For the semester, a group of potential microbiologists were given the task to identify a variety of mysterious microorganisms. A series of tests were done to determine the species of organisms that are invisible to the naked eye. The organisms thrive ubiquitously throughout the world, inhabiting the smallest cracks and crevices of the Earth. Hundreds and thousands of these amazing creatures exist within a single room. The students were provided the necessary materials needed to distinguish a species from a mixed culture. Test after test, the students embarked upon a journey to uncover the unknown. For one student, after a compilation of data, Escherichia blattae was uncovered to be the mysterious organism. The following tests were the most conclusive that provided essential information for identifying the organism.
Gram-Stain
The gram stain is a differential stain that distinguishes organisms based on their cell wall structure. The peptidoglycan layer is the main difference that distinguishes gram negative from gram positive organisms. The components of this stain include the dyes Crystal violet and Safranin, Gram's iodine as a mordant, and ethanol as a decolorizer. The primary stain is the crystal violet dye that stains all cells heat fixed to the slide. The gram positive stains are able to retain the dyes better due to the thicker layer of the peptidoglycan material present within their cell wall. Gram negative organisms have a much thinner peptidoglycan layer, therefore, retaining the dye is difficult. The outer layer of the gram negative organisms is highly porous due to the lipopolysaccharide make-up of the membrane. With the aid of the ethanol, crystal violet is completely removed from these cells. Safranin is used as a counter stain to make them visible under the microscope. Cells that appear red are stained by Safranin and therefore are determined to be gram negative organisms. Cells...