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Bio 2/18 part 2

Enrichment Media Use

  • Combination of media types: Enrichment media can act as both reducing and selective/differential media.

    • This versatility allows designers to create media tailored for specific microbiological purposes.

Commercial Media

  • Testing Water: Commercial media for testing water purity is available.

    • Fecal contamination testing: This is a common application.

    • Results: Different colonies will appear in various colors (e.g., red, green, orange) indicating different levels or types of contamination.

Laboratory Practice

  • In the upcoming lab session, the following types of media will be utilized:

    • Nutrient Agar (TSA): This is a non-selective media that has been used previously.

    • Selective Media: Designed to allow growth of specific bacteria while inhibiting others.

    • Selective and Differential Media: This medium differentiates organisms based on their metabolic characteristics.

Unknown Bacterial Identification

  • Fermentation Tubes: Students will work with two types of fermentation tubes.

    • Lactose Fermentation Tube: Starts red; changes color based on metabolic activity (production of lactic acid).

    • Sucrose Fermentation Tube: Also starts red; indicates fermentation capability through color change.

    • The tests provide clues about the metabolic capabilities of the bacteria.

Metabolic Testing

  • API Test Strips: A convenient method for conducting a series of metabolic tests.

    • How it works: Each well contains different media to test various metabolic pathways.

    • Scoring: After incubation, results are scored based on color changes compared to controls.

Entero Tube

  • Description: A plastic stylus with presterilized chambers for metabolic testing.

    • The tube allows both anaerobic and aerobic growth conditions by adjusting the chamber's exposure to air.

    • Usage: Inoculate with a colony, incubate, and assess growth and metabolic activity.

Growth Considerations in Healthcare

  • Infection Control: Important to avoid contamination of patients and healthcare instruments.

    • Growth conditions should be regulated to ensure safety and hygiene in a clinical environment.

    • The principle of concentration-time relationship explains that higher concentrations and prolonged exposure result in lower survival rates of microbes.