BSC 310 Lecture Notes - Lecture 1: Buttermilk, Electron Microscope, Interferon
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. 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.
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. The flasks did not become contaminated (as he predicted
they would not), and Pasteur's experiments put to rest the notion of spontaneous
generation. His work also encouraged the belief that microorganisms were in the air and
could cause disease. Pasteur postulated the germ theory of disease, which states that
microorganisms are the causes of infectious disease.
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
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