive when the bacteria stains a purple color. This color indicates the chemical consists of the cell wall of bacteria. The bacteria…show more content…
I also used crystal violet dye, Gram’s iodine, 95% ethanol, Safranin, bibulous paper, immersion oil, lens paper, and a compound light microscope (B-4). I first lit my Bunsen burner then sterilized my inoculating loop by passing it at an angle through the tip of the blue in the flame of a Bunsen burner until the entire wire becomes orange from the heat. I always wait thirty seconds after sterilizing loop to ensure full sterilization. I opened the unknown broth bacteria tube and flamed the mouth of the tube with one hand then inserted my loop in the tube at an angle with my other hand. I flamed the mouth of the tube again and recapped the tube then placed it in the test tube…show more content…
Meanwhile, I re-flamed the inoculating loop till orange to sterilize. After the smear was dry, I heat fixed the slide by passing it quickly three times over the Bunsen burner flame. I covered the smear with a couple drops of crystal violet dye and let it stay for one minute. Then, I held the slide at a slight angle to wash it with distilled water. I instilled a couple drops of Gram’s iodine on the smear and let it stay for another minute. After, I washed it with distilled water again. I instilled a couple drops of 95% ethanol to decolorize the smear. After one minute, I rinsed the slide with distilled water. I added a couple drops of Safranin to counterstain. Once that set for one minute, I rinsed the slide with distilled water. Finally, I blotted the slide with bibulous paper to dry. I cleared all equipment and disinfected my work area. I placed the slide in the slide holder of the compound light microscope. Using the 10x objective lens, I focused on the smear. I then used the 40x objectives lens to focus. Once it was focused, I slightly moved that lens away to place a drop of immersion oil directly on the middle of the smear. Finally, I used the 100x objective oil immersion lens to focus on the

More about Gram Stain Lab

Open Document