During a lab session an unknown bacteria, Unknown #57, was assigned to determine its Genus species. A series of tests were performed with subcultures made when needed and antiseptic techniques used throughout. How bacteria differ from each other chemically as well as their shape can be determined by a differential stain known as a Gram stain. Gram positive bacteria have thick cell walls made of many layers of peptidoglycan which enable the bacteria to retain the crystal violet stain. In contrast, gram negative bacteria have less peptidoglycan layers and contain porins in their outer membrane. For these reasons, gram negative bacteria cannot retain the crystal violet stain and must be counter stained with safranin. A Gram stain was performed on the Unknown #57 and the results concluded that this bacteria is a gram negative bacillus bacteria as it also demonstrated a rod shaped appearance under the microscope. Since the bacteria proved to be gram negative, an endospore test was not needed. The SIM test or Sulfide Indole Motility test contains three independent …show more content…
The absence of sulfate without a black precipitate ensures a clearer motility test result. This test was performed on Unknown #57 with duplicate conclusions from the SIM test stating that the bacteria is nonmotile. The phenylalanine test is performed to discover if a bacteria posses phenylalanine deaminase which gives it the ability to remove an amino group from the amino acid phenylalanine and metabolize it. A plate of phenylalanine is inoculated and if phenylalanine is broken down, phenylepyruvice acid, amonium ion, and water are formed as end products. Drops of ferric chloride are administrated on the culture and if the results are positive the phenlepyruvic acid and ferric chloride will combine to form a green byproduct. Unknown #57 concluded to be negative for the enzyme phenylalanine