Introduction to Microbiology

Learning Objectives

• Students will be introduced to Microbiology.
• Students will be introduced to the history of Microbiology.
• Students will be able to define some of the important techniques discovered in Microbiology.
• Students will understand the difference between taxonomy and classification and the taxonomy used today.
• Students will be introduced to one of the main classifications of living cells: Prokaryotes and Eukaryotes.

Microbiology

• Microbiology is the study of different organisms or life forms that can only be seen with microscopes.
• These organisms are known as "microorganisms".
• Microbiology includes fields like:
  • Virology
  • Mycology
  • Bacteriology
  • Immunology
  • Microbial Ecology
  • Biotechnological Microbiology
  • Environmental Microbiology
  • Food Microbiology
  • Molecular Biology

History of Microbiology

• Ibn cenna, in the golden age of Islamic civilization, was among the first to hypothesize the existence of microorganisms.
• Ibn Zuhr discovered scabies mites and Al-Razi gave the earliest known description of smallpox.
• Robert Hooke used the first primitive microscope in the late 1600s and observed strands of fungi.
• Antony Van Leeuwenhoek (1632-1723) used magnification lenses to observe microorganisms.
• Robert Koch (1843-1910) introduced staining techniques and methods to obtain bacteria in pure culture using solid media.
• Koch discovered the Anthrax bacillus, bacillus of tuberculosis, and Cholera vibrio.
• Louis Pasteur (1822-1895) investigated fermentation.
• Pasteurization involves heating liquids enough to kill spoilage bacteria.
• Pasteur developed a vaccine for rabies.
• Pasteur proposed aseptic techniques to prevent contamination by unwanted microbes.

Introduction to Taxonomy

• Taxonomy is the science that deals with the description, identification, naming, and classification of organisms.
• Classification is the 'grouping' of organisms based on particular characteristics.

History of Taxonomy

• The concepts of classification of organisms by type and binomial definition were first introduced.
• Aristotle was the first to attempt to classify the kinds of creatures by grouping them according to their similarities.
• He classified animals "with blood" and "without blood".
• Aristotle further divided the animals with blood into live-bearing and egg-bearing.
• Aristotle assumed that creatures could be grouped in order from lowest to highest, with the human species at the top.
• Carolus Linnaeus, a Swedish naturalist, is considered the 'Father of Taxonomy' since the 1700s.
• Linnaeus created a hierarchical classification system.
• Linnaeus established the system of binomial nomenclature.
• Linnaeus proposed three broad groups called kingdoms, into which the whole of nature could fit.
• The kingdoms of nature included animals, plants, and minerals.
• Binomial nomenclature names species using two words: genus, followed by species.

Kingdom Classification

• Carlous Linaaeus introduced the two-kingdom classification system in 1758.
• Édouard Chatton (1925) distinguished organisms in prokaryotes (without a distinct nucleus) and eukaryotes (with a distinct nucleus).
• Copeland proposed a four-kingdom system, moving prokaryotic organisms, bacteria and "blue-green algae" into the kingdom Monera.
• Robert Whittaker proposed a fifth kingdom to include fungi in 1969, and called it Kingdom Fungi.
• Carl Woese introduced the three-domain system in 1977.
• This divides cellular life forms into archaea, bacteria, and eukaryote domains based on 16S rRNA.

Other Classifications

• Artificial classification uses visible/expressed characters, exemplified by Linnaeus.
• Natural classification uses natural similarities, such as the system by Bentham and Hooker.
• Phylogenetic classification uses evolutionary relationships, exemplified by Engler & Prantle.

Naming of Microorganisms

• The Binomial Linnaeus system is used for scientific nomenclature.
• Each organism has two names: genus and specific epithet (species).
• The name is italicized or underlined.
• The genus is capitalized, and the specific epithet is in lowercase.
• Names could honor the scientist, with a Latin origin.
  • For example: Escherichia coli (E. coli) was named after Theodor Escherich.
  • The name also describes the habitat (colon/intestine).