Gram Staining Lab Report

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In this lab report I use two different techniques to identify Unknown A and Unknown B bacteria’s. These techniques are gram staining and metabolic testing. I first used Gram staining to distinguished and identify the bacteria’s. Han Christian discovered gram staining in 1882, he had biopsy a patient lung that had pneumonia. The main purpose for Gram staining is to identify if is Gram positive or Gram negative by using differential staining. While Gram staining shows the difference between Gram Positive and Gram negative and its size, shape and morphology. This techniques as it limits. For example, I was doing Gram staining and I noticed that I had more then one gram- negative with rod shapes and gram -positive with coccus
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Then I rinse with water over the staining dish. Secondly, I will add Gram iodine (Mordant) for another minute, which then the cells will the form a crystal a complex with crystal violet then rinse off the stain. The third step is to add 95% ethanol 5-10 second if the bacteria are Gram negative it would the cell would look colorless for the and if it is Gram positive the color would remain purple. I did then rinse the 95% ethanol off with out water not too much. Because the water stop bacteria from decolonization and you want to be able to see the bacteria under the microscope. The last agent you would add was safranin and this is too put back the color to the bacteria. I would then rinse and blot dry on bibulous paper. Then put oil on the slide then observed under the microscope-using eyepiece …show more content…
Indole is form when an enzyme break down tryptophan and that enzyme is called trptophanase. Indole is then broken into ammonia and pyruvate that then make other molecules. The medium I used is tryptone broths, which contain trptophan. I Then started the inoculation and take “Unknown A” bacteria using sterilized loop and place it in the broth. The indicator I use to test if typtonase break down tryptone is kovac’s reagent.

The second test I did was for gelatinase. Gelatinase is an enzyme that breaks down gelatin. Gelatin itself is a protein that derives from collagen that is found in connective tissues of bones, skin and tendons. The medium is solidification but at room temperature is liquid. I will take a sterilized needle with “Unknown A” bacteria and stab ¾ of the way down into gelatin medium. This medium need to be incubated at 25 degree Celsius before it can be read because it turns liquid at room temperature and also when gelatinase break down the gelatin.

The third test I did was lactose. Lactose has to with the fermentation of carbohydrates. Fermentation is metabolic process that some bacteria use to break down glucose when oxygen is not available. BI-311 Microbiology laboratory

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