1. Classification of Microorganisms
Microorganisms are broadly classified into:
| Type | Examples | Key Features |
|---|
| Bacteria | E. coli, Staph. | Prokaryotic, unicellular |
| Viruses | HIV, Influenza | Acellular, need host to replicate |
| Fungi | Candida, Aspergillus | Eukaryotic, unicellular (yeast) or multicellular (molds) |
| Protozoa | Plasmodium, Entamoeba | Unicellular eukaryotes |
| Algae | Chlorella, Spirogyra | Photosynthetic eukaryotes |
2. Structure of Microorganisms
Bacteria
- Prokaryotic (no true nucleus)
- Shapes: Cocci (spherical), Bacilli (rod-shaped), Spirilla (spiral)
- Components: Cell wall (peptidoglycan), plasma membrane, ribosomes, plasmids
- Flagella (movement), pili (attachment), capsule (protection)
Viruses
- Non-living outside host
- Components: DNA or RNA (not both), protein coat (capsid), sometimes an envelope
- Multiply only inside host cells
Fungi
- Yeasts (unicellular) and molds (multicellular)
- Eukaryotic cells with cell walls made of chitin
Protozoa
- Eukaryotic, motile, often parasitic
- Movement: cilia, flagella, pseudopodia
3. Microbial Growth and Nutrition
- Bacterial Growth Curve: Lag → Log → Stationary → Death
- Factors affecting growth: Temperature, pH, oxygen, nutrients
- Culture media:
- Nutrient agar: general purpose
- Selective media: inhibits unwanted microbes
- Differential media: distinguishes between species
4. Sterilization and Disinfection
| Method | Example | Purpose |
|---|
| Sterilization | Autoclave (121°C, 15 psi) | Destroys all forms of life |
| Disinfection | Alcohol, phenol | Destroys pathogens, not spores |
| Antiseptics | Iodine, chlorhexidine | Safe for use on skin |
5. Immunology Basics
- Innate immunity: First line of defense (skin, macrophages)
- Adaptive immunity: Specific response (T-cells, B-cells)
- Vaccines: Stimulate immune memory (e.g., MMR, BCG)
6. Pathogenic Microorganisms and Diseases
| Microbe Type | Example | Disease |
|---|
| Bacteria | Mycobacterium TB | Tuberculosis |
| Virus | HIV | AIDS |
| Fungi | Candida albicans | Oral/Vaginal thrush |
| Protozoa | Plasmodium falciparum | Malaria |
| Helminths | Ascaris | Ascariasis |
7. Diagnostic Microbiology
- Microscopy: Gram staining, Acid-fast staining
- Culture techniques: For bacteria, fungi
- Serological tests: ELISA, agglutination
- Molecular tests: PCR for DNA/RNA detection
8. Antibiotics and Antimicrobial Resistance
- Antibiotics: Drugs that kill or inhibit bacterial growth (e.g., penicillin)
- Resistance: Due to misuse/overuse; leads to MDR (e.g., MRSA, XDR-TB)
9. Normal Flora vs Pathogens
- Normal flora: Microbes normally living on/in the body (e.g., gut flora)
- Opportunistic pathogens: Cause disease in immunocompromised hosts
10. Applied Microbiology
- Medical: Vaccines, antibiotics
- Industrial: Fermentation (alcohol, yogurt)
- Environmental: Bioremediation, nitrogen fixation
