Microbiology 311 Lab Report

Rebekah Worley February 21, 2012 Mitchell Section 4 Biol 311 Staining and Identifying Unknown Bacteria Introduction: The microbiology lab up to this point has been used to teach the students how to stain and identify bacteria. There are several types of staining through which the bacteria can be identified based on the color and shape. The staining methods used in the lab are Gram Staining, Capsule Staining, Endospore Staining, and Acid Fast staining. One of the most significant method of staining is the Gram Staining, as it is highly dependent (McCarthy, 25).
In the specific experiment that was done, Gram Staining was used and the bacteria that was found was purple and round (cocci) shaped. Through this the bacteria was identified as Staphylococcus epidermis. Material and Methods: The first step to identifying the bacteria was to heat fix it to the slide. The materials used were a slide, water, a Bunsen Burner, bibulous paper and clothes pin. The unknown bacteria was in a vial in solid form. The steps on page 19 and 20 of the Customized Biol 311 General Microbiology Laboratory Manual were followed to heat fix the bacteria.
After this gram staining was used to identify the unknown bacteria. The materials used for gram staining include the slide the was heat fixed, bibulous paper, crystal violet, distilled water, Gram’s iodine, 95% ethyl alcohol, safranin, oil and a microscope. The steps on page 26 of the Customized Biol 311 General Microbiology Laboratory Manual were used to stain the bacteria. Several changes were made in the procedure. The crystal violet was on the slide for 1 minute rather than 20 seconds. The decolorizing step was used with alcohol for 10 seconds rather than 20 seconds.

The only other change was that the safranin was on the slide for 1 minute instead of the recommended 20 seconds. The slide was put under the microscope at 1000x magnification using oil immersion. Results: When looking under the microscope the bacteria was found to be purple and cocci shaped. Because of the specific color and shape of the bacteria it was easily identifiable as Staphylococcus epidermis. From this it is seen that only a Gram stain was necessary to identify the bacteria. Discussion: From this experiment it is seen that bacteria is easily identified when stained correctly.
Going through the procedure with accuracy is vital, and when done right the bacteria is clear and concise. When the bacteria was stained in this experiment the color was difficult to determine at first. After exploring the bacteria on the slide it was seen to be mainly purple. If the staining had not been done properly it would have been a lot more difficult to distinguish between bacteria. This was an important thing to learn because staining is so vital in identifying unknown bacterium. Works Cited McCarthy, Charlotte M and Harold Benson. Customized Biol 311 General Microbiology Laboratory Manual. 2nd. ed. New York. McGraw-Hill 2002 Print.