Chapter 1: The Microbial World and You PDF

Chapter 1 The Microbial World and You BIO 214: General Microbiology Outline Microbes in Our Lives Naming and Classifying Microbes A Brief History of Microbiology Microbes and Human Welfare Microbes and Human Disease Ask anonymous questions Micr...

Chapter 1 The Microbial World and You BIO 214: General Microbiology Outline Microbes in Our Lives Naming and Classifying Microbes A Brief History of Microbiology Microbes and Human Welfare Microbes and Human Disease Ask anonymous questions Microbes in Our Lives Questions? Microbe – _____________________ Requires microscope to see, invisible to the naked eye Single celled organisms Microbes are diverse Bacteria Archaea Fungi (yeast and mold) Protozoa Algae Viruses (non-cellular) Some microbes cause disease (________________) but the majority of microbes do not Environmental (food chain, nutrient cycling, photosynthesis) Commercial (production of chemicals, vitamins, fermented foods) The Microbiome Questions? The human body contains __________ body cells and __________ bacterial cells Human microbiota – ________________________________________ The microbiota contributes to human health Bacteria in our intestines (e.g. E. coli) aid digestion and synthesize vitamins Prevent pathogenic bacteria from colonizing Our bodies become populated by microbes at birth The Human Microbiome Initiative was launched in 2016 to expand our understanding of the role microbes in ecosystems such as the human body Microbes in our Lives Nomenclature Questions? The system of ____________________ (naming) organisms in use today was developed in 1735 by Carolus Linnaeus Assigns each organism two names, both italicized (underlined when written) _________________________ – first name, capitalized, can be abbreviated by initial _________________________ – not capitalized Names often describe the organism, honor a researcher, or identify the habitat Staphylococcus aureus Staphylo – ________________ coccus – _________________ aureus – Latin for golden, the color of the colonies Escherichia coli Escherichia – discovered by Theodor Escherich Microbes in our Lives Types of Microorganisms Questions? Bacteria Single-celled (unicellular) organisms Prokaryotes – lack a _____________ (DNA not contained within membrane-bound organelle) 3 common cell shapes ______________________ – rod-shaped ______________________ – spherical spiral Cells are surrounded by a cell wall composed of ______________ Chains of sugars (glycans) linked together by amino acids (peptide) Reproduce asexually through binary fission – dividing into two equal cells Microbes in our Lives Types of Microorganisms Questions? Archaea Single-celled (unicellular) organisms Prokaryotes Cell wall, but not composed of peptidoglycan Often __________________________ – found in extreme environments Methanogens – produce methane Halophiles – extremely salty environments Thermophiles – extremely hot environments Not known to cause disease Asexual reproduction Microbes in our Lives Types of Microorganisms Questions? Fungi Eukaryotes (DNA contained within a nuclear membrane) Can be multicellular or unicellular Cell wall, composed of chitin (polysaccharide) Fungi include: ____________ – unicellular form, larger than bacteria ____________ – form multicellular structures (mycelia – network of hyphae) Microbes in our Lives Types of Microorganisms Questions? ____________ Eukaryotes No cell wall Many move through using pseudopods, flagella, or cilia Can be free-living or parasitic (benefit at the expense of a host) Microbes in our Lives Types of Microorganisms Questions? Algae Eukaryotes Cell wall composed of cellulose (polysaccharide) ________________ Require sunlight, carbon dioxide (CO2), and water Produce oxygen (O2) and carbohydrates Microbes in our Lives Types of Microorganisms Questions? Viruses Acellular (lack cellular structure) Very small (requires electron microscope, a light microscope isn’t sufficient) Very simple structure Nucleic acid genome (either DNA or RNA) Protein coat – _____________ Optional: lipid membrane – envelope Reproduce by ________________________________ Don’t possess their own cellular machinery Strictly parasites Often considered not alive (no metabolism, host cell required for reproduction) Microbes in our Lives Classification of Microorganisms Questions? Before microbes were discovered, all organisms were classified as plants or animals Various systems were used since that time In 1978 Carl Woese developed the system used today All cellular organisms are grouped into 3 _____________ Bacteria Archaea May appear similar to bacteria but genetically distant (_______) Eukaryotes (further divided into kingdoms) Protists Fungi Plants Microbes in our Lives A Brief History of Microbiology Questions? Prokaryotes were the first organisms to appear on Earth And for a long time, microbes were the only lifeforms on Earth However, their existence went unrecognized for much of human history Microbes aren’t visible to the naked eye – required technological advances A Brief History of Microbiology The First Observations Questions? In 1665, using a simple compound microscope Robert Hooke first saw cells – life’s smallest structural unit Started the cell theory – that all organisms are composed of cells Hooke’s microscope was _____________________________ Plant/animal cells are typically larger than microbial cells A Brief History of Microbiology The First Observations Questions? In the late 17th century, _______________________________ first observed microbial cells using a high-quality lens Drew pictures of these “animalcules” he found in rainwater, feces, and dental plaque A Brief History of Microbiology The Debate over Spontaneous Generation Questions? After Leeuwenhoek discovered the invisible world of microbes, there was debate about where the microbes they were seeing came from Some believed in ___________________________________ – that microbes could arise spontaneously from non-living matter An alternative hypothesis was biogenesis – that living cells only arise from other living cells For example, nutrient-rich broth (e.g. chicken broth) is teeming with microbes if left sitting out for a few days  where do these microbes come from? A Brief History of Microbiology The Theory of Biogenesis Questions? Work by numerous scientists (spanning 100’s of years) does not support the theory of spontaneous generation Scientists observed that nutrient-rich broth (e.g. chicken broth) would be full of microbes after sitting out for a few days Lazzaro Spallanzani _________ fresh chicken broth in a flask and heated it – no microbes were found However, some argued that by sealing the flasks, Spallanzani had prevented some ‘________________’ (e.g. oxygen) from reaching the broth – and therefore prevented spontaneous generation A Brief History of Microbiology  The Theory of Biogenesis Questions? Louis Pasteur designed a flask that still allowed air to enter – while still remaining sterile _________________ flask – a curved neck prevents microbes from the air from falling into the flask Experiment 1: Experiment 2: Experiment 3: Add broth to open flask Add broth to flask, seal Add broth to swan-neck flask Sterilize broth by heatingSterilize broth by heatingSterilize broth by heating Let sit out for days Let sit out for days Let sit out for days Observe under microscope Observe under microscope Observe under microscope Cells appeared No cells appeared No cells appeared BuT nO aCcEsS tO ‘vItAl FoRcE’ A Brief History of Microbiology The Theory of Biogenesis Questions? A Brief History of Microbiology The Germ Theory of Disease Questions? For centuries, the cause of infectious diseases was unknown Many believed that disease was punishment by gods Others blamed ‘bad air’ – miasma theory The Germ Theory of Disease – microbes cause infectious disease A breakthrough occurred in 1876 when Robert Koch was investigating the cause of ________ While dissecting an animal with anthrax, Koch observed some rod- shaped bacteria in its blood He collected some cells, grew them in the lab, and used them to inoculate a healthy animal He followed these animals and saw they developed anthrax as well He found the same rod-shaped bacterium in the blood of these animals A Brief History of Microbiology The Germ Theory of Disease Questions? Led to the formation of __________________________ – a set of steps for linking a disease (i.e. illness) with the microbe responsible 1. The same microbe must be present in every individual with the disease (illness) and absent in healthy individuals 2. The microbe must be isolated from the diseased host and grown in ________________ 3. The microbe from the pure culture must cause disease when it’s inoculated into a healthy, susceptible laboratory animal 4. The microbe must be isolated from the inoculated animal and be shown to be the original microbe A Brief History of Microbiology The Germ Theory of Disease Questions? It turns out that not all pathogens (disease-causing microbes) adhere to Koch’s postulates In other words, not all of Koch’s postulates are met for certain diseases Can you think of some of these exceptions? A Brief History of Microbiology Vaccination Questions? The primary purpose of a _________________ is to prevent the development of an infectious disease Vaccination is based on the idea that exposure to a substance (i.e. vaccine) can prevent disease upon future exposure to the pathogen In the late 18th century, a physician names Edward Jenner was responsible for developing the first vaccine – a vaccine against ______________ At this time, the germ theory of disease was not widely accepted Therefore, the first vaccine was developed before _____________________________________ Later, it was discovered that smallpox is caused by a virus A Brief History of Microbiology Vaccination Questions? Edward Jenner noticed that milkmaids rarely developed smallpox Smallpox was a deadly disease, wiping out entire populations Instead, milkmaids tended to develop a milder disease called _____________ Jenner hypothesized that the development of cowpox somehow prevented the development of smallpox To test his hypothesis, Jenner scraped puss from a cowpox lesion and used it to inoculate a young volunteer (ethical?) The boy developed symptoms of cowpox but was protected (immune) from deadly smallpox Later on, it was discovered that cowpox is caused by a virus that is very similar to the virus that causes smallpox. The similarity between the two viruses is sufficient to train the immune system. A Brief History of Microbiology A Fortunate Accident – AntibioticsQuestions? The primary purpose of an _________________ is the treat an limited S. infectious disease aureus mold In 1928, a microbiologist named Alexander Fleming was growth studying the bacterium Staphylococcus aureus in his lab He went away for a week and left some S. aureus cultures on his bench After returning, he noticed that mold had contaminated one of his cultures Upon further inspection, he realized that the S. aureus bacteria did not grow next to the mold Fleming hypothesized that the mold was releasing something that prevented growth of the S. aureus bacteria He eventually isolated the compound and called it ______________ named after the mold that produced it S. aureus (Penicillium) colonies A Brief History of Microbiology Antibiotics Questions? Antibiotics have saved countless lives since their discovery However, their effectiveness has been compromised due to the development of antibiotic resistant bacteria Antibiotic resistant bacteria have mutations that them to survive in the presence of the antibiotic Antibiotic resistance is _________________ (“where there’s a will, there’s a way”) but we can _______________ Also, antibiotics are effective against _________________ Remember, virus lack cellular structure A Brief History of Microbiology The Genomics Era Questions? Today, we can learn about microbes by reading their _____________ – all the genes (DNA) that make up the microbe This allows us to see what a microbe is capable of without having to observe/culture it directly A microbe with a gene for the lactase can break down lactose We can also learn _______________________ (evolutionarily) Similar genome = closely-related A Brief History of Microbiology Microbes and Human Welfare Questions? Most microbes do not cause disease In fact, many microbes have a positive impact on human health Microbiota, as mentioned earlier Biogeochemical cycling Bioremediation Pest control Fermented foods (covered in future chapters) Biotechnology (covered in future chapters) Biogeochemical Cycling Questions? Microbes play a crucial role in converting chemical elements into various forms Nitrogen, carbon, oxygen Many organisms (including humans) can only access elements if they’re in the proper form Animals require N but can’t use N2 (atmospheric nitrogen), microbes can (nitrogen fixation) Part of microbial _________ – how microbes interact with the world around them Microbes and Human Welfare Bioremediation Questions? _____________________ can be broken down by microbes  bioremediation Helped to clean up the Deepwater Horizon oil spill in 2010 210 million gallons of oil leaked into the Gulf of Mexico Microbes learned how (evolved) to use the oil as a food source Similarly, there are microbes that break down _________ Microbes and Human Welfare Pest Control Questions? Insects often cause devastating crop damage Some bacteria naturally produce compounds that are toxic to insects (insecticides) E.g. Bacillus thuringienesis (___ for short) Bt is applied to crops to prevent insects from damaging the crops Insects consume a toxin produced by Bt The toxin only affects insects, it. has no effect on plants or other animals Microbes and Human Welfare Microbes and Human Disease Questions? Disease – a condition that prevents the body from functioning normally Exhibits signs and symptoms (e.g. nausea) Some diseases are ________________ – they develop when an individual acquires a disease-causing microbe Diseases can also have genetic or environmental causes (or a combination) Pathogen – _____________________ Important: a bacterium (such as E. coli) is not a disease. E. coli is a pathogen that is capable of causing disease. Related: COVID-19 is an infectious disease caused by the virus SARS-CoV-2 Microbes and Human Disease Microbes and Human Disease Questions? The human body has numerous defenses to combat pathogens  immune system However, pathogens have learned how to subvert these defenses, at least temporarily _________ – short-term infection _________ – long-term infection (e.g. for life) Microbes and Human Disease Microbes and Human Disease Questions? Some pathogens have been infecting humans for a very long time Malaria (first described c. 2700 BC) Tuberculosis (found in bones from c. 7000 BC) Other pathogens are relatively new – cause _____________ diseases HIV (first described in 1981, likely arose early 20th century) COVID-19 (arose in 2019, developed into pandemic by 2020) Microbes and Human Disease Microbes and Human Disease Questions? Disease is not a pathogen’s ultimate goal Just like any organism, their goal is _________ and _________ Instead, the human body represents an environment for survival and reproduction Since pathogens utilize host resources (nutrients, space in the body), they can cause damage to the host The pathogen also wants a way to find a way to _________ to new hosts; therefore, they cause symptoms that will increase their chances of spreading to a new host Microbes and Human Disease