Identifying an Unknown Bacteria

I'm having a lot of fun on my mini-project. All of us are identifying an unknown bacteria, my number is 6. The very first step was for us to create an isolation streak culture on an agar plate. I had to make 2, as the first one may have been contaminated by me breathing onto it. Luckily both plates came out pretty good. The colonies are circular, with an undulate edge, and is a glistening semi-opaque beige-yellow color.

First Plate

Second Plate

I did a gram stain from both plates and my bacteria is a gram negative bacilli. I thought it was a coccus, because the cells were very small, but when I looked at it with the oil microscope you could see that they were egg-shaped. Based on the appearance of the colonies on my plates, I suspect I have Escherichia coli, but further testing will confirm.

Next I did an Oxidase test by swabbing my culture and adding the testing fluid to it, this came out negative. I reconfirmed this by a second test which was also negative. The last test I performed was a glucose fermentation test, which was positive for acid, but negative for gas production.

The fluid turned from red to yellow, which is a positive result

I am now down to three possible species of bacteria, so if it is Escherichia coli, the next test will tell me. The SIM test, or Sulfur-indole-motility test results will be ready to read tomorrow and will be positive sulfide if it is E. coli.