Introduction: The Gram staining of bacteria is a widely used method to identify unknown bacteria. The purpose of this method is to find out identities of unidentified bacteria. By using this tool we can group bacteria into two main groups: Gram-positive and Gram-negative. In our past two labs, we streaked an unknown bacteria using aseptic technique onto two separate petri dishes leading to an isolated community of a certain bacteria. The specific communities of bacteria allowed us to perform a Gram stain for both substances. Although this Gram staining process is very important to the scientific world, it also has a major impact on our everyday life. For example, if you experienced a dog bite, a Gram stain test could be performed on your wound to determine what kind of bacteria it is and how the wound might proceed from the point it is currently at. (Ellie J. C. Goldstein, 1980) The stain would make it very easy for the doctor to look under a microscope to determine what bacteria it is and also the shape and size of the bacteria may help to conclude what might be present. Our findings from this lab should tell us the identity of the bacteria Unknown Y and Unknown G.
Methods: Using Unknown bacteria Y, and Unknown bacteria G, make two separate streaks on petri dishes and leave for one week. By means of aseptic technique, use bacteria from colonies formed in your petri dish and mix bacteria with distilled water on a new slide. Allow slide to dry and advance to performing a Gram stain procedure. When bacteria is properly stained, observe your slide under a microscope and record your observations.
Lab Reference :
Biological Sciences Department. 2011. Membrane Structure and Function. In Biology
107: Introduction to Cell Biology Laboratory Manual 2011/2012. Faculty of Arts and Science, Grant MacEwan University, Alberta, Canada. pp. #s.
Results: The first Gram stain I observed was Figure 1.0, the Unknown G bacteria under 1000X magnification. The result of the gram stain color was purple, and it had a definite cocci shape. It was very small, only one micrometer in length and the results of the KOH test were fluid and watery. The next stain I looked at was Figure 1.1, the Unknown Y bacteria which I also viewed under 1000X magnification. It had a defined bacilli shape and ended up red after the Gram staining. This bacteria was twice as large as bacteria G, and its KOH result was a gooey suspension. Both bacteria Y and G’s full results can be seen in Table 2.1. It shows a visual representation of how these bacteria compare in the various tests they went through. Seen in Figure 2.0 is a drawing of Escherichia coli showing a cluster of bacilli shaped bacteria represented at 21000X. This Escherichia coli as well as the Staphylococcus epidermis were both prepared slides that we looked at in our lab. The Staphylococcus epidermis is cocci shaped and represented at 13000X. No tests were personally done to either the Escherichia coli or the Staphylococcus epidermis because they were both previously prepared in slides.
Discussion: I believe that the Unknown bacteria Y is Gram-negative. I have come to this conclusion from the results of the tests I performed. Considering how the Gram stain color was red and the KOH result was a gooey suspension, the identification of the bacteria seems to be Gram-negative. This bacteria ends up Gram-negative and red because it does not maintain the violet dye it comes into contact with during the Gram staining process. This is primarily due to the structure of their cell wall which is made out of a thin peptidoglycan layer. Opposite of Unknown bacteria Y, I believe that Unknown bacteria G is