Microbiology Department of Microbiology University of Kwa-zulu Natal 25 October 2010 ABSTRACT Different types of bacteria in various forms are found all around us‚ and it is a microbiologist’s job to be able to identify these bacteria. Using various staining techniques and physiological tests‚ an isolated bacterium can be identified. In this experiment‚ a single bacterial colony was isolated form Mycorrhizal spores‚ and further tests done on that colony. Sub culturing was done after each week to ensure
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tube by running a series of experiments to detect which specific Gram negative organism we had. To detect your gram positive from the mixed culture was given as extra credit points also. A Gram stain was performed and isolation streak plate in order to isolate and observe the unknown organism. Before the series of test‚ a dichotomous key had to be written up in order to know what steps and tests to run to identify the unknown Gram negative organism. I had to run three experiments in all before I
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included: Gram stain‚ mannitol salt agar‚ coagulase tube test‚ and an antimicrobial susceptibility test. The tests selected were based on the results of a gram stain. Gram staining‚ the most commonly used differential stain‚ allows for the fast and easy detection between gram negative and gram positive organisms based on the presence or absence of peptidoglycan. A gram positive organism resists the decolorization process due to a large amount of peptidoglycan and appears a purple color. A gram negative
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and one result was inconclusive. The focus of this paper will be on the description of the just one of the three bacteria and some of its effects on humans. The first test done was a differential stain (gram stain) to determine the unknown microorganism cell shape and arrangement. The gram staining is done by first putting a sample of the unknown bacteria on a slide and it was heat fixed taking care not to over or under fixed the slide. The slide was flooded with crystal violet and let stand for 30
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ATM (STP). A Gram stain was then carried out to differentiate the unknown sample from a broad class to a more specific category of bacteria. The Gram stain distinguishes between Gram-positive and Gram-negative bacteria based on the composition of the cell walls. Gram-positive bacteria appear purple and Gramnegative bacteria appear pink after staining. The first Gram stain produced unsatisfactory results and was then repeated with a clear indication of negativity. Light pink staining was evident
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Sarcina lutea‚ Pseudomonas fragi‚ Micrococcus luteus‚ Alcaligenes faecalis‚ Clostridium sporogenes‚ and Micrococcus roseus. There were several qualitative tests that could be conducted to determine the identity of the unknown species‚ for example‚ Gram staining‚ Fermentation‚ Catalase‚ Oxidase‚ Starch Hydrolysis‚ Litmus Milk‚ MOI medium‚ and the Gelatin Test. All tests and techniques used were performed in accordance with The Microbiology Lab Manual. Materials and Method: A stock broth culture of
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smear my bacteria on a liquid medium. I then proceeded to incubate the medium for 24-48 hours. 1. GRAM STAIN The next step I took in finding my unknown bacteria was to gram stain it. This is used to differentiate the bacteria. The different staining reagents are: crystal violet‚ grams iodine‚ acetone-alcohol‚ and grams safranin. Under the microscope it was a pink color‚ which means Gram Negative. Also‚ the shape was a rod. 2. KLIGER’S IRON
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the knowledge gained from the sessions in the laboratory‚ we can now integrate what we have learned to the process of finding out the unknowns given. Materials and Methods The professor gave out the unknown specimens. It contained one-‐gram positive and one-‐gram negative bacteria from the given list. I was assigned unknown A. The process of identification was achieved by utilizing procedures learnt during the semester. Procedures were followed as stated in the lab manual (1). Since the sample contained
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determine the identity of unknown number 34‚ a gram stain‚ citrate utilization test‚ and a urease detection test. These tests are explained in detail‚ and the method of performing the tests is described. The tests showed that the bacterium was gram-negative bacilli that did not utilize citrate‚ and the ability to hydrolyze urea using urease. These results indicate that the identity of unknown number 34 is Proteus mirabilis. Introduction Proteus mirabilis is a gram-negative bacillus bacterium. It is found
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two slides for gram staining and viewing under a microscope. {Either my gram-stain slides were bad or the microscopes I chose for viewing were not good. No bacteria were found under the microscope.} Prepare another gram stain of the unknown bacteria. {Gram-positive‚ coccus shaped bacteria were observed under the microscope. Also noted‚ the slide may have been inadvertently contaminated during the gram stain process by another person in the laboratory.} [I do think that the gram-stain result
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