Microbiology Textbook - Chapter 1 PDF

CHAPTER 1 A Brief History of Microbiology  What is Microbiology?  The study of microorganisms or microbes  Microbiology spans a wide variety of fields:  Health care  Agriculture  Industry  Environmental sciences  Humans rely on microbes f...

CHAPTER 1 A Brief History of Microbiology  What is Microbiology?  The study of microorganisms or microbes  Microbiology spans a wide variety of fields:  Health care  Agriculture  Industry  Environmental sciences  Humans rely on microbes for:  Food production Acquiring Antibiotic resistance https://bit.ly/2P1m9g1  Making medications  Breaking down certain environmental hazards Microbiology  What Does Life Really Look Like?  Antoni van Leeuwenhoek (1632-1723) Lens Specimen holder  Began making and using simple microscopes; one per specimen  Examined water and visualized tiny animals, fungi, algae, and single-celled protozoa; “animalcules”  Microorganisms  Disease causing MO are pathogens The Early Years of Microbiology  How Are Microbes Classified?  Carolus Linnaeus (1707- 1778) developed a taxonomic system for naming plants and animals  Microorganisms can be grouped into six categories:  Bacteria  Archaea  Fungi  Protozoa  Algae  Small multicellular animals The Early Years of Microbiology  Bacteria and Archaea  Survive everywhere!  Some isolated in extreme environments (temp, pH, salt)  Reproduce asexually  Cell walls:  Bacterial cell walls contain peptidoglycan  Some bacteria lack cell walls Figure 1.4  Archaeal cell walls are composed The bacterium Streptococcus and two human cheek cells of polymers (polysaccharides) How are microbes classified? PROKARYOTES  Fungi  Eukaryotic with cell walls  Obtain food from other organisms  Molds—multicellular; grow as long filaments; reproduce by sexual and asexual spores  Yeasts—unicellular; reproduce asexually by budding; some produce sexual spores Figure 1.5 – Fungi How are microbes classified? EUKARYOTES  Fungi Macroscopic filamentous fungi – large fruiting bodies Honey Mushroom fungus – Armillaria Saccharomyces cerevisiae Multicellular Filamentous mold – Rhizopus How are microbes classified? EUKARYOTES  Fungi How are microbes classified? EUKARYOTES  Protozoa  Single-celled eukaryotes  Similar to animals in nutrient needs and cellular structure  Live freely in water;  Some live in animal hosts  Asexual (mostly) and sexual reproduction  Most are capable of locomotion by: Figure 1.5  Pseudopods  Cilia  Flagella How are microbes classified? EUKARYOTES  Protozoa  Examples that are infectious to humans:  Amoeba – Entamoeba causes dysentery (intestinal inflammation)  Ciliates – Balantidium causes dysentery  Flagellates – Giardia causes diarrhea  Non-motile – Plasmodium causes malaria (infect RBCs and liver) Amoeba proteus Blepharisma americana Peranema Figure 1.6 - Locomotive structures of protozoa How are microbes classified? EUKARYOTES  Algae  Unicellular or multicellular eukaryotes  Photosynthetic  Simple reproductive structures  Grouped on the basis of pigmentation and composition of cell wall Figure 1.7 a and b: Algae/diatoms How are microbes classified? EUKARYOTES  Algae  Exposures to the toxins can occur when people or animals have direct contact with contaminated water:  Swimming  Breathing in aerosols  Swallowing toxins by drinking contaminated water or eating contaminated fish/shellfish How are microbes classified? EUKARYOTES  Other Important “Microbes” and Infectious Agents  Parasites  Viruses  Prions Figure 1.9 A colorized electron Figure 1.8 An immature stage of a microscope image of viruses parasitic worm in blood. (phages) infecting a bacterium. How are microbes classified? Other Important “Microbes” and Infectious Agents  HELMINTH (worm) PARASITES  Flatworms (Platyhelminthes) * Flukes and tapeworms  Roundworms * Nematodes Image of a tapeworm in a person’s intestine. Tapeworms are a species of parasitic flatworms. Photo: Thinkstock Figure 1.8 An immature stage of a parasitic worm in blood. How are microbes classified? Other Important “Microbes” and Infectious Agents  HELMINTH (worm) PARASITES  Roundworms * Nematodes How are microbes classified? Other Important “Microbes” and Infectious Agents  VIRUSES  Protein and genetic material  Obligatory intracellular pathogen * Must infect a cell to replicate  Specific range of host cells * Upper respiratory tract * T lymphocytes  Not all viruses can infect humans  Zoonoses (pig, birds, bats) Figure 1.9 A colorized electron microscope image of viruses (phages) infecting a bacterium. How are microbes classified? Other Important “Microbes” and Infectious Agents  PRIONS  Infectious protein particles * PrP  Cause misfolding of normal brain proteins (on the surface of cells) and destroys healthy brain tissue * Creutzfeldt-Jakob disease (CJD) * ‘Mad cow’ in cattle Human brain tissue with CJD has a sponge-like appearance.  Generally fatal Teresa Hammett, CDC How are microbes classified?  Living and Non-Living Agents Studied in Microbiology MICROBE: CELL TYPE: NOTES: Bacteria Prokaryotic Unicellular*; pathogenic and nonpathogenic Archaea Prokaryotic Unicellular; nonpathogenic; live in extreme environments Protists/ Eukaryotic Unicellular and multicellular; pathogenic and nonpathogenic Algae (unicellular example: amoebae; multicellular example: algae) Fungi Eukaryotic Unicellular and multicellular; pathogenic and nonpathogenic (unicellular example: yeast; multicellular example: mushrooms) Helminths Eukaryotic Multicellular*; parasitic roundworms and flatworms Viruses Not cells; Infect animal, plant, or bacterial cells; can have a DNA or RNA nonliving genome Prions Not cells; Not discovered until the 1980s; transmitted by transplant or nonliving; ingestion; some prion diseases are inherited infectious proteins *Unicellular = one-celled organism; multicellular = organism made of many cells How are microbes classified?  Some Diseases Caused by MOs  Fungi  Ringworm, Athlete’s foot, Candidiasis  Protozoans  Malaria, Giardiasis, Pneumonia, Toxoplasmosis  Bacteria  Anthrax, Botulism, Cholera, Syphilis, UTIs, Leprosy, TB, Pneumonia  Viruses  HIV, Hemorrhagic fevers, Hepatitis, Smallpox, Influenza  Prions  Spongiform encephalitis (CJD) How are microbes classified?  Normal Microbiota of Human Microbiome  Normal microbiota (or normal flora) includes bacteria, archaea, and eukaryotic microbes  Functions of the normal flora:  Produce vitamins for us  Help us digest foods  They may even impact our moods and brain function Microbiota  Normal Microbiota of Human Microbiome  Human Microbiome Project (HMP) aims to characterize all of the microbes in and on our bodies  Many parts of the human body teem with microbial life  There are at least as many microbial cells in and on us as there are human cells  Our skin, nose, mouth, gut, and genital/urinary tract harbor the most microbes Microbiota  Normal Microbiota of Human Microbiome MOUTH, PHARYNX, AND SKIN UPPER RESPIRATORY SYSTEM  Populations vary by skin  At least 600 species region  At least 1,000 species STOMACH  Transient populations mainly from swallowed materials  Up to 25 species UROGENITAL TRACT INTESTINES  Approx 60 species Over 40,000 species Microbiota  The Golden Age of Microbiology  Scientists were searching for answers to four questions: 1. Is spontaneous generation of microbial life possible? 2. What causes fermentation? 3. What causes disease? 4. How can we prevent infection and disease? The Golden Age of Microbiology (1850–1920)  1. Does Microbial Life Spontaneously Generate?  Some philosophers and scientists of the past thought living things arose from three processes:  Asexual reproduction  Sexual reproduction  Nonliving matter  Aristotle proposed spontaneous generation  Living things can arise from nonliving matter The Golden Age of Microbiology  Louis Pasteur (1822 – 1895)  Father of Microbiology  Addressed research in the debates over:  Spontaneous generation  Fermentation  Developed pasteurization  Germ theory of infectious disease 1. Does microbial Life Spontaneously Generate?  2. What Causes Fermentation?  The debate over the cause of fermentation was also linked to the debate over spontaneous generation  Spoiled wine threatened the livelihood of many grape growers  Wine makers funded research of methods to promote production of alcohol and prevent spoilage during fermentation 2. What Causes Fermentation?  Pasteur’s Fermentation Experiments  Pasteur conducted a series of experiments that addressed the cause of fermentation 2. What Causes Fermentation?  Pasteurization  Louis Pasteur’s experiments led to the development of:  PASTEURIZATION * Process of heating liquids just enough to kill most bacteria  Field of Industrial Microbiology (also biotechnology) * Intentional use of microbes for manufacturing products 2. What Causes Fermentation? Industrial Microbiology  3. What Causes Disease?  Pasteur developed the ‘germ theory of disease.’  The germ theory of disease states that pathogens cause infectious diseases  A particular disease is typically accompanied by the same symptoms in all affected individuals  Robert Koch developed a technique to determine the specific etiological (causal) agent of an infectious disease 3. What Causes Disease?  Robert Koch (1843 – 1910)  Studied causative agents of disease – Etiology  Demonstrated a bacterium causes anthrax  It was the first time a bacterium was proven to cause disease *Inhaled *Gastro *Cutaneous https://bit.ly/2PLcI4G 3. What Causes Disease?  Koch’s Experiments  Laboratory advances:  Simple staining techniques  First photograph of bacteria in diseased tissue  Techniques for estimating bacterial number in a solution  Use of Petri dishes  Lab techniques to transfer bacteria  Bacteria as distinct species 3. What Causes Disease?  Koch’s Postulates  Steps that must be taken to prove cause of any infectious disease: 1. Suspected causative agent must be found in every case of the disease and be absent from healthy hosts. 2. Agent must be isolated and grown outside the host. 3. When agent is introduced to a healthy, susceptible host, the host must get the disease. 4. Same agent must be found in the diseased experimental host. 3. What Causes Disease?  Koch’s Organism present No organism present in healthy Postulates in all disease cases population The same organism must be present in every case of the disease but not present in healthy individuals. Diseased Healthy The organism must be isolated from the diseased host and grown as a pure culture. The isolated organism Formerly healthy animal should cause the disease becomes sick after in question when it is inoculation with organism inoculated into a susceptible host. The organism must then be re-isolated from the inoculated, diseased animal. 3. What Causes Disease?  The Gram Stain  The most widely used staining technique  One of the first steps to identify a bacterium  Gram positive bacteria are purple (i.e. Staphylococcus aureus)  Gram negative bacteria are pink (i.e. Escherichia coli) Figure 1.17 Results of Gram staining 3. What Causes Disease?  The above scientists used Pasteur’s theories and Koch’s postulates and lab techniques, to discover causes of protozoan, bacterial, and even viral diseases. 3. What Causes Disease?  4. How Can We Prevent Infection and Disease?  In the mid 1800’s modern practices of hygiene were not widely used  Even medical personnel and healthcare facilities lacked adequate cleanliness  Healthcare-associated infections (HAIs) or nosocomial infections were common 4. How Can We Prevent Infection and Disease?  Hand Hygiene and Aseptic Techniques  From 1800s–1900s several medical professionals emphasized the importance of aseptic techniques in medical settings:  Ignaz Semmelweis (1818–1865)  Joseph Lister (1827–1912)  Florence Nightingale (1820–1910) 4. How Can We Prevent Infection and Disease?  Hand Hygiene and Aseptic Techniques  Aseptic processes prevent healthcare-acquired infections or HAIs (nosocomial infections) and limit the spread of diseases  Types of aseptic techniques:  Washing hands  Wearing gloves  Sterilizing instruments  Decontaminating surfaces 4. How Can We Prevent Infection and Disease?  The Modern Age of Microbiology  What Are the Basic Chemical Reactions of Life?  How Do Genes Work?  What Role do Microorganisms Play in the Environment?  How Do We Defend Against Disease? Modern Age of Microbiology  Basic Chemical Reactions of Life Study of metabolism * Chemical reactions that occur in living organisms * Until the 1900’s it was thought that the metabolism of MOs were irrelevant with respect to plants and animals Biochemical research has practical applications: * Exploit metabolic pathways and enzymes when designing herbicides and pesticides * Detecting biochemical markers: enzymes, metabolic byproducts o diagnosis of illness & monitoring responses to treatment * Treatment of metabolic diseases * Drug design (antibiotics) Modern Age of Microbiology  How Do Genes Work?  Microbial Genetics  Determining cellular processes (transcription, translation)  Control of gene expression  Molecular Biology  Sequencing genomes; cell functioning at the molecular level  Recombinant DNA Technology  Genes in microbes, plants, and animals manipulated for practical applications, (CRISPR technology)  Gene Therapy  Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cells Modern Age of Microbiology  What Role do Microorganisms (MO) Play in the Environment?  Bioremediation:  Uses living bacteria, fungi, and algae to detoxify polluted environments.  MO recycle chemicals such as carbon, nitrogen, and sulfur  MO and causation of disease  Limiting the abundance of pathogenic microbes in the environment. Modern Age of Microbiology  How Do We Defend Against Disease?  Serology  The study of blood serum  Blood components (chemicals and cells) that fight infection  Immunology  The study of the body’s defenses against specific pathogens  Chemotherapy  Chemicals that could destroy pathogens and are nontoxic to humans  Fleming discovered penicillin (1929)  Domagk discovered sulfa drugs (1935) Modern Age of Microbiology