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optimal growth conditions/growth optima
things that foster microbial growth
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atmospheric requirements
amount of O2 present in the atmosphere
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Aerobe
- must have air to grow
- i.e. Bacillus
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Microaerophile
- love a little bit of oxygen, not too much
- a small amount of O2 has to be present
- i.e. Lactococcus spp (found in the gut, stomach)
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Facultative anaerobes
- they can be in the presence or absence of oxygen, they don't care
- i.e. E. coli
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Anaerobes
- must live in the absence of oxygen
- i.e. Clostridium
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Strict
strictly cannot have any oxygen, or they will die within seconds
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Obligate
can handle oxygen for an hour or so, but after will start to die
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Aerotolerant
can handle a little bit of oxygen
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pH
concentration of hydrogens in a solution
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Acidophiles
- Prefer to live in acids
- 0-6 pH
- o.e. battery acids of cars, stomach
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Neutrophiles
- prefer to live in biological pH
- pH 7
- i.e. living in and on you
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Alkalophiles
- basic pH
- pH 8-14
- i.e. living in the baking soda in the fridge to keep the odors down
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Temperature
temperature requirements
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Psychrophile
- prefer to live in cold temperatures
- 0-20
- most abundant microbial species in the planet (most abundant because of the ocean)
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Mesophile
- prefer to live in room temperature
- 15-45
- body temperature
- i.e. E. coli
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Thermophile
- prefer to live in hot temperatures
- 40-70
- i.e. found in thermal pools in Yellowstone, hot water tank
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Extreme Thermophile
65-105 degrees c
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Salinity
salt requirements
-
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Osmophiles
- prefer to live in sugar and salt
- our cells could not tolerate these osmotic pressures
- - cytoplasm would either stream out or everything would rush in
- i.e. yeast, Sacromyces rouxii
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lag phase
- living = dyine
- bacteria adapt to environment
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log growth
- living > dying
- bacteria grow and flourish
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stationary phase
- living = dying
- food source declines as population grows
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decline phase
- living < dying
- low food source and colony dies down
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