Isolating And Identifying Bacteria

Question 1

For the isolating and identifying bacteria lab, what is the purpose of the saline suspension? What is it?

Answer 1

The purpose of the saline suspension is to ensure a relatively uniform and light inoculum in each of the biochemical tests.

Question 2

For identifying my bacteria, what will sticking my inoculate(from saline) in gelatin do?

Answer 2

It will indicate if my bacteria has the enzymes to hydrolyze gelatin. Turning the gelatin liquidy.

Question 3

For identifying my bacteria, what will sticking my inoculate(from saline) in Tryptone broth do? (Tryptone has a high concentration in tryptophan in it)

Answer 3

Indicate if my bacteria is capable of breaking down tryptophan to produce indole. A colored indicator is added after incubation to detect the presence of indole.

Question 4

For identifying my bacteria, what will sticking my inoculate(from saline) in Sugar ferments do? (Inoculate the glucose, lactose, maltose, and sucrose, fermentation broth with separate loops of the saline suspension.)

Answer 4

It will indicate if my bacteria is able to ferment that sugar. This is able to be done because the fermentation broth contains the appropriate sugar and pH indicator. If the sugars fermented, then acid is produced that in turn causes the pH indicator to change color. It contains a small, and inverted tube called a Durham vial that traps any gas produced during fermentation of the carbohydrate.

Question 5

Why do we need to form a catalase test on my bacteria to identify it? What is Catalase?

Answer 5

Catalyst is an enzyme that breaks down hydrogen peroxide H2O2, a toxic byproduct of aerobic respiration. If bubbles form, this constitutes a positive test meaning this organism aerobically respirates.