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Flashcards in Lab 10 Deck (17):
1

What sugars were used in the fermentation tests?

glucose, sucrose and lactose

2

Fermentation Test:
How is a positive and negative test recognized?

Change to yellow color indicates positive result. A negative test is recognized by no color change, so it remains red or pink.

3

Fermentation Test:
Explain the "why" of a positive test.

Change to yellow color indicates positive result. this is because acid production from fermentation of the carbohydrate lowers the pH below the neutral range of the indicator and turns the medium yellow.

4

Fermentation Test:
What kind of metabolism would a non-fermenter generally exhibit?

Aerobic cellular respiration.

5

Citrate Test:
What is the substrate?

citrate

6

Citrate Test:
How is a positive and negative test recognized?

A positive test is recognized by the change in color from green to blue in the agar around the bacterial growth. If the organism can not use citrate, there will be no color change.

7

Citrate Test:
Explain the "why" of a positive test.

A positive test is recognized by the change in color from green to blue in the agar around the bacterial growth. This is because citrate is the only carbon-containing compound in the medium, thus if the organism can utilize citrate, an organic carbon source, then the agar turns blue.

8

MR-VP Test:
What are the fermentation end products for each of these tests?

For the MR test the fermentation end product is mixed acid and for the VP test its butonediol fermentation end products.

9

MR-VP Test:
What reagents are used to test for these products?

For the MR test to test for mixed acid fermentation end products we use Methyl Red dye.

10

MR-VP Test:
Would you expect an organism to be positive for both tests? Why or why not?

No because if it has mixed acid fermentation end products it wouldn't have butonediol fermentation end products. End products are either acids or alcohols.

11

MR-VP Test:
Would you expect an organism to be negative for both tests? Why or why not?

Yes an organism could be negative for both test because they could have different end products or not do fermentation at all and do aerobic cellular respiration

12

SIM Test:
What is the substrate and end product in the sulfur test?

the substrate is sulfur and the end product is H2S hydrogen sulfide gas.

13

SIM Test:
What kind of metabolic process is taking place in a positive reaction?

In a positive reaction the metabolic process that takes place is anaerobic respiration.

14

SIM Test:
What is the substrates enzyme, and end product in the indole test?

The substrate is tryptophan amino acid. The enzyme is tryptophanase and the end product is pyruvic acid + indole.

15

SIM Test:
What reagent is used to test for indole?

The reagent used to test for indole is kovacs reagent.

16

SIM Test:
One of the end products in this test could be used by the cell for what metabolic purpose?

The end product pyruvic acid could be used for fermentation, aerobic cellular respiration or anaerobic respiration.

17

SIM Test:
How is motility determined.

Motility is determined by viewing turbidity away from the stab line which means motility.