Page 1 of 6 BIOL 3702 Lecture Outline Chapter 1: The History and Scope of Microbiology Importance and Scope ◆ World wide, microbes contain ✳ 50% of the Earth’s biological carbon ✳ 90% of the Earth’s biological nitrogen ◆ Microbes are ✳ found in every environment ✳ essential for the cycling of elements ✳ the basis of the world’s food chain ◆ Microbes interact with humans on a daily basis both in beneficial and harmful ways What is Microbiology? ◆ The term “microbiology” is defined as: ✳ The study of organisms and agents too small to be seen clearly with the unaided eye. Such organisms and agents are termed microorganisms (or microbes) ✳ The use of techniques necessary to isolate, grow, and study microbes ◆ Two fundamentally different types of cells exist among microbes ✳ Procaryotic - “before nucleus” ✳ Eucaryotic - “true nucleus” ◆ Procaryotes ✳ Lack a membrane-bound nucleus and organelles ✳ Include all bacteria and the archaeobacteria (“ancient bacteria”) ◆ Eucaryotes ✳ Possess a membrane-bound nucleus and organelles ✳ Includes all algae, fungi, protozoans, and helminths (Higher plants and animals are also eucaryotic, but are not typically a focus of study by microbiologists.)BIOL 3702 Lecture Outline Chapter 1 Page 2 of 6 ◆ These observations, in addition to modes of nutrition, led to the establishment of the Five Kingdom system of classifying organisms ✳ Monera (bacteria) ✳ Protista (mainly protozoans) ✳ Fungi (molds and yeasts) ✳ Planta ✳ Animalia ◆ Through advances in cell biology, biochemistry, and genetics, it is clear that living organisms are more complex than once thought and are now divided into Domains which themselves are comprised of various kingdoms ✳ Bacteria (procaryotic - “true bacteria”) ✳ Archaea (procaryotic - “ancient bacteria”) ✳ Eucarya (eucaryotic - “true nucleus”) ◆ Domain Archaea is distinguished from Bacteria based upon ✳ Differences in ribosomal RNA sequences ✳ The absence of cell-wall peptidoglycan ✳ The presence of unique membrane lipids ◆ Domain Eucarya includes organisms formerly classified as protists in addition to plants, fungi, and animals ◆ Also studied by microbiologists are viruses - acellular, obligate intracellular parasites The Discovery of Microorganisms ◆ Before they were visibly observed, microbes were suspected not only to exist, but also to cause disease ✳ Lucretius, a Roman philosopher ✳ Fracastoro, a 16th century physician ◆ 1590 - Hans Jansen developed the first useful apparatus with compound lenses (telescope? Microscope?) ◆ In 1665, Robert Hooke published the first drawing of a microorganism in Micrographia ✳ Coined the term “cells” to describe the “little boxes” he observed in examining cork slices with a compound microscope ✳ In 1665, published the book Micrographia documenting his various observations ✳ In 1678, he was asked to confirm van Leeuwenhoek’s observationsBIOL 3702 Lecture Outline Chapter 1 Page 3 of 6 ◆ Antony van Leeuwenhoek was the first person to extensively publish observations of microorganisms ✳ Developed single lens microscopes ✳ 1673 to 1676 - published his discovery of “animalcules”, including “vinegar eels” Spontaneous Generation Debate ◆ From before the time of Aristotle (384-322 B.C.), people believed that life could arise from non-living matter, i.e., spontaneous generation ◆ “Evidence” includes: ✳ Mice from grain ✳ Beetles from dust ✳ Worms and frogs from mud ✳ Maggots from rotting meat ◆ In the late 1600s, Francesco Redi challenged this view through a series of experiments involving rotting meat ◆ Redi’s experiments, and those by others, refuted the spontaneous generation theory for larger organisms ◆ These experiments did not, however, dispel speculation that the theory still held true for microorganisms ◆ Proponents cited evidence of microbial growth in boiled extracts of hay or meat ◆ For the next 150 years, proponents for and opponents against spontaneous generation provided numerous “proofs” ◆ Proponents linked their proof to the a “vital force” that existed in the air and was sensitive to extreme heat ◆ By the late 1800s, Pasteur and Tyndall conclusively disproved the theory of spontaneous generation ◆ Louis Pasteur ✳ Father of Microbiology ✳ Contributions include: ● Wine fermentation ● Microbial diseases of grapes and silkworms ● “Pasteurization” ● Rabies vaccine ◆ In 1861, Pasteur provided definitive proof against spontaneous generation using swan-necked flasksBIOL 3702 Lecture Outline Chapter 1 Page 4 of 6 ◆ John Tyndall ✳ English physicist - first scientist to study greenhouse gases and climate change ✳ Demonstrated the existence of heat-resistant bacteria, thereby extending Pasteur’s findings Microbes and Disease ◆ Despite the discovery of microbes, their role in causing disease was not recognized until the early 1800s ◆ Prior to this, it was commonly thought that most diseases were due to supernatural forces, poisonous vapors (miasmas), or an imbalance of the four humors - blood, phlegm, yellow bile, and black bile ◆ Support for a Germ Theory of disease: ✳ 1835 - Bassi discovers that a fungus causes a form of silkworm disease ✳ 1845 - Berkeley proves that the Great Potato Blight of Ireland is due to a fungus ✳ 1853 - de Bary demonstrates fungal causes for certain cereal crop diseases ✳ Late 1800s - Pasteur demonstrates a protozoan disease of silkworms ◆ Indirect evidence for microbial disease in human comes from Joseph Lister ✳ Implemented the use of sterile surgical instruments ✳ Used carbolic acid (phenol) during surgery and on wound dressings ◆ Robert Koch - first to directly prove a role for microbes in human disease ✳ 1876 - used a set of criteria to establish the cause of anthrax ✳ Criteria first proposed by Koch’s mentor, Jacob Henle ◆ Criteria known as Koch’s Postulates: 1) The microbe must be present in each disease case, but absent from healthy individuals 2) The suspected microbe must be isolated from the disease case and grown in pure culture 3) The same disease must result when a healthy host is inoculated with the isolated microbe 4) The same microbe must be isolated again in pure culture from the diseased host ◆ Using these principles, Koch demonstrated the causes of anthrax (1876), tuberculosis (1882), and