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.

Applications of Microbiology

• Food industry.
• Agriculture.
• Medicine.
• Research.
• Biotechnology.
• Environmental conservation.
• Veterinary science.