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Microbiology Lab Report Essays

Microbiology Unknown Lab Report Essay

2396 WordsApr 16th, 201210 Pages

Lab12-Medical Microbiology- Part1– Differential Media/Biochemical Tests, Sp2012 (Set all of your margins to ½”)
Purpose: The purpose of this lab is to help you become a little familiar with some of the tests that can be typically performed in a clinical or research lab facility. These tests may help in determining a particular pathogen’s growth needs.
There are several sections to this lab. Find each section and complete the “Preparing for Class” sections.
Preparing for class - Day 1
Read in your lab manual about the following agar mediums: Blood Agar (pg 168), EMB Agar (pg 170), Mannitol Salt Agar (MSA)(pg 172) ), MacConkey Agar (pg 174), and PEA Agar (pg 176) to answer the following:

1. What does the blood agar select for?…show more content…

|bacteria, or |enterococci |
| | | |greenish/gray hue | |
| | | |around | |
|EMB Agar | |Distinguishes bacteria that ferment |Dark blue colonies with|E. coli and P. |
| |Gram-negative bacteria |lactose and or sucrose and those that|green metallic sheen or|aeruginosa |
| | |do not. |pink. | |
|MSA Agar |For organisms that are |Isolates for mannitol fermentation |Yellow color change in |Staphylococcus aureus |
| |halotolerant. | |surrounding media. |and Staphylococcus |
| | | | |epidermidis |
| | | |

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Unknown Microbiology Lab Report Essay

1128 WordsNov 23rd, 20115 Pages



The purpose of this lab was to identify two unknown bacteria from a mixed culture. The reason for identification of unknown bacteria was to help students recognize different bacteria through different biochemical tests and characteristics. This is important in the medical field because identification of unknown bacteria can help treat a patient by knowing the contributing source of a disease. Also knowledge of different bacteria helped others make antibiotics used today. This lab was completed by using the methods learned thus far in identification of bacteria.

Materials and Methods

A mixed culture of two unknown bacteria was provided by the instructor. The methods used for…show more content…

The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

The Unknown Bacteria 36/Bacteria # 2 on a TSA plate was examined by the naked eye and under a dissecting microscope. Bacteria # 2 was approximately 3 - 4 mm in diameter. They were circular in form with an entire margin and a flat elevation. The colonies were rough (granular), translucent, and white brownish color with black granules. The Gram stain resulted in a Gram negative rod. After the Gram stain was completed, the bacteria were streaked on an Eosin -Methylene Blue Agar plate and an Enterotube II was inoculated.

See Table 1 and Flow Chart 1 for results of Bacteria # 1 and Table 2 and Flow Chart 2 for results of Bacteria # 2.
Table 1: Biochemical Test Results (Bacteria # 1) TEST | PURPOSE | REAGENTS | OBSERVATIONS | RESULTS | Gram Stain | To determine the Gram reaction of Bacteria #1 | Crystal violet, Iodine, Alcohol, Safranin | Purple cocci | Gram positive cocci | MSA Agar plate | To determine Gram positive Staphylococcus species | None | Yellow halo around streak | Staphylococcus aureus | Catalase Test | To verify bacteria identification | Hydrogen peroxide | No bubbling |

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