Microbiology Chapter 1: An Invisible World

Microorganism or Microbe

Organisms too small to be seen with the unaided eye

Examples of Microbes

Bacteria, Fungi, Protozoa, Microscopic Algae, Viruses

Abilities of Microbes

- Decompose/Produce (Ecosystems)

- Create Chemicals (Vitamins, Acetone)

- Help make Biofuels, Medicines (Insulin)

- Create Fermented Foods (Cheese, Vinegar)

- Cause Diseases (Pathogenic)

Microbial Fermentation

Process when bacteria, mold or yeast convert sugar (carbs) --> Alcohol, Gases, Organic Acids

What is the early evidence that Ancient Civilizations understood that disease was transmitted to things they couldn't see?

Quarantine - Bible refers to quarantine to stop leprosy

Clean water/sanitation - Moheno-daro → wells, baths, and sanitation systems

Aqueducts and giant sewers → built in Rome to eliminate waste

Hygiene Practices - ancient Greek civilization attributed malaria to bad air

Hippocrates (Greek Physician)

Believed diseases had natural, not supernatural causes

Thucydides (Historian)

Observed that the survivors of the plague were immune to the infection

Marcus Terentius Varro

Proposed that disease could be caused by "certain minute creatures... which cannot be seen by the eye."

Abū Bakr al-Rāzī

Islamic scholar - developed experimental methods to test aspects of medicine

Antoine van Leeuwenhoek (Scientist | 1673-1723)

"Father of Biology" created simple microscope (one lens) to view microbes called "animalcules"

Golden Age of Microbiology (1857-1914)

Spawned new discoveries from 1857-1914

Louis Pasteur (French Chemist | 1822-1895)

- Invented pasteurization, a process that killed microorganisms responsible for spoilage

- Created vaccines that treated diseases (rabies)

Robert Koch (German Physician | 1843-1910)

Connected isolated microbe (bacteria) to human disease

Taxonomy

Classification, Description, Identification, and Naming of living organisms

Carolus Linnaeus ( Physician | 1701-1778)

The most famous early taxonomist

Systema Naturae (1735)

Booklet that Linnaeus published proposing Linnaean taxonomy, a standard format of categorizing/naming organisms

Kingdoms of the Natural World (Linnaeus)

Animal, Plant, Mineral (abandoned later)

Phylogenies

System used to classify organisms using genetic and evolutionary relationships

Phylogenetic Tree | Tree of Life

Diagram of organisms arranged by close relation

- Visible similarities at first | Now genetic, biochemical, and embryological analyses

Carl Woese and George Fox

Discovered a "living record" of evolution and created a genetics-based tree of life using gene sequences coding for subunit ribosomal RNA (rRNA)

3 Domains of Life

Bacteria (Prokaryotic), Archaea (Prokaryotic), Eukarya (Eukaryotic)

4 Kingdoms of Eukarya

Protists, Fungi, Plants, and Animals

What is the format of Binomial Nomenclature?

Genus (Capitalized) + Epithet (lowercase), Italicized or Underlined

How is the Genus represented after first use in Binomial Nomenclature?

Genus is abbreviated, e.g., Escherichia coli --> E. Coli

Bergey's Manuals (1923)

Bergey's Manual of Determinative Bacteriology and Bergey's Manual of Systematic Bacteriology are the standard references used to identify/classify different prokaryotes

Biochemical Tests

Used to identify chemicals unique to specific species

Serological Tests

Used to detect antibodies that react against proteins in a certain species

DNA and rRNA Sequencing

Used to identify specific bacteria species using unique genetic codes to match microorganisms

Typical measurement of Viruses

About 100 nm = 0.1 μm

Typical measurement of Bacterium

~ 1 μm

Typical measurement of plant or animal cell

~10-100 μm (Visible)

Bacterial Cellular Structure

Unicellular Prokaryotic - Single cell, lack nucleus

Bacterial Cell Wall

Composed of peptidoglycan

Photosynthetic

Obtain energy from sunlight and fixing carbon dioxide

Nonphotosynthetic

Obtain energy from organic or inorganic compounds

Coccus (Cocci)

Spherical shape of bacteria

Bacillus (Bacilli)

Rod shape of bacteria

Sprillium

Spiral shape of bacteria

Spirochete

Tight spiral shape of bacteria

Vibrio (vibrios)

Curved shape of bacteria

Coccobacillus (Coccobacilli)

Short round rod shape of bacteria

Archaea

Unicellular prokaryotic organisms found in extreme environments

- Pseudopeptidoglycan walls

Protist

Eukaryotes that are not plants, animals, or fungi

Algae

Protists that are either unicellular or multicellular, and have cell walls made of cellulose

Protozoa

Diverse protists that provide nutrients as food

Fungi

- Eukaryotes (distinct nucleus) with chitin cell walls and absorb organic chemicals for energy

Yeast

Diverse unicellular fungi

Ex. rising bread, fermentation, food spoilage, yeast infections

Mushrooms

Multicellular fungi consisting of masses of mycelia, (filaments - hyphae)

Molds

Multicellular fungi: decomposition, pharmaceuticals (penicillin), disease-causing metabolites (mycotoxins)

Helminths

(Visible) Multicellular animals - parasitic worms (flatworms and roundworms)

- Microscopic eggs and larvae cause diseases

Viruses

Acellular microbes (no cells) made up of proteins and genetic material (DNA or RNA)

- Can infect all types of cells, don't move outside of host organisms and multiply in host cells