Lab Quiz 5 Flashcards
Catalase Test
Tests for: the enzyme, catalase
Positive test: bubbles when peroxide is added
Negative test: no change when peroxide is added
Oxidase Test
Tests for: presence of cytochrome oxidase
Positive test: cotton swab will turn blue/purple with 1 drop of oxidase reagent
Negative test: no change in color when oxidase reagent is added
Carbohydrate Fermentation Test
Tests for: production of acid and/or a gas (4 tubes- glucose, lactose, sucrose, and mannitol)
Positive test: gas production in the durham tube; turns yellow in acid, pink is alkali
Citrate Slant Test
Tests for: presence of an alkaline
Positive test: converting the green citrate to bright blue
Negative test: Citrate slant remains green
Starch Hydrolysis
Tests for: the enzyme amylase
Postive Test: clear zone on the dark purple/brown plate where the bacteria was streaked
Negative test: the plate will have no clear zones and will be dark purple/brown all over
O2 Fermentation
Uses FTM which keeps O2 levels high at the top of the tube and low at the bottom
Tests for: anaerobes and aerobes
Growth at the top: aerobe
Growth throughout: facultative anaerobe
What is the indicator in carbohydrate fermentation?
phenol red
What is the indicator in the citrate slant test?
Bromophenol blue
What is citrate?
A Krebs cycle intermediate that can be converted to other organic molecules, usually alkaline
What color is bromophenol blue at neutral pH? At alkaline pH?
green; bright blue
What does amylase do?
breaks down starch
What is bacterial transformation?
when bacteria pick up genes from other bacteria in their environment
What is the selectable marker in this experiment? What selective media did we use?
The selectable marker is the ampicillin resistant genes.
We used the LB-Amp agar as the selective media
What is bioluminescence and what bacterium produces it?
Bioluminescence is the production of light by a living organism.
Vibrio fischeria is the bacterium that produces bioluminescence.
What is the protein encoded by the selectable marker? How does it work?
The protein is pVIB; it works by encoding b-lactamase, allowing the peptidoglycan to synthesize again
