Session 1 - Introduction

• Biology is the study of living organisms.
• Microbiology is an advanced biology course
• Microbiology is the study of microbes, which are extremely small (microscopic) living organisms and certain non-living entities.
• Living microbes are known as cellular microbes or microorganisms; examples include bacteria, archaea, some algae, protozoa, and some fungi.
• Nonliving microbes are known as acellular microbes or infectious particles; examples include viroids, prions, and viruses
• Microbes are ubiquitous (i.e., they are found virtually everywhere).
• Microorganisms represent the major fraction of the Earth’s biomass.
• Plants and animals are engaged in the world of microbes, their evolution and survival are influenced by microbial activities
• The microbes that cause disease are sometimes referred to as “germs.” The scientific term for disease-causing microbes are called pathogens. Microbes that do not cause disease are called non-pathogens; the vast majority of microbes are non-pathogens.
• Microbes that live on and in our bodies are referred to as our indigenous microbiota.
• Some members of our indigenous microbiota are opportunistic pathogens.
• Opportunistic pathogens are microbes that can cause disease, but usually do not; they can be thought of as microbes that are awaiting the opportunity to cause disease.
• Pathogens cause two categories of diseases: infectious diseases and microbial intoxications.
• Microbial cells first appeared between 3.8 and 4.3 billion years ago. First 2 billion years of Earth’s existence, microorganisms are capable to survive without oxygen in the atmosphere.
• Candidates for the first microorganisms on Earth are archaea and cyanobacteria. 1 billion years ago, phototrophic microorganisms (organisms that harvest energy from sunlight) occurred.
• Purple sulfur bacteria and green sulfur bacteria were anoxygenic (non-oxygen producing) were the first phototrophs.
• Cyanobacteria (oxygenic phototrophs) evolved and began the slow process of oxygenating Earth’s atmosphere, multicellular life forms eventually evolved.
• Earliest known account of pestilence occurred in Egypt in about 3180 BCE.
• Starting around 5,000 B.C.E., Sumerians and Egyptians produced many foods using fermentation, such as bread, wine, and beer. They did not have the knowledge to explain exactly how those products were made, nor why this biological process happened. Therefore, they commonly viewed this technique as a miracle provided by their gods.
• During The Dark Ages in Medieval Europe, the pandemic plague has killed as much as one-third of the continent’s population in individual pandemics in the Middle Ages.
• The plague in Medieval Europe was caused by Yersinia pestis, a zoonotic disease from domestic and wild rats.
• Robert Hooke (1635–1703)

  Illustrated the first known image of microscope and fruiting molds.

  Cut thin slices of cork and observed under the microscope the presence of “tiny little boxes”.

  He started to formulate the “Cell Theory”

  Formulate the word cell.
• The Cell Theory is proposed later on by Theodore Schwann and Matthias Jakob Schleiden in 1838, the theory states that all plants and animals are made up of cells marked a great conceptual advance in biology and resulted in renewed attention to the living processes that go on in cells.
• Antoine Van Leeuwenhoek (1632–1723)

  “Father of Microbiology”

  Not a trained scientist!

  Made many simple single-lens microscopes

  Observed “animalcules” (bacteria and protozoa)
• The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were commonplace and regular
• Spontaneous generation is a body of thought on the ordinary formation of living organisms without descent from similar organisms.
• Francisco Redi

  Italian physician who first challenged to disprove the theory of spontaneous generation in 1668 through a controlled experiment which will be later coined as the Redi’s experiment.
• John Needham

  • In 1745, he defended the theory of spontaneous generation after observing that a heated uncovered flask containing broth still developed microorganisms after cooling the broth in open air.
• Rudolf Virchow

  Famous German physician and cellular pathologist who introduced the theory of biogenesis in 1858.
• Theory of biogenesis claims that living cells arise only from preexisting living cells.
• Louis Pasteur

  • French chemist who made numerous contributions to microbiology including the resolution of the debate over spontaneous generation in 1861
• Lazaro Spallanzani disproven Needham's claim in 1765 by suggesting that microorganisms from the air probably enter Needham's solutions after they were boiled.
• Edward Jenner is a young British physician who pioneered the concept of vaccination by inoculating a healthy 8-year-old boy with scrapings of cowpox blisters from a previously cowpox-infected milkmaid.
• Edward Jenner developed vaccine for smallpox.
• Ignaz Sammelweiz is a Hungarian physician who pioneered the antiseptic procedures through the development of the proper handwashing technique. The technique lowered the death rate of newly delivered mothers by decreasing the incidence of bacterial infections during childbirth.
• Other contributions of Pasteur:

  • 1857: Investigated different fermentation products
  • 1864: Developed the pasteurization process
  • Discovered life forms that could exist without oxygen (anaerobes)
  • Developed several vaccines, including rabies and anthrax vaccines
• Joseph Lister is a British surgeon and medical scientist who introduced the aseptic technique in order to kill and prevent from microbial infection of surgical patients.
• Joseph Lister performed surgery under aseptic conditions using phenol.
• Robert Koch discovered the bacteria that causes tuberculosis and anthrax.
• Robert Koch discovered that Bacillus anthracis produced spores.