Factors Affecting Microbial Growth Flashcards
microbial growth curve (4)
lag phase
log (exponential) phase
stationary phase
death (decline) phase
physical growth requirements (3)
temperature
pH
osmotic pressure
chemical growth requirements
CHONPS
Micronutrients
Growth factors
are nutrients that the body needs in large quantities to function properly
macronutrients
lowest possible value of that factor where growth may occur
minimum factor
the best possible value that favors growth
optimum factor
the highest possible value of that factor where growth may occur
maximum parameter
degree of hotness of a certain environment or material
temperature
grow best at relatively low temperature
psychrophile
able to grow at low temperature but prefer moderate temperature
psychrotroph
most bacteria especially those living in association with warm-blooded animals
mesophile
among all thermophiles is wide variation in optimum and maximum T
thermophile
optimum temperature for psychrophile
10-15
optimum temperature for psychrotroph
15-30
optimum temperature for mesophile
30-40
optimum temperature for thermophile
50-85
a value that express the acidity and alkalinity of an environment or material
pH
optimum pH preferences between 0 and 5.5
acidophiles
optimum pH preferences between 5.5 and 8
neutrophiles
optimum pH preferences between 8.5 to 11.5
alkalophiles
optimum pH preferences pH 10 or higher
extreme alkalophiles
drastic variations in pH can harm by:
distrupting the plasma membrane
inhibiting the activity of enzymes and membrane transport systems
is the measure of solute concentration, defined as the number of osmoles of solute per liter of solution
osmolarity
factor that determines the movement of water within cells
osmolarity
can be defined as the minimum pressure that must be applied to a solution to halt the flow of solvent molecules through a semipermeable membrane
osmotic pressure
Has a lower solute concentration than another solution, so water flows into it.
hypotonic
Has the same or similar solute concentration as another solution, so there is no net flow of water.
isotonic
Has a higher solute concentration than another solution, so water flows out of it
hypertonic
are microorganisms that require some NaCl for growth
halophiles
require 1-6% salt
mild halophiles
require 6-15% salt
moderate halophiles
require 15-30% NaCl for growth
extreme halophiles
bacteria are able to grow at moderate salt concentrations, even though they grow best at the absence of NaCl
halotolerant
are “osmophiles”
halophiles
halotolerant are
osmotolerant
usually reserved for organisms that are able to live in environment high in sugar
osmophiles
live in dry environments (made dry by lack of water)
xerophiles
requires O2
aerobe
do not require O2
anaerobe
can only live with plentiful O2
obligate anaerobes
will die in presence of significant O2
obligate anaerobes
can live in either aerobic or anerobic environments; prefer O2
facultative aerobes
live in a narrow window of oxygen concentrations
microaerophiles
check oxygen requirement
+1
