Introduction to Microorganisms

Introduction to Microorganisms

• Microorganisms are very small living organisms, invisible to the naked eye.
• Observation requires a microscope or magnifying glass.

Classification of Microorganisms

• Microorganisms are divided into five main groups: bacteria, fungi, protozoa, algae, and viruses.

Activity: Observing Microorganisms in Soil

• Collect moist soil, add water, and observe a drop under a microscope to see the microorganisms present.
• Soil teems with microorganisms.

Viruses

• Viruses are microscopic entities distinct from other microorganisms.
• Reproduction occurs only inside host cells.
• Viral diseases include colds, influenza, polio, and chickenpox.

Examples of Microorganisms

• Protozoa: Amoeba and Paramecium.
• Algae: Spirogyra and Chlamydomonas.
• Fungi: Aspergillus, commonly found on bread as bread mold.

Microorganisms: Friend and Foe - Introduction

• Microorganisms exhibit both beneficial and harmful attributes.

Microorganisms in Bread Making

• Yeast is essential in bread making.
• It multiplies and releases carbon dioxide during respiration, causing dough to rise and producing soft bread and pastries.

Microorganisms in Alcohol Production

• Yeast is used in commercial alcohol and wine production.
• It converts sugars into alcohol and carbon dioxide through anaerobic respiration.
• Fermentation is the conversion of sugar into alcohol.

Activity: Observing Alcohol Production

• Prepare a solution of sugar and water in a 500 ml beaker, and add half a teaspoon of yeast.
• After 4-5 hours, the solution will contain alcohol and have a distinct smell due to yeast activity.

Medicinal Use of Microorganisms

• Microorganisms are used to produce medicines, including antibiotics.
• Antibiotics kill or inhibit the growth of disease-causing microorganisms.
• Examples include streptomycin, tetracycline, and erythromycin.
• Antibiotics are also used in plant disease control.

Vaccines

• Vaccines introduce dead or weakened microbes into the body.
• The body produces antibodies to combat the infection, providing future protection.
• Vaccination can prevent diseases like polio, chickenpox, and smallpox.

Increasing Soil Fertility

• Rhizobium bacteria fix atmospheric nitrogen, converting it into usable forms for plants.
• These bacteria reside in the root nodules of leguminous plants, forming a symbiotic relationship.
• This process enriches the soil with nitrogen, boosting fertility.

Cleaning the Environment

• Microorganisms function as decomposers.
• They break down dead plants and animals into simpler substances, enriching the soil and cleaning the environment.

Harmful Microorganisms: Spoilage

• Microorganisms can spoil food, clothing, and leather goods.

Harmful Microorganisms: Pathogens

• Disease-causing microorganisms are called pathogens.
• Pathogens enter the body through air, water, food, or direct contact.

Communicable Diseases

• Diseases spread from infected to healthy individuals and are called communicable diseases.
• Examples include the common cold, chickenpox, and tuberculosis.

Carriers of Diseases

• Insects and animals can be carriers of disease-causing microbes.
• Houseflies transmit pathogens from garbage to food.
• Female Anopheles mosquitoes carry Plasmodium, which causes malaria.
• Female Aedes mosquitoes carry the dengue virus.

Diseases in Animals and Plants

• Microorganisms cause diseases in both animals and plants.
• Anthrax, caused by bacteria, is a dangerous animal disease.
• Citrus canker is a bacterial plant disease.

Disease Control in Plants

• Chemicals are used to kill microbes and preserve plant yields, preventing plant diseases.

Food Preservation

• Various food preservation techniques can stop microorganisms from destroying food.

Chemical Method

• Chemicals like sodium benzoate & sodium metabisulphite can be added to food to preserve it.

By the use of salts

• Common salt preserves meat and fish by preventing bacterial growth.

By the use of Sugar

• Sugar preserves jams, jellies, and squashes by creating conditions that resist bacterial growth.

By the use of Oil and Vinegar

• Oil and vinegar protect food from spoilage by hindering bacterial growth.

By the use of Heat and Cold

• Heating and cooling inhibit/stops the growth of pathogens in food.
• Refrigeration helps prevent pathogen growth.

Pasteurization

• Milk is heated to 70 degrees Celsius for 15-30 seconds to kill microbes and preserve its food content.

Air tight protection

• Airtight packets preserve food and chips by preventing pathogen contamination.

Nitrogen Cycle

• Atmospheric nitrogen is abundant and crucial for plants.
• Rhizobium bacteria help plants absorb nitrogen through their roots.

Symbiotic relationship

• A symbiotic relationship is a mutually beneficial interaction.
• Bacteria get food from plants, while plants get fixed nitrogen from bacteria.

Lightening and Nitrogen

• Lightning converts nitrogen into compounds that enrich the soil.
• These compounds (nitrites) dissolve in rainwater, adding nitrogen to the soil.

Bacteria in Root Nodules

• Rhizobium bacteria in root nodules facilitate nitrogen fixation.
• Nitrogen fixation converts atmospheric nitrogen into usable nitrogenous compounds.
• These compounds are essential for plant growth and development.

Nitrogen Cycle: Maintaining Balance

• The nitrogen cycle maintains a constant amount of nitrogen in the biosphere.
• It involves the circulation and transformation of nitrogen in various forms.

Nitrogen Cycle Details

• The atmosphere contains approximately 78% nitrogen gas.
• Rhizobium bacteria and blue-green algae are essential for nitrogen fixation.
• They convert atmospheric nitrogen into nitrogen compounds usable by plants.
• Plants utilize these compounds to synthesize proteins.
• Nitrogen is converted into plant proteins, essential for growth and function.
• Animals obtain these proteins by consuming plants.

Bacteria and Nitrogen Fixation

• Rhizobium bacteria in pulses fix atmospheric nitrogen.
• Plants convert the nitrogen into plant proteins, which are then transferred to animals.

Nitrogen Recycling

• Nitrogen is recycled when plants and animals die.
• Microorganisms decompose dead organisms, returning nitrogenous waste to the soil.
• Some bacteria convert these compounds back into nitrogen gas, releasing it into the atmosphere, maintaining balance.

Diagrammatic Explanation of the Nitrogen Cycle

• Atmospheric nitrogen (78%) is fixed by lightning, bacteria, or blue-green algae.
• Plants absorb nitrogen compounds from the soil.
• Animals consume plants and assimilate the nitrogen.
• Dead plants and animals return nitrogenous waste to the soil, either for plant reuse or conversion into nitrogen gas.

Simplified Breakdown of the Nitrogen Cycle

• Nitrogen Fixation: Conversion of atmospheric nitrogen into usable compounds.
• Nitrogen Return: Conversion of organic nitrogen back into atmospheric nitrogen.

Microorganisms and Microscopy

• Microorganisms are minute and visible only with a microscope.
• Sometimes a magnifying glass can be sufficient.

Four Major Classifications of Microorganisms

• Bacteria
• Fungi
• Protozoa
• Algae

Viruses

• Viruses are also microscopic and distinct from other microorganisms.

Example Microorganisms

• Algae: Chlamydomonas, Spirogyra
• Protozoa: Amoeba, Paramecium
• Fungi: Bread Mold

Rhizobium

• Bacteria that lives in the root nodules of leguminous plants.
• It fixes nitrogen from the atmosphere.

Bacteria and Daily Life

• Lactobacillus converts milk into curd.
• Some bacteria produce antibiotics which are critical for fighting diseases.
• Microorganisms are essential in various processes and have uses in daily life.

Food Production

• Microorganisms are important for cheese production and the fermentation process to produce alcohol.
• Acetobacter aceti produces acetic acid from alcohol.
• Bread, idli, and other foods also require the use of microorganisms.

Environmental Cleaning

• Microorganisms, including bacteria, decompose dead bodies of plants and animals.
• This process helps in cleaning the environment.

Harmful Effects of Microorganisms

• Anthrax bacterium causes disease in cattle.
• Diseases like cold, flu, and polio are caused by bacteria and viruses.
• Pathogens are disease-causing microbes.
• Diseases like tuberculosis, dysentery, and malaria are caused by pathogens.
• Ringworm among other diseases are caused by fungi.

Daily Life Impact

• Bread mold develops on bread, causing spoilage.
• Microorganisms show harmful effects on our daily life.

About Antibiotics

• Antibiotics are medicines used to cure diseases caused by microorganisms.
• They either kill or inhibit the growth of disease-causing microbes.
• Antibiotics have side effects if not taken properly.
• Consulting a doctor before taking antibiotics is essential.
• The course of antibiotics must be completed.
• Overuse of antibiotics can lead to antibiotic resistance in bacteria.