Introduction of Microbiology Chapter 1 PDF

Introduction of Microbiology Chapter 1 Introduction – 1 ▪ Microbes grow everywhere, and they are incredibly abundant and diverse. A vast realm of biodiversity resides in Earth’s oceans. A human body contains roughly as many microbial cells as it does human cells! ▪ Mar...

Introduction of Microbiology Chapter 1 Introduction – 1 ▪ Microbes grow everywhere, and they are incredibly abundant and diverse. A vast realm of biodiversity resides in Earth’s oceans. A human body contains roughly as many microbial cells as it does human cells! ▪ Marine microbes were the first life forms on Earth, and they dominated the planet for nearly two billion years. ▪ Most of Earth’s microbial diversity remains a mystery. ▪ Microbiological research continues to produce novel solutions for human medicine, biotechnology, and conservation of the environment. 2 1.1 From Germ to Genome: What Is a Microbe? ▪ A microbe is a living organism that requires a microscope to be seen. ▪ Most microbes single cell, but some are multicellular. size from 0.2 micrometers (m) to just a few millimeters (mm). Viruses may be ten times smaller than the smallest cells. 3 A Microbe Is a Microscopic Organism – 1 Table 1.1 Microbe Description Approximate Size Varicella-zoster virus 1 Virus that causes chickenpox and shingles 100 nanometers (n m) equals 10 to the power minus 7 meter (m) Prochlorococcus Photosynthetic marine bacteria 500 n m equals 5 times 10 to the power minus 7 m Escherichia coli Bacteria growing within human intestine 1 micrometer (mu m) equals 10 to power minus 6 m Spirogyra Aquatic algae that form long filaments of cells 400 mu m equals 4 times 10 to the power minus 5 m (cell width) Pelomyxa Ameba (a protest) that consumes bacteria in soil or water 5 millimeters (m m) equals 5 times 10 to the power minus 3 m 4 A Microbe Is a Microscopic Organism – 2 ▪ Microbes: Prokaryotes (cells lacking a nucleus): bacteria, archaea Some eukaryotes (cells with a nucleus): algae, fungi, protists Viruses and prions (acellular entities) ▪ The bacteria, archaea, and eukaryotes—known as the three “domains”—evolved from a common ancestral cell. 5 A Microbe Is a Microscopic Organism – 3 6 Concept Check 1.1 Sari is a microbiology student attempting to identify a microbe that she can study for her senior thesis project. Which of the following headlines refers to a microbe that she might find interesting? a) “Multicellular fungus produces higher yields of commercial mushrooms” b) “Plant leaf tissue provides clues for new solar panel design” c) “Brain-eating amoeba strikes two teens in one week” d) “Human immune cells show elevated response to disease” 7 Concept Check 1.1 – Answer Sari is a microbiology student attempting to identify a microbe that she can study for her senior thesis project. Which of the following headlines refers to a microbe that she might find interesting? a) “Multicellular fungus produces higher yields of commercial mushrooms” b) “Plant leaf tissue provides clues for new solar panel design” c) “Brain-eating amoeba strikes two teens in one week” d) “Human immune cells show elevated response to disease” 8 Microbial Genomes Are Sequenced – 1 ▪ A genome comprises the total genetic information of an organism. ▪ The first method of DNA sequencing - fast enough to sequence large genomes - developed by Fred Sanger. 1980 Nobel Prize in chemistry. ▪ In 1995, first genome sequence , the bacterium Haemophilus influenzae. 9 Microbial Genomes Are Sequenced – 2 10 1.2 Microbes Shape Human History Yeasts and bacteria yielded fermented foods and beverages and spoiled meat and wine. “Rock-eating” bacteria (lithotrophs) aided metal mining and deteriorated ancient stone monuments. Microbes of all types caused diseases and famines. 11  Microbial Disease Devastates Human Populations – 1 ▪ Microbial diseases affected human demographics and cultural practices. Fourteenth century: bubonic plague caused by Yersinia pestis Nineteenth century: tuberculosis caused by Mycobacterium tuberculosis Today: Influenza and COVID- 19 Pandemic 12 Microbial Disease Devastates Human Populations – 4 ▪ More soldiers have died of microbial infections than of wounds in battle. ▪ Florence Nightingale (1820–1910): recognize the significance of disease in warfare ▪ Founded the science of medical statistics. To show the deaths of soldiers due to various causes, she devised the “polar area chart.” 13 Microscopes Reveal the Microbial World – 1 ▪ Robert Hooke (1635–1703) Built the first compound microscope Used it to observe mold Published Micrographia, the first manuscript that illustrated objects observed with a microscope Coined the term “cell” 14 Microscopes Reveal the Microbial World – 2 ▪ Antonie van Leeuwenhoek (1632– 1723) Dutch cloth draper and tailor Built single-lens magnifiers, complete with sample holder and focus adjustment First to observe single-celled microbes – He called them “small animals.” Spontaneous Generation: Do Microbes Have Parents? – 1 ▪ Theory of spontaneous generation: living creatures could arise without parents. ▪ Francesco Redi (1660s) showed that maggots in decaying meat were the offspring of flies. ▪ Lazzaro Spallanzani (1760s) showed that a sealed flask of meat broth sterilized by boiling failed to grow microbes. 16 Spontaneous Generation: Do Microbes Have Parents? – 2 ▪ Louis Pasteur (1822–1895) Discovered the microbial basis of fermentation Produced data that refuted spontaneous generation – Invented the “swan-neck” flask – Showed that a broth boiled in a swan-neck flask remained free of microbial growth, despite being exposed to air 17 1.3 Medical Microbiology ▪ Germ theory of disease: many diseases are caused by microbes. ▪ Robert Koch (1843–1910) Developed principles and methods crucial to microbial investigation Applied his methods to the study of several lethal diseases around the world 18 Growth of Microbes in Pure Culture ▪ Worked with anthrax and Mycobacterium. ▪ Demonstrated an important principle of epidemiology: the chain of infection, or transmission of a disease. ▪ Koch’s colleagues contributed important tools for the generation of pure cultures. Angelina and Walther Hesse: used the gelling agent agar to solidify liquid culture medium. Julius Petri developed the double-sided Petri dish container that bears his name. 19 Koch’s Postulates – 1 ▪ Koch’s postulates: an ordered set of criteria for establishing a causative link between an infectious agent and a disease. 1. Suspected microbe is always present in diseased hosts. – absent in healthy hosts 2. Suspected microbe is grown in pure culture outside hosts. – no other microbes present in culture 3. Cultured microbe is introduced into healthy hosts. – Individuals become sick with same disease as original hosts. 4. Same microbial suspect is re-isolated from sick individuals. 20 Concept Check 1.3 – 1 Manuel identified a microbe that is responsible for an unexplained respiratory illness in lab mice. He found the culprit in 14 ill mice, and he produced a pure culture of the microbe in the lab. He hasn’t yet received permission from the board of ethics to continue his study. Which of Koch’s four postulates has Manuel satisfied? a) Postulate #1 only b) Postulates #1 and #2 only c) Postulates #1, #2, and #3 only d) All four postulates 21 Concept Check 1.3 – 1 – Answer Manuel identified a microbe that is responsible for an unexplained respiratory illness in lab mice. He found the culprit in 14 ill mice, and he produced a pure culture of the microbe in the lab. He hasn’t yet received permission from the board of ethics to continue his study. Which of Koch’s four postulates has Manuel satisfied? a) Postulate #1 only b) Postulates #1 and #2 only c) Postulates #1, #2, and #3 only d) All four postulates 22 Immunization Prevents Disease – 1 ▪ In the eighteenth century, smallpox infected a large fraction of the European population. ▪ Lady Mary Montagu introduced the practice of smallpox inoculation to Europe in 1717. ▪ Edward Jenner (1749–1823) deliberately infected patients with material he collected from cowpox lesions. The practice of cowpox inoculation was called vaccination (from Latin vacca for “cow”). 23 Immunization Prevents Disease – 2 24 Immunization Prevents Disease – 3 ▪ Louis Pasteur developed the first vaccines based on attenuated (weakened) strains of microbes. Fowl cholera Rabies 25 Concept Check 1.3 – 2 The first vaccination was performed by _______ , and the first antibiotic was discovered by _______. a) Lady Montagu; Louis Pasteur b) Edward Jenner; Louis Pasteur c) Edward Jenner; Alexander Fleming d) Louis Pasteur; Alexander Fleming e) Louis Pasteur; Edward Jenner 26 Concept Check 1.3 – 2 – Answer The first vaccination was performed by _______ , and the first antibiotic was discovered by _______. a) Lady Montagu; Louis Pasteur b) Edward Jenner; Louis Pasteur c) Edward Jenner; Alexander Fleming d) Louis Pasteur; Alexander Fleming e) Louis Pasteur; Edward Jenner 27 Antiseptics and Antibiotics – 1 ▪ In 1847, Ignaz Semmelweis ordered doctors to wash their hands with chlorine, an antiseptic agent. Mortality rates fell. ▪ In 1865, Joseph Lister developed carbolic acid to treat wounds and clean surgical instruments. ▪ In the twentieth century, aseptic surgery was developed. Environments completely microbe-free 28 Antiseptics and Antibiotics – 2 ▪ In 1929, Alexander Fleming: discovered penicillin from Penicillium mold ▪ In 1941, Howard Florey and Ernst Chain purified penicillin. Quickly became the first commercial antibiotic used to save human lives. 29 The Discovery of Viruses – 1 ▪ In 1892, Dmitri Ivanovsky studied tobacco mosaic disease. Discovered that the agent of transmission could pass through a 0.1 μm porcelain filter that blocked all known microbes. Martinus Beijerinck proposed that the causative agent of tobacco mosaic disease is not a bacterium because it passes through a filter that retains bacteria. 30 1.4 Environment and Ecology ▪ Microbes cycle the many nutrients essential for life, including all global N2 and most of the O2 in Earth’s atmosphere. Less than 0.1% of all microbial species can be cultured in the laboratory. The remainder make up the majority of Earth’s biosphere. ▪ Only the outer skin of Earth supports complex multicellular life. 31 Environmental Microbes Support Ecosystems – 1 ▪ Sergei Winogradsky (1856–1953) Russian scientist who was among the first to study microbes in natural habitats Discovered lithotrophs, developed enrichment cultures Winogradsky column, a model of a wetland ecosystem containing regions of enrichment for microbes utilizing diverse metabolisms 32 Environmental Microbes Support Ecosystems – 2 ▪ Winogradsky and others showed the importance of bacteria in geochemical cycling. 33 1.5 The Microbial Family Tree ▪ Bewildering diversity of microbial life forms: nineteenth-century microbiologists with a seemingly impossible task of classification. ▪ The famous classifier of species, Swedish botanist Carolus Linnaeus (1707–1778), called the microbial world “chaos.” 34 Microbes Are a Challenge to Classify ▪ Early taxonomists faced two challenges as they attempted to classify microbes: 1. Resolution of the light microscope was too low. 2. Microbial species are hard to define. 35 Microbes Include Eukaryotes and Prokaryotes ▪ Ernst Haeckel (1834–1919) Determined microbes are neither plant nor animal Devised a third category of life, the Monera, for microbes ▪ Herbert Copeland (1902–1968) Divided Haeckel’s Monera into two groups: eukaryotic protists (protozoa and algae) and prokaryotic bacteria ▪ Robert Whittaker (1920–1980) Added Fungi as a fifth kingdom of eukaryotic microbes 36 Eukaryotes Evolved through Endosymbiosis – 1 ▪ Endosymbiotic theory by Lynn Margulis (1938–2011): changed classification scheme Eukaryotic organelles, such as mitochondria and chloroplasts, evolved by endosymbiosis from prokaryotic cells engulfed by pre-eukaryotes. 37 Archaea Differ from Bacteria and Eukaryotes – 1 ▪ In 1977, Carl Woese ▪ 16S rRNA revealed archaea are different than bacteria 38 Archaea Differ from Bacteria and Eukaryotes – 3 ▪ Woese’s discovery : three equally distinct groups called domains. Bacteria Archaea Eukarya 39 Concept Check 1.5 – 1 What does analysis of 16S rRNA sequences show? a) Plants and animals are as distant from bacteria as they are from each other. b) All microbes are distantly related to the eukaryotes. c) Archaea are as distant from bacteria as they are from eukaryotes. d) Viruses are closely related to prokaryotes. 40 Concept Check 1.5 – 1 – Answer What does analysis of 16S rRNA sequences show? a) Plants and animals are as distant from bacteria as they are from each other. b) All microbes are distantly related to the eukaryotes. c) Archaea are as distant from bacteria as they are from eukaryotes. d) Viruses are closely related to prokaryotes. 41 1.6 Cell Biology and the DNA Revolution ▪ More than 99% of what we know about microbes today was discovered after 1900. Advances in biochemistry and microscopy - fundamental structure and function of cell membranes and proteins. Revelation of the DNA and RNA structures - discovery of the genetic programs of model organisms. Genetic engineering 42 Cell Membranes and Macromolecules – 1 ▪ Two instruments had exceptional impact on the study of cell structure: 1. The electron microscope – Developed by Ernst Ruska – Revealed internal structure of cells 2. The ultracentrifuge – Developed by Theodor Svedberg – Enabled separation of subcellular parts 43 Cell Membranes and Macromolecules – 2 44 Microbial Genetics Leads the DNA Revolution – 1 ▪ In 1928, Frederick Griffith : Transformation in bacteria. ▪ In 1944, Oswald Avery and colleagues: transforming substance is DNA. ▪ In 1953, Rosalind Franklin used X-ray crystallography : DNA is a double helix. ▪ James Watson and Francis Crick: complementary bases and antiparallel nature of DNA. 45 Microbial Genetics Leads the DNA Revolution – 2 46 Microbial Genetics Leads the DNA Revolution – 3 ▪ Complementary pairing of DNA bases - development of techniques for DNA sequencing ▪ Reading the genomes enabled microbiologists to see the history of microbial evolution ▪ A heat-stable bacterial DNA polymerase - polymerase chain reaction (PCR). ▪ Bacteria readily recombine DNA from unrelated organisms. – Recombinant DNA ultimately enabled us to transfer genes (Recombinant DNA technology) ▪ Gene regulation discovered in bacteria provided models for animals and plants. 47 Microbial Discoveries Transform Medicine and Industry ▪ Research in microbiology finds applications in diverse fields. 48 Self Review 1. Define microbiology, microbes. 2. Identify types of microorganisms (cellular vs. acellular, prokaryotic vs. eukaryotic). 3. How do microbes shape human history? 4. Contributions of a. Florence Nightingale b. Robert Hooke c. Antonie van Leeuwenhoek d. Francesco Redi e. Lazzaro Spallanzani f. Louis Pasteur g. Robert Koch h. Lady Mary Montagu i. Edward Jenner j. Alexander Fleming k. Rosalind Franklin, James Watson, and Francis Crick 5. Spontaneous generation and Louis Pasteur’s Swan-neck flask experiment 6. Koch’s postulates. 7. Discovery of virus 8. Role of Winogradsky column. 9. Endosymbiotic theory and three domain classification (Bacteria, archaea, and eukarotes) 10. Fields of research in microbiology. 49