Ch.6 : Microbial Growth Flashcards
Physical Requirements for Growth
Temperature
pH
Osmotic Pressure
Chemical Requirements for Growth
CARBON NITROGEN PHOSPHOROUS Sulfur Trace Elements Oxygen Organic Growth Factor
Microbes classified into 3 groups based on temperature
Psychrophiles
Mesophiles
Thermophiles
Psychrophile
Cold-loving microbes. 0-20 Degrees Celsius
Mesophile
Moderate-temperature loving microbes 20-45 Degrees Celsius
Most disease-causing bacteria prefer 35-40 Degrees Celsius
Thermophiles
heat-loving microbes. 55-85 Degrees Celsius
*Psychrotrophs
0-35 Degrees Celsius
*Hyperthermophiles
85-113 Degrees Celsius
Minimum Growth Temperature
Lowest temperature at which the species will grow
Optimum Growth Temperature
Temperature which species grow best.
Microbes cannot regulate internal temperature
Maximum Growth Temperature
Highest temperature at which growth is possible.
High temperatures may inhibit enzyme functioning and be lethal.
Acidophiles
growth optimum between pH 0 and pH 5.5
Neutrophiles
growth optimum between pH 5.5 and pH 7
Alkaliphiles (alkalophiles)
growth optimum between pH 8.5 and pH 11.5
Plasmolysis
Shrinkage of cell’s cytoplasm
Microorganisms composition is 80-90% water
Hypotonic
Increase osmotic pressure (cell fills up)
Hypertonic
Decrease osmotic pressure (cell shrivels)