Microbial Metabolism I HW 1

Week 9: Microbial Metabolism 1: Day 1

1. Starch agar plates help us distinguish between those organisms that can breakdown starch and those that cannot. The components of the starch agar plates are: Beef extract, soluble starch, agar and water. What type of media do you think this is- selective/differential?

1. Pseudomonas aeroginosa is a strict aerobe. A glucose fermentation test with this organism would show which if the following results?

1. Red broth with a gas bubble
2. Yellow broth with a gas bubble
3. Red broth with no gas bubble
4. Yellow broth with no gas bubble

1. What is the purpose of placing the gelatin deeps in the ice bucket after it is removed from the incubator? (Hint: think about how incubating at 37 degrees would affect gelatin)

1. Phenol red is used as an indicator both in the fermentation tests as well as the urea hydrolysis test. Fill in the blanks based on your knowledge of how phenol red acts as a pH indicator in each of these tests.

1. In the sugar fermentation tests the phenol red broth is used to test for the production of ______________. The broth is originally __________ in color and turns ___________ in color if the result is positive.

1. In the urea hydrolysis test the urea broth is used to test for the production of _______________. The broth is originally ___________ in color and turns __________ in color if the result is positive.