INTRODUCTION TO MICROBIOLOGY
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Transcript of INTRODUCTION TO MICROBIOLOGY
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
INTRODUCTION TO MICROBIOLOGY
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Microorganisms are organisms that are too small to be
seen with the unaided eye.
“Germ” refers to a rapidly growing cell.
Microbes in Our Lives
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WHY STUDY MICROBIOLOGY
Public Health Applications
Food Applications
Industrial Applications
Biofuels Applications
Biopharmaceutical applications
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Microorganisms
Decompose organic waste
Are producers in the ecosystem by photosynthesis
Produce industrial chemicals such as ethanol
and acetone
Produce fermented foods such as vinegar, cheese,
and bread
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Microorganisms
Figure 1.1
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Microorganisms
Produce products used in manufacturing
(e.g., cellulase) and treatment (e.g., insulin)
A few are pathogenic, disease-causing
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Linnaeus established the system of scientific
nomenclature.
Each organism has two names: the genus and
specific epithet.
Naming and Classifying Microorganisms
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Scientific Names
Are italicized or underlined. The genus is capitalized
and the specific epithet is lower case.
Are “Latinized” and used worldwide.
May be descriptive or honor a scientist.
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Scientific Names
Staphylococcus aureus
Describes the clustered arrangement of the cells
(staphylo-) and the golden color of the colonies
(aur-).
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Scientific Names
Escherichia coli
Honors the discoverer, Theodor Escherich, and
describes the bacterium’s habitat–the large intestine
or colon.
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Scientific Names
After the first use, scientific names may be abbreviated
with the first letter of the genus and the specific epithet:
Staphylococcus aureus and Escherichia coli are
found in the human body. S. aureus is on skin and
E. coli in the large intestine.
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Archaea
Prokaryotic
Lack peptidoglycan
Live in extreme environments
Include
Methanogens
Extreme halophiles
Extreme thermophiles
Figure 4.5b
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Bacteria
Prokaryotes
Peptidoglycan cell walls
Binary fission
For energy, use organic
chemicals, inorganic
chemicals, or
photosynthesis
Figure 1.1a
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Viruses
Acellular
Consist of DNA or RNA core
Core is surrounded by a
protein coat.
Coat may be enclosed in a
lipid envelope.
Viruses are replicated only
when they are in a living
host cell.Figure 1.1e
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Fungi
Eukaryotes
Chitin cell walls
Use organic chemicals for
energy.
Molds and mushrooms are
multicellular consisting of
masses of mycelia, which
are composed of filaments
called hyphae.
Yeasts are unicellular.Figure 1.1b
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Protozoa (unicellular parasites)
Eukaryotes
Absorb or ingest
organic chemicals
May be motile via
pseudopods, cilia,
or flagella
Figure 1.1c
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Multicellular Animal Parasites
Eukaryote
Multicellular animals
Parasitic flatworms and round worms are called
helminths.
Microscopic stages in life cycles.
Figure 12.28a
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Algae
Eukaryotes
Cellulose cell walls
Use photosynthesis for
energy
Produce molecular oxygen
and organic compounds
Figure 1.1d
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Linnaeus’s Classification
Hierarchical system
Binomial Nomenclature Ancient Greeks
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Ancestors of bacteria were the first life on Earth.
The first microbes were observed in 1673.
A Brief History of Microbiology
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The First Observations
1673-1723, Antoni
van Leeuwenhoek
described live
microorganisms that
he observed in teeth
scrapings, rain
water, and
peppercorn
infusions.Figure 1.2b
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The Theory of Biogenesis
Pasteur’s S-shaped flask kept microbes out but let
air in.
Figure 1.3
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Fermentation and Pasteurization
Pasteur demonstrated that
these spoilage bacteria could
be killed by heat that was not
hot enough to evaporate the
alcohol in wine.
Pasteruization is the application
of a high heat for a short time.
Figure 1.4 (1 of 3)
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Pasteur
Spontaneous generation vs. biogenesis
Germ Theory
Father of aseptic techniques
Pasteurization
Fermentation research
Vaccination (rabies)
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Koch
Koch’s Postulates
Pure Culture Concept
Tuberculosis
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Vaccination
1796: Edward Jenner inoculated a person with cowpox
virus. The person was then protected from smallpox.
Vaccination is derived from vacca for cow.
The protection is called immunity.
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The Birth of Modern Chemotherapy
1928: Alexander Fleming
discovered the first
antibiotic.
He observed that Penicillium
fungus made an antibiotic,
penicillin, that killed S.
aureus.
1940s: Penicillin was tested
clinically and mass
produced.Figure 1.5
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Modern Developments in Microbiology
Bacteriology is the study of bacteria.
Mycology is the study of fungi.
Parasitology is the study of protozoa and parasitic
worms.
Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.
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Modern Developments in Microbiology
Immunology is the study of
immunity. Vaccines and interferons
are being investigated to prevent
and cure viral diseases.
The use of immunology to identify
some bacteria according to
serotypes (variants within a
species) was proposed by
Rebecca Lancefield in 1933.Figure 1.4 (3 of 3)
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Modern Developments in Microbiology
Virology is the study of viruses.
Recombinant DNA is DNA made from two different
sources. In the 1960s, Paul Berg inserted animal DNA
into bacterial DNA and the bacteria produced an animal
protein.
Recombinant DNA technology, or genetic engineering,
involves microbial genetics and molecular biology.
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1901* von Behring Diphtheria antitoxin1902 Ross Malaria transmission1905 Koch TB bacterium1908 Metchnikoff Phagocytes1945 Fleming, Chain, Florey Penicillin1952 Waksman Streptomycin1969 Delbrück, Hershey, Luria Viral replication1987 Tonegawa Antibody genetics1997 Prusiner Prions
Selected Novel Prizes in Physiology or Medicine
* The first Nobel Prize in Physiology or Medicine.
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A Brief History of Microbiology
Linnaeus
Jenner
Hooke
Leeuwenhoek
Lister
Pasteur
Koch
Darwin
Salk
Watson & Crick
Jacob and Monod
McClintock
Woese
Venter?
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Microbial ecology
Bacteria recycle carbon, nutrients, sulfur, and
phosphorus that can be used by plants and animals.
Microbes and Human Welfare
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Bioremediation
Bacteria degrade organic
matter in sewage.
Bacteria degrade or detoxify
pollutants such as oil and
mercury.
UN 2.1
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Biological Insecticides
Microbes that are pathogenic to insects are alternatives
to chemical pesticides in preventing insect damage to
agricultural crops and disease transmission.
Bacillus thuringiensis infections are fatal in many
insects but harmless to other animals, including
humans, and to plants.
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Modern Biotechnology and Genetic Engineering
Biotechnology, the use of microbes to produce foods
and chemicals, is centuries old.
Genetic engineering is a new technique for
biotechnology. Through genetic engineering, bacteria
and fungi can produce a variety of proteins including
vaccines and enzymes.
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Modern Biotechnology and Genetic Engineering (continued)
Missing or defective genes in human cells can be
replaced in gene therapy.
Genetically modified bacteria are used to protect crops
from insects and from freezing.
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Microbes and Human Disease
Bacteria were once classified as plants giving rise to
use of the term flora for microbes.
This term has been replaced by microbiota.
Microbes normally present in and on the human body
are called normal microbiota.
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Normal Microbiota
Normal microbiota prevent growth of pathogens.
Normal microbiota produce growth factors such as folic
acid and vitamin K.
Resistance is the ability of the body to ward off disease.
Resistance factors include skin, stomach acid, and
antimicrobial chemicals.
Biofilms are extremely important in microbial ecology
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Infectious Diseases
When a pathogen overcomes the host’s resistance,
disease results.
Emerging infectious diseases (EID): New diseases and
diseases increasing in incidence.
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Infectious Disease
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Emerging Infectious Diseases
West Nile encephalitis
West Nile virus
First diagnosed in the West Nile region of Uganda in
1937
Appeared in New York City in 1999
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Emerging Infectious Diseases
Avian Influenza A H5N1 Severe acute respiratory syndrome
(SARS) West Nile encephalitis (WNE) Bovine spongiform encephalitis (BSE) Creutzfeld-Jacob disease (CJD) 0157:H7 E. coli Flesh eating bacteria Ebola Marburg Cryptosporidiosis AIDS HIV virus
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Emerging Infectious Diseases
Bovine spongiform encephalopathy
Prion
Also causes Creutzfeldt-Jakob disease (CJD)
New variant CJD in humans is related to cattle fed
sheep offal for protein
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Emerging Infectious Diseases
Escherichia coli O57:H7
Toxin-producing strain of E. coli
First seen in 1982
Leading cause of diarrhea worldwide
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Emerging Infectious Diseases
Invasive group A Streptococcus
Rapidly growing bacteria that cause extensive
tissue damage
Increased incidence since 1995
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Emerging Infectious Diseases
Ebola hemorrhagic fever
Ebola virus
Causes fever, hemorrhaging, and blood clotting
First identified near Ebola River, Congo
Outbreaks every few years
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Emerging Infectious Diseases
Avian influenza A
Influenza A virus (H5N2)
Primarily in waterfowl and poultry
Sustained human-to-human transmission has not
occurred yet
Swine Flu – (H1N1) – expected to be a pandemic for
the next 3 years. May infect >1billion people
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Emerging Infectious Diseases
Severe acute respiratory syndrome (SARS)
SARS-associated Coronavirus
Occurred in 2002-2003
Person-to-person transmission
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Emerging Infectious Diseases
Acquired immunodeficiency syndrome (AIDS)
Human immunodeficiency virus (HIV)
First identified in 1981
Worldwide epidemic infecting 44 million people;
14,000 new infections every day
Sexually transmitted disease affecting males and
females
In the United States, HIV/AIDS cases: 30% are
female and 75% are African American
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Emerging Infectious Diseases
Cryptosporidiosis
Cryptosporidium protozoa
First reported in 1976
Causes 30% of diarrheal illness in developing
countries
In the United States, transmitted via water
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BIOTERRORISM
ANTHRAX
SMALLPOX
TULAREMIA, Pahvant
Valley plague, rabbit fever,
deer fly fever, and Ohara's
fever) Francisella
tularensis.
PLAGUE
OTHER AGENTS
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Exam Questions
Definitions
Abbreviations
Differentiate cell walls of
Gram +ve & Gram –ve
bacteria
Prokaryote Vs Eukaryote
Endotoxins Vs Exotoxins
Nutrition, environment,
staining
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Bacterial Membrane Structures
Structure Chemical Constituents
Plasma Membrane Phospholipids, proteins, enzymes for energy, membrane potential, transport.
Cell Wall
Gram +ve Bacteria
Peptidoglycan Glycan chains of GlcNAc and MurNAc cross linked by peptide bridge.
Teichoic Acid Polyribitol phosphate or glycerol phosphate cross linked to peptidoglycan.
Lipoteichoic Acid Lipid linked teichoic acid.
Gram -ve Bacteria
Peptidoglycan Thinner version of that found in Gram positive bacteria.
Periplasmic Space Enzymes involved in transport, degradation, and synthesis.
Outer Membrane Phospholipids with saturated fatty acids.
Proteins Porins, lipoprotein, transport proteins.
LPS Lipid A, core polysaccharide, O antigen.
Other Structures
Capsule Polysaccharides (disaccharides and trisaccharides) and polypeptides.
Pili Pilin, adhesins.
Flagellum Motor proteins, flagellin.
Proteins M proteins of streptococci (for example).
Bacterial Membrane Structures
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Function Component(s) Structural Rigidity All.
Packaging Of Internal Contents All.
Permeability Barrier Outer membrane or plasma membrane.
Metabolic Uptake Membranes and periplasmic transport
proteins, porins, permeases.
Energy Production Plasma membrane.
Adhesion To Host Cells Pili, proteins, teichoic acid.
Immune Recognition By Host All outer structures.
Escape From Host Recognition Capsule, M protein.
Antibiotic Sensitivity Peptidoglycan synthetic enzymes.
Antibiotic Resistance Outer membrane. Motility Flagella. Mating Pili. Adhesion Pili.
Functions Of The Bacterial Envelope
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings