introduction to microbiology

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

INTRODUCTION TO MICROBIOLOGY


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


WHY STUDY MICROBIOLOGY

Public Health Applications

Food Applications

Industrial Applications

Biofuels Applications

Biopharmaceutical applications


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


Microorganisms

Figure 1.1


Microorganisms

Produce products used in manufacturing

(e.g., cellulase) and treatment (e.g., insulin)

A few are pathogenic, disease-causing


Linnaeus established the system of scientific

nomenclature.

Each organism has two names: the genus and

specific epithet.

Naming and Classifying Microorganisms


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.


Scientific Names

Staphylococcus aureus

Describes the clustered arrangement of the cells

(staphylo-) and the golden color of the colonies

(aur-).


Scientific Names

Escherichia coli

Honors the discoverer, Theodor Escherich, and

describes the bacterium’s habitat–the large intestine

or colon.


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.


Archaea

Prokaryotic

Lack peptidoglycan

Live in extreme environments

Include

Methanogens

Extreme halophiles

Extreme thermophiles

Figure 4.5b


Bacteria

Prokaryotes

Peptidoglycan cell walls

Binary fission

For energy, use organic

chemicals, inorganic

chemicals, or

photosynthesis

Figure 1.1a


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


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


Protozoa (unicellular parasites)

Eukaryotes

Absorb or ingest

organic chemicals

May be motile via

pseudopods, cilia,

or flagella

Figure 1.1c


Multicellular Animal Parasites

Eukaryote

Multicellular animals

Parasitic flatworms and round worms are called

helminths.

Microscopic stages in life cycles.

Figure 12.28a


Algae

Eukaryotes

Cellulose cell walls

Use photosynthesis for

energy

Produce molecular oxygen

and organic compounds

Figure 1.1d


Linnaeus’s Classification

Hierarchical system

Binomial Nomenclature Ancient Greeks


Ancestors of bacteria were the first life on Earth.

The first microbes were observed in 1673.

A Brief History of Microbiology


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


The Theory of Biogenesis

Pasteur’s S-shaped flask kept microbes out but let

air in.

Figure 1.3


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)


Pasteur

Spontaneous generation vs. biogenesis

Germ Theory

Father of aseptic techniques

Pasteurization

Fermentation research

Vaccination (rabies)


Koch

Koch’s Postulates

Pure Culture Concept

Tuberculosis


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.


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


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.



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)



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.


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.


A Brief History of Microbiology

Linnaeus

Jenner

Hooke

Leeuwenhoek

Lister

Pasteur

Koch

Darwin

Salk

Watson & Crick

Jacob and Monod

McClintock

Woese

Venter?


Microbial ecology

Bacteria recycle carbon, nutrients, sulfur, and

phosphorus that can be used by plants and animals.

Microbes and Human Welfare


Bioremediation

Bacteria degrade organic

matter in sewage.

Bacteria degrade or detoxify

pollutants such as oil and

mercury.

UN 2.1


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.


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.


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.


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.


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


Infectious Diseases

When a pathogen overcomes the host’s resistance,

disease results.

Emerging infectious diseases (EID): New diseases and

diseases increasing in incidence.


Infectious Disease


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



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



Bovine spongiform encephalopathy

Prion

Also causes Creutzfeldt-Jakob disease (CJD)

New variant CJD in humans is related to cattle fed

sheep offal for protein



Escherichia coli O57:H7

Toxin-producing strain of E. coli

First seen in 1982

Leading cause of diarrhea worldwide



Invasive group A Streptococcus

Rapidly growing bacteria that cause extensive

tissue damage

Increased incidence since 1995



Ebola hemorrhagic fever

Ebola virus

Causes fever, hemorrhaging, and blood clotting

First identified near Ebola River, Congo

Outbreaks every few years



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



Severe acute respiratory syndrome (SARS)

SARS-associated Coronavirus

Occurred in 2002-2003

Person-to-person transmission



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



Cryptosporidiosis

Cryptosporidium protozoa

First reported in 1976

Causes 30% of diarrheal illness in developing

countries

In the United States, transmitted via water


BIOTERRORISM

ANTHRAX

SMALLPOX

TULAREMIA, Pahvant

Valley plague, rabbit fever,

deer fly fever, and Ohara's

fever) Francisella

tularensis.

PLAGUE

OTHER AGENTS


Exam Questions

Definitions

Abbreviations

Differentiate cell walls of

Gram +ve & Gram –ve

bacteria

Prokaryote Vs Eukaryote

Endotoxins Vs Exotoxins

Nutrition, environment,

staining


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


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

introduction to microbiology

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