1. What are the organisms that make up the microbial world?

- Microorganisms make up a large part of the planet's living material and play a major role in
maintaining the Earth's ecosystem. Microorganisms are divided into seven types: bacteria,
archaea, protozoa, algae, fungi, viruses, and multicellular animal parasites ( helminths ).
Each type has a characteristic cellular composition, morphology, mean of locomotion, and
reproduction.

Types of microorganisms: This tree of life shows the different types of microorganisms.

2. Research on the development and Evolution of Microbiology and Parasitology.

Illness and disease were thought to have a supernatural cause. Many people thought it was due
to the wrath of God or evil spirits. The possibility of illness and disease being linked to unseen
organisms was postulated, but not widely believed until the invention of the microscope and a
series of experiments in the 17th century.
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. He is reputed to have observed strands
of fungi among the specimens of cells he viewed. In the 1670s and the decades thereafter, a
Dutch merchant named Anton van Leeuwenhoek made careful observations of microscopic
organisms, which he called animalcules. 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.
After van Leeuwenhoek died, the study of microbiology did not develop rapidly because
microscopes were rare and the interest in microorganisms was not high. 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.
Pasteur's attempts to prove the germ theory were unsuccessful. However, 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.

3. Give the significance of Microbiology.

- Microbiology is the study of microscopic organisms, or living things, that are too small to be
visible to be seen with the naked eye. These living things can be seen with the use of a
 microscope only and they are referred to as microbes or microorganisms. Bacteria, viruses,
archaea, protozoa, microscopic yeasts and fungi, and microscopic algae are all examples of
microorganisms. Microbiology research encompasses all aspects of these microorganisms
such as their behavior, evolution, ecology, biochemistry, and physiology, along with the
pathology of diseases that they cause.

Microorganisms contribute to the world in myriads of ways. Apart from some that cause harm,
there are others who have immense importance in our ecosystem and health system. Some of these
benefits are explained below.

 Agriculture: Microbes help plants take required nutrients by breaking down complex
compounds into simpler forms. They also make the soil rich in nutrients and minerals (like
nitrates) that enhance crop yield. Microbes help plants fix nitrogen, and some of them are
used as bio fertilizers, thus contributing to a better and higher output.
 Biotechnology and genetic engineering: Microbial studies have allowed scientists to
understand their working mechanisms and engineer them in a way that helps in the
increased production of medicinal compounds. It is believed that the insertion of foreign
genes in some bacterial species might lead to creating a bacterial strain that can provide
solutions to myriads of challenges, including pollution, food and energy shortages, and the
treatment and control of the disease.
 Producing certain compounds: Bacteria are used in industries to make new products
from the provided raw materials. They can perform a metabolic reaction rapidly on a large
scale that meets the population’s demand for medicines, food materials, or other chemical
compounds, such as insulin and other growth hormones.
 Combating diseases: The study of microbes has unraveled their potential in treating
several deadly conditions. For example, several bacterial species are used to isolate
medicinal compounds, like antibiotics and develop vaccines.
 Keep the planet healthy: Microbes play an essential role in recycling minerals like
nitrogen and carbon for easy availability to other organisms, keeping the environment
oxygenated, and actively degrading organic matter.
 Food processing: The study of microbiology has enlightened us on the application of
microbes as an essential source of nutrients. For example, some algal and fungal species are
part of people’s meal, such as mushroom, Chlorella, Spirulina, and certain microbes are also
used in food processing, fermentation, baking, and producing livestock feed.