Exercise 16

Question 1

Exoenzymes

Answer 1

Enzymes secreted by the bacterial cell into their surroundings

Question 2

Exoenzymes allow

Answer 2

Cells to absorb nutrients that are too large to import through the cell wall and plasma membrane

Question 3

Exoenzyme reactions

Answer 3

Usually hydrolysis to breakdown larger more complex molecules

Question 4

Amylase

Answer 4

Breaks down carbohydrates

Question 5

Beta-lactamase

Answer 5

Exoenzyme that breaks down penicillin related antibiotics

Question 6

Substrates

Answer 6

Molecules that the enzymes act on

Question 7

Catalase

Answer 7

Breaks down hydrogen peroxide into water and oxygen gas

Question 8

Gelatinase

Answer 8

Hydrolyzes gelatin, liquifies it

Question 9

Catalase positive test

Answer 9

Bubbles appear when hydrogen peroxide is added to the bacteria

Question 10

Catalase controls

Answer 10

S. aureus (+)
Enterococcus faecalis (-)

Question 11

Gelatinase positive

Answer 11

Liquifies the gelatin after incubation and refrigeration

Question 12

Gelatinase controls

Answer 12

S. aureus (+)
E. faecalis (-)

Question 13

Bacteria that ferment carbohydrates

Answer 13

Produce acid and or gas byproducts

Question 14

Phenol red broth

Answer 14

Carbohydrate depleted medium with the pH indicator phenol red

Question 15

Is gas produced without acid

Answer 15

No, acid can be produced without gas but not vice versa

Question 16

3 carbohydrates tested

Answer 16

Glucose, lactose, fructose

Question 17

Negative control carbohydrate fermentation (all 3)

Answer 17

Pseudomonas aeruginosa

Question 18

Glucose acid positive control

Answer 18

E. faecalis

Question 19

Glucose gas positive

Answer 19

E. coli

Question 20

Acid positive control lactose

Answer 20

E. faecalis

Question 21

Gas positive control lactose

Answer 21

E. coli

Question 22

Acid positive control fructose

Answer 22

Serratia marcescens

Question 23

Gas positive control fructose

Answer 23

E. coli

Question 24

IMViC

Answer 24

Indole methyl red Vogues-Pasteur citrate

Question 25

Indole test

Answer 25

Tests for tryptophan hydrolysis

Question 26

Enzyme that hydrolyzes tryptophan

Answer 26

Tryptophanase

Question 27

Tryptophan hydrolysis products

Answer 27

Get broken down into indole, ammonia, and pyruvate

Question 28

Broth for indole test

Answer 28

Indole/tryptone broth, contains high concentration tryptophan

Question 29

What's added for indole test

Answer 29

Kovac'S reagent

Question 30

Positive indole test

Answer 30

When kovac’s is added it reacts with free indole producing a red organic layer at the top

Question 31

Indole controls

Answer 31

Positive: E. coli Negative: Enterobacter aerogenes

Question 32

Methyl red test

Answer 32

Detects mixed acid fermentation

Question 33

Medium for methyl red test

Answer 33

MR-VP medium containing glucose, peptone, dipotassium phosphate

Question 34

Methyl red procedure

Answer 34

Methyl red is added 48 hours after incubation and checked for color change

Question 35

For methyl red color changes if

Answer 35

If pH is 6.4 and below changes to red

Question 36

Methyl red controls

Answer 36

Positive: E. coli Negative: E. aerogenes

Question 37

Vogues-Proskauer test

Answer 37

Detects the production of a non-acid byproduct of glucose metabolism called acetoin

Question 38

Vogues- Praskauer procedure

Answer 38

Add 2 VP reagents after 48 hours of incubation, wait 30 mins

Question 39

Positive VP test

Answer 39

Reagents turn the broth pink/red

Question 40

VP controls

Answer 40

Positive: E. aerogenes Negative: E. coli

Question 41

Citrate test

Answer 41

Determines if bacteria can use citrate as its sole citrate source

Question 42

Media used in citrate test

Answer 42

Simmons citrate agar with bromothymol blue pH indicator

Question 43

Positive citrate test

Answer 43

Organism produces alkaline products that raise the pH turning the indicator from green to Prussian blue

Question 44

Citrate controls

Answer 44

Positive: E. aerogenes Negative: E. coli