3. Introductory Microbiology

3. Introductory Microbiology

3.1 Monera

General Introduction

• Definition: Monera is a kingdom that includes prokaryotic organisms, primarily bacteria and cyanobacteria (blue-green algae).
• Characteristics:
  • Unicellular organisms without a defined nucleus.
  • Possess a simple cell structure with no membrane-bound organelles.

Structure of Bacterial Cell

• Cell Wall: Composed of peptidoglycan; provides shape and protection.
• Cell Membrane: Semi-permeable membrane controlling the entry and exit of substances.
• Cytoplasm: Gel-like substance containing ribosomes and genetic material (nucleoid).
• Flagella: Whip-like structures used for locomotion in motile bacteria.
• Pili: Hair-like appendages aiding in adhesion and conjugation.

Mode of Nutrition

• Autotrophic Bacteria:
  • Photoautotrophs: Use sunlight for energy (e.g., cyanobacteria).
  • Chemoautotrophs: Obtain energy from inorganic compounds.
• Heterotrophic Bacteria: Obtain energy from organic compounds, including decomposers and pathogens.

Bacterial Growth

• Binary Fission: Asexual reproduction method resulting in two identical daughter cells.
• Growth Phases:
  • Lag Phase: Adaptation to new environment.
  • Log Phase: Rapid cell division and population increase.
  • Stationary Phase: Growth rate slows as resources become limited.
  • Death Phase: Decline in cell number due to depletion of resources and accumulation of waste.

Cyanobacteria (Blue-Green Algae)

• Definition: Photosynthetic bacteria capable of nitrogen fixation.
• Characteristics:
  • Contain chlorophyll a and phycobilins for photosynthesis.
  • Can form blooms in nutrient-rich waters.
• Ecological Importance: Contribute to oxygen production and nitrogen fixation, enhancing soil fertility.

3.2 Virus

General Introduction

• Definition: Viruses are acellular entities that require a host cell to replicate and reproduce.
• Characteristics:
  • Cannot reproduce independently; considered living only when inside a host.
  • Smaller than bacteria, ranging from 20 to 300 nanometers in size.

Structure and Importance of Virus

• Structure:

  • Capsid: Protein coat protecting viral genetic material (DNA or RNA).
  • Envelope: Some viruses have a lipid envelope derived from the host cell membrane.
  • Surface Proteins: Facilitate attachment and entry into host cells.

• Importance:

  • Cause various diseases in plants, animals, and humans (e.g., influenza, HIV).
  • Used in gene therapy and as tools in molecular biology (e.g., viral vectors).

Bacteriophage

• Definition: A type of virus that infects and replicates within bacteria.
• Structure: Composed of a protein coat (capsid) and a tail structure for attachment to bacterial cells.
• Significance:
  • Can be used in phage therapy to target bacterial infections, especially antibiotic-resistant strains.
  • Important tools in genetic engineering and microbiological research.

3.3 Impacts of Biotechnology in the Field of Microbiology

• Genetic Engineering:

  • Modification of microorganisms for the production of insulin, vaccines, and enzymes.
  • Use of recombinant DNA technology to enhance microbial strains for various applications.

• Bioremediation:

  • Use of bacteria and fungi to detoxify polluted environments (e.g., oil spills, heavy metal contamination).

• Food Production:

  • Fermentation processes utilizing microorganisms for the production of yogurt, cheese, and other fermented foods.

• Industrial Applications:

  • Use of microbes in the production of biofuels, biodegradable plastics, and pharmaceuticals.

• Medical Microbiology:

  • Development of antibiotics and vaccines through biotechnological methods, enhancing disease prevention and treatment.