Day 8

DAY 8

Today we first looked at our Skim Milk Agar and determined it was a negative.

Fermentation of Carbohydrates (Durham Tube)

·         We were looking for gas inside the Durham tube and then identify the color of our tube

·         What we found:

o   Mannitol: yellow positive, gas in the tube acid/gas (farthest right)

o   Lactose: yellow positive, gas in the tube acid/gas (2nd from right)

o   Glucose: yellow positive, gas in the tube acid/gas (2nd from left)

o   Sucrose: red negative, no gas in the tube no fermentation (far left) 
        (note: for the sucrose we are going to continue to incubate it and see if the color changes) 

Citrate utilization test

·         We found that our test tube agar slant was still green, so we are going to incubate it longer.

Triple Sugar Iron (TSI) Agar Test

·         We found that our agar slant was yellowish orange so it was an acid slant/acid butt with gas. We found that it used lactose and sucrose (still going to check). There is gas production because there are breaks in the agar. It changed color because of the pH indicator.

Urea Test:

·         Ours wasn’t a deep pink color, rather a yellow color means urea is not broken down and the enzyme is not there, therefore it is negative. However, we will incubate it longer to make sure this is true

Methyl Red Test

·         We divided our broth into 2 different tubes.  One for VP test and one for MR test. We added 15 drops of A and 5 drops of B to one tube. To the other tube we added 5 drops of methyl red.  The MR tube was positive because it was red. VP is negative because it remained yellow. tells us that it uses glucose and VP tells us that there are no end products.

Nitrate Reduction Test

·         We put on gloves and added 5 drops of reagent A and 5 drops of reagent B to the tube. We found that a red color developed meaning that the test is positive for nitrate reduction so nitrite ions are present).

Iodine (Tryptophan Degradation) test:

·         We added 10 drops of Kovac reagent to the culture. It produced the cherry red color on top so we found that it was positive.

We also looked at our litmus milk today and found that there is a little pink color so we are going to incubate it for a little longer and check it tomorrow.

We added hydrogen peroxide on top of our streak plate and found that the bacteria produced bubbles meaning that they are aerobic.

At the end of today we made a new broth culture. We inoculated our bacteria in the slant by poking and snaking up the top. Then we inoculated an oxic/anoxic test tube with our bacteria. We made sure to use aseptic technique while doing this. Lastly, we placed these tubes in the incubator.