Transcript Characterization and identification of bacteria

Characterization and
identification of bacteria
Based on phenotype
Systematics (taxonomy) of
bacteria
• Study of diversity of microorganisms and
their relationships
• Includes:
– clasification (ordering of B. into groups)
– nomenclature
– identification
Most important classes of
characters
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Morfological (cels including staining)
Cultural
Physiological
Nutritional
Biochemical
Ecological
Genetic
Antigenic
Phage susceptibility
In classification of bacteria
• As many charactes as posible should be
studied
– describtion of new species
In identification of bacteria
• Number of tests applied should be kept to a
minimum
– concetration for simple methods and for
characters with very good distinguishing value
– tests must be standardized
Characteristics of primary
importance I.
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1. Pure culture (make sure to have)
2. Examine Gram-stained cells
3. Look for motility or flagela
4. Examine colonies
Characteristics of primary
importance II.
• 5.Test for oxygen requirements
• 6.Test for dissimilation of glucose
(oxidative/fermentative)
• 7.Select tests useful for distinguishing
between the genera
• 8.Select the test apllicable for species
identification
Mistakes
• Determination of shape
• Gram reaction
• Motlity
Biochemical characters
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Oxidase test
Catalase test
Carbohydrate breakdown
O-F of glucose
Acid formation from sugars
Gas formation from glucose
ONPG test (beta-galactosidase activity)
Biochemical characters
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Reduction of nitrate to nitrite
Indole test
VP test (acetoin production)
Arginin dihydrolase test