Chapter 1
A Brief History of Microbiology
Additional reading: Blevins and Bronze. 2010. Robert Koch and the ‘golden age’ of
bacteriology. -- on eReserve at Library
You need only peruse final section of chapter: “The Modern Age of Microbiology”
While we will not now be covering all of the historic individuals presented in this chapter, several will be brought
up later in the semester (e.g., Jenner, Snow, Ehrlich, etc), so this is a good time to familiarize yourself with many of
the key figures in the history of microbiology
What is resolving power
of the human eye?
How Big Is It?
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When were microbes first
discovered?
Antoni van Leeuwenhoek
The greatest lens maker of all time?
Reported seeing microbes
late 17th century (1680s)
Used a “simple microscope”
aka “flea lens”
Observed all sorts of things…
cause of taste and protozoa
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Van Leeuwenhoek’s discovery of bacteria
“ van Leeuwenhoek was proud of his clean teeth and described his regimen for keeping them in
that condition in his letter of 17 September 1683. Each morning he rubbed his teeth, using salt as
an abrasive, and then rinsed his mouth with water. After eating he picked his teeth with a
toothpick and then rubbed them well with a piece of cloth. He was well satisfied with his regimen
and commented that few people of his age had such clean and white teeth. He was then just 5
weeks short of his 51st birthday. Despite his thorough regimen, on examining his teeth with a
magnifying mirror he found that they were not as clean as he thought: "Yet by doing so my teeth
are not clean, for when I look at them with a magnifying mirror there remains or grows between
some of the molars and teeth a little white matter, about as thick as batter. ... Although the
consistency of the batter-Iike matter prevented good microscopic observations, van
Leeuwenhoek's suspicion was aroused as to the possibility that living organisms were present in
the white matter. He then mixed some white matter with clean rainwater, after determining that the
water was free of little animals. ....Microscopic examination revealed
that the preparations contained "many very small living animals, which
moved very prettily" On this occasion van Leeuwenhoek made
drawings of the organisms, which are now reproduced in virtually
all introductory microbiology books and also in many higher-level
books.”
from Bardell, D. (1982) The role of the sense of taste and clean teeth
in the discovery of bacteria by Antoni van Leeuwenhoek.
Microbiological Reviews 47:121-126.
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What were Robert Hooke’s
Contributions to Science?
1635-1703
Physics,
Mechanics
Meteorology
Biology
Microscopy
Hooke’s microscope
The Micrographia
Bookworm
http://www.gutenberg.org/ebooks/15491
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Hooke wrote that cork consists of …
“solid or hardened froth, or a congeries of very small bubbles
consolidated in that form, into a pretty stiff as well as tough
concrete, and that each Cavern, Bubble, or Cell, is definitely
separate from any of the rest, without any kind of hole in the
encompassing films…”
He wondered about nutrient transport in plants…
“But though I could not with my Microscope, nor with my breath, nor any other way I have yet
tried, discover a passage out of one of those cavities into another, yet I cannot thence
conclude, that therefore there are none such, by which the Succus nutritius, or appropriate
juices of Vegetables, may pass through them; for, in several of those Vegetables, whilst green,
I have with my Microscope, plainly enough discovered these Cells or Poles filled with juices…
Now, though I have with great diligence endeavoured to find whether there be any such thing
in those Microscopical pores of Wood or Piths, as the valves in the heart, veins, and other
passages of Animals, that open and give passage to the contained fluid juices one way, and
shut themselves, and impede the passage of such liquors back again, yet have I not hitherto
been able to say anything positive in it; though, me thinks, it seems very probable, that Nature
has in these passages, as well as in those of Animal bodies, very many appropriated
Instruments and contrivances, whereby to bring her designs and end to pass, which 'tis not
improbable, but that some diligent observer, if helped with better Microscopes, may in time
detect.”
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Pasteur’s contributions were many:
-- yeasts and fermentation
-- ‘Pasteurization’
-- germ theory of disease
-- immunology
Resolved debate over
‘spontaneous generation’
of microorgansisms
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Some classic experiments in the debate over spontaneous generation
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Early Microbiologists advanced the Germ Theory of disease
-- radically altered society
Notion not readily accepted: religious beliefs; contrary to perceptions
From Nancy Tomes (1998) The Gospel of Germs Harvard Univ Press, Cambridge, MA pp 34-35
“It is not surprising that idea of microbes causing disease was difficult to accept. Objections
came not just from poorly educated or marginal physicians, but also from some of the most
intelligent, systematic thinkers of the period. Many physicians committed to making medicine
more scientific were deeply suspicious of overly simplistic theories of any sort, which they felt
harkened back to the sterile hypothesizing of eighteenth-century medicine. Reducing the whole
complex origin of an epidemic to the agency of a microbe struck them as a step backward, not
forward, in medical thinking. Others objected to the premises of experimentalism itself. To their
way of thinking, the behavior of test tube cultures or experimental animals bore no useful analogy
to human disease; close observation of many cases of illness provided a much more authoritative
body of evidence about the nature of illness. Still others objected not to the validity of laboratory
evidence, but rather to its interpretation. ...
The very ubiquity claimed for the germ made it difficult for physicians to accept its causal
role in disease. Microscopists routinely found many microbial forms on the body and in the
secretions of healthy people, so it seemed obvious that the presence of germs alone did not
cause illness. As Massachusetts physician Edward P. Hurd remarked in an 1874 review of the
evidence for the germ theory, "All the higher organisms seem to be indifferent to them," at least
so long as they remained in good overall health. Moreover, skeptics argued, the growth of unusual
bacteria in the secretions of the sick could be the consequence rather than the cause of their
illness.”
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Robert Koch: second only to Pasteur?
Lab made numerous discoveries
-- and new methodologies
The Petri plate (R.J. Petri)
Solid media
-- Potato slices
-- Agar as solidifying agent
-- better than gelatin
Advances in Sterile technique
Pure cultures from colony formation
Photomicroscopy
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Koch’s Postulates: 1881
-- in Chapter 14
Bacillus anthracis causes anthrax
1. Show that the suspected agent
is present in all cases of the
disease;
i.e., there are no exceptions.
2. Isolate the agent and grow as a
pure culture.
3. Show that the same disease
develops when the pure culture
is inoculated into a healthy
animal.
What are some limitations
to Koch’s Postulates?
4. Re-isolate the pathogen from the
inoculated animal and show that
it is the same organism.
Serious human pathogens
Viruses
“Causative associations”
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Bacillus Anthracis and Anthrax
(in Chapters 19 & 22)
The Pathogen – a bacterium
habitat
The Disease
of animals & humans
modes of exposure
-- cutaneous
-- gastrointestinal
-- pulmonary
Bioterrorism potential
Wikipedia link
http://en.wikipedia.org/wiki/Anthrax
Eschar lesion
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