Characterization and identification of bacteria.ppt
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The document discusses the characterization and identification of bacteria through phenotype systematics, emphasizing the importance of various classification criteria such as morphological, cultural, and biochemical characteristics. It highlights the need to conduct a minimum number of standardized tests that provide clear distinguishing values, including methods for assessing oxygen requirements and carbohydrate utilization. The document also outlines critical biochemical tests for effective species identification while cautioning against common mistakes in morphological and biochemical determinations.
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Characterization and identification of bacteria.ppt
- 1. Characterization and identification of bacteria Based on phenotype
- 2. Systematics (taxonomy) of bacteria • Study of diversity of microorganisms and their relationships • Includes: – clasification (ordering of B. into groups) – nomenclature – identification
- 3. Most important classes of characters • Morfological (cels including staining) • Cultural • Physiological • Nutritional • Biochemical • Ecological • Genetic • Antigenic • Phage susceptibility
- 4. In classification of bacteria • As many charactes as posible should be studied – describtion of new species
- 5. 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
- 6. Characteristics of primary importance I. • 1. Pure culture (make sure to have) • 2. Examine Gram-stained cells • 3. Look for motility or flagela • 4. Examine colonies
- 7. 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
- 8. Mistakes • Determination of shape • Gram reaction • Motlity
- 9. Biochemical characters • Oxidase test • Catalase test • Carbohydrate breakdown • O-F of glucose • Acid formation from sugars • Gas formation from glucose • ONPG test (beta-galactosidase activity)
- 10. Biochemical characters • Reduction of nitrate to nitrite • Indole test • VP test (acetoin production) • Arginin dihydrolase test