Lecture 1 Intro to Microbiology: History and Taxonomy

Microbiology The study of organisms to small to be seen without a microscope Includes living microorganisms: bacteria, algae, fungi, protozoa AND non-cellular infectious agents: viruses, viroids, prions

Why study Microorganisms? Microorganisms are the foundation for all life on earth They effect your everyday life Only a minority of microorganisms are pathogenic Microorganisms are found almost everywhere

Microbes and Human Welfare Recycle chemical elements Decompose organic matter Bioremediation Biotechnology Gene therapy Genetic engineering

Microbes can be used to clean up oil spills such as this one in Alaska Courtesy of the Exxon Valdez Oil Spill Trustee Council/NOAA

Microbes and Human Disease Everyone has microbes in and on body Person may or may not contract disease once they are in contact with it

Infectious Disease Pathogens invade susceptible host Emerging infectious diseases Ebola BSE, Mad cow disease Know other emerging infectious diseases from book for exam

Major Groups of the Microbial World Bacteria Archeae Fungi Algae Protozoans Helminths Viruses Major Features Small size Diverse appearance Diverse genetics

Bacteria

Archaea Found in extreme environments

Fungi

Fungi

Algae

Protozoa

Helminths

Viruses

The Spectrum of Microorganisms is Diverse - There are over 10 million species of prokaryotes There are over 3600 known viruses There are about 70,000 described species of fungi

Discovery of Microorganisms Robert Hooke published Micrographia (1665) Anton van Leeuwenhoek (1632-1723) He peered at a drop of lake water through a lens that he carefully ground -

Hooke’s Micrographia © Library of Congress [LC-USZ62-95187]

Cork cells © Library of Congress [LC-USZ62-95187]

Anton van Leeuwenhoek Courtesy of Pfizer, Inc.

Leeuwenhoek’s drawings of bacteria Courtesy of Royal Society, London

Next Question: Where did microorganisms originate? Spontaneous generation: Life originates from non-life, believed from the time of Aristotle (384-322 B.C.) Works of Redi, Pasteur, and Tyndall refute this theory Prove Germ Theory of Disease -

Francesco Redi (1626-1697) Proponents of spontaneous generation believed that worms in rotting meat came from meat itself Redi debunked this theory Experiments with meat

New Experiments Needed to Refute Spontaneous Generation Typical Experiment: used nutrient broth (infusion): contains nutrients needed for microorganisms to grow 1. boil to kill all forms of life 2. seal vessel If cloudy after standing: spontaneous generation If clear: no spontaneous generation Different investigators: Different results -

Louis Pasteur (1822-1894) Father of microbiology Demonstrated air is filled with microorganisms Demonstrated that sterile infusions will stay sterile in specially constructed flasks even when they were left open to the air

John Tyndall Explained differences in results obtained from different laboratories Proved Pasteur correct He concluded that different infusions require different boiling times to be sterilized Because of heat resistant microorganisms: Endospores

Endospores Some microorganisms exist in two forms: 1. a cell that is readily killed by boiling 2. one that is heat resistant

Golden Age of Microbiology Rapid advances by Pasteur and Robert Koch Discovery of agents of many diseases and role of immunity in prevention and cure of disease Discoveries include: Fermentation and pasteurization Germ theory of disease Vaccination

Fermentation and Pasteurization Pasteur- why did wine sour? Believed at time, that converted sugars into alcohol Yeasts do the work of fermentation Bacteria cause spoilage Pasteurization

Germ Theory of Disease Pasteur: to fight silkworm disease Ignaz Semmelweis: Instructed hospital staff to wash hands Lister: treated surgical wounds with phenol solution John Snow: Interviewed sick and healthy Londoners during cholera epidemic Robert Koch

Ignaz Semmelweiss encouraged hospital staff to wash their hands Courtesy of Pfizer, Inc.

Robert Koch (1843-1910) Demonstrated that anthrax caused by Bacillus anthracis Usual means of transmission: resistant endospores Introduced use of pure culture techniques for handling bacteria in lab Cultured bacteria on agar Discovered Mycobacterium tuberculosis – causative agent for tuberculosis Proved germ theory of disease

Vaccination Edward Jenner: Introduced vaccine for smallpox Inoculate with fluid from cowpox blisters prevented smallpox

Modern developments in Microbiology Bacteriology Mycology Parasitology Immunology Virology Recombinant DNA technology

Taxonomy

Taxonomy Involves three steps: 1. Identification 2. Classification 3. Nomenclature Objective is to arrange organisms into categories that reflect the similarities of the individuals within the groups 40

History Carolus Linnaeus: 1700’s: Two Kingdoms: Plants and Animals Ernst Haekel: 1866: Kingdom Protista R.H. Whittaker: 1969: Five Kingdoms Carl Woese: 1990: Three Domains

Taxonomic Hierarchy Species: basic unit Group of related species: strain Genus: group of similar species Family: group of similar genera, ends in - aceae Order: group of similar families, ends in - ales Class: group of similar orders, ends in - ia Phylum: group of similar classes Kingdom: group of similar Phyla Domain: group of similar Kingdoms 42

Domains of the Living World Bacteria Archaea Eucarya Bacteria and Archaea look identical Also both are prokaryotes, however differ in chemical composition and are unrelated 44

Eucarya All members of living world that are not prokaryotes are in domain eukarya May be single celled or multi-cellular Always contain true membrane-bound nucleus and other internal organelles Far more complex than prokaryotes 46

Four Kingdoms within Domain Eukarya Animalia Multicellular, heterotrophic Plantae Protista: many single celled eukaryotes Ex. Paramecium, algae, protozoa Fungi Single celled: yeast Multicellular: molds and mushrooms 47

Bacteria Single-celled prokaryotes Most have specific shapes: cylindrical, spherical, and spiral Most have rigid cell walls Multiply by binary fission Many move using appendages - 48

Archaea Have same size, shape, and appearance as bacteria Multiply by binary fission and move primarily with flagella Also have cell walls, but differ from bacteria: no peptidoglycan Interesting Feature: able to grow in extreme environments 49

Identification of Microorganisms Microscopic examination Culture characteristics Biochemical tests Nucleic Acid Analysis Serological Tests Person’s symptoms also play a role 50

Classification of Microorganisms Phenotype: Physical appearance Genotype: Genes Development of molecular techniques has made this possible Bergey’s Manual of Systematic Bacteriology All known species described here If properties of newly isolated organism do not agree with any description, considered new organism 51

Nomenclature International code for Nomenclature of Bacteria Uses two-word naming system: Binomial Nomenclature First name is the Genus, capital Second name is the species, lower case Both are italicized Example: Escherichia coli, or E.coli Strains; minor differences with in species: E. coli strain B or E.coli strain K-12 53

Nonliving Members of Microbial World In order to be considered alive, must be composed of one or more cells Viruses, Viroids, and prions are termed agents Viruses: Piece of nucleic acid surrounded by protein coat Can only multiply inside human host cells Obligate intercellular parasites - 54

Non-living members of the bacterial world Viroids: Simpler than viruses Single short piece of RNA No protective coat Can only multiply inside cells Prions: Appear to only be protein without nucleic acid Possible another agent is causing the disease 55