Microorganisms: Friend and Foe

Microorganisms: Friend and Foe

Microorganisms and Their Characteristics

• Microorganisms, or microbes, are tiny living organisms that cannot be seen with the naked eye.
• They are classified into four major groups: bacteria, fungi, protozoa, and some algae.
• Viruses are also microscopic, but they are different from other microorganisms and can only reproduce inside the cells of a host organism.

Habitat and Distribution of Microorganisms

• Microorganisms can be found in all types of environments, including ice cold climates, hot springs, deserts, and marshy lands.
• They are also found inside the bodies of animals, including humans, and can be beneficial or harmful.

Beneficial Microorganisms

• Microorganisms are used in various industries, such as:
  • Preparation of curd, bread, and cake
  • Production of alcohol, wine, and acetic acid (vinegar)
  • Cleaning up the environment by breaking down organic waste
  • Increasing soil fertility through nitrogen fixation
• Microorganisms are used to produce medicines, such as antibiotics, which kill or stop the growth of disease-causing microorganisms.
• Vaccines are made from microorganisms to protect against diseases.

Harmful Microorganisms

• Disease-causing microorganisms, or pathogens, can cause diseases in humans, plants, and animals.
• They can spread through air, water, food, or physical contact with an infected person or animal.
• Examples of diseases caused by microorganisms include:
  • Cholera, tuberculosis, and common cold in humans
  • Malaria, caused by a protozoan parasite transmitted through the bite of a female Anopheles mosquito
  • Dengue, caused by a virus transmitted through the bite of a female Aedes mosquito

Control and Prevention of Microbial Diseases

• Communicable diseases can be prevented by:
  • Keeping a distance from infected persons
  • Covering the nose and mouth while sneezing
  • Washing hands regularly
  • Maintaining personal hygiene and good sanitary habits
  • Getting vaccinated against specific diseases
• Controlling the spread of malaria and dengue can be done by:
  • Preventing water collection and mosquito breeding
  • Using mosquito nets and repellents
  • Spraying insecticides to control mosquito populations### Microorganisms: Friend and Foe

Disease Causing Microorganisms

• Microorganisms can cause diseases in humans, animals, and plants.
• Examples: anthrax disease caused by bacterium (Bacillus anthracis), citrus canker caused by bacteria, rust of wheat caused by fungi, and yellow vein mosaic of bhindi (Okra) caused by virus.

Food Poisoning

• Food poisoning can occur due to the consumption of food spoilt by microorganisms.
• Microorganisms that grow on food can produce toxic substances, making food poisonous.
• Examples: spoilage of food due to microorganisms, and food poisoning caused by consumption of spoilt food.

Food Preservation

• Methods of preserving food:
  • Chemical method: using salts and edible oils to prevent the growth of microorganisms.
  • Heat and cold treatments: boiling, refrigeration, and freezing to kill or inhibit microorganisms.
  • Preservation by sugar: reducing moisture content to prevent bacterial growth.
  • Preservation by oil and vinegar: creating an environment where bacteria cannot live.
  • Common salt: used to preserve meat, fish, and fruits.

Nitrogen Fixation

• Nitrogen is an essential constituent of all living organisms.
• Nitrogen fixation: the process of converting atmospheric nitrogen into compounds that can be used by plants.
• Examples: Rhizobium bacterium that fixes nitrogen in leguminous plants, and blue-green algae that fix nitrogen directly from air.

Nitrogen Cycle

• The nitrogen cycle involves the conversion of nitrogen into various forms that can be used by plants and animals.
• Steps involved:
  • Nitrogen fixation: conversion of atmospheric nitrogen into compounds.
  • Nitrogen uptake: plants absorb nitrogen from the soil.
  • Nitrogen release: plants and animals release nitrogen back into the soil.
  • Denitrification: conversion of nitrogen back into atmospheric nitrogen.

Key Concepts

• Microorganisms: too small to be seen with the naked eye, but can be seen with a microscope.
• Types of microorganisms: bacteria, fungi, protozoa, algae, and viruses.
• Microorganisms can be found in air, water, and the bodies of plants and animals.
• Microorganisms can be useful for commercial production of medicines and alcohol, and for decomposition of organic waste.
• Microorganisms can also cause diseases and food poisoning.