Introduction to Microbiology

What is Microbiology?

• The study of microscopic living organisms
• Derived from Greek words "micros" (small), "bios" (life), and "logos" (science)
• Requires magnification tools like microscopes

Characteristics of Microorganisms

• Very small, invisible to the naked eye
• Unicellular, one cell capable of performing all functions
• Ubiquitous (found everywhere): on bodies, plant surfaces, air, water, soil, inside animals and insects

Brief History of Microbiology

• Spontaneous generation theory: microbes arise from non-living matter
• Pioneers:
  • Antony van Leeuwenhoek (1632): First useful microscopes
  • Robert Hooke (1665): Observed and drew plant cell and microbe structures
  • Louis Pasteur (1822): Proved microbes are in the air
    • Heated broth in sealed flask – no growth
    • Heated broth in unsealed flask – growth
  • Robert Koch and colleagues: Developed techniques for pure culture of bacteria and fungi
  • Paul Ehrlich: Synthesized the first drug against syphilis
  • Gerhardt Domagk: Developed the first effective drug against bacterial infections (sulfa drug)
  • Sir Alexander Fleming: Discovered penicillin, the first antibiotic
  • Waksman: Discovered streptomycin and other antibiotics

Branches of Microbiology

• Bacteriology: Study of bacteria, including their types, characteristics, diseases, and applications
  • Medical, industrial, and agricultural bacteriology
• Mycology: Study of fungi and yeast, including their types, characteristics, diseases, and applications
  • Medical, industrial mycology
  • Applications include antibiotic production, baking, and dairy products
• Phycology: Study of algae, found in various environments
  • Floating in oceans and aquatic environments
• Parasitology: Study of parasites, including their relationship with hosts
  • Protozoa (amoeba) and Helminths (worms) are major human and animal infection causes
• Virology: Study of viruses, which are non-cellular microbes that require living cells to multiply
  • Viruses are seen only under electron microscopes
  • Responsible for diseases like AIDS, common cold, SARS, hepatitis, COVID
• Immunology: Study of the immune system of organisms and its response to pathogens

Microbes and Disease

• Although microbes are often associated with disease, the majority are beneficial
  • 87% of known bacteria species are beneficial
  • 10% are opportunistic pathogens, causing disease only under certain conditions
  • Only 3% are true pathogens