Intro to Microbiology and Naming Microorganisms

• Microbiology studies microorganisms like bacteria, fungi, protozoa, viruses and algae. The key areas of study are bacteriology, mycology, parasitology, virology, and immunology.
• Microbes are beneficial, used in normal flora, food, waste recycling, bioremediation, sewage treatment, biotech, gene therapy, and pest control. Specific examples include the production of fermented foods, antibiotics, insulin, and biofuels.

Naming Microorganisms

• Carolus Linnaeus established the method of standardized nomenclature.
• Each organism has two Latin names, a genus and species; both are underlined or italicized. For example, Staphylococcus aureus.
• Staphylococcus indicates a clustered arrangement of cells and aureus denotes golden color.
• Abbreviations can be used after the full name is introduced (e.g., S. aureus).

Types of Cells

• The two cell types are prokaryotes (no nucleus) and eukaryotes (have a nucleus).
• Bacteria and Archaea are prokaryotes
• Fungi, Protozoa, Helminths, animals, plants, and algae are eukaryotes

Bacteria

• Bacteria are prokaryotic with no nucleus and the genetic material (DNA) is not enclosed by a nuclear membrane.
• Bacteria cells are unicellular and contain a cell wall composed of peptidoglycan.
• Basic shapes of Bacteria are rod, sphere, and spiral.
• Bacteria have varied nutritional requirements.

Fungi

• Fungi are Eukaryotic and posses nuclei (eu = true, kary = nucleus)
• Fungi are generally multicellular, with yeast (Candida albicans) being a unicellular exception.
• They require organic materials for nutrition and decompose dead plant matter.
• Some drugs, like penicillin, are produced by fungi.
• Examples of fungi include mushrooms, mold, and yeast.

Protozoa

• Protozoa are eukaryotic and unicellular
• The literal meaning of protozoan is "first animal"
• Protozoa move by pseudopods, flagella, or cilia.
• Protozoa can be free-living or parasitic and form cysts under adverse conditions. They survive in water or soil, and possess approximately 20,000 different species.

Helminths

• Helminths are eukaryotic and multicellular.
• Helminths worms are not technically microorganisms, but they remain microscopic during some part of their life.
• Platyhelminths (flatworms) and nematoda (roundworms) are included

Viruses

• Viruses are non-cellular entities consisting of a protein coat enclosing a DNA or RNA core.
• Viruses are neither living or non-living, but are borderline between the classifications in that they are obligate intracellular parasites, and require cells to reproduce.

Bacteriophage

• Bacteriophages are viruses that infect bacteria through a specific "host range".
• They are useful in bacterial species identification, with lytic and lysogenic replication cycles.
• Lytic Cycle: Phage attaches to host and injects DNA, the cell then lyses releasing phage virions
• Lysogenic cycle: the phage DNA is integrated with the bacterial chromosome, recombining into the cell, becoming a prophage, eventually excising out and starting the lytic cycle.

History of Microbiology

• Robert Hooke in 1665 was the first to observe cells using a crude microscope, but lacked staining techniques.
• Hooke called observed specimens "little boxes" or "cells", and cells became known as the smallest structural units of like, starting cell theory.
• Hooke was likely unable to observe living specimens .

Spontaneous Generation vs. Biogenesis

• Spontaneous generation is the hypothesis stating that living organisms arise from non-living matter, from a vital force, or spontaneously.
• Biogenesis is the alternative hypothesis stating that living organisms arise from preexisting life.
• Louis Pasteur demonstrated microbes are present in the air and support the theory of biogenesis.
• Nutrient broth heated in a flask open to air underwent microbial growth.
• Nutrient broth heated in a sealed flask showed no microbial growth.
• S-shaped flasks allow air to flow , but keep microbes out, showing air does not spontaneously grow microbes.
• Pasteur demonstrated microbes can contaminate sterile solutions and that microbes can be destroyed by heat.
• As a result, Pasteur's work formed the basis for aseptic technique, and lead into the Golden Age of Microbiology.

Golden Age of Microbiology

• The Golden Age of Microbiology occurred from 1857-1914.
• During this period, microbiology was established as a science.
• The main contributors of the time were Louis Pasteur, Robert Koch, and Alexander Fleming.
• Before this, many thought microbes arose from spontaneous generation and that microbes had no connection to disease

Pasteurization

• In 1864, Louis Pasteur sought a solution for why wine and beer spoil during transport.
• The popular theory believed air converted sugar to alcohol.
• It was discovered yeast converts sugar to alcohol without air via fermentation.
• Microbes (bacteria) were shown to convert alcohol to acetic acid (vinegar), causing spoilage.
• Heating liquid foods to kill spoilage bacteria is the process called Pasteurization.

Germ Theory of Disease

• At the time, disease was thought to be a punishment, or caused by demons.
• It was inconceivable to early scholars that "invisible" microbes could be the source of illness.
• Ignaz Semmelweis, in 1840, showed that doctors were spreading infection by interacting with multiple obstetric patients, and recommended handwashing to prevent it.
• Joseph Lister, in 1860, heard of Pasteur's work and believed he could connect bacteria to disease through antiseptic surgery via microbes.
• Lister used phenol to treat surgical wounds and reduce infection and death, eventually reasoning that microbes may be the cause wound infections.

Robert Koch

• In 1876, Robert Koch was the first to successfully prove that bacteria cause disease.
• Koch was working with anthrax, and set in motion the sequence of experimental steps to relate a microbe to a disease, known as Koch's Postulates.
• Pathogen must be present in every case.
• Pathogen must be isolated and cultured outside of host.
• Cultured pathogen must cause disease in healthy host upon inoculation.
• Pathogen must be isolated from diseased inoculated animal

Vaccination Pioneer

• Edward Jenner 1796 was the first to explore immunity and protection from disease by using vaccinations.
• Jenner also connected cowpox as a protective inoculation against smallpox, noting vacca is also Latin for cow as well.
• The connection between microbes and disease was established.
• Vaccines now include attenuated, killed, subunit, and genetically engineered varieties.

Antibiotics Discovery

• The relationship between microbes and disease was established, and researchers sought an ideal drug.
• The ideal drug should be able to destroy microbes without damaging the host.
• Paul Erlich, in 1910, searched for a "magic bullet", resulting in the first synthetic drug Salvarsan.
• Salvarsan was effective at treating syphilis & trypansomiasis, and was an arsenic derivative.
• Alexander Fleming, in 1928, was a physician whom identified Penicillin notatum mold.
• Fleming discovered that cultures contaminated with the Penicillium mold actually prevented bacterial growth. The active inhibitor was named penicillin, with initial testing production starting in 1940