Microbiology of Bacteria
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Questions and Answers

Which of the following characteristics is NOT common to all Lactobacillus species?

  • Perform fermentation of vegetable, meat, and milk
  • Heat and chemical resistant (correct)
  • Psychotropic bacteria
  • Fastidious (require vitamin B)

    • Which genus of bacteria is responsible for spoilage of red meat?

  • Listeria
  • Propionibacterium
  • Lactobacillus
  • Brochothrix (correct)

    • What is a unique feature of Bacillus stearothermophilus?

  • It is a pathogenic bacterium
  • It can grow at temperatures below 40°C (correct)
  • It is commonly found in the human gut
  • It is a psychotropic bacterium

    • Which of the following bacteria is NOT a spore former?

    <p>Lactobacillus</p> Signup and view all the answers

    What is the primary role of Propionibacterium in the dairy industry?

    <p>Starter culture for cheese production</p> Signup and view all the answers

    Which of the following characteristics is typical of Bacillus species?

    <p>Heat and chemical resistant</p> Signup and view all the answers

    Study Notes

    Rods Overview

    • Two main categories: spore formers and non-spore formers.

    Non-Spore Forming Rods

    • Aerobic Organisms

      • Listeria monocytogenes
        • Psychotropic and facultative anaerobic.
        • Pathogenic, problematic in food industries.
        • Can survive up to 20% NaCl, exhibiting preservative resistance.
      • Brochothrix
        • Associated with spoilage of red meat.
        • Lipolytic, also psychotropic.
      • Lactobacillus
        • Fastidious, requiring vitamin B.
        • Performs fermentation in vegetables (Lactobacillus plantarum), meat, and milk as lactic acid bacteria.
        • Probiotic strains provide health benefits.

    • Anaerobic Organism

      • Propionibacterium
        • Heterofermentative, ferments glucose or lactic acid into propionic acid and CO2 in cheese, creating gas bubbles.
        • Found on human skin, some species used as starter cultures in dairy.

    Spore Forming Rods

    • Gram-Positive, Endospore Forming Rods

      • Aerobic Organisms

        • Bacillus
          • Spoilage microorganisms found in soil and gut of humans and animals.
          • Notable for heat and chemical resistance.
          • Growth ceases below 43 °C; canned foods (e.g., Bacillus stearothermophilus) should be stored under 40 °C, especially low-acid foods (pH > 4.5).
          • Bacillus cereus and Bacillus subtilis are pathogenic; other species typically non-pathogenic.

      • Anaerobic Organism

        • Clostridium
          • Recognized as pathogenic microorganisms involved in various infections.

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    Description

    This quiz covers the characteristics and classification of various bacteria, including Listeria, Brochothrix, and Lactobacillus, and their roles in food spoilage and preservation.

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