Unit 17: Microbiology and Microbiological
Technique
CLASSIFICATION OF MICROORGANISMS
In the nature scientists make the special classification system to simplify the differentiation of different living
organisms. As there are a lot of different types of microorganisms, some of them are eukaryotes and some are
prokaryotes. Microorganisms are microscopic organisms that the human eye cannot see that include bacteria, fungi,
protists, and viruses.
All living organisms on Earth are classified by three main domains: Archaea, Bacteria and Eukarya (eukaryotes).
Within last domain Eukarya we can find different
kingdoms: protists (Protista), fungi (Fungi), plants (Plantae) and animals (Animalia).
Those three main groups then can be divided into another group like kingdom, where there are sub-groups called
phyla. Phyla have sub-group called classes, then orders, families, genera, and species.
As shown belove in table with different classification of some organisms.
BACTERIA (PROKARYOTES)
,Bacteria are microscopic and their range in size is from 0.2 x 0.5 micrometres to 0.3 x 2.0 micrometres, or 1–10
micrometres long and 0.2–2 micrometres in diameter.
Bacteria have characteristic shapes, such as: cocci, rods,
spirals, etc. They often occur in characteristic
aggregates like pairs, chains, tetrads, clusters, etc. These
traits are usually typical for a genus and are
diagnostically useful. (Wikipedia Contributors)
Bacteria has several different organelles, they are
1. Pili - hair-like structures that help bacteria attach
to surfaces and to other bacteria.
https://www.vectorstock.com/royalty-free-
2. Plasmid - a small, circular, double-stranded vector/types-of-bacteria-vector-1654506
molecule of DNA. Plasmids contain genes that help
when the bacteria are in danger, such as when it is exposed to an antibiotic.
3. Ribosomes - little round structures that produce proteins. They are found floating in the cytoplasm.
4. Cytoplasm - a thick, water-based (aqueous) solution.
Ribosomes and nuclear materials are found in the
cytoplasm. Salts, nutrients, minerals, and enzymes are also
found in the cytoplasm.
5. Cytoplasmic Membrane - the first thin layer of
phospholipids and proteins. It controls the
movement of nutrients in and out of the cell.
6. Cell Wall - a second rigid layer that gives the bacteria
its structure. It also protects the cytoplasmic
membrane. https://slidetodoc.com/all-have-cell-
membrane-dna-cytoplasm-ribosomes-
7. Capsule - a third layer that helps keep the bacteria from drying out. It can also help protect the bacteria. It is
kingdom/
only present in some types of bacteria.
8. Nucleoid - is made of DNA, RNA, and proteins. The nucleoid controls the activity of the cell. The nucleoid is
found within the cytoplasm.
9. Flagellum - a structure that helps the bacteria move around and sense their environment.
Bacteria is a motile cell as it can move around; they do it to escape unfavourable conditions and find better ones and
find new resources. Motility is achieved through variety of mechanisms, such as:
• Flagellum
• Capsule shape
(Let's Talk Science)
Bacteria reproduce asexually through the binary fission, process similar to
mitosis. A process where a single cell divides into two identical daughter cells:
1. The cell grows to double its size
2. The cell's chromosomes replicate
3. The copied DNA separates to opposite sides of the cell
4. The cell's cytoplasm splits
5. The cell divides into two new cells
Bacteria are pathogenic. Bacteria are microscopic, one-celled organisms that
can be harmful or helpful. Some bacteria that live in the body, like those in the intestines, can help digest food,
, destroy disease-causing organisms, and provide nutrients. However, other bacteria can cause illness by reproducing
quickly in the body and releasing chemicals called toxins that damage cells and tissues. The examples of the harmful
bacteria are: Streptococcus, Staphylococcus, E. coli, and Mycobacterium tuberculosis.
Bacteria has many uses in industries, food and drinks production. They are used to:
• Decomposers: Bacteria break down dead organisms, animal waste, and plant litter into simpler substances
that provide nutrients for new plants and animals.
• Food digestion: Bacteria in the large intestine help break down food into compounds that the body can
absorb and use for growth.
• Neutralizing toxins: Bacteria in the body can help neutralize toxins.
• Making products: Bacteria can be used to create products like ethanol and enzymes.
• Making drugs: Some bacteria produce antibiotics, vaccines, and other drugs.
• Making biogas: Methanogens are anaerobic bacteria that grow by producing methane gas.
• Cleaning up: Bacteria can be used to clean up oil spills and toxic wastes.
• Fermenting foods: Bacteria are used to ferment foods like milk into curd.
• Biological nitrogen fixation: Some bacteria can convert atmospheric nitrogen into ammonia through a
process called biological nitrogen fixation.
Bacteria don’t do not have high requirements for the environment that they live. Therefore, they can be found
everywhere that include water, soil, air, and on or in living organisms.
Bacteria require oxygen to grow because their methods of energy production and respiration depend on the transfer
of electrons to oxygen, which is the final electron acceptor in the electron transport reaction. Also, for growth and
nutrition of bacteria, the minimum nutritional requirements are water, a source of carbon, a source of nitrogen and
some inorganic salts, where water is the vehicle of entry of all nutrients into the cell and for the elimination of waste
products. (Baniya)
FUNGI, INCLUDING YEASTS (EUKARYOTES)
Fungi are eukaryotic organisms. In general, most microscopic or smaller fungi are 2 to 10 micrometers (MGRm) in
diameter and several tenths of an inch in length. The average size of fungi hyphae is 5 to 50 micrometers (MGRm) in
length. Some fungi are unicellular such as yeasts, and some are multicellular such as mushrooms. Fungi are abundant
around the world together with bacteria, are the main decomposers; they feed on and break down dead matter in
ecosystems, helping recycle the nutrients. Fungi are heterotrophically (to grow they use organic carbon); they secrete
acids and enzymes into an environment to later digest it and they absorb through their surface. Mould fungi can spoil
foods. Whereas some fungi are parasites and infect other organisms, they are described as pathogenic. From the
fungi infect humans, some of them cause:
• Candidiasis (thrust)
• Ring worm and Athlete’s foot (Tinea spp.)
• Farmers’ lungs (aspergillosis)
• Opportunistic infections, such as a type of pneumonia
in immunosuppressed people.
Other types of fungi cause disease in livestock, fish and crop
plants.
However, fungi are also of great economic importance, as sources of:
Technique
CLASSIFICATION OF MICROORGANISMS
In the nature scientists make the special classification system to simplify the differentiation of different living
organisms. As there are a lot of different types of microorganisms, some of them are eukaryotes and some are
prokaryotes. Microorganisms are microscopic organisms that the human eye cannot see that include bacteria, fungi,
protists, and viruses.
All living organisms on Earth are classified by three main domains: Archaea, Bacteria and Eukarya (eukaryotes).
Within last domain Eukarya we can find different
kingdoms: protists (Protista), fungi (Fungi), plants (Plantae) and animals (Animalia).
Those three main groups then can be divided into another group like kingdom, where there are sub-groups called
phyla. Phyla have sub-group called classes, then orders, families, genera, and species.
As shown belove in table with different classification of some organisms.
BACTERIA (PROKARYOTES)
,Bacteria are microscopic and their range in size is from 0.2 x 0.5 micrometres to 0.3 x 2.0 micrometres, or 1–10
micrometres long and 0.2–2 micrometres in diameter.
Bacteria have characteristic shapes, such as: cocci, rods,
spirals, etc. They often occur in characteristic
aggregates like pairs, chains, tetrads, clusters, etc. These
traits are usually typical for a genus and are
diagnostically useful. (Wikipedia Contributors)
Bacteria has several different organelles, they are
1. Pili - hair-like structures that help bacteria attach
to surfaces and to other bacteria.
https://www.vectorstock.com/royalty-free-
2. Plasmid - a small, circular, double-stranded vector/types-of-bacteria-vector-1654506
molecule of DNA. Plasmids contain genes that help
when the bacteria are in danger, such as when it is exposed to an antibiotic.
3. Ribosomes - little round structures that produce proteins. They are found floating in the cytoplasm.
4. Cytoplasm - a thick, water-based (aqueous) solution.
Ribosomes and nuclear materials are found in the
cytoplasm. Salts, nutrients, minerals, and enzymes are also
found in the cytoplasm.
5. Cytoplasmic Membrane - the first thin layer of
phospholipids and proteins. It controls the
movement of nutrients in and out of the cell.
6. Cell Wall - a second rigid layer that gives the bacteria
its structure. It also protects the cytoplasmic
membrane. https://slidetodoc.com/all-have-cell-
membrane-dna-cytoplasm-ribosomes-
7. Capsule - a third layer that helps keep the bacteria from drying out. It can also help protect the bacteria. It is
kingdom/
only present in some types of bacteria.
8. Nucleoid - is made of DNA, RNA, and proteins. The nucleoid controls the activity of the cell. The nucleoid is
found within the cytoplasm.
9. Flagellum - a structure that helps the bacteria move around and sense their environment.
Bacteria is a motile cell as it can move around; they do it to escape unfavourable conditions and find better ones and
find new resources. Motility is achieved through variety of mechanisms, such as:
• Flagellum
• Capsule shape
(Let's Talk Science)
Bacteria reproduce asexually through the binary fission, process similar to
mitosis. A process where a single cell divides into two identical daughter cells:
1. The cell grows to double its size
2. The cell's chromosomes replicate
3. The copied DNA separates to opposite sides of the cell
4. The cell's cytoplasm splits
5. The cell divides into two new cells
Bacteria are pathogenic. Bacteria are microscopic, one-celled organisms that
can be harmful or helpful. Some bacteria that live in the body, like those in the intestines, can help digest food,
, destroy disease-causing organisms, and provide nutrients. However, other bacteria can cause illness by reproducing
quickly in the body and releasing chemicals called toxins that damage cells and tissues. The examples of the harmful
bacteria are: Streptococcus, Staphylococcus, E. coli, and Mycobacterium tuberculosis.
Bacteria has many uses in industries, food and drinks production. They are used to:
• Decomposers: Bacteria break down dead organisms, animal waste, and plant litter into simpler substances
that provide nutrients for new plants and animals.
• Food digestion: Bacteria in the large intestine help break down food into compounds that the body can
absorb and use for growth.
• Neutralizing toxins: Bacteria in the body can help neutralize toxins.
• Making products: Bacteria can be used to create products like ethanol and enzymes.
• Making drugs: Some bacteria produce antibiotics, vaccines, and other drugs.
• Making biogas: Methanogens are anaerobic bacteria that grow by producing methane gas.
• Cleaning up: Bacteria can be used to clean up oil spills and toxic wastes.
• Fermenting foods: Bacteria are used to ferment foods like milk into curd.
• Biological nitrogen fixation: Some bacteria can convert atmospheric nitrogen into ammonia through a
process called biological nitrogen fixation.
Bacteria don’t do not have high requirements for the environment that they live. Therefore, they can be found
everywhere that include water, soil, air, and on or in living organisms.
Bacteria require oxygen to grow because their methods of energy production and respiration depend on the transfer
of electrons to oxygen, which is the final electron acceptor in the electron transport reaction. Also, for growth and
nutrition of bacteria, the minimum nutritional requirements are water, a source of carbon, a source of nitrogen and
some inorganic salts, where water is the vehicle of entry of all nutrients into the cell and for the elimination of waste
products. (Baniya)
FUNGI, INCLUDING YEASTS (EUKARYOTES)
Fungi are eukaryotic organisms. In general, most microscopic or smaller fungi are 2 to 10 micrometers (MGRm) in
diameter and several tenths of an inch in length. The average size of fungi hyphae is 5 to 50 micrometers (MGRm) in
length. Some fungi are unicellular such as yeasts, and some are multicellular such as mushrooms. Fungi are abundant
around the world together with bacteria, are the main decomposers; they feed on and break down dead matter in
ecosystems, helping recycle the nutrients. Fungi are heterotrophically (to grow they use organic carbon); they secrete
acids and enzymes into an environment to later digest it and they absorb through their surface. Mould fungi can spoil
foods. Whereas some fungi are parasites and infect other organisms, they are described as pathogenic. From the
fungi infect humans, some of them cause:
• Candidiasis (thrust)
• Ring worm and Athlete’s foot (Tinea spp.)
• Farmers’ lungs (aspergillosis)
• Opportunistic infections, such as a type of pneumonia
in immunosuppressed people.
Other types of fungi cause disease in livestock, fish and crop
plants.
However, fungi are also of great economic importance, as sources of:
