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64 Cards in this Set
- Front
- Back
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psychrophiles
optimum growth temperature |
15*C
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psychrotrophs
optimum growth temperature |
25*C
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what group of organism grows well at refrigerator temperatures?
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psychrotrophs
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mesophiles
optimum growth temperature |
35*C
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thermophiles
optimum growth temperature |
55*C
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hyperthermophiles
optimum growth temperature |
80*C
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most bacteria grow in what pH level?
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6.5-7.5
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thyobacillus ferroxidans
can survive at what pH level? |
2.0
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plasmolysis
definition |
shrinkage of the cell's cytoplasm
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obligate halophiles
definition |
organisms that have adapted o well to high salt concentrations that they actually require them for growth
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obligate halophiles
can be located where? |
in the Dead Sea
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facultative halophiles
are what? |
organisms that do not require high salt concentrations but are able to grow at salt concentrations up to 2%
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most organisms grow at what level of osmolarity?
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.85% NaCl concentration
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halophiles grow at what level of osmolarity?
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15-30% NaCl
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obligate aerobes
definition |
organisms that require oxygen to live
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facultative anaerobes
definition |
organisms that have the ability to grow in the absence of oxygen
can use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available |
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obligate anaerobes
definition |
bacteria that are unable to use molecular oxygen for energy-yielding reactions (most are harmed by it)
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example of facultative anaerobes
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Escherichia coli
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example of obligate anaerobes
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Clostridium
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singlet oxygen
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¹O2ˉ
extremely reactive |
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superoxide free radicals
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O2ˉ
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superoxide dismutase (SOD)
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an enzyme that destroys superoxide free radicals
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hydrogen peroxide
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H2O2
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hydroxyl radical
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OH·
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effect of oxygen on growth of
obligate aerobes |
oxygen required
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effect of oxygen on growth of
facultative anaerobes |
both aerobic and anaerobic growth
greater growth in presence of oxygen |
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effect of oxygen on growth of
obligate anaerobes |
growth ceases in presence of oxygen
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effect of oxygen on growth of
aerotolerant anaerobes |
only anaerobic growth,
but continues in presence of oxygen |
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effect of oxygen on growth of
microaerophiles |
only aerobic growth,
oxygen required in low concentration |
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growth patterns
obligate aerobes |
occurs only where high concentrations of oxygen have diffused into the medium
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growth patterns
facultative anaerobes |
best where most oxygen is present, but occurs throughout tube
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growth patterns
obligate anaerobes |
occurs only where there is no oxygen
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growth patterns
aerotolerant anaerobes |
occurs evenly; oxygen has no effect
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growth patterns
microaerophiles |
occurs only where a low concentration of oxygen has diffused into medium
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chemical requirements for microbial growth
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water
carbon nitrogen, sulfur, phosphorus trace elements/metals oxygen |
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composition of nutrient agar
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peptone
beef extract sodium chloride agar water |
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chemically defined medium
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a medium whose exact chemical composition is known
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complex media
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media made up of nutrients
the exact chemical composition varies slightly from batch to batch |
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anaerobic cultivation techniques
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candle jars
CO2 packets Gas-pak anaerobic jar anaerobic glove bag |
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example of anaerobe?
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clostridium
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selective media
purpose |
to suppress the growth of unwanted bacteria and encourage the growth of the desired microbes
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differential media
purpose |
to make it easier to distinguish colonies of the desired organism from other colonies growing on the same plate
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enrichment media
purpose |
to increase numbers of desired microbes to detectable levels
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reducing media
purpose |
growth of obligate anaerobes
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lyophilization
definition |
freeze-drying
suspension of microbes is quickly frozen at temperatures ranging from -54*C to -72*C and the water is removed by a high vacuum (sublimation) |
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lyophilization
how long can the microbes be stored? |
100 years
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cryogenic freezing with glycerol
how long can the microbes be stored? |
2-5 years
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slants
how long can the microbes be stored? |
6 months - 1 year
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serial dilutions
method |
count the colonies that appear on the plate, then multiply by reciprocal of dilution of sample
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4 phases of bacterial growth
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lag
log stationary death |
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lag phase
characteristics & time length |
little or no cell division
1 hour - several days |
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log phase
characteristics |
cellular reproduction is most active & generation time reaches a constant minimum
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stationary phase
characteristics |
population stabilizes
metabolic activities of individual surviving cells slow |
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death phase
characteristics |
number of deaths exceeds the number of new cells formed
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plate counts are reported as what units?
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Colony-Forming Units
CFU |
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pour plate
method & drawbacks |
colonies are mixed in with agar and grow inside of it
may damage microorganisms with the melting agar |
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spread plate
method |
inoculum is added to the surface of a solidified agar medium & the inoculum is spread over the surface
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filtration
method |
pass water through a thin membrane filter, and transfer the filter contents to a petri dish
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3 types of
indirect methods of estimating bacterial numbers |
turbidity
metabolic activity dry weight |
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turbidity
method |
spectrophotometer
a beam of light is transmitted through a bacterial suspension to a light-sensitive detector as bacterial numbers increase, less light will reach the detector |
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metabolic activity
method |
assumes that the amount of a certain metabolic product, such as acid or CO2, is in direct proportion to the number of bacteria present
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what is the normal reproductive method of bacteria?
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binary fission
a single cell divides into two identical cells |
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what is an example of a bacteria that must be cultured in a living animal?
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mycobacterium leprae
in armadillo |
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specific growth rate constant
formula |
N (specific growth rate)
= ln2/+ gen (+gen = doubling time) |
