Intro to MicrobiologyA Brief History of MicrobiologyThe Microbes of Microbiology

Updated 1/2011

What is Microbiology?

Why should we study Microbiology?

Why should we study Micro?

http://www.tutorvista.com/science/pictures-of-food-webs

Microbes form the base of the food

chain.10X more

bacteria than our own cells

Help protect us from pathogens by taking up space and activating our immune system. Make us healthy by producing vitamins.

http://www.cof.orst.edu/cof/teach/for442/cinfof.htm

Help plants absorb nutrients and grow faster

Can be used to

produce food,

medicines, and more.

Understanding microbes is vital for other study of life!

Conclusion:

Advances in microbiology have followed advances in technologyAnd vice-versa…

The Early Years of Microbiology

Anton van Leeuwenhoek (Dutch) Began making and looking

through simple microscopes Examined water, semen, teeth

scrapings ~1683 Visualized tiny animals, fungi,

algae, and single celled protozoa; “animalcules”

By end of 19th century, these organisms were called microorganisms

http://www.history-of-the-microscope.org/anton-van-leeuwenhoek-microscope-history.php

The Golden Age of Microbiology

Scientists searched for answers to four questions Is spontaneous generation of microbial life

possible? What causes fermentation? What causes disease? How can we prevent infection and disease?

Is Spontaneous Generation of Microbial Life Possible?

Aristotle proposed spontaneous generation living things can arise from nonliving

matter Explained many observations

Theory came under challenge in 17th century Redi’s Experiments (late 1600s) Needham’s Experiments (mid 1700s) Spallanzani’s Experiments (1799) Pasteur’s Experiments (mid 1800s)

Redi’s Experiments

Meat exposed toflies developedmaggots, whenmeat is kept isolated maggots do not develop Conclusion: Animals only come from other animals.

After Leeuwenhoek discovered microbes scientists assumed that microbes arose spontaneously Thought they were too small/simplistic to reproduce Incorrect conclusions misled scientists.

The Scientific Method

Debate over spontaneous generation led in part to development of scientific method Observations lead a scientist to ask questions

about some phenomenon The scientist generates hypothesis (potential

answer to question) The scientist designs and conducts experiment to

test hypothesis Based on observed results of experiment, scientist

either accepts, rejects, or modifies hypothesis

Louis Pasteur

Performed a similarexperiment to Spallanzani Instead of completely sealing his flasks he

bent the necks which allowed air to enter but prevents contamination

Flasks remained pure until they were exposed to dust

Conclusion: Microbes in the flask are the progeny of microbes on the dust

Pasteur also researched Fermentation and Infection

Cell Theory

Pasteur’s evidence and conclusions led to the cell theory. The cell is the fundamental unit of Life. All organisms are made of cells. All cells come from previously existing

cells.

What Causes Disease?

Pasteur developed germ theory of disease Microbes are responsible for disease

Robert Koch studied causative agents of disease Anthrax Examined colonies

of microorganisms Developed

Koch’s Postulates

Koch’s Postulates

1. Suspected causative agent must be found in every case of the disease and be absent from healthy hosts(a)

2. Agent must be isolated and grown outside the host(b).

3. When agent is introduced into a healthy(c), susceptible host, the host must get the disease(d).

4. Same agent must be re-isolated from diseased experimental host(e,f)

http://media.wiley.com/Lux/26/8326.nfg002.jpg

Laboratory Microbiology Advances by Koch and Others

Simple staining techniquesFirst photomicrograph of bacteriaFirst photomicrograph of bacteria in diseased tissueTechniques for estimating CFU/mlUse of steam to sterilize mediaUse of Petri dishesAseptic techniquesBacteria as distinct species

How Can We Prevent Infection and Disease?

Semmelweis and handwashingLister’s antiseptic techniqueNightingale and nursingSnow and epidemiology – infection control and epidemiologyJenner’s vaccine – field of immunologyEhrlich’s “magic bullets” – field of chemotherapy

The Modern Age of MicrobiologyWhat are the basic chemical reactions of life? Biochemistry

How do genes work? Microbial genetics, Molecular biology, Recombinant

DNA technology, Gene therapy

What role do microorganisms play in the environment? Environmental microbiology

How do we defend against disease? Serology, Immunology, Chemotherapy

Meet the Microbes!

Microorganisms we will study: Fungi, Protozoa, Algae, Bacteria, Archaea,

certain Animals

Non-living particles are also included: Viruses, virons, prions

No plants!

Fungi

Eukaryotic (have membrane-bound nucleus)Obtain food from other organismsPossess cell walls of chitinExamples: Molds – multicellular; have hyphae;

reproduce by sexual and asexual spores Yeasts – unicellular; reproduce asexually by

budding; some produce sexual spores [Mushrooms – not discussed in

Microbiology]

Protozoa (Protist)

Single-celled eukaryotesSimilar to animals in their nutritional needs and cellular structureMost reproduce asexually; some sexuallySometimes classified by type of movement

Pseudopods

Cilia

Flagella

Algae (Protist)

Unicellular or multicellularPhotosyntheticCategorized by: Pigmentation storage products cell wall composition

Bacteria and Archaea

Unicellular and lack nucleiMuch smaller than eukaryotesFound everywhere there is sufficient moisture; some found in extreme environments Use every type of metabolism

Reproduce asexually

Two Groups of Prokaryotes

Methanopyrus kandleri Copyright K.O.Stetter and R.Rachel, Univ. Regensburg, Germany

Bacteria Cell walls contain

peptidoglycan (some lack cell walls)

most do not cause disease and some are beneficial

Archaea cell walls composed of

polymers other than peptidoglycan

Some live in extreme environments, none identified that cause disease

Other Microbes of Importance

Animals Eukaryotic, multicellular,

heterotrophs Parasites or vectors for

other diseasesViruses Non-cellular infectious

particles DNA or RNA in a protein

coatViroids Smaller than viruses RNA without protein or

protein genesPrions Infectious proteins

http://universe-review.ca/I11-45-viroid.jpg

http://health.enotes.com/images/neurological-disorders/gend_02_img0088.jpg