Bacteria vary in their metabolic &

enzymatic activities.
Used in identification of different
genera & species of bacter...
Biochemical Reactions
1. Sugar fermentation
2. Oxidase test
3. Catalase test
4. Coagulase test
5. API Test
1. Sugar fermentation
Sugar media are composed of:

Peptone water
+ 1% test sugar
+ Andrade’s indicator
+ A small inverte...
Sugar fermentation test

uninoculated

Not fermented

fermented with A only

fermented with A & G
1. Sugar fermentation
Sugar fermentation can be indicated
by change colour of the medium
from yellow to red.

Glucose
+ve
...
Catalase Test
Principle:
H2O2

Procedure:

1
2

Catalase enzyme

3

H2O2

H2 O

+

O2
Air bubbles
Results:

Catalase Test

Positive test: rapid appearance of gas bubbles.

Catalase +ve

Catalase –ve
Catalase Test
Coagulase Test
Principle:
Fibrinogen
Plasma

Procedure:

2

Coagulase enzyme

Fibrin
Visible Clot

1
1 ml rabbit plasma

3...
Coagulase Test
Coagulase +ve

Coagulase -ve
Oxidase Test
Principle:
Tetramethyl p-phenylene diamine hydrochloride
(oxidase reagent)
colourless
Cytochrome oxidase enzy...
Oxidase Test
API (Analytical Profile Index)
Incubation

Interpretation acc. to given charts
Bacterial
Typing
Classification of a certain species of bacteria into Types.
Importance: Epidemiological investigation (e.g. food
poisoning...
Bacteriophage Typing
Bacterial strain on surface of media + drops of different phages
homogenous bacterial growth
+ areas ...
Questions
1- In sugar fermentation, Andrade's indicator is added
to the sugar media to test for gas production:
( ) True
( ) False
2...
MCQ
4-Catalase test is:
a) negative if oxygen bubbles are released
b) positive if a visible clot is formed
c) done by addi...
Thank you
Biochemical Reaction - Prac. Microbiology
Biochemical Reaction - Prac. Microbiology
Biochemical Reaction - Prac. Microbiology
Biochemical Reaction - Prac. Microbiology
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Biochemical Reaction - Prac. Microbiology

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Biochemical Reaction - Prac. Microbiology

  1. 1. Bacteria vary in their metabolic & enzymatic activities. Used in identification of different genera & species of bacteria. Biochemical reactions are done on bacteria grown in pure culture.
  2. 2. Biochemical Reactions 1. Sugar fermentation 2. Oxidase test 3. Catalase test 4. Coagulase test 5. API Test
  3. 3. 1. Sugar fermentation Sugar media are composed of: Peptone water + 1% test sugar + Andrade’s indicator + A small inverted tube (Durham’s tube) .
  4. 4. Sugar fermentation test uninoculated Not fermented fermented with A only fermented with A & G
  5. 5. 1. Sugar fermentation Sugar fermentation can be indicated by change colour of the medium from yellow to red. Glucose +ve Lactose +ve maltose +ve mannite +ve Sucrose - ve
  6. 6. Catalase Test Principle: H2O2 Procedure: 1 2 Catalase enzyme 3 H2O2 H2 O + O2 Air bubbles
  7. 7. Results: Catalase Test Positive test: rapid appearance of gas bubbles. Catalase +ve Catalase –ve
  8. 8. Catalase Test
  9. 9. Coagulase Test Principle: Fibrinogen Plasma Procedure: 2 Coagulase enzyme Fibrin Visible Clot 1 1 ml rabbit plasma 3 Place at 37oC, observe for formation of visible clot for up to 4 hrs.
  10. 10. Coagulase Test Coagulase +ve Coagulase -ve
  11. 11. Oxidase Test Principle: Tetramethyl p-phenylene diamine hydrochloride (oxidase reagent) colourless Cytochrome oxidase enzyme Indophenol (Purple colour) within 1-2 min
  12. 12. Oxidase Test
  13. 13. API (Analytical Profile Index)
  14. 14. Incubation Interpretation acc. to given charts
  15. 15. Bacterial Typing
  16. 16. Classification of a certain species of bacteria into Types. Importance: Epidemiological investigation (e.g. food poisoning) Examples of Typing methods:  bacteriophage typing  bio-typing  serotyping  plasmid analysis  + others
  17. 17. Bacteriophage Typing Bacterial strain on surface of media + drops of different phages homogenous bacterial growth + areas of lysis (= susceptibility)
  18. 18. Questions
  19. 19. 1- In sugar fermentation, Andrade's indicator is added to the sugar media to test for gas production: ( ) True ( ) False 2- In the coagulase test, coagulation of plasma occurs in positive cases: ( ) True ( ) False 3- Biochemical reactions must be done on a pure culture of the organism to be identified: ( ) True ( ) False
  20. 20. MCQ 4-Catalase test is: a) negative if oxygen bubbles are released b) positive if a visible clot is formed c) done by adding a drop of H2O2 d) done to test for the presence of urease enzyme 5- Oxidase test is: a) done using catalase reagent b) positive when a deep purple color is produced c) positive after a few hours d) negative when a yellow color is produced
  21. 21. Thank you
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