This document provides an overview of the history of microbiology. It discusses how microbiology is the study of microorganisms that are invisible to the naked eye, including viruses, bacteria, algae, fungi and protozoa. It describes how microorganisms are found everywhere and play important roles in ecosystems and human health, though some can cause disease. Key events discussed include the discovery of microorganisms by Van Leewenhoek in the 1600s, challenges to the theory of spontaneous generation in the 1700s, establishing the germ theory of disease in the late 1800s, and the development of vaccines including Jenner's smallpox vaccine in 1796.

1. History of microbiology
Course code: HMB 5111 2(1+1)
Course name: Introductory Microbiology
CHRS, JAGDALPUR

2. Microbiology:
- In the broadest sense, microbiology is the study of all organisms that are
invisible to the naked eye-that is the study of microorganisms.
- Its subjects are viruses, bacteria, many algae and fungi, and protozoa.

3. Microorganisms:
- Microorganisms are everywhere; almost every natural surface is colonized by
microbes, from body to ocean. Some microorganisms can live hot springs, and
others in frozen sea ice.
- Most microorganisms are harmless to humans; You swallow millions of
microbes every day with no ill effects. In fact, we are dependent on
microbes to help us digest our food.
- Microbes also keep the biosphere running by carrying out essential functions
such as decomposition of dead animals and plants. They make possible the
cycles of carbon, oxygen, nitrogen and sulfur that take place in terrestrial
and aquatic systems.
- Microorganisms have also harmed humans and disrupted society over the
millennia.

4. - They sometimes cause diseases in man, animals and plants. They are
involved in food spoilage.
- Infectious diseases have played major roles in shaping human history
(decline of Roman Empire & conquest of the New World.
- The "Great Plague", reduced population of western Europe by 25%.
- Smallpox and other infectious diseases introduced by European explorers to
the Americas in 1500's were responsible for decimating Native American
populations.
- Until late 1800's, no one had proved that infectious diseases were caused by
specific microbes.

5. Discovery of Microorganisms:
• Invisible creatures were thought to exist long before they were observed.
- Antony van Leewenhoek (1632 –
1723) who invented the first
microscope (50-300x), was the first
to accurately observe and describe
microorganisms.

6. Spontaneous Generation of Organisms
• The theory of spontaneous generation states that the microbes arise
automatically in decomposing organic matter.
• In the 17th century Francesco Redi worked out the appearance of maggots
in decomposing meat depended on the decomposition of eggs by flies, but
the idea of spontaneous generation persisted for the new world of microbes.
• T. Needham in 1748 experienced the appearance of organisms not present
previously and concluded that these organisms appeared from the
decomposition of the vegetables and meat.

9. Spontaneous Generation Conflict:
- From earliest times, people believed that Living organisms could developed
from nonliving or decomposing matter.
- The SGT was challenged by Redi, Spallanzani and many others.
- Louis Pasteur (1822-1895) settled the conflict once for all; heated the
necks of flasks

16. Role of Microorganisms in Disease:
- Bassi – showed that silkworm disease was caused by a fungus.
- Berkeley and Pasteur showed that Microorganisms caused disease.
- Joseph Lister – developed system for sterile surgery.
- Robert Koch (1843 – 1910) established the relationship between Bacillus
anthracis and anthrax; also isolated the bacillus that causes tuberculosis.
- Charles Chamberland (1851-1908) discovered viruses and their role in
disease.

19. Development of Vaccines
and Antisera
• Edward Jenner in 1796 discovered that
cowpox (vaccinia) induced protection
against human smallpox
• Called procedure vaccination

20. Vaccination:
• Inoculation of healthy individuals with weakened (or
attenuated) forms of microorganisms, that would otherwise
cause disease, to provide protection, or active immunity from
disease upon later exposure.

23. Pasteur and Chamberland developed other
vaccines:
Attenuated anthrax vaccine
○ Chemical and heat treatment (potassium dichromate)
Attenuated rabies vaccine
○ Propagated the virus in rabbit following injection of infected
brain and spinal cord extracts