Microorganisms Introduction Study Notes

Microorganisms: Introduction

• Definition: Microorganisms are organisms that are too tiny to be seen with the naked eye.

  • Also known as microbes, they can typically be viewed under a microscope or magnifying glass.

• Field of Study: The science dealing with the study of microorganisms is called microbiology.

• Habitat: Microbes are omnipresent and can live:

  • Underground
  • On the earth's surface
  • In the air
  • On and inside living beings (hosts), where they find food and shelter.

Activity: Demonstrating the Presence of Microorganisms in Soil

• Aim: To demonstrate the presence of microorganisms in moist soil.

• Materials Required:

  • Beaker
  • Moist soil
  • Water
  • Dropper
  • Glass slide
  • Microscope

• Procedure:

  1. Collect soil from the field and add water to make it moist.
  2. Stir well and leave it undisturbed for 30 minutes.
  3. Once the soil settles at the bottom of the beaker, take a drop of water from the beaker and place it on a glass slide.
  4. Observe the slide under a microscope.

• Observation: Microscopic viewing reveals tiny organisms that were not visible to the naked eye.

• Conclusion: The tiny moving organisms observed are microbes, visible only under a microscope.

Classification of Microorganisms

• Microorganisms are categorized into five groups:
  1. Bacteria:
  • Characteristics:
    • Unicellular (single-celled) microorganisms.
    • Found everywhere, including surface environments and inside living organisms.
    • Obtain their nutrients as either:
      • Parasites: organisms that live off a host and harm it.
      • Saprophytes: organisms that feed on dead organic matter.
    • Size: Ranges from 0.2 microns to 100 microns (1 micron = 1/1000 of a millimeter).
  • Types based on shape:
    • Cocci: spherical shaped bacteria.
    • Bacilli: rod-shaped bacteria.
    • Spirilla: spiral-shaped bacteria.
    • Vibrio: comma-shaped bacteria.