Foundations of Microbiology

Chapter 1: The Microbial World and You

Learning Objectives

  • Define:

    • Microorganisms

    • Microbe

    • Microbiome/Microbiota

  • List the different types of microbes

  • Recognize the system of scientific nomenclature

  • Discuss the history of microbiology

  • Explore how microbes affect our lives (human welfare and disease)

Definitions in Microbiology

  • Microorganisms: Organisms too small to be seen with the unaided eye.

    • Definition of an organism: Individual life form, made of cells.

    • Does not include viruses due to non-cellular nature.

  • Microbes: Include all viruses and microorganisms, also too small to be seen with the unaided eye.

  • Microbiota: Physical microbes in and on the body, which help maintain good health.

  • Microbiome: All microbes and their genome (where
    genome = DNA).

Types of Microbes

  • Categories:

    • Bacteria

    • Archaea

    • Fungi

    • Protozoa

    • Algae

    • Viruses

    • Multicellular Animal Parasites (not strictly microorganisms; e.g., flatworms, roundworms)

Microbial Roles

  • Benefits:

    • Prevent food spoilage

    • Modifications of microbes for medicine creation

    • Understanding disease causes and transmission to prevent epidemics

    • Injecting microbes into the body for protection

  • Challenges:

    • Emerging Infectious Diseases (EIDs) due to evolutionary changes, rapid transportation, and human activity.

Naming & Classifying Microbes

  • Key Figure: Carolus Linnaeus

    • Established scientific nomenclature in 1735.

  • Naming Structure: Each organism has two names (genus and specific epithet):

    • Genus: Capitalized

    • Specific Epithet: Lowercase, italicized or underlined

    • Example: Escherichia coli (E. coli)

  • Descriptive Naming: Names can honor a scientist or describe habitat.

    • Example: Escherichia coli - honors Theodor Escher, describes habitat being large intestine (colon).

History of Microbiology

Key Concepts

  • Spontaneous Generation: Hypothesis that life arises from nonliving matter, requiring a "vital mystical force".

  • Biogenesis: Hypothesis that living cells arise only from preexisting living cells.

Historical Experiments

  • Francesco Redi (1668):

    • Experiment with decaying meat in three types of jars: opened, sealed, gauze-covered.

    • Results: Maggots developed only in open jars, no maggots in sealed or gauze-covered jars.

    • Conclusion: Refutes Spontaneous Generation.

  • John Needham (1745):

    • Boiled nutrient broth placed into covered flasks, resulted in microbial growth.

  • Lazzaro Spallanzani (1765):

    • Nutrient solutions boiled in sealed flasks, showed no microbial growth.

  • Louis Pasteur (1861):

    • Demonstrated that microorganisms exist in air.

    • Used S-shaped flasks to prevent microbial contamination yet allow air access.

Impact of Microbes on Human Welfare

  • Microbes play crucial roles in health, including:

    • Preventing pathogen growth (normal microbiota)

    • Production of medicines, vaccines, and medical tests

  • Types of Medical Uses:

    • Antibiotics

    • Insulin production

    • Vaccine development

Microbes and Human Diseases

  • Definition: Pathogen invades a host and overcomes its resistance, causing disease.

  • Emerging Infectious Diseases (EIDs):

    • New diseases or those increasing incidence due to evolution, transportation, and human interaction with environments.

Next Chapter

  • Upcoming focus: Chapter 4 - Functional Anatomy of Prokaryotic and Eukaryotic Cells, including cell structures like capsule, cell wall, plasma membrane, and more