Humans and the Microbial World - Chapter 1 - Microbiology Overview

Humans and the Microbial World Chapter 1 In this chapter we will cover History of microbiology and major discoveries Scientific methods A human perspective of the subject Members of the Microbial world Microorganisms Examples? Good or bad? Known terms: Prokaryotes vs Eukaryo...

Humans and the Microbial World Chapter 1 In this chapter we will cover History of microbiology and major discoveries Scientific methods A human perspective of the subject Members of the Microbial world Microorganisms Examples? Good or bad? Known terms: Prokaryotes vs Eukaryotes A Glimpse of History Antony van Leeuwenhoek Made simple magnifying glass (1674) Studied lake water Observed ‘animalcules’ Robert Hooke Also credited with discovery of microbes Described ‘microscopical mushroom’ (common bread mold) in 1665 First microscope In this chapter History 1.1-The dispute over spontaneous generation Work of various scientists to disapprove spontaneous generation Golden age of microbiology Scientific process 1.2-Human perspective of Microbiology Benefits to humans- health, environment, industry, research 1.3-Members of the Microbial world Cellular and acellular agents 1.1 Learning outcomes Describe the key experiments of scientists who disproved spontaneous generation Explain how the successful challenge to the idea of spontaneous generation led to the Golden Age of Microbiology. Describe the scientific method, using Pasteur’s swan-necked flask experiment as an example. 1.1 Spontaneous Generation Spontaneous Generation Belief that life arises spontaneously from non-living material Took over 200 years and many experiments to provide evidence that microorganisms do not arise by spontaneous generation  1.1 The Dispute Over Spontaneous Generation Francesco Redi demonstrated worms on rotting meat came from eggs of flies landing on meat (1668) Placed meat in two jars Covered one jar with gauze Gauze prevented flies from depositing eggs No eggs →no worms John Needham demonstrated boiled broths still produced microorganisms (1749) Father Spallanzani contradicted Needham’s results (1776) Boiled broths longer; sealed flasks by melting necks Broths remained sterile unless neck cracked Controversy remained Some argued heating destroyed “vital force” necessary for spontaneous generation Work of Louis Pasteur Demonstrated air is filled with microorganisms Filtered air through cotton plug Observed trapped microorganisms Many looked identical to those found in broths Plug in sterilized broth gave rise to microorganisms Dispute over Pasteur’s results-1 Pasteur’s results not fully reproducible English physicist John Tyndall explained conflicting data and showed Pasteur correct Sterilizing broths required different times Some sterilized in 5 minutes; others not sterilized after 5 hours! Realized broths made from hay contained heat-resistant microbes Labs that could not reproduce Pasteur’s results used broths made from hay Dispute over Pasteur’s results-2 In same year (1876), German botanist Ferdinand Cohn discovered endospores Heat-resistant form of bacteria Extreme heat resistance of endospores explains differences between Pasteur’s results and those of other investigators Pasteur used broths made with sugar or yeast extract Highlights importance of reproducing all conditions as closely as possible when conducting research The Golden Age of Microbiology  Scientists to remember 1674- Antony van Leeuwenhoek- first microscope 1796- Edward Jenner- first vaccine against smallpox 1847-Semmelweis- handwashing reduces childbed fever- postpartum infections 1857- Pasteur- fermentation by yeast 1867- Lister- first use of an antiseptic 1876-81- Koch- bacteria cause infections- medical microbiology, pure culture technology 1892- Iwanowsky- first description of a virus 1928- Flemming- first antibiotic- Penicillin The Scientific Method Scientific methods- approaches Qualitative methods Quantitative methods Looks at overall problem but no Focusses on data that can be numerical evidence measured numerically generalizes data across various subjects Looks for categories like events, Data collected in numbers and descriptions, comments, analyzed in statistics behavior etc. An inductive process- developing A deductive process- theories from the data gathered experimental, descriptive or other type of comparison 1.2 Microbiology, a Human Perspective- Learning outcomes Explain the importance of microorganisms in the health of humans and the surrounding environment. List three commercial benefits of microorganisms. Describe why microorganisms are useful research tools. Describe the role of microbes in disease, including examples of past triumphs and remaining challenges.  The Human Microbiome Human body carries enormous population of microorganisms called the normal microbiota Play essential role in human health Prevent disease by competing with disease-causing microbes Aid in digestion Promote development of immune system May decrease allergies, asthma May affect brain chemistry and body weight Human Microbiome Project Started in 2007  Microorganisms in the Environment Recycling of nutrients Oxygen production through photosynthesis Nitrogen fixation Decomposers of material Cellulose degraded in the environment and in the digestive tracts of ruminants National Microbiome Initiative (NMI) Started in 2016 Expands scope of microbiome research Commercial Benefits of Microorganisms Food production Fermentation- beer, yogurt, cheeses, buttermilk, baking bread using yeast Biodegradation Degrade environmental pollutants, lessen damage from oil spills Bioremediation: use of microorganisms to hasten decay of pollutants Bacteria synthesize commercially valuable products Antibiotics (treatment of diseases), Ethanol (biofuel), Hydrogen gas and certain oils (possible biofuels), Amino acids (dietary supplements) Insect toxins (insecticides), Cellulose (headphones), Hydroxybutyric acid (disposable diapers and plastics) Biotechnology Use of microbiological and biochemical techniques to solve practical problems Genetic engineering Production of medications by certain microorganisms, including insulin for treatment of diabetes Production of plants with desirable qualities  Microbes as Research Tools Model organisms have same fundamental metabolic and genetic properties as higher life forms All cells composed of same chemical elements Synthesize cell structures by similar mechanisms Duplicate DNA Degrade foods via same metabolic pathways “What is true of elephants is also true of bacteria, and bacteria are much easier to study” (Jacques Monod) Grow very quickly on inexpensive growth media  Microbes and Disease Most microorganisms are beneficial or not harmful Some are pathogens that can cause disease Damage to body tissues Result of pathogen’s growth and products Result of body’s defense mechanisms Influenza in 1918 to 1919 killed more Americans than died in WWI, WWII, Korean, Vietnam, and Iraq wars combined The COVID-19 pandemic has resulted in the death of more than 1,000,000 people worldwide, including over 200,000 Americans.  Nonhuman Epidemics Epidemics are not limited to human populations. The great Irish famine in the 1800s- due to a microbial disease of potatoes. 2013- Southern Italy - A bacterial disease that kills olive trees was found, spread to Spain and France, contributing to a worldwide drop in olive oil production. A fungal disease called “wheat blast” devastated wheat crops in South America. Spread to Bangladesh in 2016, resulting in the loss of over 35,000 acres of crops that year. Frog populations around the world have been decimated by a fungal disease called chytridiomycosis.  Microbes and Disease - Figure 1.4 Modern sanitation, vaccination, and antibiotic treatments have reduced incidence of infectious diseases Past Triumphs Smallpox eradicated Once killed one-third of victims; left others blind or scarred Devastated unexposed populations, such as native inhabitants of Americas No reported cases since 1977, but laboratory stocks of virus remain Black death- Plague deaths less than 100 per year Killed one-third of population of Europe (approximately 25 million people) between 1347 to 1351 Control of rodent populations and human respiratory secretions to prevent spread Antibiotics for treatment Polio nearly eliminated by vaccination Emerging Infectious Disease 1 An Emerging Infectious Disease (EID) is one that has become more common in last several decades. Newly recognized diseases Covid-19 - caused by a virus called SARS-CoV-2 Ebola virus disease Congenital Zika syndrome Middle East respiratory syndrome (MERS) Influenza (certain types) Lyme disease AIDS Hantavirus pulmonary syndrome Mad cow disease (bovine spongiform encephalopathy) Microbes and Disease - Figure 1.5 Emerging Infectious Disease 2 Diseases that have become more common Malaria Tuberculosis Disease agents evolve Infect new host (HIV-1) COVID-19 arose from a strain of virus that infects bats Cause different types of damage to host (E. coli O104:H4) Become resistant to antibiotics (tuberculosis, malaria) Changes in society Mobile populations can carry pathogens around globe Diseases such as malaria and cholera have largely been eliminated from developed countries, but still exist in many parts of the world Expansion off cities into rural areas allows closer contact with organisms that people have not encountered previously Emerging Infectious Disease 3 Decades of vaccination have controlled many common diseases in developed countries Lack of first-hand knowledge of the dangers of diseases can lead people to fear vaccines more than the diseases they prevent Diseases such as measles, mumps, and whooping cough are nearly eliminated from developed countries, but could become common again with declining vaccination rates Chronic Diseases Chronic diseases may be caused by microorganisms: Stomach ulcers, once thought to be caused by stress, are often caused by the bacteria Helicobacter pylori Cervical cancer caused by human papilloma virus (HPV) 1.3-Members of the Microbial World Compare and contrast characteristics of members of the Bacteria, Archaea, and Eukarya. Explain the features of an organism’s scientific name. Compare and contrast the algae, fungi, and protozoa. Compare and contrast viruses, viroids, and prions. Members of the Microbial World Members of the Microbial World – Table 1.1 Characteristic Bacteria Archaea Eukarya Cell Type Prokaryotic Prokaryotic Eukaryotic Number of Cells Unicellular Unicellular Unicellular or multicellular Membrane- No No Yes bound organelles Ribosomal RNA Yes Yes Yes sequences unique to the group Peptidoglycan in Yes No No cell wall Typical size 0.3 to 2 0.3 to 5 to range micrometers 2 micrometers 50 micrometers  Scientific Names 1 Binomial System of Nomenclature: two words Genus (capitalized) Specific epithet, or species name (not capitalized) Genus and species are italicized or underlined Genus may be abbreviated (E. coli) Name often reflects characteristic of organism or honors a scientist Escherichia (honors Theodor Escherich) coli (indicates the colon, where the bacteria live) Members of a species with important minor differences may be indicated with a strain designation (E. coli K12) Informal names that resemble genus names are not italicized Members of the genus Staphylococcus are often called staphylococci Sizes in the Microbial World - Figure 1.7  Bacteria Bacteria: single-celled prokaryotes Most have specific shapes (cylindrical, spherical, spiral) Rigid cell wall contains peptidoglycan (unique to bacteria) Many move using flagella Multiply via binary fission Obtain energy from a wide variety of sources; some are photosynthetic Bacteria come in a variety of shapes, but cells of a given species are usually only one shape. Common Bacterial Cell Arrangements Figure 1.9  Archaea Archaea: single-celled prokaryotes similar in size, shape, and properties to bacteria Major differences from Bacteria in chemical composition Cell walls lack peptidoglycan Ribosomal RNA sequences different Many are extremophiles High salt concentration, temperature Many are common in moderate environments Eukarya – Table 1.3 Organism Characteristics Fungi Use organic material for energy. Size range from microscopic (yeasts) to macroscopic (molds; mushrooms are the reproductive structures of some fungi. Algae Use sunlight for energy. Size range from microscopic (single-celled algae) to macroscopic (multicellular algae). Protozoa Use organic material for energy. Single-celled microscopic organisms. Helminths Use organic material for energy. Adult worms are typically macroscopic and often quite large, but their eggs and larval forms are microscopic. Acellular Infectious Agents – Table 1.4 Agent Characteristic Viruses Consist of either DNA or RNA, surrounded by a protein coat. Obligate intracellular agents that use the machinery and nutrients of host cells to replicate. Viroids Consist only of RNA; no protein coat. Obligate intracellular agents that use the machinery and nutrients of host cells to replicate. Prions Consist only of protein; no DNA or RNA. Misfolded versions of normal cellular proteins that cause the normal versions to misfold. In this chapter we covered History of microbiology and major discoveries The dispute over spontaneous generation Credit to scientists Scientific methods Qualitative and quantitative A human perspective of the subject Importance of microbes to humans- health, study, environment, industry Members of the Microbial world Prokaryotes, eukaryotes and acellular