Lab #12

Question 1

Citrate Test

Green ► Blue

Answer 1

= positive

= pH change

= uses citrate

Question 2

Still Green

Answer 2

= negative

= no pH change

= does not use citrate

Question 3

Lactose Fermentation Test

purple ► yellow

Answer 3

= positive

= pH change (acidic)

= ferments lactose

Question 4

Lactose Fermentation Test

still purple

Answer 4

= negative

= no pH change

= does not ferment lactose

Question 5

Hydrogen Sulfide Production

black precipitate

Answer 5

= positive

= produces H2S

= has cysteine desulfurase

Question 6

Hydrogen Sulfide Production

no precipitate

Answer 6

= negative

= does not produce H2S

= lacks cysteine desulferase

Question 7

What is the Principle of the Indole Production Test?

Answer 7

To determine the ability of an organism to catabolize (breaking down) the amino acid tryptophan into indole, pyruvic acid, and ammoniaI

Question 8

Indole Production tests for the…

Answer 8

presence of the enzyme tryptophanase

Question 9

Indole Production Test

Formula

Answer 9

tryptophan tryptophanase → indole + pyruvate + NH3

Question 10

Indole Production Test

Medium

Answer 10

Tryptone broth

♦ Contains tryptophan, which is the substrate for the enzyme tryptophanase

Question 11

Indole Production Test

What is added after inoculation and incubation for 24-48 hours?

Answer 11

Kovac’s Reagent

Question 12

Indole Production Test

True or False?

You will not know if the test is positive or negative until the addition of Kovac’s Reagent

Answer 12

True

Question 13

Indole Production Test

Inoculation and incubation

Red ring in broth

Answer 13

= positive

= has Trp-ase

Question 14

Indole Production Test

Inoculation and incubation

Yellow ring in broth

Answer 14

= negative

= does not have Trp-ase

Question 15

Indole Production Test

Enterobacter aerogenes (-) vs. E. coli (+)

Question 16

Methyl Red Test

Principle

Answer 16

Determine the ability of bacteria to produce large quantities of acid from glucose fermentation

Question 17

Methyl Red Test

True or False

Some bacteria can ferment glucose to produce a large quantity of acids

Answer 17

True

Question 18

Methyl Red Test

Test for the presence of the …

Answer 18

multiple enzymes

Question 19

Methyl Red Test

Medium

Answer 19

Methyl red (MR) broth containing glucose

Question 20

Methyl Red Test

methyl red is a ___ indicator

Answer 20

pH indicator

Question 21

Methyl Red Test

Methyl red is red at pH < __

Answer 21

pH < 5

Question 22

Methyl Red Test

Methyl red is yellow at pH > __

Answer 22

pH > 6

Question 23

Methyl Red Test

True or False

You will not know if the test is positive or negative until the addition of the indicator

Answer 23

True

Question 24

Methyl Red Test

Inoculation and incubation

Red

Answer 24

= positive

= pH < 5

= presence of acids

= has necessary enzymes

Question 25

Methyl Red Test Inoculation and incubation **Yellow**

Answer 25

**= negative** = ph \> 6 = no acids produces = lacks necessary enzymes

Question 26

Klebsiella spp./Enterobacter aerogenes (-) vs. E. coli (+)

Question 27

Motility Test **True** or **False** Bacteria can be motile and non-motile

Answer 27

**True**

Question 28

Motility Test Some bacteria use ______ for motility a. tails b. wheels c. flagella (singular flagellum) d. nitrogen

Answer 28

c. flagella (singular flagellum)

Question 29

Motility Test A mobile genus of bacteria is \_\_\_\_

Answer 29

Proteus

Question 30

Motility Test ## Footnote **Medium**

Answer 30

Motility stab

Question 31

Motility Test Contains a semi-solid \_\_\_\_\_

Answer 31

semi-solid gelatin agar

Question 32

Motility Test **Motile bacteria** are __________ from the stab into the agar a. able to swim away b. not able to swim away

Answer 32

a. able to swim away

Question 33

Motility Test **Non-motile bacteria** _____ spread from the stab a. can b. cannot

Answer 33

b. cannot

Question 34

Motility Test Also contains _____ \_\_\_\_ to indicate growth: turns reddish-pink anywhere there is growth

Answer 34

**tetrazolium sal**

Question 35

Motility Test Stab! and incubate **Reddish-pink** radiating out from stab

Answer 35

**= positive** = bacteria are motile via flagella

Question 36

Motility Test Stab! and incubate **Reddish-pink** limited to stab area

Answer 36

**= negative** = bacteria are non-motile because they lack flagella

Question 37

Nitrate Reduction ## Footnote **Principle**

Answer 37

Determine the ability of an organism to reduce nitrate to nitrites or free nitrogen gas while undergoing anaerobic respiration

Question 38

Nitrate Reduction Test for the presence of the enzyme \_\_\_\_\_

Answer 38

**nitratase**

Question 39

Nitrate Reduction ## Footnote **Three possible cases**

Answer 39

1. nitrate ► nitrite 2. nitrate ► nitrite ► nitrogen gas (denitrification) 3. no nitrate reduction

Question 40

Nitrate Reduction ## Footnote **Medium**

Answer 40

Nitrate broth

Question 41

Nitrate Reduction ## Footnote **Reagents**

Answer 41

Sulfanilic acid (A) Alpha naphthylamine (B) Zinc dust (only if necessary)

Question 42

Urease Test ## Footnote **Principle**

Answer 42

Determine the ability of an organism to break down **urea** into **ammonia** and **carbon dioxide**

Question 45

Urease Test The presence of ammonia drives the pH ____ (i.e. makes the pH more alkaline/basic) a. up b. down

Answer 45

a. up

Question 46

Urease Test _urease (NH₂)₂CO + H₂O ————\> CO2 + 2NH₃ ^urea

Question 47

Urease test ## Footnote **Medium**

Answer 47

Urea slant

Question 48

Urease test Contains a pH indicator that turns ____ when **pH shifts to alkaline** and ____ when there is **no pH change**

Answer 48

**pink** **orange**

Question 49

Urease test Differentiates between ____ \_\_\_\_ and _____ that cause UTIs from the _____ \_\_\_\_\_ \_\_\_\_\_

Answer 49

Differentiates between **Proteus (urease+)** and **pathogens** that cause UTIs from the **Enterobacteria family (urease-)**

Question 50

Urease test Inoculate urea slant **Orange ► Pink**

Answer 50

**= positive** = pH alkaline = has urease

Question 51

Urease test Inoculate urea slant **Still Orange**

Answer 51

**= negative** = no pH change = no urease