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microbiology and staining 100% VERIFIED NOTES WITH BRIEF EXPLANATIONS AND (UNDERSTANDING)
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100% VERIFIED NOTES WITH BRIEF EXPLANATIONS AND (UNDERSTANDING) microbiology and staining
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MICROBIOLOGY
100% VERIFIED NOTES WITH BRIEF EXPLANATIONS AND
(UNDERSTANDING)
A Brief History of Microbiology
Microbiology has had a long, rich history, initially centered in the causes of
infectious diseases but now including practical applications of the science.
Many individuals have made significant contributions to the development of
microbiology.
Early history of microbiology. Historians are unsure who made
the first observations of microorganisms, but the microscope was
available during the mid‐1600s, and an English scientist named
Robert Hooke made key observations.
Until his death in 1723, van Leeuwenhoek revealed the microscopic world
to scientists of the day and is regarded as one of the first to provide
accurate descriptions of protozoa, fungi, and bacteria.
In those years, scientists debated the theory of spontaneous
generation, which stated that microorganisms arise from lifeless
matter such as beef broth.
This theory was disputed by Francesco Redi, who showed that fly
maggots do not arise from decaying meat (as others believed) if the
meat is covered to prevent the entry of flies.
An English cleric named John Needham advanced spontaneous
generation, but Lazzaro Spallanzani disputed the theory by showing
that boiled broth would not give rise to microscopic forms of life.
Louis Pasteur and the germ theory. Louis Pasteur worked in the
middle and late 1800s. He performed numerous experiments to discover
why wine and dairy products became sour, and he found that bacteria
were to blame.
Pasteur called attention to the importance of microorganisms in
everyday life and stirred scientists to think that if bacteria could make
the wine “sick,” then perhaps they could cause human illness.
Pasteur had to disprove spontaneous generation to sustain his theory,
and he therefore devised a series of swan‐necked flasks filled with
,broth.
,He left the flasks of broth open to the air, but the flasks had a curve
in the neck so that microorganisms would fall into the neck, not the
broth.
Pasteur postulated the germ theory of disease, which states that
microorganisms are the causes of infectious disease.
the German scientist Robert Koch provided the proof by cultivating
anthrax bacteria apart from any other type of organism.
He then injected pure cultures of the bacilli into mice and showed that
the bacilli invariably caused anthrax.
The procedures used by Koch came to be known as Koch's postulates
(Figure). They provided a set of principles whereby other microorganisms
could be related to other diseases.
The development of microbiology. In the late 1800s and for the first
decade of the 1900s, scientists seized the opportunity to further develop the
germ theory of disease as enunciated by Pasteur and proved by Koch. There
emerged a Golden Age of Microbiology during which many agents of
different infectious diseases were identified.
Many of the etiologic agents of microbial disease were discovered during
that period, leading to the ability to halt epidemics by interrupting the
spread of microorganisms.
Despite the advances in microbiology, it was rarely possible to render life‐
saving therapy to an infected patient. Then, after World War II, the
antibiotics were introduced to medicine. The incidence of pneumonia,
tuberculosis, meningitis, syphilis, and many other diseases declined with
the use of antibiotics.
Work with viruses could not be effectively performed until instruments
were developed to help scientists see these disease agents. In the 1940s,
the electron microscope was developed and perfected.
In that decade, cultivation methods for viruses were also introduced,
and the knowledge of viruses developed rapidly.
With the development of vaccines in the 1950s and 1960s, such viral
diseases as polio, measles, mumps, and rubella came under control.
Modern microbiology. Modern microbiology reaches into many fields of
human endeavor, including the development of pharmaceutical products,
the use of quality‐control methods in food and dairy product production, the
control of disease‐causing microorganisms in consumable waters, and the
industrial applications of microorganisms.
, Microorganisms are used to produce vitamins, amino acids, enzymes, and
growth supplements. They manufacture many foods, including fermented
dairy products (sour cream, yogurt, and buttermilk), as well as other
fermented foods such as pickles, sauerkraut, breads, and alcoholic
beverages.
One of the major areas of applied microbiology is biotechnology. In this
discipline, microorganisms are used as living factories to produce
pharmaceuticals that otherwise could not be manufactured. These
substances include the human hormone insulin, the antiviral substance
interferon, numerous blood‐clotting factors and clot dissolving enzymes,
and a number of vaccines. Bacteria can be reengineered to increase plant
resistance to insects and frost, and biotechnology will represent a major
application of microorganisms in the next century.
USES OF MICRO-ORGANISMS
1. Bioremediation: Certain microorganisms are used to clean up
environmental pollution by breaking down organic pollutants, such as
oil spills or industrial waste. This process, known as bioremediation,
helps to detoxify polluted environments.
2. Fermentation: Microorganisms are used in fermentation processes
to produce various foods and beverages, including yogurt, cheese,
bread, beer, wine, and pickles. They break down sugars and other
organic compounds to produce alcohol, acids, and gases, which
contribute to flavor and preservation.
3. Medicine: Microorganisms are used in the production of antibiotics,
vaccines, and other pharmaceuticals. Antibiotics are derived from
microorganisms or synthesized based on compounds produced by
them, and they are used to treat bacterial infections. Vaccines are
also developed using weakened or killed microorganisms to stimulate
the immune system's response.
4. Agriculture: Microorganisms play crucial roles in soil fertility and
plant health. Certain bacteria, like Rhizobium, form symbiotic
relationships with leguminous plants, fixing atmospheric nitrogen into
a form that plants can use. Other microorganisms help decompose
organic matter, releasing nutrients for plants. Additionally, some
fungi form mycorrhizal associations with plant roots, aiding in
nutrient uptake.
5. Biotechnology: Microorganisms are used in biotechnological
processes to produce enzymes, proteins, and biofuels. Enzymes
produced by microorganisms are used in various industries,
including food processing, textile manufacturing, and detergent
production. Microorganisms can also be genetically engineered to
produce specific compounds or proteins for medical or industrial
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