HS 1 The Microbial World
I Exploring the Microbial World
1.1 Microorganisms, Tiny Titans of the Earth
Mircoorganisms à Life forms that are too small to be seen by the unaided human eye
à Diverse in form and function
à Live in microbial communities
Microbiology = the study of the dominant form of life on Earth, and the effect that microbes
have on our planet and all the living things that call it home
Growth à the increase in cell number as a result of cell division
Microbial applications:
1.2 Structure and Activities of Microbial Cells
Elements of microbial structure:
- Cytoplasmic membrane à separates the inside of the cell (cytoplasm) from the
outside
- Ribosomes à responsible for protein synthesis
- Some cell wall à strength and permeability
- Prokaryotic cell structure
o Bacteria and Archaea
o Few internal structures (lack a nucleus and organelles)
o Long before eukaryotes
- Eukaryotic cell structure
o Contain an assortment of membrane-enclosed cytoplasmic structures called
organelles
Genes, genomes, nucleus, and nucleoid:
- Every cell possesses a DNA genome (full set of genes in a cell)
,Activities of microbial cells:
- Properties of all cells:
o Structure
o Metabolism
o Growth (transcription, translation, DNA replication)
o Evolution
- Properties of some cells:
o Differentiation
o Communication
o Motility
o Horizontal gene transfer
1.3 Cell Size and Morphology
Morphology = cell size and shape
Cell size is influenced by cell structure
- Eukaryotes: can actively transport molecules and macromolecules within the
cytoplasm
- Prokaryotes: rely on diffusion for transport through the cytoplasm and this limits
their size
Small cells à more surface area relative to cell volume
- Have a higher surface-to-volume ratio than larger cells
- Can exchange nutrients and wastes more rapidly (efficient)
Morphologies of prokaryotic cells:
- Cell division has a high impact on morphology
- There are even more different morphologies than described above
1.4 An Introduction to Microbial Life
Bacteria:
- Prokaryotic cell structure
- Diverse in appearance, size, and function
- 30 major phylogenetic lineages (4 major phyla: actinobacteria, firmicutes,
proteobacteria, bacteroidetes)
,Archaea:
- Prokaryotic cell structure
- 5 phyla: euryarcheota, crenarchaeota, thaumarchaeota, nanoarchaeota,
korarchaeota
- Associated with extreme environments (not all)
- Lacks any known disease-causing species of plants or animals
Eukarya:
- Plants, animals, and fungi
- Relatively young
- Major lineages are called kingdoms (six kingdoms)
- Largest single-celled organisms
Viruses:
- Not found in the tree of life (they are not truly alive)
- Can replicate, but only within the host cell
- Do not carry out metabolic processes (they take over metabolic systems)
- Viral genomes are small and consist of DNA or RNA
- Bacteriophages (infect bacteria)
1.5 Microorganisms and the Biosphere
History of life on earth:
Microbes à are a major fraction of global biomass and key reservoirs of nutrients essential
for life
Extremophiles are present in habitats that are much too harsh for other forms of life
- Their properties define the physiochemical limits to life as we know it
, 1.6 The Impact of Microorganisms on Human Society
Microorganisms as agents of disease:
- Microbiology has fueled advances in medicine (vaccination and antibiotic therapy), in
engineering (water and wastewater treatment), in food safety (pasteurization)
- Most microorganisms are beneficial and essential to human welfare and the
functioning of the planet
Microorganisms, agriculture, and human nutrition:
- Bacteria allow legumes to make their own fertilizer, thereby reducing the need for
farmers to apply fertilizers
- Bacteria regulate nutrient cycles, transforming and recycling the nutrients required
by plants and animals
- Microorganisms help with digesting plant matter (rumen)
- Gut microbiome: helps humans to break down complex carbohydrates
Microorganisms and food:
- Microbial growth in food can cause food spoilage and foodborne disease
- Every manner we do with food is influenced by the goal of eliminating harmful
organisms from our food
- Beneficial microbes have been used to improve food safety and to preserve foods
Microorganisms and industry:
- Focused on the use of microorganisms as tools for major industries such as
pharmaceuticals and brewing
- Wastewater treatment à to clean wastewater
- Bioremediation à to clean contaminated environments
- Biofilms à grow on surfaces and can foul pipes and pipelines
- Biotechnology à genetically modified to produce high-value products such as
pharmaceuticals and enzymes
- Fermentation à to make chemicals, solvents, enzymes, and pharmaceuticals
- Biofuels à to convert biomass into ethanol and wastes into natural gas
- Microbes can grow in almost every environment containing liquid water
II Microscopy and the Origins of Microbiology
1.7 Light Microscopy and the Discovery of Microorganisms
Robert Hooke à first illustrated many microscopic images
Antoni v Leeuwenhoek à first to see bacteria (smallest microbial cells)
Light microscope:
- Magnification = the capacity of a microscope to enlarge an image
- Resolution = ability to distinguish two adjacent objects as distinct and separate
- 2 lenses, that function in combination to magnify the image:
o Objective lens
o Ocular lens
- Numerical aperture à light-gathering ability of the objective lens
o A higher magnification have higher numerical apertures
- Oil-immersion lenses are lenses on which oil is used (increases light-gathering ability)
I Exploring the Microbial World
1.1 Microorganisms, Tiny Titans of the Earth
Mircoorganisms à Life forms that are too small to be seen by the unaided human eye
à Diverse in form and function
à Live in microbial communities
Microbiology = the study of the dominant form of life on Earth, and the effect that microbes
have on our planet and all the living things that call it home
Growth à the increase in cell number as a result of cell division
Microbial applications:
1.2 Structure and Activities of Microbial Cells
Elements of microbial structure:
- Cytoplasmic membrane à separates the inside of the cell (cytoplasm) from the
outside
- Ribosomes à responsible for protein synthesis
- Some cell wall à strength and permeability
- Prokaryotic cell structure
o Bacteria and Archaea
o Few internal structures (lack a nucleus and organelles)
o Long before eukaryotes
- Eukaryotic cell structure
o Contain an assortment of membrane-enclosed cytoplasmic structures called
organelles
Genes, genomes, nucleus, and nucleoid:
- Every cell possesses a DNA genome (full set of genes in a cell)
,Activities of microbial cells:
- Properties of all cells:
o Structure
o Metabolism
o Growth (transcription, translation, DNA replication)
o Evolution
- Properties of some cells:
o Differentiation
o Communication
o Motility
o Horizontal gene transfer
1.3 Cell Size and Morphology
Morphology = cell size and shape
Cell size is influenced by cell structure
- Eukaryotes: can actively transport molecules and macromolecules within the
cytoplasm
- Prokaryotes: rely on diffusion for transport through the cytoplasm and this limits
their size
Small cells à more surface area relative to cell volume
- Have a higher surface-to-volume ratio than larger cells
- Can exchange nutrients and wastes more rapidly (efficient)
Morphologies of prokaryotic cells:
- Cell division has a high impact on morphology
- There are even more different morphologies than described above
1.4 An Introduction to Microbial Life
Bacteria:
- Prokaryotic cell structure
- Diverse in appearance, size, and function
- 30 major phylogenetic lineages (4 major phyla: actinobacteria, firmicutes,
proteobacteria, bacteroidetes)
,Archaea:
- Prokaryotic cell structure
- 5 phyla: euryarcheota, crenarchaeota, thaumarchaeota, nanoarchaeota,
korarchaeota
- Associated with extreme environments (not all)
- Lacks any known disease-causing species of plants or animals
Eukarya:
- Plants, animals, and fungi
- Relatively young
- Major lineages are called kingdoms (six kingdoms)
- Largest single-celled organisms
Viruses:
- Not found in the tree of life (they are not truly alive)
- Can replicate, but only within the host cell
- Do not carry out metabolic processes (they take over metabolic systems)
- Viral genomes are small and consist of DNA or RNA
- Bacteriophages (infect bacteria)
1.5 Microorganisms and the Biosphere
History of life on earth:
Microbes à are a major fraction of global biomass and key reservoirs of nutrients essential
for life
Extremophiles are present in habitats that are much too harsh for other forms of life
- Their properties define the physiochemical limits to life as we know it
, 1.6 The Impact of Microorganisms on Human Society
Microorganisms as agents of disease:
- Microbiology has fueled advances in medicine (vaccination and antibiotic therapy), in
engineering (water and wastewater treatment), in food safety (pasteurization)
- Most microorganisms are beneficial and essential to human welfare and the
functioning of the planet
Microorganisms, agriculture, and human nutrition:
- Bacteria allow legumes to make their own fertilizer, thereby reducing the need for
farmers to apply fertilizers
- Bacteria regulate nutrient cycles, transforming and recycling the nutrients required
by plants and animals
- Microorganisms help with digesting plant matter (rumen)
- Gut microbiome: helps humans to break down complex carbohydrates
Microorganisms and food:
- Microbial growth in food can cause food spoilage and foodborne disease
- Every manner we do with food is influenced by the goal of eliminating harmful
organisms from our food
- Beneficial microbes have been used to improve food safety and to preserve foods
Microorganisms and industry:
- Focused on the use of microorganisms as tools for major industries such as
pharmaceuticals and brewing
- Wastewater treatment à to clean wastewater
- Bioremediation à to clean contaminated environments
- Biofilms à grow on surfaces and can foul pipes and pipelines
- Biotechnology à genetically modified to produce high-value products such as
pharmaceuticals and enzymes
- Fermentation à to make chemicals, solvents, enzymes, and pharmaceuticals
- Biofuels à to convert biomass into ethanol and wastes into natural gas
- Microbes can grow in almost every environment containing liquid water
II Microscopy and the Origins of Microbiology
1.7 Light Microscopy and the Discovery of Microorganisms
Robert Hooke à first illustrated many microscopic images
Antoni v Leeuwenhoek à first to see bacteria (smallest microbial cells)
Light microscope:
- Magnification = the capacity of a microscope to enlarge an image
- Resolution = ability to distinguish two adjacent objects as distinct and separate
- 2 lenses, that function in combination to magnify the image:
o Objective lens
o Ocular lens
- Numerical aperture à light-gathering ability of the objective lens
o A higher magnification have higher numerical apertures
- Oil-immersion lenses are lenses on which oil is used (increases light-gathering ability)
