Gram negative unknown lab report for enterobacter aerogenes

Microorganisms are often described as single-celled, or unicellular organisms; however, some unicellular protists are visible to the naked eye, and some multicellular species are microscopic. The study of microorganisms is called microbiology.

Gram negative unknown lab report for enterobacter aerogenes

The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium.

The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible bacteria based on specific biochemical characteristics.

Whether the tests performed identified specific enzymatic reactions or metabolic pathways, each was used in a way to help recognize those specifics and identify the unknown cultures.

The differential tests used to identify the unknown cultures were Each person in the class was given a heterogeneous broth mixture of 2 microbes. We will write a custom essay sample on Microbiology Unknown Paper.

Order now More Essay Examples on This mixture was streaked onto the following plates: On the nonspecific TSA plate a large hazy white colonies was formed. On the other hand, there were also small orange colonies fewer in growth. This test is used to detect the presence of catalase, which helps to breakdown toxic hydrogen peroxide produced from the transport of high-energy electrons directly to oxygen.

Catalase is tested for by adding hydrogen peroxide to the culture, and looking for the production of gas bubbles. If gas bubbles appear immediately, the culture is catalase positive. However, if no bubbles are observed, the culture is negative for catalase.

The citrate test was performed only on the gram - bacteria and was used to determine the ability of an organism to use citrate as its sole carbon source. Bacteria that possess citrate-permease are able to do this.

The medium used for this test contains bromthymol blue dye, which is green at neutral pH, but blue at a basic pH. Bacteria that is able to survive and utilize the citrate, convert ammonium phosphate to ammonia and ammonium hydroxide, which alkalinize the agar, turning it blue.

Thus, the conversion of the medium to blue is a positive citrate test.

Gram negative unknown lab report for enterobacter aerogenes

No color change is negative. However, I believe that the citrate test had failed and should have been positive. Urea hydrolysis to ammonia by urease-positive organisms will overcome the buffer in the medium and change it from orange to fuchsia.

Rapid urease-positive bacteria will turn the broth pink within 24 hours. Urease-negative bacteria will produce no color change or turn the broth yellow. The results for both organisim yielded yellow which indicated negative reaction.

A bacitracin test was performed on the gram - bacteria, testing for resistance and sensitivity towards antibiotic. If there is a zone of inhibition around the disc then that means the bacteria is sensitive to bacitracin.


If there is not a clear zone around disc the bacteria is resistant to the antibiotic. After streaking the unknown S on to BAP plate 1 bacitracin disc was placed on the plate and incubated for 48 hrs.

After 48 hrs of incubation a zone of inhibition was formed around the bacitracin disc which indicated that the bacterium is sensitive to bacitracin. Nitrate reduction was tested for by inoculating a nitrate broth with the unknown gram - culture, and allowing growth to take place.

Adding 2 drops of both sulfanilic acid and? If nitrite is present, the medium turns red, indicating a positive test. However, if the medium does not change, a second test is performed to see if nitrite was further reduced.Identification of Unknown Bacteria Identify unknown bacteria.

Review microbiology core technical competencies. Introduction Identification of unknown bacteria will allow the student to review. Maura Gongora 12th December, MCB L- Section Unknown #16 Abstract This report contains the background information on gram positive and gram negative bacteria, which will aid in understanding the use of specific laboratory experiments to distinguish between the two types of bacteria.

The unknown gram-negative bacteria is Enterobacter aerogenes. The other bacteria which was microscopically viewed as gram positive was missing in the incubator, another tube of sample was derived from the lab professor.

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Gram Negative Unknown Lab Report Enterobacter Aerogenes. Name: Danielle Title: Unknown Lab Report Introduction: There are many reasons for identifying an unknown bacterium.

The reasons range from medical purposes, such as determining if the unknown could cause ailments in living things or knowing what microorganisms are needed to make antibiotics. UNKNOWN LAB REPORT. Unknown Number Then Citrate was tested and the result was negative, which eliminated Klesiella Pneumoniae and Enterobacter aerogenes.

Now the Gram negative (-) bacteria in question were narrowed down to Proteus vulgaris and Escherichia coli. Nitrate reduction test was then performed, if the result was positive the.

Apr 29,  · Today was the last day of identifying my unknown in lab. Unfortunately, I'm getting some odd results: For my gram negative bacteria, I have done the following tests and am undecided between E. coli and E.

aerogenes Glucose (+) (with gas bubble) Lactose (+) (with gas bubble) Indole (-) Methyl-red show more Today was the last day of identifying my unknown in Resolved.

Enterobacter Aerogenes – What Are Bacteria?