Introduction to Microbiology and Immunology

General Microbiology and Immunology

• Presented by Dr./Hend Zeitoun, M.Sc., Ph.D.
• Lecturer of Microbiology and Immunology
• Faculty of Pharmacy, Alexandria University

What is Microbiology?

• Microbiology is the study of microorganisms that are too small to be seen with the naked eye.
• Microorganisms are typically smaller than 1mm in diameter.

Why Study Microbiology?

• Microorganisms are ubiquitous, found everywhere on Earth.
• In the human body, microorganisms outnumber human cells by a ratio greater than 10:1.
• While most microorganisms are beneficial, some cause disease.
• Less than 0.01% of bacteria cause disease.
• Microbiology is tied to multiple facets of human life:
  • Human health: food source, role in decomposition, aids in digestion
  • Environmental: safe drinking water, bioremediation
  • Industrial: foodstuffs (beer, wine, cheese, yogurt), antibiotics, insulin
  • Agricultural: healthier livestock, disease-free crops

The Overwhelming Majority of Microbes Are Beneficial to Mankind

• Microorganisms aid in environmental recycling.
• Microorganisms aid in bioremediation.
• Microorganisms are used in mining.
• Microorganisms aid in agriculture.
• Microorganisms are essential for human health.
• Microorganisms are vital in biotechnology.
• Microorganisms are involved in the food/beverage industry.

Microbes and Human Disease

• Many microorganisms are beneficial, but some cause infectious diseases.
• Microbes normally present on the human body are called normal microbiota or normal flora.
• Normal microbiota prevent growth of pathogens.
• Normal microbiota produce growth factors (e.g., folic acid, vitamin K).

Beneficial Microorganisms

• Microorganisms function as decomposers, breaking down dead plants and animals.
• Bacteria are used to decompose organic matter, such as sewage.
• Microorganisms are used in the food industry: (cheese, yogurt, yogurt drinks, baked goods, alcoholic beverages, vinegar)

Branches of Microbiology by Taxonomy

• Bacteriology: the study of bacteria.
• Virology: the study of viruses
• Mycology: the study of fungi
• Parasitology: the study of parasites
• Nematology: the study of nematodes (roundworms)
• Protozoology: the study of single-celled organisms like amoebae
• Immunology: the study of the immune system, its relationship with pathogens (bacteria and viruses)
• Phycology: the study of algae

Branches of Microbiology by Type of Research

• Pharmaceutical microbiology: study of microorganisms used for vaccines and antibiotics.
• Medical microbiology: study of microorganisms responsible for human disease.
• Microbial biotechnology: using microbes for industrial or consumer products.
• Food microbiology: study of spoilage microorganisms and those used in food production.
• Agricultural microbiology: study of microorganisms interacting with plants and soils.

Microbial Research Topics

• Microbial Morphology: detailed structure of microorganisms.
• Microbial Physiology: microbial function (metabolism), cellular and molecular levels.
• Microbial Taxonomy: classification, naming, and identification of microorganisms.
• Microbial Genetics (Molecular Biology): function of genetic material, biochemical reactions in cellular metabolism and growth.
• Microbial Ecology: relationships between microbes and the environment.
• Genetic engineering and recombinant DNA technology: techniques that manipulate genetic material in organisms.

Bioinformatics and Bioremediation

• Bioinformatics: interdisciplinary field, develops methods and software tools for understanding biological data.
• Bioremediation: using genetically modified microorganisms to process industrial waste, creating less toxic products.
• Genomics: interdisciplinary field focusing on structure, function, evolution, mapping, and editing of genomes.
• Proteomics: large-scale study of proteins.
• Metabolomics: scientific study of chemical processes involving metabolites.

Microbes and You

• Normal microbiota (normal flora): microorganisms that colonize the body without causing disease under normal conditions.
• Normal microbiota includes bacteria that make up most of the normal flora. For example, E. coli in the large intestine.
• Pathogen: organism that causes disease.
• Opportunistic pathogens: cause disease when introduced to unprotected sites in the body.
• Strict pathogens: always cause disease in the body.

Types of Symbiotic Microbe-Host Relationships

• Mutualism: both organisms benefit.
• Commensalism: one organism benefits, the other is neither harmed nor helped.
• Parasitism: one organism benefits (the parasite), the other (the host) is harmed.

Nomenclature of Microorganisms

• Carolus Linnaeus established the system of scientific nomenclature in 1735.
• Binomial nomenclature: each organism has two names (Genus + species) - italicized or underlined.
• Examples: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli). These reflect the way prokaryotes are named; viruses are not.

Diversity of Microbes

• Microorganisms are diverse. This includes bacteria, archaea, protozoa, fungi, viruses, and algae, as well as other organisms.
• Bacteria: single-celled prokaryotes
• Archaea: primitive prokaryotes, adapted to extreme habitats and modes of nutrition.
• Protozoa: eukaryotic, single-celled, colonial, many ways of nutrition.
• Fungi: single-celled or filamentous; mostly eukaryotic
• Viruses: acellular
• Algae: photosynthetic eukaryotes

Microbes Can be Cellular or Acellular

• Cellular microbes have cell membranes. They are divided into prokaryotes (e.g., bacteria, archaea) or eukaryotes (e.g., protozoa, algae, fungi).
• Acellular microbes (e.g., viruses, viroids, prions) lack a cytoplasmic membrane or any other cellular organization. They are not considered cellular and cannot be seen with a light microscope.

Prokaryotes and Eukaryotes

• Prokaryotes (e.g., bacteria, archaea): small, lack a nucleus and organelles. Reproduction is asexual.
• Eukaryotes (e.g., protists, fungi, plants, animals): larger, have a nucleus and organelles. Reproduction is either asexual or sexual.

Evolutionary Timeline

Classification of Microorganisms

• Classifications of microbes have evolved over time, with increasing detail and accuracy.
• The major classification schemes are: The Linnaean System, Whittaker System, and the Woese-Fox System.

Woese-Fox Classification

• Three-domain system: Archaea, Bacteria, and Eukarya.
• Based on rRNA gene sequences.
• Eubacteria (true bacteria) are important in pharmacy and medicine.
• Archaea have little or no pharmaceutical importance but are capable of living in extreme environments.

Modern Taxonomy - 6 Kingdom System

• Involves using Linnaeus's naming system, but with added kingdoms. (Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia)

Classification Systems in the Procaryotae

• Microscopic Morphology: examines the morphology/shapes and/or appearance, and/or size of microorganisms
• Macroscopic Morphology: involves the examination of the colony morphology
• Physiological/Biochemical Characteristics involve metabolic properties
• Chemical analysis: involves the chemical/physical analyses of components of a microorganism
• Serological analysis: involves analyzing the antibodies and antigens of a microorganism
• Genetic & Molecular Analysis involves characterizing microorganisms based on their genetic makeup: - G+C base composition: percentage of guanine and cytosine in DNA - DNA analysis using genetic probes
  - Nucleic acid sequencing (including rRNA analysis)

Classification of Bacteria

• The hierarchical classification of bacteria similar to those used for other groups of organisms.
• Classification include, Kingdom, Phylum, Class, Order, Family, Genus, Species
• For example, the bacteria S. aureus.

Species and Subspecies

• Species: a group of bacteria sharing characteristics
• Strain: a culture derived from a single bacterial ancestor.
• Type: subspecies with differences in antigenic makeup, susceptibility to viruses, and pathogenicity

Classification of Bacteria (Domain Bacteria)

• Domain Bacteria, with phyla such as Proteobacteria, Firmicutes, Actinobacteria, Spirochetes, Cyanobacteria, and Chlamydiae.

Eubacteria Diversity

• Different types/classes of eubacteria (Gram-positive, Gram-negative bacteria, photosynthetic bacteria, etc)

Classification of Microorganisms(Protozoa, Fungi, Algae, Viruses)

• Protozoa: unicellular eukaryotic microbes, often larger than bacteria. Important groups in medicine include amoebas, mastigophora, ciliophora, and sporozoa.
• Fungi: Eukaryotic organisms (saprophytic or parasitic) with rigid cell walls, including molds, yeasts, dimorphic fungi, and yeast-like fungi.
• Algae: unicellular or multicellular photosynthetic eukaryotes with cellulose cell walls.
• Viruses: non-cellular entities with a nucleic acid core (DNA or RNA) enclosed in a protein coat (capsid); they are obligate intracellular parasites.

This quiz explores the foundational concepts of microbiology and immunology. Learn about the importance of microorganisms in human health, the environment, and various industries. Assess your understanding of how these tiny organisms impact our lives.