TD Khang

TD Khang - Khang TD Khang Microbiology 251 Lab Unknown...

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Khang TD Khang Microbiology 251 Lab Unknown Report April 15, 2011 Identification of Unknown Bacteria Bacteria found on all surfaces and environments are so numerous and different. There are certain ways to identify different bacteria. Selective media and differential media are examples of ways to identify different types and strains of bacteria. Selective media stops growth from occurring in a certain type of bacteria while allowing growth to occur in other bacteria. Mannitol salt is an example of a selective media. Differential media will allow for different bacteria to grow but it will show different characteristics for each bacterium such as a difference in color. Sheep Blood Agar is an example of differential media because it shows if bacterium are Alpha, Beta, or Gamma hemolytic. Many tubes and plates used in this experiment are differential media because they show different characteristics or differentiate among various strains of bacteria. Multiple tests are performed in order to determine the identity of the bacteria by eliminating bacteria that do not match the test results and narrowing down possibilities. Identification of bacteria using these techniques can allow one to determine the cause of certain diseases and respond with the appropriate resistance. Sheep blood agar plates and one MacConkey agar plate are used to grow the three unknowns. In experiment 11, the upper respiratory track (URT) bacterium numbered 137 was identified as Streptococcus viridans, and the enteric organisms numbered 96 were identified as Enterobacter aerogenes and Klebsiella pneumoniae . The URT an unknown bacterium was identified using multiple steps. Aseptic techniques were used in order to avoid contamination and to provide the best results. Firstly, a gram stain
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Khang was performed in order determine if the unknown bacteria was gram-positive or gram-negative. After following the procedure for gram staining, the slide contained clusters of cocci with a purple tint to them. This result eliminated Moraxella catarrhalis as a possibility because it was gram-negative and it would have stained pink. After determining that the unknown bacterium was a gram positive cocci, a catalase test was performed to determine if the bacteria was a strain of Staphylococcus sp. or Streptococcus sp. The catalase test showed if the bacteria could break down hydrogen peroxide like the Staphylococcus sp. The results were negative, meaning that Staphylococcus aureus and Staphylococcus epidermidis
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This note was uploaded on 02/29/2012 for the course BIO 101 taught by Professor Desaix during the Spring '11 term at UNC.

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TD Khang - Khang TD Khang Microbiology 251 Lab Unknown...

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