Introduction to Microbiology Lecture Notes

Microbes: Tiny but Mighty

• Microbes reproduce rapidly and can be grown quickly in large populations (culture).
• Growth medium provides nutrients and optimal temperature for bacteria growth.
• Microscopes and biochemical methods are essential for studying bacteria.

Nature of Microbes and Microbiology

• Microbiology deals with microorganisms too small to be seen without magnification.
• Includes bacteria, archaea, fungi, helminths, algae, viruses, and prions.
• Viruses and prions are acellular.
• Helminths are visible but have microscopic life stages.

Microbes' Role in Earth's History

• Single-cell organisms appeared ~3.8 billion years ago.
• Life originated from a last universal common ancestor.
• Divided into three domains: Eukarya, Archaea, and Bacteria.

Evolutionary Distinctions

• Eukaryotes: True nucleus, include plants, animals, fungi.
• Prokaryotes: No true nucleus, include bacteria and archaea.

Theories in Science

• Germ Theory: Microbes cause infectious diseases.
• Cell Theory: All organisms are made of cells.
• Theory of Evolution: Accumulation of mutations leads to adaptation.

Major Metabolic Processes

• Metabolism: Chemical reactions in the cell.
  • Catabolism: Breaking down complex molecules.
  • Anabolism: Synthesis of complex molecules.
• Photosynthesis: Light-driven synthesis of carbohydrates.
  • Oxygenic photosynthesis: Produces oxygen.
  • Anoxygenic photosynthesis: Ancient process, produces sulfur.

Role of Microbes in the Environment

• Microbes are abundant in extreme environments and essential to life.
• Decomposers: Break down dead matter, release gases like CO2 and CH4.

Human Uses of Microbes

• Biotechnology: Using microbes to produce goods like bread, alcohol, and cheese.
• Genetic Engineering: Creating GMOs, e.g., insulin production.
• Bioremediation: Using microbes to clean pollutants.
• Pathogenic Microbes: Cause diseases in animals and plants.

Historical and Current Uses of Microbes

• Antibiotics revolutionized medicine.
• Microbes used in mining and environmental restoration.
• Resistant strains of microbes emerging.

Divisions of Living Organisms

• Eukaryotic: Membrane-bound organelles, multicellular.
• Prokaryotic: Simpler, no nucleus, include bacteria and archaea.
• Acellular: Viruses and prions, not part of life domains.

The Debate: Abiogenesis vs. Biogenesis

• Abiogenesis: Non-living matter can create life spontaneously.
• Biogenesis: Life arises from pre-existing life (disproved abiogenesis).

Contributions of Key Scientists

• Louis Pasteur: Disproved spontaneous generation, developed rabies vaccine, pasteurization.
• Robert Koch: Developed germ theory, Koch’s postulates.
• Anton van Leeuwenhoek: Improved microscope, observed first microbes.
• Ignaz Semmelweis: Advocated handwashing to prevent infection.
• Joseph Lister: Developed aseptic techniques in surgery.

Summary of Contributions

• Understanding of microbes led to breakthroughs in medicine and biotechnology.
• Continued advancements in microbiology are essential for health and environmental sustainability.