General Microbiology Lecture 1: Introduction

General Microbiology and Immunology Lecture 1: Introduction

• The course covers general microbiology and immunology.
• Midterm exam is worth 30%, practical exam is worth 60%, final exam is worth 60%.
• Microbiology is the study of microorganisms.
• Microorganisms are organisms too small to be seen with the naked eye.
• Microorganisms include bacteria, fungi, viruses, algae, and protozoa.
  • Microorganisms are found almost everywhere, including hot springs and frozen sea ice.
  • Most microbes are harmless to humans.
  • Microbes decompose dead organisms and matter, playing a role in the balance of nature (ecosystem).
  • Bacteria, for example, are instrumental in the digestion of food.
  • Microorganisms played an important role during the development of antibiotics.

Impact on Human Health

• Many microbes are beneficial.
• Some microbes can cause infectious diseases (hazard effect).
• Microbes that reside in the body are called normal microbiota.
  • Normal microbiota protect the human body from harmful microbes by inhibiting their growth.
  • Normal microbiota synthesize vitamins such as folic acid and vitamin K.

Balance of Nature (Ecosystem Balance)

• Microbes play a role in decomposition.
• Decomposers break down organic material (e.g., remains of dead organisms).
• Decomposers include bacteria and fungi.
• Microbes can be used for ecological purposes, like cleaning oil spills (bioremediation).

Environmental

• Microbes can be used to create safe drinking water.
• Microbes can be used to create biodegradable products.

Industrial

• Microbes are used in the production of antibiotics.
• Microbes are used in the production of insulin.
• Microbes are used in genetic engineering.
• Microbes are used to produce a lot of food products (cheese, pickles, green olives, yogurt, soy sauce, vinegar, bread, beer, wine).

Agricultural

• Microbes are involved in livestock health to make them healthier.
• Research into microbes can create disease-resistant crops.

Branches of Microbiology (By Taxonomy)

• Bacteriology: study of bacteria.
• Virology: study of viruses.
• Mycology: study of fungi.
• Protozoology: study of single-celled organisms like amoebae.
• Phycology: study of algae.
• Immunology: study of the immune system and responses to pathogens.

Branches of Microbiology (By Type of Research)

• Medical microbiology: study of diseases caused by microorganisms.
  • Pharmaceutical microbiology: microorganisms in the production of drugs (antibiotics, vaccines, vitamins).
  • Food microbiology: study and control of microorganisms involved in food production and spoilage.
    • Agricultural microbiology: study of microorganisms that affect crop production, soil fertilization, and plant diseases.
  • Aquatic microbiology: study of microorganisms and their activities in aquatic environments (fresh or marine water).
  • Microbial biotechnology: using microorganisms for industrial applications and tasks related to human and environmental health.

Nomenclature of Microorganisms

• Carl Linnaeus established modern taxonomy in 1735.
• Binomial nomenclature is used, comprising genus and species (e.g., Staphylococcus aureus or S. aureus).
• Genus is always capitalized.
• All eukaryotes and prokaryotes use this naming convention.
  • Viruses use a different method.

Nomenclature of Microorganisms: Examples

• Escherichia coli (E. coli): Discovered by Theodor Escherich, lives in the colon.
• Staphylococcus aureus (S. Aureus): Cells are clustered, spherical, and their colonies have a golden colour.

Classification of Microorganisms

• Microorganisms are classified into two main groups:
• Acellular: Viruses, they lack cells.
• Cellular:
• Prokaryotes: Prior to having a nucleus, bacteria and archaea. - These lack a nucleus, membrane-bound organelles, and have simple internal structures.
• Eukaryotes: True nucleus, fungi, algae, protists, plants, and animals. - These have a nucleus, complex internal structures, and membrane-bound organelles.

Two Types of Cells

• Prokaryotic cells (bacteria): lack membrane-bound organelles.
  • Notable examples are Chlamydia and Rickettsia.
• Eukaryotic cells (others): contain membrane-bound organelles.
  • Includes plants, algae, fungi, protists.

Prokaryotic vs Eukaryotic Cells (Comparison Table)

Bacteria

• Bacteria are tiny prokaryotic organisms (one-tenth the size of eukaryotic cells).

• They have peptidoglycan cell walls (some exceptions).

• Bacteria reproduce through binary fission.

• Bacteria metabolize organic/inorganic chemicals or via photosynthesis.

• Most bacteria fall into general dimensions of 0.75-4 µm.

• Bacteria occur in various shapes: bacilli (rod-shaped), cocci (spherical), spirilla (spiral).

• Bacteria are abundant in soil, water, and the human gut.

• Many bacterial species cause disease, yet some are very beneficial to humans.

Bacteria: Classifications

• Shape (spherical, rod-shaped, spiral forms)
• Arrangement
• Clusters
• Chains
• Pairs

Normal Microbiota (Flora)

• Microorganisms that are found on the surface or deep layers of skin, saliva, oral mucosa, conjunctiva, and gastrointestinal tract.
• Most normal microbiota are not harmful.
• Some are even beneficial to humans and help maintain health.

Pathogens

• Microorganisms that can cause diseases.
  • Includes viruses, bacteria, fungi, and parasites.
• Pathogens cause disease by invading and replicating within the host.
• Opportunistic pathogens: cause disease under specific conditions.
• Strict pathogens: always cause disease when the host is infected.

Opportunistic vs Strict pathogens

• Opportunistic pathogens usually do not harm the host in normal conditions.

• They pose harm only when the host's body is compromised and their immunity is weakened.

• Strict pathogens commonly cause infection and similar diseases in almost every infected patient.

Bacterial Classification

• Bacteria are classified according to various characteristics (shape, staining properties, biochemical tests, nutrition, and genetic characteristics.)
• Bacteria can be categorized based on their habitat (saprophytic/parasitic).

This quiz focuses on the foundational concepts of general microbiology and immunology. It covers the study of microorganisms, their roles in the ecosystem, and their impact on human health. Understanding these principles is crucial for grasping the complexities of microbial interactions and their implications.