Archetype, Oxidase Test

The tube that contained my unknown material was tube number twenty. I did a gram stain, oxidase test, and used three different medias to narrow down and identify my unknown organism.

The first step I took in identifying was a gram stain. This gram stain would reveal whether my organism is gram positive or gram negative which would narrow my choices from fifteen options down to six. After completing the gram stain, my unknown was the color pink. This revealed my unknown as being gram negative. I also used the microscope to identify the morphology of the organism. I recognized the unknown to be staphylobacillus. Staphylobacillus means rod shaped cells in grape-like clusters. After establishing the morphology and gram stain I had six options for what my unknown was.

For my first selective and differential test I choose a media that would split my options in half. I choose a MAC plate for my first test. Using MAC was the best option because not only did it cut my options from six to three, depending on whether there was a positive or negative reaction, but it also was the easiest to read. For MAC each reaction was a clear good growth with a positive or negative reaction, whereas the other options had uncertainly because you had to distinguish variable reaction and weak reactions as well. After
SIM tests for sulfur, indole, motility. For sulfur your organism should have a black color it its positive. My unknown had no black color, so negative for H2S. If the organism is positive for indole it's pink, and yellow for negative. My unknown stayed more of a yellow color, there wasn’t much pink. At most I would call it a weak positive. Motility tests for the turbidity, if its positive it’ll have a grey looking cloud near the top of the tube. My unknown had the grey cloud and tested positive. My assumption that my uknown was Providencia Stuartii is now verified. P.S fits every test result for MAC, SIM, TSI, and