Microbiology
CHAPTER 1: The Microbial World and You
Microorganisms: organisms that are too small to be seen with the unaided eye
- Germ refers to a rapidly growing cell
Microbes in our lives
A few are pathogenic (disease-causing)
- 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
- Produce products used in manufacturing (e.g., cellulase) and treatment
(e.g., insulin)
Knowledge of microorganisms
- Allows humans to
o Prevent food spoilage
o Prevent disease occurrence
- Led to aseptic techniques to prevent contamination in medicine and in
microbiology labs
Naming and Classifying Microorganisms
- Linnaeus established the system of scientific nomenclature
- Each organism has two names: the genus and specific epithet
Scientific Names
- Are italicized or underlined. The genus is capitalized, specific epithet is
lowercase.
- Are “Latinized”
- May be descriptive or honor a scientist
Staphylococcus aureus-
- Describes the clustered (staphylo-) spherical (cocci) cells
- Describes the gold-colored (aureus) colonies
,Escherichia coli-
- Honors the discoverer, Theodore Escherich
- Describes the bacterium’s habitat (large intestine, or colon)
Types of Microorganisms
- Bacteria
o Prokaryotes
o Peptidoglycan cell walls
o Binary fission
o For energy, use organic chemicals, inorganic chemicals, or
photosynthesis
- Archaea
o Prokaryotic
o Lack peptidoglycan
o Live in extreme environments
o Include
▪ Methanogens
▪ Extreme halophiles
▪ Extreme thermophiles
- Fungi
o Eukaryotes
o Chitin cell walls
o Use organic chemicals for energy
o Molds and mushrooms are multicellular, consisting of masses of
mycelia, which are composed of filaments called hyphae
o Yeasts are unicellular
- Protozoa
o Eukaryotes
o Absorb or ingest organic chemicals
o May be motile via pseudopods, cilia, or flagella
- Algae
o Eukaryotes
o Cellulose cell walls
o Use photosynthesis for energy
o Produce molecular oxygen and organic compounds
, - Viruses
o Acellular
o Consist of DNA or RNA core
o Core is surrounded by a protein coat
o Coat may be enclosed in a lipid envelope
o Viruses are replicated only when they’re in a living host cell
- Multicellular animal parasites
o Eukaryotes
o Multicellular animals
o Parasitic flatworms and roundworms, helminths
o Microscopic stages in life cycles
Three domains-
- Bacteria
- Archaea
- Eukarya
o Protists
o Fungi
o Plants
o Animals
Cell theory: All living things are composed of cells and come from preexisting
cells (Virchow).
- 1673-1723: Anton van Leeuwenhoek described live microorganisms
The First Observations
- Robert Hooke observed that cork was composed of “little boxes”; he
introduced the term cell (1665).
- Hooke’s observations laid the groundwork for development of the cell
theory, the concept that all living things are composed of cells.
- Anton van Leeuwenhoek, using a simple microscope, was the first to
observe microorganisms (1673).
Spontaneous generation: The hypothesis that living organisms arise from
nonliving matter, a “vital force” forms life
Biogenesis: the hypothesis that living organisms arise from preexisting life
, The Debate over Spontaneous Generation
- Until the mid-1880s, many people believed in spontaneous generation, the
idea that living organisms could arise from nonliving matter.
- Francesco Redi demonstrated that maggots appear on decaying meat
only when flies are able to lay eggs on the meat (1668).
- John Needham claimed that microorganisms could arise spontaneously
from heated nutrient broth (1745).
- Lazzaro Spallanzani repeated Needham’s experiments and suggested
that Needham’s results were due to microorganisms in the air entering his
broth (1765).
- Rudolf Virchow introduced the concept of biogenesis: living cells can
arise only from preexisting cells (1858).
- Louis Pasteur demonstrated that microorganisms are in the air
everywhere and offered proof of biogenesis (1861).
- Pasteur’s discoveries led to the development of aseptic techniques used
in laboratories and medical procedures to prevent contamination by
microorganisms.
o Proved biogenesis (S-shaped flask)
The Golden Age of Microbiology
- 1857-1914
- Beginning with Pasteur’s work, discoveries include the relationship
between microbes and disease, immunity, and antimicrobial drugs.
Fermentation and Pasteurization-
- Pasteur found that yeast ferment sugars to alcohol and that bacteria can
oxidize the alcohol to acetic acid.
- Fermentation: the conversion of sugar to alcohol to make beer and wine
- A heating process called pasteurization is used to kill bacteria in some
alcoholic beverages and milk. (High heat, short time)
The Germ Theory of Disease
- Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship
between microorganisms and disease.
CHAPTER 1: The Microbial World and You
Microorganisms: organisms that are too small to be seen with the unaided eye
- Germ refers to a rapidly growing cell
Microbes in our lives
A few are pathogenic (disease-causing)
- 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
- Produce products used in manufacturing (e.g., cellulase) and treatment
(e.g., insulin)
Knowledge of microorganisms
- Allows humans to
o Prevent food spoilage
o Prevent disease occurrence
- Led to aseptic techniques to prevent contamination in medicine and in
microbiology labs
Naming and Classifying Microorganisms
- Linnaeus established the system of scientific nomenclature
- Each organism has two names: the genus and specific epithet
Scientific Names
- Are italicized or underlined. The genus is capitalized, specific epithet is
lowercase.
- Are “Latinized”
- May be descriptive or honor a scientist
Staphylococcus aureus-
- Describes the clustered (staphylo-) spherical (cocci) cells
- Describes the gold-colored (aureus) colonies
,Escherichia coli-
- Honors the discoverer, Theodore Escherich
- Describes the bacterium’s habitat (large intestine, or colon)
Types of Microorganisms
- Bacteria
o Prokaryotes
o Peptidoglycan cell walls
o Binary fission
o For energy, use organic chemicals, inorganic chemicals, or
photosynthesis
- Archaea
o Prokaryotic
o Lack peptidoglycan
o Live in extreme environments
o Include
▪ Methanogens
▪ Extreme halophiles
▪ Extreme thermophiles
- Fungi
o Eukaryotes
o Chitin cell walls
o Use organic chemicals for energy
o Molds and mushrooms are multicellular, consisting of masses of
mycelia, which are composed of filaments called hyphae
o Yeasts are unicellular
- Protozoa
o Eukaryotes
o Absorb or ingest organic chemicals
o May be motile via pseudopods, cilia, or flagella
- Algae
o Eukaryotes
o Cellulose cell walls
o Use photosynthesis for energy
o Produce molecular oxygen and organic compounds
, - Viruses
o Acellular
o Consist of DNA or RNA core
o Core is surrounded by a protein coat
o Coat may be enclosed in a lipid envelope
o Viruses are replicated only when they’re in a living host cell
- Multicellular animal parasites
o Eukaryotes
o Multicellular animals
o Parasitic flatworms and roundworms, helminths
o Microscopic stages in life cycles
Three domains-
- Bacteria
- Archaea
- Eukarya
o Protists
o Fungi
o Plants
o Animals
Cell theory: All living things are composed of cells and come from preexisting
cells (Virchow).
- 1673-1723: Anton van Leeuwenhoek described live microorganisms
The First Observations
- Robert Hooke observed that cork was composed of “little boxes”; he
introduced the term cell (1665).
- Hooke’s observations laid the groundwork for development of the cell
theory, the concept that all living things are composed of cells.
- Anton van Leeuwenhoek, using a simple microscope, was the first to
observe microorganisms (1673).
Spontaneous generation: The hypothesis that living organisms arise from
nonliving matter, a “vital force” forms life
Biogenesis: the hypothesis that living organisms arise from preexisting life
, The Debate over Spontaneous Generation
- Until the mid-1880s, many people believed in spontaneous generation, the
idea that living organisms could arise from nonliving matter.
- Francesco Redi demonstrated that maggots appear on decaying meat
only when flies are able to lay eggs on the meat (1668).
- John Needham claimed that microorganisms could arise spontaneously
from heated nutrient broth (1745).
- Lazzaro Spallanzani repeated Needham’s experiments and suggested
that Needham’s results were due to microorganisms in the air entering his
broth (1765).
- Rudolf Virchow introduced the concept of biogenesis: living cells can
arise only from preexisting cells (1858).
- Louis Pasteur demonstrated that microorganisms are in the air
everywhere and offered proof of biogenesis (1861).
- Pasteur’s discoveries led to the development of aseptic techniques used
in laboratories and medical procedures to prevent contamination by
microorganisms.
o Proved biogenesis (S-shaped flask)
The Golden Age of Microbiology
- 1857-1914
- Beginning with Pasteur’s work, discoveries include the relationship
between microbes and disease, immunity, and antimicrobial drugs.
Fermentation and Pasteurization-
- Pasteur found that yeast ferment sugars to alcohol and that bacteria can
oxidize the alcohol to acetic acid.
- Fermentation: the conversion of sugar to alcohol to make beer and wine
- A heating process called pasteurization is used to kill bacteria in some
alcoholic beverages and milk. (High heat, short time)
The Germ Theory of Disease
- Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship
between microorganisms and disease.
