MicroorganismsBy:-Piyush Mohite

What are Microorganisms?¤A microorganism is a

microscopic organism that comprises either a single cell, or multicellular organisms.

¤The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek’s discovery of microorganisms in 1675, using a microscope of his own design.

Types of Microorganisms

BacteriaFungiProtozoaAlgaeVirus

VirusesViruses are too small to be seen with the naked eye. They can’t multiply on their own, so they have to invade a ‘host’ cell and take over its machinery in order to be able to make more virus particles.Viruses consist of genetic materials (DNA or RNA) surrounded by a protective coat of protein. They are capable of latching onto cells and getting inside them.The cells of the mucous membrane, such as those lining the respiratory passage that we breathe through, are particularly open to virus attacks because they are not covered by protective skin.

FungiFungi are like plants that are not ‘green'; they do not have the photosynthetic material chlorophyll. They have no roots, stems or leaves but grow as masses of protoplasm in dead and living organic matter. There are about 1,00,000 different fungi. Some like the yeasts are single cells but most fungi grow as branching tubes of protoplasm called hyphae. Fungi also contain chitin which is also found in animal cells. A single organism is called fungus.

BacteriaBacteria are organisms made up of just one cell. They are capable of multiplying themselves, as they have the power to divide. Their shapes may vary, and doctors use these characters to separate them into groups.Bacteria are omnipresent. Most are harmless, even useful.But some cause diseases, either because they end up in wrong place or simply because they are ‘designed’ to invade us.

ProtozoaProtozoa are small (but not simple) organisms.They are single-celled heterotrophic eukaryotes, which eat bacteria and other food sources.There are about 30,000 protozoan species.They are found only in moist or aquatic habitats. Many protozoan species are symbionts, some are parasites, and some are predators of soil bacteria and algae.

AlgaeAlgae are a type of living thing that usually live in really wet environments, like the oceans. They are a little bit like plants.They too, carry out photosynthesis, just like the plants do!The difference between algae and plants, is that plants have a lot of more distinct parts, like roots, stem and leaves.

Useful microorganisms Bacteria live on and in our bodies and keep us alive!

Helpful Fungus Mould is a type of fungus. A mould called penicillin is an antibiotic (medicine) we

take to kill bad bacteria.

Yeast is another type of fungus. We use yeast when

baking bread (releases CO2) and to make wine (creates ethanol).

Helpful Bacteria

Bacteria are used to make cheese and yogurt!

Different types of bacteria cause different tastes!

Harmful microorganisms

o Some microorganisms cause diseases in plants and animals. Such disease causing microorganisms are called pathogens.

o Some microorganisms grow in food substances and produce toxic substances and makes the food poisonous. Food poisoning causes illness and even death.

o Some microorganisms spoil materials like clothing, leather, wood etc.

Disease causing microorganisms in Humans o Disease causing microorganisms enter our body through

air, water, food, contact or insects. These microorganisms are called pathogens.

o Diseases which can spread from an infected person to a healthy person are called communicable diseases.

o Eg :- cholera, common cold, chicken pox, tuberculosis etc.o Some insects and animals act as carriers of disease

causing microbes.o Eg :- House fly, Female anopheles mosquito (malaria),

Female aedes mosquito (dengue fever) etc.

Disease causing microorganisms in plantsMicroorganisms cause diseases in plants like rice, wheat, potato, sugarcane, apple, orange etc. These diseases reduce crop yield. They can be controlled by using chemicals which kill the microbes.

Some common human diseases caused by microorganisms

Human disease Causative Mode of

microorganism transmission Chicken pox Virus Air / Contact Polio Virus Air / Water Measles Virus Air Hepatitis – B Virus Water Tuberculosis Bacteria Air Typhoid Bacteria Water Cholera Bacteria Water / Food Malaria Protozoa Mosquito

Some common plant diseases caused by microorganisms

Plant disease Causative Mode of microorganism transmission Citrus canker Bacteria Air Rust of wheat Fungi Air / Seed Yellow mosaic of Okra (Lady’s finger) Virus Water

Food preservation Food is spoilt by microorganisms. Spoilt food has bad smell and bad taste and causes food poisoning. Food can be preserved by protecting it from microorganisms. Food can be preserved by different methods. They are :- Chemical method :- Food like pickles can be preserved by using chemicals

like salts and edible oils. Jams and squashes can be preserved by using sodium benzoate, sodium metabisulphite. These chemicals are called preservatives.

By using common salt :- Food items like fish, meat, amla, raw mangoes, tamarind etc. can be preserved by using common salt. It prevents the growth of microbes.

By using sugar :- Food items like jams, jellies, squashes etc. can be preserved by using sugar solution. It prevents the growth of microbes.

By using oil and vinegar :- Food items like pickles, vegetables, fish, meat etc. are preserved by using oil and vinegar. It prevents the growth of microbes.

By heat and cold treatments :- Heating food items kills microbes. Similarly storing food items at low temperatures prevents growth of microbes.

Pasteurization :- The process of heating milk to about 70oC for 15 to 30 seconds and then suddenly chilling it to prevent the growth of microbes is called pasteurization. This process was discovered by Louis Pasteur.

By storage and packing :- Many food items are stored in air tight containers to protect them from microbes.

Nitrogen cycle The nitrogen in the atmosphere is converted into nitrogen compounds in the soil by nitrogen fixing bacteria and blue green algae. Lightning also converted into nitrogen compounds in the soil. The nitrogen compounds in the soil is used by plants for the synthesis of proteins and other compounds. Animals feeding on plants get these proteins and other compounds. When plants and animals die, bacteria and fungi in the soil converts the nitrogenous waste into nitrogen compounds in the soil which are again use by plants. Some other bacteria converts some nitrogen compounds in the soil into nitrogen gas which goes back into the atmosphere. Hence the nitrogen in the atmosphere almost remains constant.

Nitrogen cycle ATMOSPHERIC NITROGEN

LIGHTNING FIXES NITROGEN

NITROGEN FIXING BACTERIA AND BLUE GREEN ALGAE

FIX ATMOSPHERIC NITROGEN

COMPOUNDS OF NITROGEN IN THE SOIL

UPTAKE BY PLANTS

ANIMAL EATS PLANTS

BACTERIA TURN COMPOUNDS OF NITROGEN INTO

GASEOUS NITROGEN

NITROGENOUS WASTE FROM

EXCRETION AND DEATH

Thank You

Piyush Mohite