Ap Biology Catalase Test

The second test tube 11 was identified as a gram negative bacteria. The biochemical tests that I performed that were positive were catalase, glucose, SIM, indole, citrate, and urea. First, the catalase test has the presence of an enzyme in the test isolated detected using hydrogen peroxide. Bacteria possess catalase with a small number of bacteria; isolation is added to hydrogen peroxide when bubbles occur. When the bubbles occurred on gram positive bacterium it was a conformation of being positive. Next, the glucose tests an organism’s ability to ferment the sugar glucose as well as its ability to convert the end product of glycolysis, pyruvic acid into gaseous byproducts. If an organism is capable of fermenting the sugar glucose, then acidic …show more content…
If an organism can reduce sulfur to hydrogen sulfide, the hydrogen sulfide will combine with the iron to form ferric sulfide, which is a black precipitate. My SIM turned black, so it indicates the reduction of sulfur. Next, Indole helps to determine the ability of the organism to convert tryptophan into the indole. Which resulted to have a red color on top. Next, the citrate has the ability of organisms to utilize citrate as a carbon source. It contains sodium citrate as the sole source of carbon ammonium dihydrogen phosphate as the sole source of nitrogen, other nutrients, and the pH indicator of bromothymol blue and turns to royal blue. Lastly, the urea tests the ability of an organism to produce an exoenzyme, that hydrolyzes urea to ammonia and carbon dioxide. The urea in the broth is degraded and ammonia is produced, an alkaline environment is created then the media turns pink. The biochemical has allowed me to find the bacterium identified as Proteus Vulgaris. Proteus vulgaris are small, gram-negative rods and are facultative anaerobes. Gram-negative bacterium that inhabits the intestinal tract of humans and animals. It can be found in soil, water, raw