The Microbial World and You

Transcription

1 What is microbiology? The Microbial World and You Chapter 1 BIO 220 This is the study of microorganisms (microbes), which are living organisms that can not be visualized with the naked eye. We will discuss beneficial as well as diseasecausing microbes. What are the characteristics of life? Composed of one or more cells, which are made of biomolecules Growth Reproduction Metabolism Respond to their environment Evolve and adapt No Do all microbes fulfill all of these conditions of life? i.e. prions and viruses 1

2 Nomenclature of living microbes Binomial nomenclature Carolus Linnaeus Genus and specific epithet i.e. Bacillus anthracis Genus name is capitalized, specific epithet is not Underlined or italicized Genus can be abbreviated after first use How are microbes named? Shape and arrangement of cells (bacteria) Staphylococcus aureus Scientist Escherichia coli(theodor Escherich) Microbe habitat Appearance Micrococcus luteus Fig

3 Types of microbes Bacteria Prokaryotic cells Common shapes include bacillus, coccus, spiral Cell walls contain peptidoglycan Archaea Prokaryotic cells Cell walls Some, but not all, live in extreme environments (methanogens, extreme halophiles, extreme thermophiles) Not known to cause disease in humans Types of microbes Fungi Eukaryotic cells Mushrooms, molds, yeasts Protozoa Unicellular eukaryotic cells Cell walls Move by cilia, flagella, or pseudopods Free-living or parasitic Amoeba proteus vs. Entamoeba histolytica Types of microbes Algae Eukaryotic cells Perform photosynthesis Viruses Acellular Nucleic acid and protein Prions Acellular Infectious proteins Areas of study within microbiology Bacteriology study of bacteria Mycology study of fungi Parasitology study of protozoa & parasitic worms Virology study of viruses 3

4 Robert Hooke 1665 published Micrographia, which was a series of detailed observations on a variety of organisms Used a compound microscope Hook observed individual cells in thin slices of cork Cell theory all living things are composed of cells Cell Theory All living organisms are composed of cells. The cell is the fundamental unit of structure and function of living organisms. Cells arise from pre-existing cells. Anton van Leeuwenhoek observed animalcules through simple microscopes he constructed Probably first to observe living cells Spontaneous Generation For centuries, some scientists believed in the theory of spontaneous generation, which said that some forms of life (i.e. flies, maggots, toads, snakes, mice) could be produced from non-living material. 4

5 Francesco Redi In 1668, he conducted a series of experiments in an attempt to discount the theory of spontaneous generation. The controversy continued... John Needham (1745) Theory of spontaneous generation lives! Lazzaro Spallanzani (1765) Theory of Biogenesis In 1858, Rudolf Virchow came up with the concept of Biogenesis, which hypothesizes that living cells arise only from preexisting living cells. Is it biogenesis or spontaneous generation? In 1861, Louis Pasteur conducted a series of experiments that resolved the question. Fig

6 Germ theory of disease Maybe microorganisms could cause disease , Agostino Bassi identified a fungus (Beauveria bassiana) as the causative agent of white muscardine in silkworms 1865, Luis Pasteur identified a protozoan (Nosema bombycis) as another infective agent of silkworms Germ theory of disease applications to medicine 1840s, Hungarian physician Ignaz Semmelweisnoted an unacceptably high percentage of patients in the obstetrics ward died shortly after childbirth Hand washing greatly reduced deaths due to childbed fever but Semmelweis s conclusions were not welcomed by the medical establishment Germ theory of disease applications to medicine 1860s, Joseph Lister, an English surgeon, was aware of the work done by Semmelweisand Pasteur Experimented with using dressings soaked in carbolic acid on patients, which ultimately significantly reduced the loss of patients due to postoperative infections Microbes caused surgical wound infections Father of antiseptic surgery Germ theory of disease applications to medicine 1876, Robert Koch, a German physician, was the first to definitively show that bacteria could cause disease Koch isolated a bacterium (Bacillus anthracis) from the blood of cattle that had died of anthrax He isolated and cultured the bacteria and injected it into healthy cows, which then died 6

7 Koch s postulates A series of experimental steps for directly relating a specific microbe to a specific disease. Vaccination 1796, Edward Jenner collected skin scrapings from a dairy maid with cowpox To test his hypothesis that infection with cowpox would convey protection against smallpox, Jenner scraped the skin of a healthy boy with a cowpox-infected needle The boy did not get smallpox Pasteur also did some work with vaccinations against anthrax, chicken cholera, and rabies Fig Disease-causing microbes Bacillus anthracis anthrax Neisseria gonorrhoeae gonorrhea Trypanosoma brucei African sleeping sickness Prions Creutzfeldt Jakob disease Giardia lamblia giardiasis Human immunodeficiency virus (HIV) Good microbes Foods and beverages Saccharomyces cerevisiae, Penicillium roquefortii Pharmaceuticals Penicillium, Bacillus, Streptomyces Sewage treatment Bioremediation Insect pest control Bacillus thuringiensis Biotechnology 7