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what is microbiology?
- the study of living things too small to be seen by the naked eye
- the study of the biology of microscopic organisms
what types of organisms does microbiology include?
viruses, bacteria, fungi, yeast, protozoa, algae, slime molds
What is the Linnaeus classification of microbes?
KPCOFGS
What does the acronym KPCOFGS stand for in microbial classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
How many categories does Leewenhoeks classification of microbes have?
6 categories
what are these 6 categories?
Bacteria
Archaea
Fungi
Protozoa
Algae
Viruses
What is the format for scientific names?
- italicized or underlined
- genus is capitalized
- species is lower case
Who gets to name a new microorganism?
the person who discovered it
what are two main themes for microbiology?
basic and applied
what is basic microbiology?
cellular processes, learning about different microbial pathways and how they function
what is applied microbiology?
use of microbiology in health, agriculture, industry, food production
what are some examples of basic microbiology?
bacteriology, phycology, mycology, protozoology, parasitology, virology, microbial metabolism, microbial genetics
what are some examples of applied microbiology?
serology, immunology, epidemiology, etiology, infection control, chemotherapy, agricultural microbiology, pharmaceutical microbiology, recombinant DNA technology
what are Koch's postulates?
a set criteria to establish a causative relationship between a microbe and a disease
What is the first step in Koch's postulates?
The suspected causative agent must be absent in all healthy organisms but present in diseased organisms
What is the second step in Koch's postulates?
The causative agent must be isolated from the diseased organisms and grown in a pure culture
What is the third step in Koch's postulates?
The cultured agent must cause the same disease when inoculated into a healthy, susceptible organism
What is the fourth step in Koch's postulates?
The same causative agent must then be reisolated from the inoculated, diseased organism
What is mutualism?
both sides benefit
What is an example of mutualism?
normal gut flora:
bacteria - benefit bc they have a place to eat, survive, and multiply
human - benefit bc they gain vitamins, break down food, and have protection against pathogens
What is commensalism?
one partner benefits, the other is NOT harmed
what is an example of commensalism?
staphylococcus epidermis:
skin microbiota that eats dead skin cells but doesn't affect host
What is parasitism?
one partner benefits, the other is harmed, can be slight or severe, has ecto and endo parasites
What is an example of parasitism?
a tick on a dog
What are the characteristics of a prokaryote?
-circular DNA
- cell wall
- lack of membrane bound organelles
- unicellular
- lack of nucleus
What are two types of prokaryotes?
archaea and bacteria
What is a differences between the cell walls of archaea and bacteria?
archaea does not have peptidoglycan and bacteria does
What is the difference between the membrane lipids of both archaea and bacteria ?
archaea is linked by eTHer
bacteria is linked by eSTer
What is the first amino acids in archaea and bacteria?
archaea - methionine
bacteria - formylmethionine
Are archaea and bacteria antibiotic sensitive?
archaea - NO
bacteria - YES
What is the DNA organization of archaea?
circular with histones
What is the DNA organization of bacteria?
circular
What are extremophiles?
organisms (archaea) that thrive in extreme environmental conditions that are detrimental to most life forms.
What are two main groups of extremophiles?
Euryarchaeota and Crenarchaeota
What form a part of Euryarchaeota?
methanogens, extreme halophiles, hyperthermophiles
What are methanogens?
produce methane after going through the cow's digestive system
What are extreme halophiles?
require oxygen gas for energy metabolism, need high concentrations of salt, often pink pigments
What are hyperthermophiles?
grow optimally in above 80 C, typically found in volcanic environments & deep-sea hydrothermal vents, and grow in low pHs
What from a part of Crenarchaeota?
mostly hyperthermophiles, typically found in hot springs & marine hydro-thermal vents others can be found in cold oceans of deep sea and polar oceans
What is the role of methanogens in global warming?
very common in the digestive system of cows and when cows burp & fart they release high amounts of methane which can contribute to global warming
What are some characteristics of Pseudomonadota?
- Gram-negative bacteria
- Common pathogens in humans
- Includes Rickettsia
- They have a mitochondria
What are some examples of the diseases caused by pseudomonadota?
Escherichia coli, Shigella, Salmonella, Yersinia, Vibrio
What are some characteristics of Bacillota?
- Gram Positive
- Common pathogens in humans =>
- Contains Mycoplasma - lacks a cell wall and is among the smallest free living bacteria
What are some examples of diseases caused by bacillota?
Bacillus, Clostridium, Staphylococcus, Streptococcus
What are some characteristics of Actinomycetota?
- Gram Positive
- Common in terrestrial (soil) & aquatic environments
- Includes Streptomyces & Mycobacterium
- Have similar filamentous aspects that are similar to fungi
What are some characteristics of Cyanobacteriota?
- Gram Negative
- Unicellular, filamentous, or colonial
- Used to be known as blue-green algae
- Pigmented
- Carry out photosynthesis
- Chloroplasts
Which bacterial phyla is responsible for "oxygen revolution"?
Cyanobacteriota
What are some characteristics of Spirochaetota?
- Gram Negative
- Unique cell body
- Diverse environments
- Includes Treponema pallidum & Borrelia
Why does Spirochaetota have a unique cell body?
bc it has a helix coil and moves in a corkscrew motion
What are the shapes of bacteria?
- Cocci - circular
- Bacillus - rod-shaped
- Spirochetes - spiral
Flagella
1
Inclusion Body
2
Ribosome
3
Pilus
4
Nucleoid DNA
5
Plasmid
6
Cytoplasm
7
Plasma Membrane
8
Cell Wall
9
Capsule/Glycocalyx
10
What are pili?
- Numerous short, thin fibers
- Found in most gram-negative bacteria and a few gram-positive bacteria
- Important for adhesion
- Composed of pilin with adhesions at tip
What is the role of pili?
Act as a virulence factor, important in conjugation
What are flagella?
hair-like structures that help cells move and can also act as sensory organs
How many flagella?
One or more with ranging attachment sites and lengths (10-20um)
What makes flagella move?
endoflagella, propels cell in desired direction (chemotaxis)
how does the endoflagella help the flagella move?
fold back along cell body, motility from torsion generated by flagella rotation
how does chemotaxis help the flagella move?
causing the flagellar motor to rotate in a way that allows the cell to move in a specific direction, "runs" counterclockwise
What is glycocalyx?
produced by many bacterial species, layer of polysaccharides, can be thick and covalently boun to cell (capsule), often appear wet and shiny
What is the purpose of glycocalyx?
- Buffer between cell & environment
- Prevent desiccation
- Adhesion
- Immune system evasion
- Can form bioflims
What is the cell wall composed of?
peptidoglycan
Cell wall with gram positive?
Large peptidoglycan wall outside & plasma membrane inside
Cell wall with gram negative?
The outer membrane then peptidoglycan & plasma membrane inside
What are characteristics of a nucleoid?
- Chromosome region
- Appears as a diffuse mass
- No nuclear membrane
- Usually single chromosome/cell
- Usually exists as a closed loop of DNA/protein
- Contains hereditary information for cell growth, metabolism, reproduction
- Generally haploid (single chromosome)
What are the characteristics of a plasmid?
- Smaller molecules of DNA
- 1/10th size of nucleoid
- Closed loops containing 5-100 genes
- 1+ plasmid/cell
- Replicate independently of the nucleoid
- Can be transferred between cells
What are the periods of bacterial growth?
lag phase, exponential (log) phase, stationary phase, decline (death) phase
What is the lag phase?
- Bacterial cells adapting to a new environment
- Compensating for changes in nutritional conditions
- Length depends on metabolic activity
What is the exponential (log) phase?
- All cells undergoing binary fission
- Doubling time applies
- Highest vulnerability to antibiotics
- Most taxing metabolically
What is the stationary phase?
- Reduction of nutrients
- Accumulation of waste products
- Decline in growth rates
- The number of cells stabilizes
- Nonviable and viable cell numbers roughly equal
What is the decline (death) phase?
- Occurs if nutrients remain limited
- Viable cells decrease, non-viable increase
- The whole population can be lost if the last cell dies
- This can lead to cell entering dormancy
What is dormancy?
- Metabolically inactive states
- Occurs in unfavorable environments
Are all bacteria capable of dormancy?
- Not all bacteria are capable of this
- The bacteria will "revive" once conditions are favorable again
What is persister cell formation?
Produce cells that stop dividing and have low rates of metabolism
What are two kinds if perister cell formation?
spontaneous which happens when there is exponential growth and triggered which happens when stress happens
What endospore formation?
- Primarily in Gram-positive
- Used in persister cells
What is the human disease Bacillus anthracis is associated with w/ endospore formation?
Anthrax
What is the human disease Clostridium tetani is associated with w/ endospore formation?
Tetanus
What is the human disease Clostridium botulinum is associated with w/ endospore formation?
botulism
What are the factors of bacterial growth?
temperature, oxygen, pH, hydrostatic and osmotic conditions
what are the three groups that make up temperature?
psychrophiles, thermophiles, mesophiles
what are psychrophiles?
cold loving, optimal growth near 15C, found in deep water, cannot be human pathogens
what are thermophiles?
heat loving, best around 60C, present in compost heaps & hot springs, can contaminate dairy products and pose little threat to human health. IMPORTANT FOR PCR
what are mesophiles?
moderate temp, best characterize species, thrive 10-40C, have a large impact on human health, found in Aquatic & terrestrial environments
what are obligate aerobes?
needs oxygen
what are faculative anaerobes?
prefer oxygen but can grow w/o it
what are aerotolerant anaerobes?
can tolerate oxygen and grow in its presence even though they cannot use it
what are obligate anaerobes?
die in the presence of oxygen
What are capnophilic bacteria?
require an atmosphere low in oxygen and rich in carbon dioxide
What are neutrphils?
pH=7, more in humans
what are acidophiles?
prefer acidic environments; extremophiles
what are alkaliphiles?
prefer basic environments; extremophiles
