What is Microbiolgy?• The study of microorganisms

– Unicellular organisms

• Bacteria

• Viruses

– Multicellular organisms:

• algae

• Yeasts

• mold

Characteristics of Living Organisms

• Cellular organisms share the following characteristics:

– Metabolism

– Differentiation

– Reproduction

– Movement

– Evolution

– Communication

Microorganisms and their surroundings• Microbes live in a variety of ecosystems

– Water– Soil– Organic surfaces

• Plants• skin

– Non-organic surfaces• Dishes• Countertops• plastic

Microorganisms and Agriculture• Microorganisms are both beneficial and harmful to

agriculture:– Benefits:

• Nitrogen fixation in legumes N2 2NH3

• Digestion of cellulose in ruminants (cows, sheep, and goats). Bacteria reside in the beginning of the digestive tract (rumen) and digest cellulose. This allows animals to extract enough nutrients from plants for survival.

Cellulose CO2 + CH4 + animal protein

Pathogenic Microorganisms• Due to improved conditions and development of

antimicrobial drugs, the number of deaths from infectious diseases in the United States has declined significantly.

• In 1900 – influenza, pneumonia, tuberculosis and gastroenteritis were the leading cause of death in the United States.

• Infectious diseases are still the leading cause of death in the 3rd world countries.– Ex: 3000 African children die from malaria

each day

Microorganisms and Food• Microorganisms are important to the food

industry:– Yeast used to produce:

• Yogurt• Beer• wine

– Fungi used to produce:• cheese

– Bacteria used to produce:• vinegar

Microorganisms and the Environment

• Microorganisms are both detrimental and beneficial to the environment:– Bioremediation: use of microbes to clean the

environmental spills• Bacteria oxidize oil to CO2 in oil spills

– Microbial leaching: use of microbes to extract metals from low grade ores.

• Bacteria solubilize minerals around trapped gold to release pure gold

– Red tide: growth of toxin producing algae in warm, polluted costal waters.

• Toxic to fish and humans

Biotechnology• Microorganisms can be used to produce:

– Large quantities of biological substances:

• Ex: insulin, blood clotting factors

– DNA used to replace unhealthy genes in diseased individuals.

• Ex: Gene therapy

– More durable crop plants resistant to herbicides, insects and viruses

History of Microbiology

• Some names to remember:–Robert Hooke: (1664)

•Used microscope to see cells–Anton van Leeuwenhoek: (1684)–Ferdinand Cohn: (1850)–Louis Pastuer: (1880)

Robert Koch

• In 1905 he won the Nobel Prize–Studied the transmission of

diseases from one organism to the next.

–Devised a set of conditions that mut be met to prove that a certain organism causes a disease.

Koch’s Postulates1. Suspected pathogen should be present

in all cases of diseased individuals and absent from healthy individuals.

2. Suspected pathogen should be grown in a pure culture.

3. Cells from the pure culture of suspected pathogen should cause disease in healthy individual.

4. Organism should then be re-isolated and shown to be the same as the original.