Essay On Catalase Test

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The first step to the unknown is selecting an actual organism. The best way to select a culture is based on a high-quality distribution. Equally important, shaking up the broth tube facilitates in the distribution. Upon selection, a gram check for purity is performed. Step by step instructions for this procedure can be found in Benson’s, Microbiological Applications p. 99. Furthermore, an aseptic technique must be performed for this test and the entire tests following the unknown. The purpose of this test is to differentiate between gram positive and gram-negative bacteria. The key indicator of gram-positive bacteria is a purple stain and a pink stain for gram-negative bacteria. A slide is viewed with a microscope under oil immersion. Equally…show more content…
Use the same plate from the TSA streak. Determine if catalase is produced through the break down of hydrogen peroxide. Proceed by adding reagent hydrogen peroxide and pay attention to bubbling. In other words, bubbling takes place due to breaking down hydrogen peroxide and the fabrication of oxygen gas (Benson, 2010). The control for this test is S. aureus. Blood Agar Plate A streak for isolation is made on the plate. In addition, check plate for hemolysis. Look for the organism’s ability to produce hemolysin. Bacteria with hemolysin will generate different patterns. To start with, partially green around the colony is alpha. Secondly, complete clearing around the colony is betta. Thirdly, cloudiness or no result is gamma. The controls are K. pneumoniae, B. cereus, and S. saprophyticus in order based on previous results. Simmons Citrate Agar Slant The use of this check is to uncover whether or not an organism is capable of exercising citrate as a carbon source. Position a needle of your organism along the surface of the slant. Next, start from the bottom and work your way up with the needle. The indicator that is already in the media is Bromothymol blue. An increase in PH will generate a bright blue for a positive result. The control is E.

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