Bacterial Growth Flashcards
By what process do bacteria divide?
binary fision
By what process do eukaryotes divide?
cell cycle
How do biofilms form?
- Attachment (reversible)
- Cell-cell adhesion (irreversible)
- Proliferation
- Maturation
- Dispersion
What is a single colony?
It is a colony that comes from a single cell that undergoes multiple divisions
How can you store cultures?
- Agar slants
- Freezer cultures (needs a cryoprotectant)
- lyophilized powder (freeze-dried)
What do cryoprotectants do?
Slow down crystal formation, a common one is glycerol
What can affect bacteria growth?
- Temperature
- Oxygen
- pH
- Osmolarity
How are bacteria separated based on temperature preferences?
- Psychrophile
- Psychrotroph
- Mesophile (associated with animals)
- Thermophile
- Hyperthermophile
What can you use to look at oxygen preferences?
shake tubes or fluid thioglycollate medium
How are bacteria separated based on oxygen preferences?
- Obligate anaerobe (only oxygen)
- Facultative anaerobe (prefer oxygen)
- Obligate anaerobe
- Microaerophile (small amounts of oxygen)
- Aerotolerant (don’t use oxygen for respiration)
What is catalase?
An enzyme that converts H2O2 into O2 and H2O
Obligate aerobes, facultative anaerobe, and microaerophile (in small amounts) make these
What is superoxide dismutase?
Enzyme that converts superoxide (O2-) and H into H2O2
Obligate aerobes, facultative anaerobes, microaerophiles, and aerotolerant make these
How are bacteria separated based on pH preferences?
- Acidophiles (pump out excess H+)
- Neutrophiles
- Alkalophiles (use Na+ gradient)
Why is osmolarity of environment important?
- avoid lysis (burst)
- avoid plasmolysis (shrink)
How can you avoid plasmolysis?
- synthesize osmoprotectants (proline, trehalose)
- “adsorb” salt
What is needed for metabolism?
- Elements
- Growth factors
What elements are needed for metabolism?
C, H, O, N, P, S
K+, Mg++, Ca++ (protein folding)
Fe++
Chemotroph vs phototroph
Chemotroph: get energy from free energy of redox reactions
Phototroph: get energy from sunlight (photosynthesis)
Heterotroph vs autotroph
Heterotroph: get carbon from organic compounds
Autotroph: fix carbon from atmospheric CO2
Organotroph vs Lithotroph
Organotroph: gets electrons from reduced organic compounds
Lithotroph: get electrons from reduced INorganic compounds
What is defined media?
all ingredients can be listed by chemical formula and by amount
What is complex media?
at least one ingredient is not defined, often contains “extracts” of various things
What is specialty media?
media that prevents the growth of some organisms (ie. salt and antibiotic agars)
What is differential media?
media that looks different with different organisms (ie. blood and MacConkey’s agar)
