IDENTIFY CITROBACTER FREUNDII BY BIOCHEMICAL TESTS.Jebin Jacob15 November 14Naghmeh HassanzadehUnknown - 10ObjectiveThe aim of this study is to identify an unknown bacterium from a mixed culture, by carrying out different biochemical tests. Bacteria are an integral part of our ecosystem. They are found everywhere and their identification becomes crucial to understanding their characteristics and their effects on other living beings, notably humans. Biochemical tests help us identify the microorganism present with great precision. The tests used in this experiment are rudimentary but provide fundamental starting points for tests used in medical laboratories and help students better understand how tests are performed in a real laboratory. The first step in this process is to use a Gram stain technique to narrow down unknown bacteria into one of two broad areas; Gram negative and Gram positive. Once the gram type is identified, biochemical tests are performed to narrow down the specific bacterial species. These biochemical tests are an elimination process that relies on the bacteria's ability to break down certain types of food sources, their respiratory capabilities, and other biochemical conditions found in nature. The results of these tests prove that the unknown organism is Citrobacter freundii, hereinafter referred to as C. .freundii. C. freundii is part of the Enterobacteriaceae family, like all other unknowns indicated in this test. The species is facultatively anaerobic and is a Gram-negative bacillus. C. freundii is a motile, non-sporulating, long rod-shaped bacterium, typically 1 to 5 μm in length. The seven biochemical tests performed to refine the Gram-negative stain are Phe...... middle of paper ...... identify unknown bacteria and their implications for humans and nature.BibliographyPang, A., Warren, MJ and Pickersgill, RW (2011), Structure of PduT, a trimeric bacterial microcompartment protein with a 4Fe–4S cluster binding site. Acta Crystallographica D, 67: 91–96. doi: 10.1107/S0907444910050201Whalen JG, Mully TW, English JC. Spontaneous Citrobacter freundii infection in an immunocompetent patient. Arch Dermatol. 2007;143(1):124-125. Puchenkova, S.G. (1996). "Enterobacteria in water areas along the Crimean coast". Mikrobiolohichnyi zhurnal (kyiv, Ukraine: 1993) 58 (2): 3–7 Wang, JT; Chang, South Carolina; Chen, YC; Luh, K. T. (2000). "Comparison of antimicrobial susceptibility of Citrobacter freundii isolates over two different time periods". Journal of Microbiology, Immunology and Infection = Wei mian yu gan ran za zhi 33 (4): 258–262.