Scientists from all over set out to use Ehrlich’s findings to find drugs that could make infected patients well again. One of the most striking breakthroughs came in 1929 when Alexander Fleming discovered Penicillin notatum, the organ- ism that synthesizes penicillin. Penicillium notatum is a fungus that kills the
Fleming grew cultures of Staphylococcus aureus, a bacterium, in the laboratory. He was also conducting experiments with Penicillium notatim, a mold. By acci- dent the Staphylococcus aureus was contaminated with the Penicillium notatum, causing the Staphylococcus to stop reproducing and die. Penicillium notatumbe- came one of the first antibiotics. An antibioticis a substance that kills bacteria.
A summary of the scientists and their contributions can be found in Table 1-2.
CHAPTER 1
The World of the Microorganism
17
Fig. 1-9. Penicillium notatumis a fungus that kills the staphylococcus aureus.
Table 1-2. Scientists and Their Contributions
Year Scientist Contribution
1590 Zacharias Janssen Developed the first compound microscope. 1590 Robert Hooke Observed nonliving plant tissue of a thin slice of
cork.
1668 Francesco Redi Discovered that microorganisms did not spontane- ously appear. His contribution led to the finding that killing the microorganism that caused the disease could prevent the disease.
1673 Antoni van Invented the single-lens microscope, grinding the Leeuwenhoek microscope lens to improve magnification. First
person to view a living organism.
1798 Edward Jenner Developed vaccinations against disease-causing microorganisms.
Year Scientist Contribution
1850s Mathias Schleiden, Developed cell theory. Theodore Schwann,
Rudolf Virchow
1847 Ignaz Semmelweis Reported a dramatic decline in childbirth fever after physicians used antiseptic techniques when deliver- ing babies.
1864 Louis Pasteur Discovered that microorganisms were everywhere, living on organisms and in nonliving things such as air. His work led to improved sterilization techniques called pasteurization. One of the founders of bacteriology. 1867 Joseph Lister Reduced infections after surgery by spraying car-
bolic acid over the patient before bandaging the wound. This was the first surgical antiseptic. 1876 Robert Koch Discovered how microorganisms spread contagious
diseases by studying anthrax. Developed the Germ Theory. Developed techniques for cultivating microorganisms.
1870s John Tyndall, Discovered that some microorganisms are resistant to Ferdinand Cohn certain sterilization techniques. One of the founders
of bacteriology.
1884 Elie Metchnikoff Discovered that white blood cells (leukocytes) engulf and digest microorganisms that invade the body. Coined the word phagocytes. Founded the branch of science called immunology.
1887 Richard Petri Developed the technique of placing agar into a spe- cially designed dish to grow microorganisms, which was later called the Petri dish.
1890 Paul Ehrlich Developed the first drug to fight disease-causing microorganisms that had already entered the body. 1928 Alexander Fleming Discovered Penicillium notatum,the fungus that
kills staphylococcus aureus,a microorganism that is a leading cause of infection.
Quiz
1. What is a microorganism?
(a) A microorganism is a small organism that takes in and breaks down food for energy and nutrients, excretes unused food as waste, and is capable of reproduction.
(b) A microorganism is a small organism that causes diseases only in plants.
(c) A microorganism is a small organism that causes diseases only in animals.
(d) A microorganism is a term that refers to a cell.
2. What is a pathogenic microorganism? (a) A microorganism that multiplies (b) A microorganism that grows in a host (c) A microorganism that is small
(d) A disease-causing microorganism
3. Name the parts of this microorganism using the nomenclature system:
Mycobacterium tuberculosis.
(a) A bacterium is a one-cell organism that does not have a distinct nucleus.
(b) Mycobacterium is the presemous and tuberculosis is the specific postsemous.
(c) Mycobacteriumis the epithet and tuberculosisis the specific genus. (d) Mycobacteriumis the genus and tuberculosisis the specific epithet.
4. Why is a bacterium called a prokaryotic organism?
(a) A bacterium is a one-cell organism that does not have a distinct nucleus.
(b) A bacterium is a one-cell organism that has a distinct nucleus. (c) A bacterium is a multicell organism that does not have a distinct
nucleus.
(d) A bacterium is a multicell organism that has a distinct nucleus.
5. Why is a fungus called a eukaryotic microorganism?
(a) Fungus has cells that have a nucleus, nuclear envelope, cytoplasm, and organelles.
(b) Fungus has cells that have a nucleus and no nuclear envelope. (c) Fungus has cells that have a nucleus, nuclear envelope, cytoplasm,
but no organelles.
(d) Fungus has cells that have no nucleus, no nuclear envelope, no cyto- plasm, and no organelles.
6. What is Archaea?
(a) Archaea is a classification for organisms that have two nuclei. (b) Archaea is a classification for organisms that use phagocytosis. (c) Archaea is a classification of an organism that identifies prokaryotes
that do not have peptidoglycan cell walls.
(d) Archaea is a classification of an organism that identifies prokaryotes that have peptidoglycan cell walls.
7. What is phagocytosis?
(a) The ability of a cell to reproduce.
(b) The ability of a cell to move throughout a microorganism.
(c) The ability of a cell to engulf and digest solid materials by use of pseudopods, or “false feet.”
(d) The ability of a cell to change shape.
8. What is a compound microscope? (a) A microscope that has one lenses.
(b) A microscope that has two sets of lenses: an ocular lens and an eye- piece.
(c) A microscope whose lenses are concave. (d) A microscope whose lenses are convex.
9. What is Germ Theory?
(a) Germ Theory states that a disease-causing microorganism should be present in animals infected by the disease and not in healthy animals. (b) Germ Theory states that a disease-causing microorganism should be
present in healthy animals and not in infected animals.
(c) Germ Theory states that a disease-causing microorganism should be destroyed.
(d) Germ Theory states that a disease-causing microorganism cannot be destroyed.
10. What is Edward Jenner’s contribution to microbiology? (a) Edward Jenner discovered the Germ Theory.
(b) Edward Jenner discovered how to create vaccinations to trigger the body’s immune system to develop antibodies that fight micro- organisms.
(c) Edward Jenner discovered the compound microscope.
(d) Edward Jenner discovered the compound nomenclature system.
2
CHAPTER
23
The Chemical
Elements of
Microorganisms
No doubt you’re asking yourself what chemistry has to do with microbiology since they seem to be two different branches of science. The simple answer is that microorganisms are made up of chemicals, as is every organism—and all matter. Remember that matter is anything that occupies space and has mass.
You might say that an organism is a chemical processing plant where things are broken down into chemical elements; these chemical elements are then re- arranged to form new things. You do this every time you ingest food. Food is a group of chemical compounds. The digestive process rearranges these digested chemical compounds into new substances that provide you with energy and nutrients that are necessary for you to live. Some microorganisms called auto- trophic organismsmanufacture their own food. Microorganisms that derive energy from other microorganisms (food) are called heterotopic organisms.
When you catch a cold or become infected by pathogenic microorganisms, your body is no longer in homeostasis. You feel rotten, but what’s really hap- pening is that the microorganism is disrupting your chemical processing plant’s normal operation. Some microorganisms prevent necessary chemical processing from occurring. Other microorganisms cause your chemical processing plant to execute different processes designed to fight the microorganism attack and return your body to homeostasis—then your body is back to normal.
As you can see, chemistry is a crucial component of microbiology. It is for this reason that we begin the study of microorganisms with a close look at chemistry.