Microbiology Lecture

Scope and History of Microbiology

Microbiology is a field that deals with the study of microorganisms, including their characteristics, growth, and interactions with the environment and hosts.
The scope of microbiology includes understanding the biology of microorganisms, their role in disease, and the development of vaccines, antibiotics, and other treatments.

History of Microbiology

The golden age of microbiology began in the mid-19th century, with contributions from Louis Pasteur, Robert Koch, and other pioneers.
Before the 19th century, the concept of spontaneous generation, which held that living organisms could arise from non-living matter, was widely accepted.
Francesco Redi disproved spontaneous generation in 1668, and later, Louis Pasteur and others demonstrated the importance of microorganisms in disease and fermentation.

Key Contributors to Microbiology

Anton van Leeuwenhoek (1632-1723): Father of Microbiology, known for his improvements to the microscope and his discovery of microorganisms, including bacteria, yeast, and fungi.
Robert Hooke (1665): Discovered cells and coined the term "cell" to describe the basic units of life.
Louis Pasteur (1822-1895): Developed pasteurization, saved the French wine industry, and made significant contributions to the field of microbiology, including the development of vaccines and the germ theory of disease.
Robert Koch (1843-1910): Developed Koch's postulates, which relate a specific microorganism to a specific disease, and made significant contributions to the field of bacteriology.

Microbiology Techniques

Culturing microorganisms: Isolating and growing microorganisms in pure cultures to study their characteristics and behavior.
Staining techniques: Using dyes to enhance the visibility of microorganisms under a microscope.
Sterilization and disinfection: Using heat, chemicals, and other methods to eliminate or reduce microorganisms.

Immunology

Immunology is the study of immunity and the defense of the body against pathogens.
Edward Jenner (1796): Developed the first vaccine against smallpox, using cowpox to provide immunity.
Elie Metchnikoff (1845-1916): Discovered phagocytes, which are cells that ingest and digest foreign particles and microorganisms.

Virology

Virology is the study of viruses, including their structure, replication, and interactions with hosts.
Charles Chamberland (1884): Demonstrated the existence of viruses using a porcelain filter.
Martinus Beijerinck (1898): Characterized viruses as replicating in host cells.
Wendell Stanley (1935): Crystallized Tobacco Mosaic Virus, showing that it consists of a helical core of RNA surrounded by a coat of protein.### Structure of Viruses
Viruses have a regular structure that allows them to be crystallized.
The electron microscope is capable of magnifying biological specimens up to one million times.

History of Microbiology

Reska (1938) - First Electron Microscope.
1939 - First VIRUS observed with an electron microscope.
Thomas Sydenham - Quinine from tree bark was long used to treat malaria.
Paul Ehrlich (1910) - Pioneer in the development of chemotherapy for infectious disease.
Paul Ehrlich - Developed the concept of a "Magic bullet" - a chemical that would destroy specific bacteria without damaging surrounding tissues.

Chemotherapy

Treatment with chemicals is chemotherapy.
Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics.
Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill other microbes.

Antibiotics

1928 - Alexander Fleming discovered the first antibiotic, penicillin.
1940s - Penicillin was tested clinically and mass produced.
Selected Nobel Prizes in Physiology or Medicine:
- 1901 - von Behring - Diphtheria antitoxin.
- 1902 - Ross - Malaria transmission.
- 1905 - Koch - TB bacterium.
- 1908 - Metchnikoff - Phagocytes.
- 1945 - Fleming, Chain, Florey - Penicillin.
- 1952 - Waksman - Streptomycin.
- 1969 - Delbrück, Hershey, Luria - Viral replication.
- 1987 - Tonegawa - Antibody genetics.
- 1997 - Prusiner - Prions.

Founders of Microbiology

Leeuwenhoek - First observed microbes.
Pasteur - Proved living cells can arise only from other living cells.
Koch - Confirmed the Germ Theory of Disease.

Scope of Microbiology

The variety of microbes.
The kinds of work microbiologists do.

Classification of Microorganisms

Domain 1: Bacteria.
Domain 2: Archaea.
Domain 3: Eukarya.

Types of Microorganisms

Bacteria:
- Prokaryotes.
- Single-celled.
- No nucleus.
- Lack membrane-enclosed intracellular structure.
- Peptidoglycan cell walls.
- Shapes: spherical, rod, spiral.
- Binary fission.
- Use organic chemicals, inorganic chemicals, or photosynthesis for energy.
Archaea:
- Very similar to bacteria.
- Prokaryotic.
- Single-celled.
- No nucleus.
- Lack peptidoglycan.
- Lipids, cell wall, and flagella differ from those of bacteria.
- Live in extreme environments.
Fungi:
- Eukaryotes.
- Chitin cell walls.
- Use organic chemicals for energy.
- Molds and mushrooms are multicellular, consisting of masses of mycelia, which are composed of filaments called hyphae.
- Yeasts are unicellular.
- Widely distributed in water and soil as decomposers of dead organisms.
Viruses:
- Acellular.
- Too small to be seen with a light microscope.
- Composed of nucleic acid and protein.
- Consist of DNA or RNA core.
- Core is surrounded by a protein coat.
- Coat may be enclosed in a lipid envelope.
- Replicated only when they are in a living host cell.
Algae:
- Defined cell nucleus.
- Membrane-enclosed intracellular structure.
- Cellulose cell walls.
- Use photosynthesis for energy.
- Produce molecular oxygen and organic compounds.
- Freshwater and marine environments.
Protozoa:
- Single-celled.
- Have a nucleus.
- Membrane-bound and other intracellular structures.
- Absorb or ingest organic chemicals.
- May be motile via pseudopods, cilia, or flagella.
- Water and soil environments.
Multicellular Animal Parasites:
- Eukaryote.
- Multicellular.
- Parasitic flatworms and roundworms are called helminths.
- Microscopic stages in life cycles.

Microbes in Our Life

Are producers in the ecosystem by photosynthesis.
Produce industrial chemicals such as ethyl alcohol and acetone.
Produce products used in manufacturing (e.g., cellulase) and treatment (e.g., insulin).
Produce fermented foods such as vinegar, cheese, and bread.
Decontaminate wastes.
Produce bio-fuel.
Help in agriculture through nitrogen fixation, rumen microbes, and nutrient cycling.
Help in disease prevention and treatment.