MICROORGANISMS FRIEND AND FOE
What are Microorganisms?
Microorganisms (or microbes) are tiny living organisms that cannot be seen with the naked eye. They can
only be seen through a microscope or sometimes a magnifying glass (like fungus on bread).
Major Groups:
1. Bacteria: Single-celled (e.g., Lactobacillus, Rhizobium).
2. Fungi: Multi-cellular or unicellular (e.g., Yeast, Bread Mould).
3. Protozoa: Unicellular organisms (e.g., Amoeba, Paramecium).
4. Algae: Plant-like organisms (e.g., Spirogyra, Chlamydomonas).
5. Viruses: Unique because they only reproduce inside the cells of a host (plant, animal, or bacteria).
Microorganisms as Friends (Helpful)
1. Food Industry: Lactobacillus helps turn milk into curd. Yeast is used in baking (bread, cakes)
because it releases Carbon Dioxide (CO_2), making the dough rise.
2. Commercial Use: Yeast is used for the large-scale production of alcohol and wine through
Fermentation (discovered by Louis Pasteur).
3. Medicinal Use: Antibiotics (like Penicillin) are made from fungi and bacteria to kill disease-causing
microbes. Vaccines protect us by introducing dead or weakened microbes into the body to produce
antibodies.
4. Soil Fertility: Bacteria like Rhizobium (found in root ••nodules of leguminous plants) fix
atmospheric nitrogen into the soil.
5. Environment: Microbes act as decomposers, breaking down dead organic waste into simple
substances.
Microorganisms as Foes (Harmful)
1. Human Diseases: Pathogens cause diseases like Tuberculosis (bacteria), Common Cold (virus), and
Malaria (protozoa).
2. Carriers: Insects like the Female Anopheles mosquito (carries Malaria parasite) and Houseflies
spread diseases.
3. Food Spoilage: Microbes grow on food and produce toxic substances, leading to Food Poisoning.
4. Food Preservation: Methods to prevent spoilage include:
•Chemical: Salt, sugar, oil, and vinegar.
•Heat/Cold: Boiling milk or keeping food in the fridge.
•Pasteurization: Heating milk to 70^\circ\text{C} and cooling it quickly to kill microbes.
A. Fill in the blanks
Microorganisms can be seen with the help of a __________. (Microscope)
Blue-green algae fix __________ directly from air to enhance fertility of soil. (Nitrogen)
Alcohol is produced with the help of __________. (Yeast)
What are Microorganisms?
Microorganisms (or microbes) are tiny living organisms that cannot be seen with the naked eye. They can
only be seen through a microscope or sometimes a magnifying glass (like fungus on bread).
Major Groups:
1. Bacteria: Single-celled (e.g., Lactobacillus, Rhizobium).
2. Fungi: Multi-cellular or unicellular (e.g., Yeast, Bread Mould).
3. Protozoa: Unicellular organisms (e.g., Amoeba, Paramecium).
4. Algae: Plant-like organisms (e.g., Spirogyra, Chlamydomonas).
5. Viruses: Unique because they only reproduce inside the cells of a host (plant, animal, or bacteria).
Microorganisms as Friends (Helpful)
1. Food Industry: Lactobacillus helps turn milk into curd. Yeast is used in baking (bread, cakes)
because it releases Carbon Dioxide (CO_2), making the dough rise.
2. Commercial Use: Yeast is used for the large-scale production of alcohol and wine through
Fermentation (discovered by Louis Pasteur).
3. Medicinal Use: Antibiotics (like Penicillin) are made from fungi and bacteria to kill disease-causing
microbes. Vaccines protect us by introducing dead or weakened microbes into the body to produce
antibodies.
4. Soil Fertility: Bacteria like Rhizobium (found in root ••nodules of leguminous plants) fix
atmospheric nitrogen into the soil.
5. Environment: Microbes act as decomposers, breaking down dead organic waste into simple
substances.
Microorganisms as Foes (Harmful)
1. Human Diseases: Pathogens cause diseases like Tuberculosis (bacteria), Common Cold (virus), and
Malaria (protozoa).
2. Carriers: Insects like the Female Anopheles mosquito (carries Malaria parasite) and Houseflies
spread diseases.
3. Food Spoilage: Microbes grow on food and produce toxic substances, leading to Food Poisoning.
4. Food Preservation: Methods to prevent spoilage include:
•Chemical: Salt, sugar, oil, and vinegar.
•Heat/Cold: Boiling milk or keeping food in the fridge.
•Pasteurization: Heating milk to 70^\circ\text{C} and cooling it quickly to kill microbes.
A. Fill in the blanks
Microorganisms can be seen with the help of a __________. (Microscope)
Blue-green algae fix __________ directly from air to enhance fertility of soil. (Nitrogen)
Alcohol is produced with the help of __________. (Yeast)
