Differentiating Staphylococcus epidermidis and Escherichia coli

Staphylococcus epidermidis bacteria stain blue-purple and Escherichia coli bacteria stain pink-red Introduction  The purpose of this experiment is to determine the shape and Gram stain of the bacteria under a microscope. The reason for staining bacteria is due to the fact that most bacteria are transparent and cannot be seen through the microscope. The Gram stain is a type of differential stain that allows a (micro) biologist to identify the differences between organisms and differences within the same organism.  Gram staining bacteria requires the use of the aseptic technique to ensure the sterility of the experiment. The purpose of the Gram stain is to show whether the bacteria are Staphylococcus epidermidis (S.  After a minute and a half was up, the slide was rinsed with deionized water and blotted dry.

 The next step was to use 95% Ethanol to wash off the dyes from the Gram-negative bacteria.  To distinguish when to stop using ethanol, the first drop of non-colored solution that slides off the slide was the indicator.  Again the slide was rinsed with deionized water and blotted dry. Lastly, the saffarin dye was placed on the slide to counterstain the Gram-negative bacteria for one minute, rinsed with deionized water, and blotted dry. Conclusion From the experiment that we have done, finally, we can conclude that gram staining is the method of distinguishing between gram positive and Escherichia coli bacteria. In this experiment, we were provided some material to help us for reaching the aim of this experiment such as Crystal violet, Gram’s iodine, 95 % ethyl alcohol, safranin, and microscope slide.