The Scope of Microbiology (1) Microbiology: the specialized area of biology that deals with organisms too small to be seen with the naked eye Microorganisms or microbes Germs, viruses, or agents “Bugs”

The Scope of Microbiology (2) Major groups of microorganisms: Bacteria Algae Protozoa Helminths Fungi Viruses: noncellular, parasitic, protein-coated genetic elements that cause harm to host cells

The Scope of Microbiology (3) Microbes are easy and difficult to study Reproduce rapidly, large populations can be grown in the laboratory Can’t be seen directly, must be analyzed through indirect methods in addition to using microscopes

The Scope of Microbiology (4) Microbiologists study: Cell structure and function Growth and physiology Genetics Taxonomy and evolutionary history Interactions with living and nonliving environment

Branches of Microbiology Medical Microbiology Deals with microbes that cause diseases in humans and animals Public Health Microbiology and Epidemiology Monitor and control the spread of diseases in communities USPHS, CDC, WHO

Branches of Microbiology Immunology Complex web of protective substances and cells produced in response to infection Includes vaccination, blood testing, and allergy Role of the immune system in cancer and autoimmune diseases Industrial Microbiology Safeguards our food and water Biotechnology Microbes used to create amino acids, beer, drugs, enzymes, and vitamins

Branches of Microbiology Agricultural Microbiology Relationships between microbes and domesticated plants and animals Plant specialists, animal specialists Environmental Microbiology Study the effect of microbes on the earth’s diverse habitats Aquatic, soil, and geomicrobiology, and astrobiology

The Impact of Microbes on Earth Eukary: true nucleus Cells with a nucleus are classified as eukaryotes Prokary: pre nucleus Bacteria and archaea do not have a nucleus and have been traditionally classified as prokaryotes This classification is no longer used because bacteria and archaea are so distant genetically

The Impact of Microbes on Earth (3) Bacteria are ubiquitous. They are found: deep in the earth’s crust polar ice caps oceans inside the bodies of plants and animals

The Impact of Microbes on Earth (4) Evolution: the accumulation of changes that occur in organisms as they adapt to their environments Theory of Evolution: Documented every day in all corners of the planet An observable phenomenon testable by science A label for a well-studied and well-established natural phenomenon

Microbial Involvement in Shaping Our Planet Microbes are deeply involved in the flow of energy and food through the earth’s ecosystems Bacteria: anoxygenic photosynthesis The production of oxygen by microbes allowed species diversification Photosynthetic microorganisms (bacteria and algae) account for more than 70% of the earth’s photosynthesis, contributing the majority of the oxygen to the atmosphere

Microbial Involvement in Shaping Our Planet Decomposition: Breakdown of dead matter and wastes Accomplished by bacteria and fungi (b) © Michel & Christine Denis-Huot/Science Source

Human Use of Microorganisms (1) Humans have been using microorganisms for thousands of years to improve life and even shape civilizations Yeast for production of bread, wine, and beer Other fungi used for cheese production Moldy bread used in Egypt to treat wounds

Human Use of Microorganisms (2) Biotechnology: Manipulation of microorganisms to make products in an industrial setting Genetic Engineering: Manipulates the genetics of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms (GMOs) (a) NREL/US Department of Energy/Dennis Schroeder (b) © Bloomberg via Getty Images

Human Use of Microorganisms (3) Recombinant DNA technology: Techniques that allow the transfer of genetic material from one organism to another and deliberately alter DNA Bioremediation: Introduction of microbes into the environment to restore stability or to clean up toxic pollutants (c) © Accent Alaska.com/Alamy

Infectious Diseases and the Human Condition Pathogen: any agent such as a virus, bacterium, fungus, protozoan, or helminth that causes disease Nearly 2000 different microbes can cause disease

Infectious Diseases and the Human Condition New (emerging) diseases as well as older (reemerging) diseases are increasing Ebola, AIDS, hepatitis C, and viral encephalitis Polio, leprosy, and parasitic worm diseases have largely been eradicated

Infectious Diseases and the Human Condition Certain diseases once considered noninfectious are now found to be caused by microbes: Gastric ulcers caused by Helicobacter pylori Link between certain cancers and bacteria and viruses Cocksackie virus has been associated with diabetes and schizophrenia Multiple sclerosis, OCD, coronary artery disease, obesity linked to chronic microbial infections

Infectious Diseases and the Human Condition First Golden Age of Microbiology: “obvious” diseases were characterized and cures or preventions were devised Today, we are discovering the subtler side of microorganisms and the quiet, slow, destructive diseases they cause Female infertility caused by Chlamydia infection Liver cancer (hepatitis viruses) and cervical cancer (human papillomavirus)

Infectious Diseases and the Human Condition An increasing number of patients with weakened immune systems are subject to infections by common microbes not pathologic to healthy people Drug-resistant microbes also contribute to the increase in infectious disease

General Characteristics of Microorganisms Bacterial and Archaeal cells: About 10x smaller than eukaryotic cells Lack organelles: small, double-membrane-bound structures that perform specific functions The majority of microorganisms are single-celled (all bacterial and archaeal and some eukaryotes)

Cell Structure

Five Types of Microorganisms Top Left) CDC; (Middle Left) CDC/Dr. Lucille K. Georg; (Bottom Left) © Nancy Nehring/E+/Getty Images RF; (Bottom Center) CDC/Janice Carr; (Bottom Right) CDC

Lifestyles of Microorganisms Majority of microorganisms: Live in habitats such as soil and water Are relatively harmless and often beneficial Derive food and other factors from the nonliving environment Parasites: Harbored and nourished by the host Cause damage and disease in the host

Development of the Microscope Robert Hooke: First observations of microbes in the 1600s Antonie van Leeuwenhoek: Made a crude microscope to examine threads in fabrics Made drawings of what he called “animalcules” in rainwater and scraped from his teeth (a) © Biophoto Associates/Science Source; (b) CDC/Dr. Lucille K. Georg © Tetra Images/Alamy RF

Development of Aseptic Techniques Robert Koch: Linked a specific microorganism with a specific disease Dr. Oliver Wendell Holmes and Dr. Ignaz Semmelweis: Showed that women became infected in the maternity ward after examinations by physicians who had been working in the autopsy rooms

Development of Aseptic Techniques Joseph Lister: First to utilize hand washing and misting operating rooms with antiseptic chemicals Techniques became the foundation for modern microbial control still in use today © Bettmann/Corbis

Discovery of Pathogens and the Germ Theory of Disease Pasteur: Invented pasteurization Showed that human diseases could arise from infection Robert Koch: Established a series of proofs that verified the germ theory of disease

Binomial System of Nomenclature A combination of the generic (genus) and species name The genus name is always capitalized and the species name begins with a lower case letter Both names should be italicized when in print or underlined when written by hand Abbreviations: The genus name can be abbreviated to save space or if the genus name has already been stated Example: Staphylococcus aureus can be abbreviated as S. aureus