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Figure a is a drawing of Louis Pasteur in his lab. Figure b is a photograph of Robert Koch.
(a) Louis Pasteur (1822–1895) is credited with numerous innovations that advanced the fields of microbiology and immunology. (b) Robert Koch (1843–1910) identified the specific microbes that cause anthrax, cholera, and tuberculosis.

As microbiology has developed, it has allowed the broader discipline of biology to grow and flourish in previously unimagined ways. Much of what we know about human cells comes from our understanding of microbes, and many of the tools we use today to study cells and their genetics derive from work with microbes.

  • How did the discovery of microbes change human understanding of disease?

Microbiology toolbox

Because individual microbes are generally too small to be seen with the naked eye, the science of microbiology is dependent on technology that can artificially enhance the capacity of our natural senses of perception. Early microbiologists like Pasteur and Koch had fewer tools at their disposal than are found in modern laboratories, making their discoveries and innovations that much more impressive. Later chapters of this text will explore many applications of technology in depth, but for now, here is a brief overview of some of the fundamental tools of the microbiology lab.

  • Microscopes produce magnified images of microorganisms, human cells and tissues, and many other types of specimens too small to be observed with the naked eye.
  • Stains and dyes are used to add color to microbes so they can be better observed under a microscope. Some dyes can be used on living microbes, whereas others require that the specimens be fixed with chemicals or heat before staining. Some stains only work on certain types of microbes because of differences in their cellular chemical composition.
  • Growth media are used to grow microorganisms in a lab setting. Some media are liquids; others are more solid or gel-like. A growth medium provides nutrients, including water, various salts, a source of carbon (like glucose), and a source of nitrogen and amino acids (like yeast extract) so microorganisms can grow and reproduce. Ingredients in a growth medium can be modified to grow unique types of microorganisms.
  • A Petri dish is a flat-lidded dish that is typically 10–11 centimeters (cm) in diameter and 1–1.5 cm high. Petri dishes made out of either plastic or glass are used to hold growth media ( [link] ).
  • Test tubes are cylindrical plastic or glass tubes with rounded bottoms and open tops. They can be used to grow microbes in broth, or semisolid or solid growth media.
  • A Bunsen burner is a metal apparatus that creates a flame that can be used to sterilize pieces of equipment. A rubber tube carries gas (fuel) to the burner. In many labs, Bunsen burners are being phased out in favor of infrared microincinerators , which serve a similar purpose without the safety risks of an open flame.
  • An inoculation loop is a handheld tool that ends in a small wire loop ( [link] ). The loop can be used to streak microorganisms on agar in a Petri dish or to transfer them from one test tube to another. Before each use, the inoculation loop must be sterilized so cultures do not become contaminated.
Figure a is a photograph of a round disk streaked with lines. The thickest lines go back and forth along an area spanning one fifth of the plate. The next fifth of the plate also has thick lines. The next fifth of the plate has thinner lines that are made of tiny dots. The final fifth of the pate only has large dots. Figure b shows a hand holding a metal rod that is the diameter of a pretzel stick; projecting from tis is a thick wire that is formed into a loop at the end.
(a) This Petri dish filled with agar has been streaked with Legionella , the bacterium responsible for causing Legionnaire’s disease. (b) An inoculation loop like this one can be used to streak bacteria on agar in a Petri dish. (credit a: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by Jeffrey M. Vinocur)

Key concepts and summary

  • Microorganisms (or microbes ) are living organisms that are generally too small to be seen without a microscope.
  • Throughout history, humans have used microbes to make fermented foods such as beer, bread, cheese, and wine.
  • Long before the invention of the microscope, some people theorized that infection and disease were spread by living things that were too small to be seen. They also correctly intuited certain principles regarding the spread of disease and immunity.
  • Antonie van Leeuwenhoek, using a microscope, was the first to actually describe observations of bacteria, in 1675.
  • During the Golden Age of Microbiology (1857–1914), microbiologists, including Louis Pasteur and Robert Koch, discovered many new connections between the fields of microbiology and medicine.

Fill in the blank

Thucydides is known as the father of _______________.

scientific history

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Researchers think that Ötzi the Iceman may have been infected with _____ disease.


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The process by which microbes turn grape juice into wine is called _______________.


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Short answer

What did Thucydides learn by observing the Athenian plague?

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Why was the invention of the microscope important for microbiology?

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What are some ways people use microbes?

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Questions & Answers

what is the size of virus
Beatrice Reply
What is the difference between TVC and Bioburden test
structure of bacteria and 10 types
Jennifer Reply
what is accidental host?
Domingo Reply
what is endomembrane system
Ikpi Reply
what is human anatomy
okay. Go ahead and ask
Blessing Reply
Industrial microbiology mcq
Okay. What's your question?
life arises from living matter or live organism.
Swami Reply
I think live matter arises from non living matter
I dont think so...can u explain with an example
living maters made by non living matters
non living matters like stones? rocks?
cells are made by C N O minerals etc
I mentioned these as non living maters
that's all
cells are made up of those things but they originate from living things..
Ok..good chat:-)
where are you from
Tamil nadu
I am from Maharashtra
what about your studies
completed bsc.. preparing for msc entrance...wbu?
are you microbiologist
yes i am
what s the scope for micro in ur state?
did you find your college to higher studies
have to give an entrance exam for every college here...so lets c
food industries, medical lab, vaccine industries ,etc
hoping for pune University...wbu?
is that centeral University right
what is your namr
Family kindly help me with this question? 1) Shortlist the configurative measurements of the following human anatomical ranges of÷ - Blood ( haemeglobin) in both male and female - Haematocytes in both male and female - Hepatocytes in both male and female - Lymphocyte / T. Lymphocytes in both male
My names are Gift Mwale and am a Zambian. Kindly help me with this research which goes like this... 1) Shortlist the configurative measurements of the following human anatomical ranges of ÷ - Blood ( haemeglobin) in both male and female - Hepatocytes in both male and female - Haematocytes in both
please what is the full meaning for TCDS
from a single cell
tcds means transcranial direct current stimulation...in this small electric currents are given to brain( specific parts) to help increase brain performance or to help with depression.. current should be in range 0.5-2.0mA
what's underlying disease relating unsanitary diet microorganism with the highest rate of epidemology solution and efficacy leading molecules elucidated structural solutions
please can anybody talk about brain tumour and its cure.
enlargement of the thyroid gland resulting in over production of hormone.
Kamal Reply
What can u say on Thyroid Cancer?
Please, talk about the thyroid cancer.
explain the Grave's disease
John Reply
what is cell
Avi Reply
is unit of life
who is an industrial microbiologist
Cynthia Reply
I want to know the biochemical composition of bacteria
Josh Reply
It contains peptidoglcon, DNA nd RNA
what are Carrier protein
bacteriophage disadvantage
Momina Reply
disease due to __________ abnormalities are termed primary immunodeficiencies
Tayee Reply
Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system.
Examples of primary immunodeficiencies include: chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency etc
thank you
explain microbial mutation
what is mutation
Cynthia Reply
alteration in genetic makeup

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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