Microbiology Unknown Organism Assignment

Unknown Organism Assignment

Lacey Fagan

Microbiology: Mrs. Rossman

I was given unknown organism #14, in order to find out what organism I had, I had to perform several different biochemical tests to identify it. Starting with the Gram stain test, which is performed to differentiate Gram-positive and Gram-negative cells. After staining, when observed through the microscope Gram-positive cells are a purple color with thick peptidoglycan cell walls. Gram-negative cells are a pinkish/red color with thinner cell walls. (handout G. s.) My organism was observed to be pinkish rod shaped meaning it is Gram-negative bacteria. The Phenol Red Carbohydrate Fermentation Broth test. This test is to determine the ability of microorganisms to ferment in a specific carbohydrate. If fermentation occurs, the pH level will change and your broth will

If the organism can use the Citrate it will produce alkaline by products that will raise the pH level of the medium and growth will occur, causing a positive result. If Citrate cannot be used there will be no growth and no change in color due to no pH level changes causing a negative result. My organism showed signs of growth and color change from green to blue, meaning a positive result for my organism. ( handout Citrate) The Amylase test is to determine if the bacteria produces amylase which cleaves the starch into di- and monosaccharides. Iodine turns into a blue/black color when in the presence of starch, after using iodine if the blue/black color is absent then the starch has been used usually making a halo around the inoculum, resulting in a positive result. If it stays blue/black then the starch is still present meaning the organism cannot produce amylase causing a negative result. My color stayed blue/black and there was no evidence of a halo, meaning my organism is negative for producing amylase. (handout,