Bacteria Identification Methods PDF
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This document provides an overview of various methods used to identify different types of bacteria, covering different tests and processes for determining species and properties. Methods include identification media, growth, Gram staining, motility tests, biochemical characteristics, and sugar fermentation tests.
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6. Identification media Chemicals are added to help identify bacteria isolated The identification process through chemical reaction: change the color of the organisms and/or production of a gas Examples: Peptone water sugars Urea broth Kligler iron agar Growth of bacterial c...
6. Identification media Chemicals are added to help identify bacteria isolated The identification process through chemical reaction: change the color of the organisms and/or production of a gas Examples: Peptone water sugars Urea broth Kligler iron agar Growth of bacterial cultural Generation time: the time required for a cell or population to divide The number of dead Equilibrium between cell cells exceeds the division and death number of new cells Bacteria multiply at the fastest rate formation High metabolic activity but no change in the number of cells Tests used to differentiate bacteria 1. Gram stain: Named after Hans Christian Gram in 1844 Differentiate between Gram-positive bacteria and Gram-negative bacteria Gram-positive have a higher peptidoglycan and lower lipid content The importance of the stain test: Are the bacteria positive or negative for the stain The shape of the bacteria (cocci, bacilli, spiral,..) Arrangement of bacterial cells (Staph, Strept, Diplo, …) 2. Motility tests Differentiate between motile and non-motile bacteria by using two methods: Hanging drop method Semisolid culture media 3. Biochemical characteristics 1. Catalase test 2. Oxidase test An enzyme called cytochrome c oxidase found in some bacteria that transfer electrons to oxygen (electron donor) 3. Coagulase test Coagulase used as a defense mechanism by clotting the areas of plasma around them, thereby enabling themselves to resist phagocytosis by the host immune system 4. Sugar fermentation tests Used to determine the ability of an organism to ferment various sugar samples Gram staining https://www.youtube.com/watch?v=AZS2wb7pMo4 Coagulase test https://youtu.be/NBcMypWZo18 Motility test/Hanging drop method https://youtu.be/mjrYIAye1J4 Sugar fermentation test https://youtu.be/vJcL9f52Zuk Motility test/Semisolid culture media https://youtu.be/VpfPxoTlpLE Catalase test https://youtu.be/SBmL2vg-IN0 Oxidase test https://youtu.be/W3RY8o6By-A
