Identifying Two Unknown Species of Bacteria Essay -- Escherichia Coli

Identifying Two mystical Species of BacteriaMaterials and Methods calendar week 1, solar day 1 (10 November 2000)The first day an unknown sample was assigned to distributively group of students. The first test applied was a gram lubricating oil to test for gram positive or gram-negative bacteria. The morphology of the deuce types of bacteria was viewed under the microscope and recorded. so the sample was put on agar-agar-agar-agar plates using the quadrant streak method for isolation. There were three agar plates one was incubated at room temperature, the second at 30 degrees Celsius, and the ordinal at 37 degrees Celsius. By placing each plate at a different temperature optimal getth temperature can be predicted for both species of bacteria.Week 1, Day 2 (12 November 2000)After 48 hours of incubation the agar plates were viewed. individualist colonies were tested for successful isolation by gram patch and and so viewing the stained bacteria under a microscope. Isolation was successful. adept colony of each unknown bacteria was transferred to an agar slant for growth. The agar slants were stored at room temperature over the weekend so that they would not grow too much.Week 2, Day 1 (17 November 2000)After 5 age of growth each slant was tested using the gram staining technique to confirm the complete isolation of the bacteria. Both isolations were completely successful. Then each sample of bacteria was subjected to a series of tests for identification. One bacterium was gram negative. It underwent four different tests. These tests were the EMB test ( bromeosin Mehylene Blue), the Sulfur Indole Motility (SIM) test, the Urease test, and the Simmons Citrate Utilization test. The EMB test checks for a bacterias tycoon to ferment lactose. This test is accomplished by placing the bacteria on Eosin Methylene Blue agar. The agar is selective for gram negative bacteria and those bacteria that can ferment lactose will have color in grow th, usually a metallic green sheen. The Sulfur Indole Motility agar tests for three separate characteristics sulfur reduction, indole production, and motility. The SIM intermediate is a semisolid medium this facilitates the motility test. The medium contains sulfur, if the bacterium has the ability to reduce sulfur the medium will turn black. The medium withal contains tryptophan. If the bacterium has the enzyme tryptophanase, indole will be ... ...indole, it is motile, there is no urease present and there is no coagulase activity. By logical implication and logical reasoning Unknown 10a was determined to be Escherichia coli. Unknown 10b is staphylococci epidermidis. According to Bergeys Manual Staphylococcus bacteria are gram positive spherical cells that occur singly, in pairs or in impermanent clusters. Unknown 10b was gram positive, spherical and occurred in clusters. Bergeys Manual also says the bacteria grow well in high salt concentrations. Unknown 10b grew we ll on the mannitol salt agar. The optimum growing temperature is 30-37 degrees Celsius (Bergeys Manual). Unknown 10b grew best at 37 degrees Celsius. The lab manual and erstwhile(prenominal) lab results confirmed all other test results. Unknown 10b was solitary(prenominal) able to use gamma lysis, it was unable to ferment mannitol and had no coagulase activity. When comparing to past labs it is confirmed that Unknown 10b is Staphylococcus epidermidis.Unknown 10 contained two bacteria they are Escherichia coli and Staphylococcus epidermidis. References1.Holt, John G. et al Bergeys Manual of Determinative Bacteriology, 1994.2.Merkel, Brian Microbiology Laboratory, 2000.