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Prof. Dr. Sevgi ERTUĞRUL KARATAY

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Prof. Dr. Sevgi ERTUĞRUL KARATAY

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Biochemical Tests

Enzymatic Activity Tests

Enzymes play a vital role in cell metabolism.

Enzymes can be divided into two main groups in microbiological tests.

Intracellular enzymes

Extracellular enzymes

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Biochemical Tests

Enzymatic Activity Tests

Intracellular enzymes:

Example: Enzymes involved in fermentation.

Extracellular enzymes:

Example: Enzymes which digest cellulose or starch

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Biochemical Tests

Enzymatic Activity Tests Catalase Testing

Catalase is an enzyme that converts toxic forms of oxygen to less harmful compounds. Bubbles is observed

in organisms with catalase activity because oxygen is released into the environment.

Microorganisms with bubbles are evaluated as Catalase (+) and non-bubbles organisms are evaluated as catalase

(-).

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Biochemical Tests

Enzymatic Activity Tests

Catalase Test-Intracellular Activity

The reaction is carried out as follows.

•2H

2

O

2

2H Catalase

2

O + O

2

Staphylococcus: catalase (+), Streptococcus: catalase (-)

Bacillus türleri: catalase (+), Clostridium türleri: catalase (-)

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Biyokimyasal Testler Enzymatic Activity Tests

Amylase Test-Extracellular Activity

Starch is a polymer in which the glucose units are linked to each other by a glycoside bond.

This polymer can be broken down into glucose units by

an enzyme called as amylase.

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Biochemical Tests

Enzymatic Activity Tests

Amylase Test-Extracellular Activity

Starch gives black color with lugol but does not give

color with glucose (Lugol's original color is brown-red).

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Biochemical Tests

Enzymatic Activity Tests

Amylase Test-Extracellular Activity

If the microorganism has the amylase activity, it will break down starch molecules and use glucose when added to starchy agar medium. In this case, clear zones

are observed when lugol is added to the starchy agar medium.

Zone observed microorganisms is considered as amylase

(+), (otherwise amylase (-).

Referanslar

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