Microorganisms: Friend and Foe - Comprehensive Notes
Introduction
Microorganisms are tiny organisms not visible to the naked eye.
Microbiology is the study of microorganisms.
Microorganisms can only be observed with a microscope.
Learning New Words
Pasteurization: Heating milk to for 15 seconds followed by rapid cooling to prevent microbial growth.
This process prevents the spoilage of milk by destroying harmful bacteria while preserving its nutritional qualities.
Protozoa: Microorganisms, often pathogens, causing human diseases.
Examples include Giardia and Plasmodium, which cause diseases like giardiasis and malaria, respectively.
Fungi: Microorganisms primarily involved in decomposition.
Fungi break down organic matter, recycling nutrients back into the environment.
Virus: Microorganism acting as a bridge between living and non-living entities.
Viruses require a host cell to replicate, making them obligate intracellular parasites.
Bacteria: Microorganisms that can be both beneficial and harmful.
Beneficial bacteria aid in digestion, while harmful bacteria can cause infections.
Yeast: Single-celled fungi aiding in fermentation.
Yeast converts sugars into alcohol and carbon dioxide, essential in baking and brewing.
Rhizobium: Bacteria facilitating atmospheric nitrogen fixation in soil.
Rhizobium lives in a symbiotic relationship with leguminous plants, enriching the soil with nitrogen.
Soil fertility: Enhancement of humus and nitrogen content in the soil.
Fertile soil supports plant growth by providing essential nutrients and a favorable environment.
Microorganism: Organism visible only with a microscope.
These organisms include bacteria, viruses, fungi, protozoa, and algae.
Microbe: A disease-causing organism.
Microbes can cause a wide range of diseases in plants, animals, and humans.
Lactobacillus: Bacteria involved in curd formation.
Lactobacillus converts lactose into lactic acid, resulting in the coagulation of milk proteins.
Carrier: Organism transmitting diseases from infected to healthy individuals.
Carriers may not show symptoms of the disease but can still transmit the pathogen.
Antibodies: Proteins produced by the body to combat disease-causing microbes.
Antibodies bind to antigens on pathogens, neutralizing them and marking them for destruction by immune cells.
Antibiotics: Medicines derived from microorganisms used to inhibit or kill disease-causing microorganisms.
Antibiotics target specific bacterial processes, disrupting their growth and replication.
Vaccine: Dead or weakened microbes introduced to stimulate antibody production for future protection.
Vaccines prime the immune system to respond quickly and effectively upon subsequent exposure to the pathogen.
Pathogen: Disease-causing agent (microorganism).
Pathogens can be bacteria, viruses, fungi, protozoa, or helminths.
Fermentation: Process of converting sugar into alcohol.
Fermentation is used in the production of various foods and beverages, such as yogurt, bread, and beer.
Nitrogen fixation: Conversion of atmospheric nitrogen into usable forms by bacteria like Rhizobium and blue-green algae such as Anabaena and Nostoc.
Nitrogen fixation is essential for plant growth, as plants cannot directly use atmospheric nitrogen.
Where do we find microorganisms?
Microorganisms are found everywhere: soil, water, and air.
They inhabit diverse environments, from extreme temperatures to high-pressure conditions.
Their wide distribution results from their resilience and tolerance to extreme conditions (temperature, dryness).
Some microorganisms can survive in dormant states, reactivating when conditions become favorable.
Microorganisms secrete a protective cyst under unfavorable conditions, becoming active again when conditions improve.
Cysts protect microorganisms from desiccation, radiation, and toxic chemicals.
Their presence is noted through their actions, both beneficial (e.g., curd formation, fermentation) and harmful (e.g., diseases, food spoilage).
Microorganisms play crucial roles in nutrient cycling, decomposition, and disease.
Activities to observe Microorganisms
Activity 1: Filtrate pond water and observe under a microscope to see minute organisms.
Filtration removes larger particles, allowing for better visualization of microorganisms.
Activity 2: Mix moist soil with water, let settle, and observe a drop under a microscope.
Soil contains a diverse array of microorganisms, including bacteria, fungi, and protozoa.
Microorganisms are microscopic, usually single-celled living organisms that cannot be seen with the naked eyes and can only be observed through a microscope.
The small size of microorganisms necessitates the use of microscopes for their observation and study.
Some fungi, like those on bread, can be seen with a magnifying glass, but most require a microscope.
Magnifying glasses provide limited magnification, whereas microscopes offer much higher resolution.
Classification of Microorganisms
Microorganisms are classified into four major groups:
Bacteria
Fungi
Protozoa
Algae
Viruses are distinct; they reproduce only inside a host organism (bacteria, plant, or animal cells).
Viruses hijack the host cell's machinery to replicate their genetic material and produce new viral particles.
Common ailments caused by viruses include cold, influenza, and coughs. Serious diseases like polio and chickenpox are also viral.
Viral infections can range from mild to life-threatening, depending on the virus and the host's immune response.
Diseases caused by protozoans include dysentery and malaria.
Protozoan diseases are often transmitted through contaminated food or water or by insect vectors.
Bacterial diseases include typhoid and tuberculosis (TB).
Bacterial infections can be treated with antibiotics, but antibiotic resistance is an increasing concern.
The Habitat and Size of Microorganisms
Microorganisms exist in various forms and habitats.
Their adaptability allows them to thrive in a wide range of ecological niches.
They can be single-celled (bacteria, protozoa) or multicellular (algae, fungi).
The cellular organization of microorganisms varies depending on the group.
They survive in diverse environments, from ice-cold to hot springs and deserts to marshes.
Extremophiles are microorganisms that thrive in extreme environments, such as high temperatures or high salinity.
Habitats include marine environments, water rich in organic matter, animal bodies (including humans), and decaying organic matter.
Microorganisms play essential roles in these habitats, such as nutrient cycling and decomposition.
Some microorganisms, like amoeba, exist independently, while others, like bacteria, live in colonies.
Colonial living provides benefits such as increased access to nutrients and protection from predators.
Size of Microorganisms
Microorganisms range in size from micron to over micron.
Role of Microorganisms in Our Life
Microorganisms play both useful and harmful roles.
Their impact on human life is significant, affecting health, agriculture, and industry.
Useful Roles
Preparation of curd, bread, cake, and alcohol.
Environmental cleaning via decomposition of organic waste.
Medicine preparation.
Increased soil fertility through nitrogen fixation by Rhizobium.
Production of cheese, pickles, and other edible items.
How curd is formed
Curd forms when Lactobacillus bacteria in milk multiply rapidly, converting milk into curd.
Thiomargarita namibiensis is a macroscopic bacterium visible without a microscope.
Harmful Roles
Cause diseases in plants and animals (cold, flu, malaria, skin infections).
Classification of Microorganisms (Detailed)
Five major groups:
Algae
Bacteria
Fungi
Protozoa
Viruses
Algae
Aquatic green plants in puddles, streams, ponds, and oceans.
Algae are photosynthetic organisms that play a vital role in aquatic ecosystems.
May be single-celled, multi-celled, or colonial.
Their structural diversity allows them to occupy different niches in aquatic environments.
Plant-like organisms with chlorophyll, making them autotrophs (producing their own food).
Algae convert carbon dioxide and water into organic matter and oxygen through photosynthesis.
Some algae have pigments besides chlorophyll.
These pigments allow algae to absorb different wavelengths of light, maximizing their photosynthetic efficiency.
Types based on pigments:
Green algae (chlorophyll only).
Brown algae (brown pigment and chlorophyll).
Red algae (red and blue pigments with chlorophyll).
Green Algae (Structure-Based Classification)
Unicellular Algae:
Chlamydomonas: Uses flagella for movement; Chlorella: Cup-shaped chloroplast, used to study photosynthesis.
These algae are often used as model organisms in biological research.
Multicellular Algae:
Spirogyra and Ulothrix: Found floating on water; Spirogyra filaments are unbranched chains of cylindrical cells.
These algae form filamentous structures that can be easily observed under a microscope.
Characteristics of Algae
The algal body is called a thallus, undifferentiated into true roots, stems, or leaves.
The simple organization of algae reflects their evolutionary history.
Plant-like organisms containing chlorophyll and multicellular algae may form colonies (e.g., Volvox).
Colonial algae exhibit a division of labor among cells, with some cells specialized for specific functions.
Uses of Algae
Produce food for aquatic animals.
Algae are the primary producers in aquatic food webs, supporting a wide range of organisms.
Blue-green algae like Nostoc and Anabaena fix nitrogen, increasing soil fertility.
These algae are used as biofertilizers in agriculture, reducing the need for synthetic nitrogen fertilizers.
Kelps (sea weeds) are sources of iodine and potassium.
Kelps are harvested for their valuable minerals and used in various industries.
Bacteria
Microscopic unicellular organisms lacking a distinct nucleus, multiplying by fission.
Bacteria are prokaryotes, meaning they lack a membrane-bound nucleus and other organelles.
Shaped like spheres, rods, or spirals, inhabiting soil, water, organic matter, and animal bodies.
The diverse shapes of bacteria reflect their adaptation to different environments.
Utilize liquid food and synthesize vitamins.
Bacteria obtain nutrients from their surroundings and can synthesize essential vitamins for their own use and for their hosts.
Some perform photosynthesis with bacteriochlorophyll, different from plant chlorophyll.
Photosynthetic bacteria play a role in carbon cycling in various ecosystems.
Bacteria are not considered plants as their cell wall is not made of cellulose.
Shapes of Bacteria
Rod-shaped (Bacilli):
Example: Escherichia coli in human intestines.
E. coli is a common bacterium that can be both beneficial and harmful, depending on the strain.
Spherical-shaped (Cocci):
Example: Pneumococcus; may occur as single cells (cocci), pairs (diplococci), chains (streptococci), or clusters (staphylococci); cause bacterial pneumonia.
The arrangement of cocci cells provides clues to their identity and pathogenicity.
Spiral-shaped (Spirilla):
Enrich the soil.
Vibrios:
Comma-shaped bacteria.
Useful Actions of Bacteria
Promote curd and cheese formation via fermentation.
Bacteria ferment lactose and other sugars, producing lactic acid that coagulates milk proteins.
Produce vinegar and wines from fruit juices.
Bacteria convert ethanol to acetic acid in vinegar production.
Act as natural scavengers, rapidly decomposing organic waste.
Bacteria break down complex organic molecules into simpler compounds, recycling nutrients in the environment.
Aid in compost and manure formation.
Bacteria are essential for the decomposition of organic matter in compost and manure.
Digest cellulose in the intestines of ruminant animals (cows, sheep).
Bacteria enable ruminants to digest plant material that would otherwise be indigestible.
Rhizobium (in legume nodules) and Azotobacter (soil bacteria) convert atmospheric nitrogen into nitrates.
These bacteria play a crucial role in nitrogen fixation, enriching the soil with usable nitrogen compounds.
Used to make antibiotics like streptomycin and vitamin B complex tablets.
Activity to study effects of temperature of bacteria growth:
Take three cups and label them as A, B and C. Put cold milk, lukewarm milk and hot milk in the three cups respectively. Add a spoonful of curd in each cup and stir. After 4-5 hours note the nature of the contents in all the three cups. Record your observations separately and give interpretation for the result so obtained. Determine the conditions necessary for the setting of curd. Explain why the nature of the contents different in each case?
Harmful Actions of Bacteria
Cause plant diseases (citrus canker, potato scab, cotton leaf spot).
Plant diseases caused by bacteria can significantly reduce crop yields.
Cause human and animal diseases (cholera, diphtheria, plague, tetanus, typhoid, pneumonia, tuberculosis).
Bacterial infections can range from mild to life-threatening, depending on the pathogen and the host's immune response.
Responsible for food spoilage and rotting.
Bacteria produce enzymes that break down food, leading to spoilage and the production of undesirable flavors and odors.
Salmonella and Staphylococcus cause food poisoning.
Viruses
Minute microorganisms (ranges from micron) smaller than bacteria, visible only with an electron microscope.
Viruses are acellular entities that require a host cell to replicate.
Grow inside living cells of plants and animals.
Characteristics of Viruses
Simple structure: core of RNA or DNA surrounded by a protein coat (capsid).
The capsid protects the viral genome and facilitates entry into host cells.
Grow and multiply inside living cells.
Viruses hijack the host cell's machinery to replicate their genetic material and produce new viral particles.
Outside a living system, they are non-living and do not respire or reproduce.
Viruses are inert outside of host cells and cannot carry out metabolic processes on their own.
Antibiotics are ineffective against viruses.
Disease-Causing Viruses (Harmful Viruses)
Parasitic, causing diseases in hosts.
Viruses cause disease by disrupting normal cell function and triggering immune responses.
Cause human diseases (influenza, common cold, measles, mumps, chicken pox, rabies).
Viral infections can range from mild to life-threatening, depending on the virus and the host's immune response.
HIV (Human Immunodeficiency Virus) causes AIDS (Acquired Immuno Deficiency Syndrome), spread through sexual contact.
HIV attacks the immune system, leading to a weakened ability to fight off infections and cancers.
Tobacco Mosaic Virus (TMV) infects tobacco plants.
TMV causes characteristic mosaic patterns on tobacco leaves, reducing plant growth and yield.
FMDV (Foot and Mouth Disease Virus) causes foot and mouth disease in cattle.
FMDV is a highly contagious virus that affects livestock, causing significant economic losses.
Polio virus causes poliomyelitis (polio).
Activity to see the growth of microorgansims on moistened bread:
Keep a piece of moistened bread on a glass plate. Cover it with a bell jar. Keep it at a warm place. After few days, you would find greyish white cotton like substance growing on the bread. These are nothing but few type of microorganisms growing on the bread which might have landed on the bread from air.
Fungi
Non-green plants including molds, rusts, and puffballs.
Fungi are heterotrophic organisms that obtain nutrients from organic matter.
Heterotrophic due to lack of chlorophyll; can be parasitic or saprophytic.
Parasitic fungi obtain nutrients from living hosts, while saprophytic fungi obtain nutrients from dead organic matter.
Secrete enzymes to digest external organic matter.
Activity to see the growth of Yeast (Fungi)
Take 250 g flour (atta or maida), add some sugar and mix with warm water. Add a small amount of yeast powder and knead to make a soft dough. Yeast will reproduce rapidly and produce carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume Due to this fact, yeast is being used in the baking industry for making breads, pastries and cakes.
Common Examples of Fungi
Yeasts: Tiny, round, unicellular fungi living in colonies; can survive in aerobic and anaerobic conditions.
Yeasts reproduce by budding and are used in various industrial processes.
Mildews: Unicellular fungi, mostly parasites on plants (grapes, roses, wheat, barley).
Mildews cause powdery or downy coatings on plant surfaces, leading to reduced growth and yield.
Moulds: Multicellular fungi with branching threads (hyphae) forming mycelium; grow on stale bread, pickles, rotting fruits; aerobic.
Moulds produce spores that are easily dispersed, allowing them to colonize various substrates.
Mushrooms: Largest fungi, growing on decaying wood or grassy grounds.
Importance of Fungi
Yeast is used in making bread, cakes, idli and dosa, rich in Vitamin B.
Yeast ferments sugars, producing carbon dioxide that leavens dough and B vitamins that enhance nutritional value.
Used for commercial production of alcohol and wine.
Yeast converts sugars into ethanol during fermentation.
Some fungi (mushrooms) are directly consumed as food.
Mushrooms are a good source of protein, vitamins, and minerals.
Some medicines (Penicillin from Penicillium notatum) are derived from fungi.
Penicillin inhibits bacterial cell wall synthesis, making it an effective antibiotic.
Helpful in decomposing organic waste.
Harmful Effects of Fungi
Cause skin diseases.
Fungal skin infections can cause itching, redness, and scaling.
Cause plant diseases (loose smut of wheat, potato blight).
Plant diseases caused by fungi can lead to significant crop losses.
Spoil food and rot clothes, shoes, wooden material, books.
Activity to study the process of fermentation
Take a 500 mL beaker filled upto 3/4 with water. Dissolve 2-3 teaspoons of sugar in it. Add half a spoon of yeast powder to the sugar solution. Keep it covered in a warm place for 4-5 hours. Now, smell the solution. This is the smell of alcohol as sugar has been converted into alcohol by yeast. This process of conversion of sugar into alcohol is known as fermentation.
Louis Pasteur discovered fermentation in 1857
Protozoa
Most primitive and simplest animals; unicellular, found in stagnant and salt water, decaying leaves, soil.
Protozoa are eukaryotic microorganisms that exhibit animal-like characteristics.
Some (Giardia, Entamoeba) live as parasites inside the human body.
Parasitic protozoa obtain nutrients from their hosts, causing disease.
Common examples: Amoeba, Paramecium, Euglena, Giardia, Entamoeba, Trypanosoma.
Useful Effects of Protozoa
First step in the food chain after producers (green plants), acting as primary consumers.
Protozoa feed on bacteria, algae, and other microorganisms, transferring energy up the food chain.
Help in waste and sewage treatment by feeding on decomposers (fungi and bacteria).
Harmful Effects of Protozoa
Entamoeba causes amoebic dysentery.
Entamoeba histolytica infects the colon, causing diarrhea, abdominal pain, and fever.
Trypanosoma causes sleeping sickness.
Trypanosoma brucei is transmitted by tsetse flies and infects the blood and central nervous system, leading to fatigue, confusion, and coma.
Plasmodium causes malaria.
Plasmodium is transmitted by Anopheles mosquitoes and infects red blood cells, causing fever, chills, and anemia.
Giardia causes diarrhea.
Role of Microorganisms: Medicinal Uses
Some microorganisms are the source of medicines that kill or prevent the growth of other disease-causing microorganisms.
Many antibiotics are derived from bacteria and fungi.
These medicines are called antibiotics (anti = against, biotic = living).
Examples: chloramphenicol, erythromycin, tetracyclin, streptomycin, ciprofloxacin.
Vaccines & Antibodies
Vaccine: A preparation of modified viruses or bacteria that is introduced in a healthy body to induce the specific antibody reaction that produces immunity against a particular disease. In 1796, English physician Edward Jenner was the first to discover the vaccine for small pox.
Vaccines stimulate the immune system to produce antibodies and memory cells, providing long-lasting protection against specific pathogens.
Antibodies: Protein molecules produced in blood by immune system (lymphocytes) to fight antigens (disease-causing agents).
Antibodies bind to antigens on pathogens, neutralizing them and marking them for destruction by immune cells.
Vaccination prevents diseases like smallpox, measles, diphtheria, cholera, tuberculosis.
In Increasing Soil Fertility
Some bacteria and algae (blue-green algae) increase soil fertility.
These microorganisms convert atmospheric nitrogen into usable forms, enriching the soil with essential nutrients.
Known as Biological Nitrogen Fixers.
Rhizobium fixes nitrogen in root nodules of leguminous plants through a symbiotic relationship.
Rhizobium bacteria provide plants with fixed nitrogen, while plants provide bacteria with carbohydrates and a protected environment.
Free-living bacteria like Azotobacter and blue-green algae (Anabaena and Nostoc) fix nitrogen directly from the atmosphere.
Activity to study the role of Microorganisms in cleaning our environment:
Take two pots of different colours (Green and Red) and fill them upto half of their capacity with soil. Put plant waste in green pot and polythene bags, glass pieces, broken plastic articles and leather articles in red pot. Cover both the pots with soil and keep them in open for 4-6 weeks and observe afterwards.
Microorganisms decompose organic matter, thus, help clean the environment.
Harmful Effects of Microorganisms
Microorganisms can cause diseases in plants and animals.
Disease-causing microorganisms are called pathogens.
How Microorganisms spread
Microorganisms may enter the human body through air, water, or food.
Transmission routes vary depending on the pathogen and its mode of infection.
They can be transmitted through vectors (animal carriers) or by direct contact with an infected person.
Vectors transmit pathogens from one host to another, while direct contact involves physical contact with an infected individual.
Microbial diseases that spread from an infected person to a healthy person are called communicable diseases.
Examples: common cold, influenza (eye flu), chicken pox, cholera, tuberculosis.
Preventing Communicable Diseases
Complete isolation of the diseased person.
Isolation prevents the spread of pathogens to susceptible individuals.
Maintaining a safe distance from an infected person.
Covering the nose while sneezing.
Vectors (Carriers of Diseases)
Organisms (animal, fungus) that carry parasites and transmit them from one host to another are called vectors.
Vectors play a crucial role in the transmission of vector-borne diseases.
Insects (houseflies, ticks, mites) often act as vectors.
Insects transmit pathogens through bites, contaminated surfaces, or other means.
Female Anopheles mosquitoes transmit Plasmodium (malaria).
Aedes aegypti mosquitoes transmit the viral cause of dengue fever.
Preventing Diseases Spread by Vectors
Prevent mosquitoes from breeding by not allowing water to accumulate and keeping surroundings clean and dry.
Mosquito control measures are essential for preventing the spread of mosquito-borne diseases.
Diseases Caused by Microorganisms in Animals & Plants Several microorganisms not only cause diseases in humans and plants, but also in other animals. For example, anthrax is a dangerous human and cattle disease caused by a bacterium. Foot and mouth disease of cattle is caused by a virus.
Robert Koch discovered the bacterium that caused anthrax disease (Bacillus anthracis) in 1876.
Human Diseases Table 2.1 Some Common Human Diseases Caused by Microorganisms
Preventive Measures (General)
Isolation of the infected person.
Vaccination at a suitable age.
Maintaining personal hygiene.
Consuming properly cooked food.
Drinking boiled water.
Using mosquito nets or repellents.
Spraying insecticides.
Destroying breeding grounds of mosquitoes such as stagnant water.
Plant Diseases Table 2.2 Some of the Common Plant Diseases caused by Microorganisms
Microorganisms cause diseases in plants such as wheat, rice, lady finger, lemon, potato, sugarcane, orange, and apple.
Plant diseases can cause significant economic losses in agriculture.
These diseases reduce crop yield and can be controlled by fungicides.
Food Poisoning
Occurs when food is contaminated with harmful bacteria, toxins, or chemicals.
Food poisoning can cause a range of symptoms, from mild discomfort to severe illness.
Microorganisms that grow on food produce dangerous substances called toxins.
Toxins produced by bacteria, fungi, and other microorganisms can cause food poisoning.
Food can become contaminated in many ways, such as from bacteria in the air or water or from flies or other insects.
Proper food handling and hygiene practices are essential for preventing food contamination.
Chemicals that may cause food poisoning include copper, lead, zinc, and chemicals in certain herbicides and pesticides.
Chemical contamination of food can occur through various routes, such as industrial pollution or improper use of pesticides.
Symptoms may include vomiting, cramps, and diarrhea.
Common bacteria causing food poisoning include Salmonella and Staphylococcus.
Food Preservation
Preservation maintains food color, flavor, nutritive value, and texture over time.
Food preservation techniques aim to prevent spoilage and extend the shelf life of food products.
Involves treating food to prevent spoilage due to chemical changes or contamination by pathogens.
Methods of Food Preservation
(i) Salting: Meat and fish preserved using common salt to inhibit bacterial growth.
Salt reduces the water activity of food, inhibiting the growth of bacteria and other microorganisms.
(ii) Pickling: Acetic acid (vinegar), salt, and mustard oil stop mold and bacteria growth.
Acetic acid lowers the pH of food, inhibiting the growth of many microorganisms.
(iii) Refrigeration (below ): Slows, but does not stop, spoilage.
Refrigeration slows down the metabolic activity of microorganisms, delaying spoilage.
(iv) Deep freezing (): Stops most spoilage processes but not enzyme activity.
Freezing inhibits microbial growth and enzymatic reactions, preserving food for extended periods.
(v) Pasteurization: Heating milk to for 15 seconds, then rapidly chilling.
Pasteurization destroys harmful microorganisms while preserving the nutritional quality of milk.
(vi) Drying: Effective because microorganisms and enzymes need water to be active.
Drying reduces the water activity of food, inhibiting microbial growth and enzymatic reactions.
(vii) Canning: High temperatures destroy microorganisms and enzymes; food is sealed to prevent recontamination.
Canning involves heating food to sterilize it and then sealing it in airtight containers to prevent spoilage.
(viii) Irradiation: Exposure of food to low-level irradiation to kill microorganisms.
Irradiation kills bacteria, fungi, and insects, extending the shelf life of food.
(ix) Adding sugar: Preserves jams, jellies, and squashes by reducing moisture content.
Sugar increases the osmotic pressure of food, inhibiting microbial growth.
(x) Smoking: Method of drying that also imports flavour to the food.
Smoking also deposits preservatives on the food surface, further inhibiting spoilage.
(xi) Using chemical: Sodium benzoate and sodium metabisulphite are common chemical preservatives.
Conditions for the Growth of Microorganisms & Spreading of Diseases
Microorganisms grow fast under moist conditions and an optimum temperature range of to
*
Ways of Spreading of Disease
By direct contact with an infected person
Through sneezing, coughing, etc
By contact with infected soil
Through bite of an animal
Through contaminated food, water and air
Through carriers or vectors like housefly, mosquitoes, etc
Preventive Measures to avoid infection
Proper sanitation
Provision of safe drinking water
Proper disposal of waste (excreta)
Spray of insecticides, pesticides to prevent mosquito and pest breeding
Immunization
Personal and domestic hygiene
Health education
Use of resistant varieties of crops, use of crop rotation and multiple cropping system to prevent infections in plants
Nitrogen Cycle
Nitrogen is essential for living organisms.
Nitrogen is a key component of proteins, nucleic acids, and other essential biomolecules.
The atmosphere is 78% nitrogen gas.
The atmospheric nitrogen cannot be taken directly by plants and animals.
Fixing of Nitrogen: Nitrogen-fixing bacteria and algae convert atmospheric nitrogen into usable forms