Lipid, Casein, and Starch Tests {Lab 7 - May 20, 2015}

     These tests told us what our bacteria could eat. If the bacteria gave positive results to these tests, then we would know that it could a) hydrolyze or digest a triglyceride, a type of lipid; b) hydrolyze casein, the major protein in milk; and c)hydrolyze starch.

Lipid Test

     For this test we used a blue spirit agar plate to test for the ability of our bacteria to digest triglycerides. After inoculating the blue spirit agar with our bacteria, we incubated it. When we checked on it after the incubation period, we found that our sample had a negative result for the lipid test.

Our bacteria (on right)
- Negative

Casein Test

      With this test, we were able to tell whether our bacteria could digest the major protein in milk, casein. We inoculated a skim  milk agar plate with our bacteria and incubated it for the appropriate time. Afterwards, we observed the results: our bacteria was unable to digest casein. 

Starch Test

     With the starch test, we were able to determine our bacteria's ability to hydrolyze starch. Using a starch agar plate, we inoculated our bacteria on it and incubated for the appropriate time, after which we filled the petri dish with Gram's iodine. Iodine reacts with starch to produce a purple color. So if our bacteria had digested the starch, there would have been a clear area around the streak line of the bacteria. However, after observing it, we realized our bacteria had a negative result for starch hydrolysis. 

Our bacteria (on right)
- Negative