bacterial growth requirments Flashcards
name physical requirements
temperature
PH
Osmotic pressure
name chemical requirements
Carbon hydrogen nitrogen phosphorus sulphur oxygen
CHONPS
why do bacteria require carbon
biosynthesis
what are bacteria called that can use C02 as main source of energy
Autotrophs
what are bacteria called that use organic sources of energy
heterotrophs
define Growth factors
any compound which an organism needs for growth but cannot synthesise its self .
e.g- amino acids, vitamins
all organisms require water. what is this expressed as?
water activity
define water activity
measure of water avaliable for use by microorganisms
most bacteria only grow well at what water activity
AW 0.98 or above
what does cardinal temperatures mean?
the min, optimum and max temperature at which each organism can grow
if a bacteria lives in extreme temperature it is called
extreamophile
what bacteria live in the poles and have a optimum of 15 and a min of 0
psychrophiles
what bacterias optimum temp is 20 and cannot grow above 40
psychrotrophs
what bacteria has its optimum growth at 37-40
pathogens and commensal flora belong in this group
called MESOPHILES
what bacterias optimum is 60
Thermophiles
what happens to bacteria in a hypertonic solution
shrinks
what happens to cells in a hypotonic solution
lysis/turgid
what does a Osmophile do
tollerate sugar solutions
what does a Xerophile do
tolerate dry conditions
what does a Halophile do
need a certain amount of salt to grow
what does hallotollerant mean
can tollerate high levels of salt
do all organisms need oxygen
nope
what do bacteria always need for metabolism
electron acceptor
what bacteria grow only if oxygen is present
Obligate aerobes
