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Identifying An Unknown Bacterium From A Mixed Culture, By Conducting Different Biochemical Tests

IDENTIFYING CITROBACTER FREUNDII THROUGH BIOCHEMICAL TESTING.
Jebin Jacob
November 15th, 14
Naghmeh Hassanzadeh
Unknown - 10

Purpose

The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.

The results of these tests prove that the unknown organism is Citrobacter freundii hereby referred to as C. freundii. C. freundii is a member of the Enterobacteriaceae family, like all the other unknowns given in this test. The species is a facultative anaerobic and is a gram-negative bacilli. C. freundii is a non-spore forming, motile bacteria that are long rod-shaped with a typical length of 1-5 μm.

The seven biochemical tests conducted to narrow down the gram-negative stain are Phe...

... middle of paper ...

...dentifying unknown bacteria are and its implications for humans and nature.

Bibliography
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Whalen JG, Mully TW, English JC. Spontaneous Citrobacter freundii infection in an immunocompetent patient. Arch Dermatol. 2007;143(1):124–125.

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Wang, J. T.; Chang, S. C.; Chen, Y. C.; Luh, K. T. (2000). "Comparison of antimicrobial susceptibility of Citrobacter freundii isolates in two different time periods". Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi 33 (4): 258–262.

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