Sugar Fermentation Test/ ONPG Test Flashcards
What is the purpose of the sugar fermentation test?
to determine if your organism ferments a desired sugar into acid or acid/ gas
What media is used for the sugar fermentation test? What two things does it contain?
PR- Carbohydrate broth - fermentable sugar -durham tube: traps gas
What is the pH indicator for the sugar fermentation test and the colors associated with it?
Phenol red Acidic: yellow Neutral: red Basic: shocking pink
What is the inoculation and incubation guide for the sugar fermentation test?
loopful; 37C for 48 hours
What is the theory of the sugar fermentation test?
if sugar is fermented it will create an acid and react with the phenol red. The durham tube traps gas that is produced
What are the results of the sugar fermentation test?
(+) for acid only: yellow, no gas bubble (+) for acid and gas: yellow, with gas bubble (-) for acid and gas: red or shocking pink, no gas bubble
In the ONPG test, a lactose fermenter requires two enzymes, what are they and what do they do?
Beta-galactoside permease: allows lactose to enter the cell Beta-galactosidase: breaks down lactose to glucose and galactose
Which enzyme do late lactose fermentors require?
beta-galactosidase
What is the purpose of the ONPG test?
to detect the presence of Beta-galactosidase in an organism
What media is used for the ONPG test?
any media that contains lactose (TSA)
What is the inoculation guide for the ONPG test?
add a heavy inoculum from a previously grown plate to a test tube with 1/2 mL of water, then add an ONPG tablet
What is the incubation period for the ONPG test?
37C for 48 hours
What is ONPG a synthetic substrate of? What does it not require?
It is a synthetic substrate of beta-galactosidase and does not require permease to enter a cell
What is the theory of the ONPG test?
ONPG will turn beta-galactosidase into o-nitrophenol
What are the results of the ONPG test?
(+)- yellow (-)- colorless
Which of these is positive for acid and gas? Which is negative for acid or gas?
+= yellow
- = shocking pink
Which of these is postive for beta-galactosidase?
the yellow one
