Microorganisms
Friend or foe
Topics we will cover
• What are microorganisms
• Where do microorganisms live ?
• Use of microorganisms
• Friendly and Harmful microorganisms
• Disease causing microorganisms
• Food poisoning
• Food preservation
• Nitrogen fixation
What are microorganisms ?
• A microorganism or microbe is
a microscopic organism, which may be singlecelled or multicellular. The study of microorganisms
is called microbiology, a subject that began with the
discovery of microorganisms in 1674 by Antonie van
Leeuwenhoek, using a microscope of his own design.
Microorganisms are very diverse and include
all bacteria, archaea and most protozoa.
• This group also contains some fungi, algae,
and some micro-animals such as rotifers.
Many macroscopic animals and plants have
microscopic juvenile stages. Some
microbiologists classify viruses and viroids as
microorganisms, but others consider these as
nonliving.
Where do microorganisms live ?
• Microorganisms live in every part of the biosphere,
including soil , hot springs, inside rocks at least 19 km
(12 mi) deep underground, the deepest parts of
the ocean, and at least 64 km (40 mi) high in
the atmosphere . Microorganisms, under certain test
conditions, have been observed to thrive in the vacuum
of outer space .Microorganisms likely far outweigh all
other living things combined. The mass
of prokaryote microorganisms including the bacteria and
archaea may be as much as 0.8 trillion tons of carbon, out
of the total biomass of between 1 and 4 trillion tons.
Uses of microorganisms
Commercial use of
microorganisms
Microorganisms are used in brewing, wine making,
baking, pickling and other food-making processes.
They are also used to control the fermentation
process in the production of cultured dairy products
such as yogurt and cheese. The cultures also provide
flavor and aroma, and inhibit undesirable organisms.
Fermentation
• Fermentation is a metabolic process that converts sugar to
acids, gases, or alcohol. It occurs in yeast and bacteria, and
also in oxygen-starved muscle cells, as in the case of lactic
acid fermentation . Fermentation is also used more broadly
to refer to the bulk growth of microorganisms on a growth
medium, often with the goal of producing a specific
chemical product. French microbiologist Louis Pasteur is
often remembered for his insights into fermentation and its
microbial causes. The science of fermentation is known
as zymology.
Medical use of microorganisms
• Antibiotics, also known as antibacterials,
are medications that destroy or slow down
the growth of bacteria. They include a
range of powerful drugs and are used to
treat diseases caused by bacteria. Infections
caused by viruses, such as colds, flu, most
coughs, and sore throats cannot be treated
with Antibiotics.
Vaccine
• A vaccine typically contains an agent that resembles a
disease-causing microorganism and is often made from
weakened or killed forms of the microbe, its toxins or one
of its surface proteins. The agent stimulates the
body's immune system to recognize the agent as a threat,
destroy it, and keep a record of it so that the immune
system can more easily recognize and destroy any of
these microorganisms that it later encounters. Edward
Jenner discovered the vaccine for small pox in 1798.
Friendly Microorganisms
• Friendly microorganisms help in breaking down organic waste and thus
replenishing the soil with nutrients. This phenomenon is used in making
compost and is a great way to manage organic waste. It prevents
garbage containing organic waste from rotting, emanating a foul smell
and spreading diseases. The enriched soil containing nutrients after
breakdown of organic waste due to the friendly microorganisms include
inorganic nutrients like nitrogen, phosphorus and potassium as well as
fiber. Find out how to make compost and take the help of friendly
microorganisms to do gardening and to reduce the organic waste and
enrich the soil in your neighborhood.
Harmful and disease causing microorganisms
• Except for congenital diseases, all other diseases are caused by certain
microorganisms. Such microbes are called pathogens. They may affect or
damage the whole body system or some specific tissues or organs. Some
human diseases caused by pathogens are cholera, rabies, mumps, malaria etc.
Plants and animals are also victims of these microbial effects.
• Some microorganisms need vectors or agents for their transmission. Malaria is
an example for the harmful microorganism. Here, Anopheles mosquitoes are
agents used by the protozoan Plasmodium vivax to transmit their spores.
Whereas some directly enter the body through contaminated food, water or air.
Most of the pathogenic diseases are communicable and infectious. Once
pathogens enter the host body, they utilize the host nutrients; also invade the
immune system of the host.
Food poisoning
• Food poisoning (also known as foodborne illness or
foodborne disease) is any illness that results from eating
contaminated food. Food poisoning is a common, usually
mild, but sometimes deadly illness. Typical symptoms include
nausea, vomiting, abdominal cramping, and diarrhea, fever
and chills, bloody stools, dehydration may follow. Serious
long-term effects like Kidney failure, chronic arthritis, brain
damage and nerve system damage lead to death.
Food preservation
• Food preservation is to prevent the growth of bacteria, fungi (such
as yeasts), or other micro-organisms (although some methods work by
introducing benign bacteria or fungi to the food), as well as slowing
the oxidation of fats that cause rancidity. Food preservation may also include
processes that inhibit visual deterioration, such as the enzymatic browning
reaction in apples after they are cut during food preparation.
• Many processes designed to preserve food involve more than one food
preservation method. Preserving fruit by turning it into jam, for example,
involves boiling (to reduce the fruit’s moisture content and to kill bacteria,
etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar
(to prevent recontamination). Some traditional methods of preserving food
have been shown to have a lower energy input and carbon footprint , when
compared to modern methods.
Methods of preservation
• Cooling preserves food by slowing down the growth and reproduction of
microorganisms and the action of enzymes that causes the food to rot. The
introduction of commercial and domestic refrigerators drastically
improved the diets of many in the Western world by allowing foods such
as fresh fruit, salads and dairy products to be stored safely for longer
periods, particularly during warm weather.
• Before the era of mechanical refrigeration, cooling for food storage
occurred in the forms of root cellars and iceboxes. Rural people often did
their own ice cutting, whereas town and city dwellers often relied on
the ice trade. Today, root cellaring remains popular among people who
value various goals, including local food, heirloom crops, traditional
home cooking techniques, family farming, frugality, selfsufficiency, organic farming, and others.
• Boiling - Boiling liquid food items can kill any existing microbes. Milk and
water are often boiled to kill any harmful microbes that may be present in
them.
• Heating - Heating to temperatures which are sufficient to kill
microorganisms inside the food is a method used with perpetual stews.
Milk is also boiled before storing to kill many microorganisms.
• Salting- Salting or curing draws moisture from a substance by osmosis.
Substances are cured with salt, sugar or a combination of the two.
Nitrates and nitrites are also often used to cure meat and contribute the
characteristic pink colour. It was a main method of preservation in
medieval times and around the 1700s etc.
Nitrogen Fixation
• Nitrogen fixation is a process by which nitrogen in the Earth's
atmosphere is converted into ammonia (NH3) or other molecules available
to living organisms. Atmospheric nitrogen or molecular dinitrogen (N2) is
relatively inert: it does not easily react with other chemicals to form new
compounds. The fixation process frees nitrogen atoms from their triply
bonded diatomic form, N≡N, to be used in other ways.
• Nitrogen fixation, natural and synthetic, is essential for all forms of life
because nitrogen is required to biosynthesize basic building blocks of
plants, animals and other life forms, e.g., nucleotides for DNA and RNA, the
coenzyme nicotinamide adenine dinucleotide for its role in metabolism
(transferring electrons between molecules), and amino acids for proteins.
Thank
you
Made By – Anant singhal
Class- VIII B
School- Delhi Public School
Ghaziabad International