Microorganisms: Friend and Foe

Micro-organisms:

• Living organisms which are not visible through naked eyes are known as micro-organisms.
• These micro-organisms are present everywhere.
• Some micro-organisms like fungus on bread can be seen with the help of  a magnifying glass.
• Micro-organisms are classified into 4 major groups: Bacteria, Fungi, Protozoa and some algae.
• Micro-organisms can live in all types of environments.
• They can live in icy cold areas to hot places like desserts.
• They also live under human body and animals.
• Micro-organisms are both helpful and harmful to humans.
• Friendly Micro-organisms are used in the preparation of curd, bread , cake etc..
• They also help in the production of alcohols.
• They are used to make various medicines.
• They are also used in agriculture to increase soil fertility.
• The microbes which are capable of converting the atmospheric nitrogen into fixed nitrogen are called as nitrogen-fixers.
• Some of the biological nitrogen-fixers are Cyanobacteria, Azolla, Frankia etc..
• Harmful micro-organisms causes various types of diseases in human beings , animals and in plants.
• Disease causing micro-organisms are called Pathogens.
• Microbial diseases which can be spread through air, water, food or through physical contact are known as Communicable Diseases.
• Examples of communicable diseases are Cholera, Common Cold, Chicken Pox etc..
• Some insects and animals spread diseases by acting as Carriers of disease-causing microbes.
• Example of carriers are: Housefly, female Anopheles Mosquito( causes Malaria),  Female Aedes Mosquito (causes dengue).
• Some common Plant diseases caused by Micro-organisms are: Rust of wheat caused by fungi, Citrus Canker caused by Bacteria etc..
• Some common Animal diseases caused by Micro-organisms are: Anthrax in cattle caused by Bacteria, Foot and mouth disease of cattle caused by a virus.

Bacteria:

• Bacteria are prokaryotic unicellular organisms.
• They develop through Binary Fission.
• Prokaryotic organisms are those organisms which do not have a nucleus.
• Diseases caused by bacteria are Typhoid, Tuberculosis, cholera, Plague etc..

Fungi:

• Fungi are eukaryotic organisms.
• Eukaryotic organisms are those organisms which contain a nucleus.
• Fungi develop through Spore Formation.
• Diseases caused by Fungi are skin problems.

Protozoa:

• Protozoans are eukaryotic organisms,
• They are single- celled organisms.
• They can be free- living or parasitic.
• Protozoans develop asexually through binary fission or multiple fission.
• Disease caused by protozoans are Dysentery, Malaria, Leishmaniasis etc..

Algae:

• Algae are eukaryotic organisms.
• Algae is developed both  through sexual and asexual reproduction.
• Diseases caused by algae are Diarrhoea, skin problems etc..

Viruses:

• Virus replicates only inside the living cells of organisms.
• They contain both RNA and DNA.
• They do not get affected by antibiotics.
• Diseases caused by Viruses are Common Cold, Flu, Polio etc..

Making of Curd and Bread:

• Lactobacillus helps in the formation of Curd.
• Lactobacillus multiplies in milk and thus curd is formed.
• Yeast is used in the making of breads and cakes.
• Yeast produces Carbon dioxide during respiration.
• We can tell this by seeing the formation of bubbles where yeast is used.

Fermentation:

• The process in which sugar is converted into alcohol with the help of enzymes is called Fermentation.
• Fermentation process was discovered by Louis Pasteur.

Vaccine:

• Vaccine stimulates the production of antibodies in our body.
• It provides immunity against various diseases.
• Antibodies helps us to fight the disease carrying microbe in our body.
• Antibodies also remember the disease if it comes again.
• This memory of antibodies helps us to get cured from a particular disease forever.
• For example: when we were kids, we have been vaccinated against polio and now we are cured from that disease forever.
• Some diseases which can be prevented from vaccination are Cholera, tuberculosis, small pox etc..

Food Preservation:

• We need to preserve our food from micro-organisms as it spoils our food making it poisonous and unhealthy to eat.
•  Salt and edible oils are the common preservatives used to check micro-organisms.
• Sodium benzoate and sodium meta bisulphite  are common preservatives.
• Common salt is used to preserve meat and fish.
• Jam and Jellies are prevented by sugar.
• Oil and vinegar prevents the spoilage of pickles.
• Keeping the food at low temperature prevents the growth of micro-organisms.
• Storing in air-tight packets prevent the entry of micro-organisms.

Nitrogen Cycle:

•  78% of nitrogen is present in our atmosphere.
• This atmospheric nitrogen cannot be taken directly by plants and animals.
• The atmospheric nitrogen is converted into fixed nitrogen with the help of certain bacteria and blue-green algae.
• This converted nitrogen is used for the synthesis of plant proteins and other compounds.
• After the death of plants and animals, their nitrogenous waste is converted into nitrogenous compounds by bacteria and fungi.
• These nitrogenous compounds can be used by the plants again.
• Some part is also converted into nitrogen gas which goes into the atmosphere.
• And thus the concentration of nitrogen in the atmosphere remains constant.