History of Microbiology

Lecture 1: History of Microbiology

• Spontaneous generation: Life can arise from non-living matter. Miasma theory proposed disease came from decomposing matter.
• Germ theory: Diseases result from microbial infection. Replaced spontaneous generation.
• Handwashing and Aseptic Techniques: Decreased post-birth mortality rate to 1% after using chlorine to wash hands.
• Louis Pasteur: Observed microbes were responsible for infections. Disproved spontaneous generation using swan-neck flasks.
• John Snow: Identified cholera source as contaminated water, demonstrating disease can spread through contaminated items (not just air).
• Ignaz Semmelweis: Proposed handwashing by medical personnel to prevent post-birth sepsis.
• Joseph Lister: Tried to find post-surgical infection cause and promoted antiseptic handwashing during surgery.
• Florence Nightingale: Studied hygiene in hospitals.
• Robert Koch: Established link between microbes and specific diseases.

Lecture 2: Observing Microbes

• Structure:
  • Prokaryotes (bacteria, archaea): Unicellular, simple structure, no membrane-bound organelles.
  • Eukaryotes (fungi, protozoa, algae): Uni/multicellular, complex structure, with membrane-bound organelles.
  • Viruses (HIV, bacteriophages): Acellular, replicate inside host cells.
• Size Comparison:
  • Prokaryotes range from 0.05-0.1 micrometers to 15-100 nanometers.
  • Eukaryotes range 5-100 micrometers.
• Descriptions of Taxonomy:
  • Species are capitalized and lowercase (e.g., Homo sapiens- genus species)
  • Hierarchical classification system (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
• Microscopy:
  • Simple vs. Compound microscopes: Simple use one lens (light passes through one); Compound use two (light passes through two lenses).
  • Calculating magnification: Ocular magnification x Objective magnification
  • Fluorescence microscopy: Used to identify pathogens & molecules.
  • Electron microscopy: High-resolution, to view smaller structures but kills the specimen.
  • Staining: highlights morphological features (simple & complex stains distinguish things).

Lecture 3: Prokaryotes

• Parts and Structure
  • Capsule: Polysaccharide/protein layer for protection.
  • Plasma Membrane: Fluid mosaic model that encloses the cytoplasm.
  • Cell Wall: Supports cell. Gram-positive vs. Gram-negative differ in their structure/thickness.
  • Gram-negative has a thin layer w/ LPS endotoxins and a thin cell wall
  • Nucleoid: Holds genetic material (DNA)
  • Plasmids: Extra-chromosomal DNA (small circular loop of DNA usually in prokaryotes) that offer antibiotic resistance.
  • Ribosomes: Involved in protein synthesis.
  • Pili: Appendages for attachment and DNA transfer.
  • Fimbriae: Short bristle-like appendages to attach to surfaces.
  • Flagella: Stiff spiral filaments that move cell.
• Functions of parts: Each part plays a definite role in the cell's function.

Lecture 4: Eukaryotes

• Structure:
  • Cytoskeleton: Network of filaments (microtubules, microfilaments, intermediate filaments) providing structural support and intracellular transport..
  • Mitochondria: Organelle that performs cellular respiration.
  • Endomembrane System: Includes organelles like ER, Golgi, and lysosomes.
  • Nucleus: Contains genetic material (DNA).
  • Ribosomes: Synthesize proteins.
  • Plasma membrane: Regulates passage of materials.
• Function: The function of each part describes the specific role in the eukaryotic organism's function.
• Movement: Flagella and cilia are primarily used to move cells for prokaryotes.

Lecture 5: Fungi, Protozoa, Algae, Viruses

• Four eukaryotic Kingdoms:
  • Animal, Plant, Fungi, Protists
• Characteristics: Each Kingdom has unique characteristics (multicellular, motile, heterotrophic, autotrophic, etc.).
• Life cycle: Fungi have both asexual (spore formation) and sexual reproductive lifecycles.
• Importance of asexual & sexual reproduction: Important for sustaining growth and diversity.

Lecture 6: Microbial Growth

• Prokaryotic Division (Binary Fission): Asexual reproduction common in prokaryotes involving DNA replication followed by cell division.
• Doubling Time (Generation Time): The time it takes for a population of cells to double in size.
• Growth Curve: A four-stage process characterized by: lag, log, stationary, death phase.
• Important Factors for Growth: Nutrients, pH, Temperature, Oxygen, Salt Concentration and others. Conditions define the growth and activities within these conditions.

Lecture 7: Metabolism

• Exergonic reactions: Releases energy
• Endergonic reactions: Require energy
• Catabolism: Breaks down complex molecules to release energy.
• Anabolism: Builds complex molecules from simpler ones.
• Carbohydrates: Monosaccharides, disaccharides, polysaccharides, provide energy.
• Cellular Respiration: Aerobic process to generate ATP using oxygen and Glucose.
• Fermentation: Anaerobic process that generates ATP using other molecules than oxygen.

Lecture 8: Microbial Metabolism 2

• Amino Acids: Building Blocks of proteins
• Nucleic Acids: Building blocks of DNA and RNA
• Lipids: Important for storing energy
• Other metabolic pathways: Pathways involved in the synthesis of molecules and the building blocks.

Lecture 9: Environmental Conditions

• Normal Growth Conditions: Optimal conditions for microbial growth.
• Extremophiles: Organisms adapted to extreme environments.
  • Temperature
  • pH
  • Salinity
  • Oxygen requirements are important.
• Oxygen requirements: Aerobes, anaerobes, facultative anaerobes, and others, depending on the needs.